ȱ ȱ LinköpingȱUniversityȱMedicalȱDissertationsȱ No.ȱ998ȱ ȱ ȱ ȱ PelvicȱGirdleȱPainȱandȱLumbarȱPainȱ inȱRelationȱtoȱPregnancyȱ ȱ ȱ ȱ ȱ ȱ ȱ ȱ ȱ ȱ ȱ ȱ ȱ AnnelieȱGutkeȱ ȱ ȱ ȱ ȱ DepartmentȱofȱHealthȱandȱSociety,ȱDivisionȱofȱPhysiotherapyȱ FacultyȱofȱHealthȱSciencesȱ LinköpingȱUniversity,ȱSwedenȱ ȱ ȱ ȱ

ȱȱ ȱ Linköpingȱ2007ȱ ȱ

ȱ ȱ ȱ ȱ ȱ ȱ ȱ ȱ ȱ ȱ ȱ ȱ ȱ ȱ ȱ ȱ ȱ ȱ ȱ ȱ ȱ ȱ ȱ ȱ ȱ ȱ ¤AnnelieȱGutke,ȱ2007ȱ [email protected] http://www.ihs.liu.seȱ ȱ Coverȱpicture/illustration:ȱMarjutȱMolénȱ ȱ ȱ Publishedȱarticleȱhasȱbeenȱreprintedȱwithȱtheȱpermissionȱofȱtheȱcopyrightȱholder.ȱ ȱ PrintedȱinȱSwedenȱbyȱUniTryck,ȱLinköping,ȱSweden,ȱ2007ȱȱ ȱ ȱ ISBNȱ978Ȭ91Ȭ85715Ȭ14Ȭ5ȱȱ ISSNȱ0345Ȭ0082ȱ ȱ

ȱ ȱ ȱ ȱ ȱ ȱ ȱ ȱ ȱ ȱ ȱȱȱȱȱȱȱToȱJanne,ȱ JuliaȱandȱJanelleȱ ȱ ȱ ȱ ȱ ȱ ȱ ȱ ȱ ȱ ȱ ȱ ȱ ȱ ȱ ȱ ȱ ȱ ȱ ȱ ȱ ȱ ȱ ȱ “Nothingȱinȱscienceȱhasȱanyȱvalueȱtoȱsocietyȱifȱitȱisȱnotȱcommunicated.”ȱ ȱȱȱȱȱȱȱȱAnneȱRoeȱ ȱ ȱ ȱ ȱ ȱ

Contentsȱ

CONTENTSȱ

ABSTRACT ...... 1

LISTȱOFȱPAPERS ...... 3

ABBREVIATIONS...... 4

DEFINITIONS...... 5

INTRODUCTION...... 7

BACKGROUND...... 8 TERMINOLOGY...... 8 EPIDEMIOLOGY...... 9 Prevalenceȱofȱlowȱbackȱpainȱinȱwomen...... 9 Courseȱandȱpredictorsȱofȱlowȱbackȱpain...... 10 PREGNANCYȬRELATEDȱPELVICȱGIRDLEȱPAINȱANDȱLUMBARȱPAIN 11 Classificationȱofȱlowȱbackȱpain ...... 12 CAUSESȱOFȱPREGNANCYȬRELATEDȱPELVICȱGIRDLEȱPAIN ...... 14 Muscleȱfunctionȱinȱrelationȱtoȱlumbopelvicȱstability...... 15 Gait ...... 17 CONSEQUENCESȱOFȱPREGNANCYȬRELATEDȱLOWȱBACKȱPAIN ...... 17 HealthȬrelatedȱqualityȱofȱlife...... 18 Pain...... 18 Disability...... 20 DEPRESSION ...... 21 Postpartumȱdepression...... 21

AIMSȱOFȱTHEȱTHESIS...... 23

MATERIALSȱANDȱMETHODS...... 24 DESIGN...... 24 STUDYȱPOPULATION...... 26 MEASUREMENTSȱANDȱPROCEDURES...... 26 Contentsȱ ȱ SelfȬreportedȱquestionnaires...... 26 HealthȬrelatedȱqualityȱofȱlife ...... 27 Pain...... 27 Disability...... 28 Postpartumȱdepression...... 29 Classificationȱofȱtheȱcohort ...... 29 Criteriaȱforȱtheȱcohortȱclassification ...... 31 Reliabilityȱofȱtheȱclassificationȱprocedure ...... 32 Physicalȱfunctioning ...... 32 Backȱflexorȱmusclesȱendurance ...... 33 Backȱextensorȱmusclesȱendurance ...... 33 Maximalȱvoluntaryȱisometricȱhipȱextension ...... 34 Gaitȱspeed...... 34 STATISTICALȱANALYSES ...... 35

ETHICALȱCONSIDERATIONS ...... 38

RESULTS ...... 39 PREVALENCEȱOFȱLOWȱBACKȱPAINȱINȱPREGNANCYȱANDȱ POSTPARTUM...... 39 DropȬoutȱanalysis...... 42 THEȱCOURSEȱOFȱLOWȱBACKȱPAIN ...... 44 PREDICTORSȱFORȱPELVICȱGIRDLEȱPAINȱORȱCOMBINEDȱPAIN...... 45 HEALTHȬRELATEDȱQUALITYȱOFȱLIFEȱINȱEARLYȱPREGNANCY...... 45 PAINȱANDȱDISABILITYȱINȱEARLYȱPREGNANCY ...... 47 POSTPARTUMȱDEPRESSIVEȱSYMPTOMS ...... 47 PHYSICALȱMEASURESȱINȱPREGNANCYȱANDȱPOSTPARTUM ...... 49 Backȱflexorȱmusclesȱendurance...... 49 Backȱextensorȱmusclesȱendurance ...... 49 Maximalȱvoluntaryȱisometricȱhipȱextension ...... 51 Gaitȱspeed ...... 51 Painȱintensityȱinȱrelationȱtoȱphysicalȱmeasures...... 51

DISCUSSION ...... 53 PREVALENCEȱOFȱLOWȱBACKȱPAINȱINȱPREGNANCYȱANDȱ POSTPARTUM...... 53

ȱ ȱ ȱ Power...... 54 Classificationȱofȱlowȱbackȱpain ...... 55 COURSEȱANDȱPREDICTORS ...... 58 HEALTHȬRELATEDȱQUALITYȱOFȱLIFE,ȱPAINȱANDȱDISABILITY...... 62 MeasuresȱofȱhealthȬrelatedȱqualityȱofȱlifeȱandȱdisability ...... 63 POSTPARTUMȱDEPRESSION ...... 64 MUSCLEȱFUNCTION...... 66 INTERNATIONALȱCLASSIFICATIONȱOFȱFUNCTIONING,ȱDISABILITYȱ ANDȱHEALTH...... 68 CLINICALȱIMPLICATIONS...... 71 FUTUREȱRESEARCH...... 71

CONCLUSIONS ...... 73

SUMMARYȱINȱSWEDISH...... 74

ACKNOWLEDGEMENTS...... 76

REFERENCES ...... 78 ȱ

ȱ

Abstractȱ

ABSTRACTȱ

Theȱprevalenceȱofȱlowȱbackȱpainȱ(LBP)ȱisȱhigherȱinȱpregnantȱwomenȱcomparedȱ toȱ womenȱ ofȱ theȱ sameȱ ageȱ inȱ aȱ generalȱ population.ȱ PregnancyȬrelatedȱ LBPȱ persistsȱ6ȱyearsȱafterȱpregnancyȱinȱ16%ȱofȱwomen.ȱConsequently,ȱpregnancyȱ representsȱaȱspecificȱriskȱforȱLBPȱandȱpersistentȱLBP.ȱPregnancyȬrelatedȱLBPȱisȱ usuallyȱ studiedȱ asȱ aȱ singleȱ entity,ȱ however,ȱ onlyȱ oneȱ subgroupȱ ofȱ LBP,ȱ i.e.ȱ pelvicȱgirdleȱpainȱ(PGP),ȱseemsȱtoȱbeȱassociatedȱwithȱpregnancy.ȱAccordingly,ȱ possibleȱdifferencesȱinȱsubgroupsȱofȱpatientsȱwithȱLBPȱareȱunknown.ȱ ȱ Theȱaimsȱofȱthisȱthesisȱwereȱtheȱfollowing:ȱ1)ȱtoȱdescribeȱtheȱprevalenceȱofȱ clinicallyȱclassifiedȱsubgroupsȱofȱwomenȱwithȱLBPȱinȱaȱcohortȱ(noȱLBP,ȱlumbarȱ pain,ȱPGP,ȱandȱcombinedȱpainȱ(PGPȱandȱlumbarȱpain))ȱduringȱpregnancyȱandȱ postpartum,ȱandȱ2)ȱtoȱdetermineȱifȱthereȱwasȱaȱdisparityȱinȱtheȱcourse,ȱhealthȬ relatedȱqualityȱofȱlifeȱ(HRQL),ȱpainȱintensity,ȱdisability,ȱdepressiveȱsymptoms,ȱ orȱmuscleȱfunctionȱinȱsubgroupsȱofȱtheȱcohort,ȱandȱ3)ȱtoȱidentifyȱpredictorsȱforȱ havingȱpersistentȱpregnancyȬrelatedȱPGPȱpostpartum.ȱ ȱ ConsecutivelyȬenrolledȱ pregnantȱ womenȱ wereȱ classifiedȱ intoȱ LBPȱ subgroupsȱ byȱ mechanicalȱ assessmentȱ ofȱ theȱ lumbarȱ spine,ȱ pelvicȱ painȱ provocationȱtests,ȱstandardȱhistory,ȱandȱpainȱdrawings.ȱAllȱwomenȱansweredȱ questionnairesȱ (backgroundȱ data,ȱ EQȬ5D).ȱ Womenȱ withȱ LBPȱ completedȱ theȱ Oswestryȱ Disabilityȱ Indexȱ andȱ painȱ measures.ȱ Theȱ Edinburghȱ Postnatalȱ Depressionȱ Scaleȱ wasȱ usedȱ toȱ evaluateȱ depressiveȱ symptomsȱ atȱ 3ȱ monthsȱ postpartumȱ(cutȬoffȱǃ10).ȱTrunkȱmuscleȱendurance,ȱhipȱmuscleȱstrength,ȱandȱ gaitȱspeedȱwereȱinvestigated.ȱMultipleȱlogisticȱregressionȱwasȱusedȱtoȱidentifyȱ predictorsȱfromȱselfȬreportsȱandȱclinicalȱexamination.ȱ ȱ Atȱ theȱ 12Ȭ18ȱ gestationalȱ weekȱ evaluation,ȱ 118/308ȱ (38%)ȱ womenȱ hadȱ noȱ LBP,ȱ 33ȱ (11%)ȱ hadȱ lumbarȱ pain,ȱ 101ȱ (33%)ȱ hadȱ PGP,ȱ andȱ 56ȱ (18%)ȱ hadȱ combinedȱpain.ȱThreeȱmonthsȱpostpartum,ȱ183/272ȱ(67%)ȱwomenȱhadȱnoȱLBP,ȱ 29ȱ(11%)ȱhadȱlumbarȱpain,ȱ46ȱ(17%)ȱhadȱPGP,ȱandȱ14%)ȱ(5 ȱhadȱcombinedȱpain.ȱ PregnantȱwomenȱwithȱcombinedȱpainȱwereȱmostȱaffectedȱinȱtermsȱofȱHRQL,ȱ painȱ intensity,ȱ andȱ disability.ȱ Depressiveȱ symptomsȱ wereȱ threeȱ timesȱ moreȱ prevalentȱ inȱ womenȱ withȱ LBPȱ (27/87,ȱ 31%)ȱ thanȱ inȱ womenȱ withoutȱ LBPȱ (17/180,ȱ 9%).ȱ Womenȱ withȱ PGPȱ and/orȱ combinedȱ painȱ hadȱ lowerȱ valuesȱ forȱ trunkȱ muscleȱ endurance,ȱ hipȱ extensorȱ strengthȱ andȱ gaitȱ speedȱ comparedȱ toȱ womenȱ withoutȱ LBP.ȱ Postpartum,ȱ 16Ȭ20%ȱ ofȱ theȱ womenȱ hadȱ persistentȱ combinedȱ painȱ orȱ PGP,ȱ whereasȱ 1/29ȱ hadȱ lumbarȱ pain.ȱ Predictorsȱ forȱ

ȱ 1 Abstractȱ persistentȱ PGPȱ orȱ combinedȱ painȱ wereȱ workȱ dissatisfaction,ȱ olderȱ age,ȱ combinedȱpainȱinȱearlyȱpregnancy,ȱandȱlowȱenduranceȱofȱtheȱbackȱflexors.ȱ ȱ Inȱconclusion,ȱwomenȱwithȱcombinedȱpainȱwereȱidentifiedȱtoȱbeȱaȱtargetȱ groupȱ sinceȱ theyȱ hadȱ theȱ lowestȱ recoveryȱ rateȱ andȱ sinceȱ theȱ classificationȱ ofȱ combinedȱ painȱ wasȱ foundȱ toȱ beȱ aȱ predictorȱ forȱ persistentȱ PGPȱ orȱ combinedȱ painȱ postpartum.ȱ Theȱ hypothesisȱ ofȱ anȱ associationȱ betweenȱ muscleȱ dysfunctionȱ andȱ PGPȱ wasȱ strengthened.ȱ Basedȱ onȱ theȱ findingȱ ofȱ highȱ comorbidityȱofȱpostpartumȱdepressiveȱsymptomsȱandȱLBP,ȱitȱseemsȱimportantȱ toȱscreenȱforȱandȱconsiderȱtreatmentȱstrategiesȱforȱbothȱsymptoms.ȱȱ ȱ ISBNȱ978Ȭ91Ȭ85715Ȭ14Ȭ5ȱ ISSNȱ0345Ȭ0082ȱ ȱ

2ȱ Listȱofȱpapersȱ

LISTȱOFȱPAPERSȱ

I. Annelieȱ Gutke,ȱ Hansȱ Christianȱ Östgaard,ȱ Birgittaȱ Öberg.ȱ Pelvicȱ Girdleȱ Painȱ andȱLumbarȱ Painȱ inȱPregnancy:ȱ Aȱ cohortȱ studyȱofȱ theȱ consequencesȱ inȱ termsȱofȱhealthȱandȱfunctioning.ȱSpineȱ2006;ȱ31(5):ȱE149Ȭ155ȱ ȱ II. Annelieȱ Gutke,ȱ Annȱ Josefsson,ȱ Birgittaȱ Öberg.ȱ Pelvicȱ Girdleȱ Painȱ andȱ LumbarȱPainȱinȱRelationȱtoȱPostpartumȱDepressiveȱSymptoms.ȱAcceptedȱforȱ publicationȱinȱSpineȱJuneȱ1ȱ2007ȱ ȱ III. AnnelieȱGutke,ȱHansȱChristianȱÖstgaard,ȱBirgittaȱÖberg.ȱMuscleȱfunctionȱ inȱ pregnancyȬrelatedȱ lowȱ backȱ pain.ȱ Aȱ prospectiveȱ cohortȱ studyȱ inȱ earlyȱ pregnancyȱandȱpostpartum.ȱSubmittedȱ ȱ IV. Annelieȱ Gutke,ȱ Hansȱ Christianȱ Östgaard,ȱ Birgittaȱ Öberg.ȱ Predictingȱ persistentȱpregnancyȬrelatedȱlowȱbackȱpain.ȱSubmittedȱ ȱ

ȱ 3 Abbreviationsȱ ȱ

ABBREVIATIONSȱ

ASLRȱ ActiveȱStraightȱLegȱRaisingȱTestȱ BMIȱ BodyȬMassȬIndexȱ EPDSȱ EdinburghȱPostnatalȱDepressionȱScaleȱ EQȬ5Dȱ EuropeanȱQualityȱofȱLifeȱ5ȱDimensionsȱQuestionnaireȱ HRQLȱ HealthȬRelatedȱQualityȱofȱLifeȱ ICCȱ IntraclassȱCorrelationȱCoefficientȱ LBPȱ LowȱBackȱPainȱ LPȱȱ LumbarȱPainȱ(PaperȱI)ȱ MDTȱ MechanicalȱDiagnosisȱandȱTherapyȱ MICȱ MinimalȱImportantȱChangeȱ MIDȱ MinimalȱImportantȱDifferenceȱ ODIȱ OswestryȱDisabilityȱIndexȱ ORȱȱ OddsȱRatioȱ PGPȱ PelvicȱGirdleȱPainȱ PPGPȱ PregnancyȬrelatedȱ Pelvicȱ Girdleȱ Painȱ (Paperȱ I);ȱ theȱ sameȱ classificationȱasȱPGPȱinȱPapersȱIIȬIVȱ RCTȱ RandomisedȱControlledȱTrialȱ RDQȱ TheȱRolandȬMorrisȱDisabilityȱQuestionnaireȱ SFȬ36ȱ TheȱShortȱFormȱ36ȱHealthȱSurveyȱ SIJȱȱ SacroiliacȱJointȱ VASȱ VisualȱAnalogueȱScaleȱ ȱ

ȱ 4 Definitionsȱ

DEFINITIONSȱ

Backȱpainȱ Aȱgeneralȱtermȱusedȱwhenȱtheȱstudyȱreferredȱtoȱdoȱnotȱ specifyȱlocalisation.ȱ Centralisationȱȱ If,ȱ asȱ aȱ resultȱ ofȱ repeatedȱ movementsȱ orȱ positions,ȱ theȱ radiatingȱ symptomsȱ originatingȱ fromȱ theȱ spineȱ andȱ referredȱ distally,ȱ regressȱ proximallyȱ towardsȱ theȱ lumbarȱ midlineȱ ofȱ theȱ spineȱ (57).ȱ Oppositeȱ ofȱ peripheralisation.ȱ Clinicalȱnaturalȱcourseȱ Definedȱasȱwithoutȱdirectedȱinterventionȱfromȱtheȱstudyȱ exceptȱforȱevaluationȱofȱlowȱbackȱpainȱ(269).ȱ Combinedȱpainȱ Affectedȱbyȱtheȱtwoȱsyndromesȱpelvicȱgirdleȱpainȱandȱ lumbarȱpain.ȱ Deliveryȱȱ Givingȱbirth.ȱ Disabilityȱ Aȱgeneralȱtermȱforȱimpairment,ȱactivityȱlimitations,ȱandȱ participationȱ restrictionsȱ fromȱ theȱ problematicȱ aspect,ȱ accordingȱtoȱICFȱ2001ȱ(255).ȱ Functioningȱ Aȱ generalȱ termȱ forȱ allȱ bodyȱ functions,ȱ activities,ȱ andȱ participationȱ fromȱ aȱ healthyȱ perspective,ȱ accordingȱ toȱ theȱICFȱ2001ȱ(255).ȱ Lowȱbackȱpainȱ Painȱ andȱdiscomfortȱ localisedȱ belowȱ theȱ costalȱ marginȱ andȱaboveȱtheȱinferiorȱglutealȱfolds,ȱwithȱorȱwithoutȱlegȱ painȱ(242).ȱ Lumbarȱpainȱ Painȱ perceivedȱ asȱ arisingȱ fromȱ anywhereȱ withinȱ aȱ regionȱboundedȱsuperiorlyȱbyȱanȱimaginaryȱtransverseȱ lineȱthroughȱtheȱtipȱofȱtheȱlastȱthoracicȱspinousȱprocess,ȱ inferiorlyȱ byȱ anȱ imaginaryȱ transverseȱ lineȱ throughȱ theȱ tipȱ ofȱ theȱ firstȱ sacralȱ spinousȱ process,ȱ andȱ laterallyȱ byȱ verticalȱ linesȱ tangentialȱ toȱ theȱ lateralȱ bordersȱ ofȱ theȱ lumbarȱerectorȱspinaeȱ(151).ȱ Lumbopelvicȱpainȱ Includingȱ theȱ syndromesȱ pelvicȱ girdleȱ painȱ and/orȱ lumbarȱpainȱ(267).ȱ NonpregnancyȬȱ relatedȱlowȱbackȱpainȱ Lowȱ backȱ painȱ presentȱ outsideȱ pregnancyȱ withȱ noȱ ȱȱ ȱ knownȱassociationȱtoȱaȱpregnancyȱlikeȱtimeȱofȱdebut.ȱ Pelvicȱgirdleȱpainȱ Painȱ experiencedȱ betweenȱ theȱ posteriorȱ iliacȱ crestȱ andȱ theȱ glutealȱ fold,ȱ particularlyȱ inȱ theȱ vicinityȱ ofȱ theȱ

ȱ 5 Definitionsȱ ȱ sacroiliacȱ joints.ȱ Theȱ painȱ mayȱ radiateȱ inȱ theȱ posteriorȱ thighȱ andȱ canȱ alsoȱ occurȱ inȱ conjunctionȱ with/orȱ separatelyȱinȱtheȱsymphysisȱ(258).ȱ Peripheralisationȱ If,ȱ asȱ aȱ resultȱ ofȱ repeatedȱ movementsȱ orȱ positions,ȱ theȱ radiatingȱ symptomsȱ originatingȱ fromȱ theȱ spineȱ andȱ referredȱdistally,ȱprogressȱfartherȱdistallyȱ(57).ȱOppositeȱ ofȱcentralisation.ȱ Persistentȱpainȱ Painȱpresentȱmostȱofȱtheȱtimeȱorȱrecurrentȱepisodesȱǃ12ȱ weeks.ȱ Postpartumȱ Afterȱdeliveryȱ(AmericanȱEnglish),ȱsimilarȱtoȱpostnatalȱ (BritishȱEnglish).ȱ Predictorȱvariableȱ Explanatoryȱvariableȱorȱcovariateȱ(6).ȱ PregnancyȬrelatedȱ lowȱbackȱpainȱ Lowȱbackȱpainȱpresentȱinȱpregnancy.ȱ Redȱflagȱ Aȱsymptomȱdescribedȱbyȱtheȱpatientȱthatȱmayȱindicateȱ seriousȱpathologyȱ(242).ȱ Riskȱfactorȱ Aȱ determinantȱ thatȱ influencesȱ theȱ incidenceȱ (relativeȱ risk)ȱ(193).ȱ Sensitivityȱ Theȱ abilityȱ ofȱ aȱ testȱ toȱ identifyȱ theȱ patientsȱ withȱ theȱ conditionȱ(224).ȱ Specificityȱ Theȱ abilityȱ ofȱ aȱ testȱ toȱ identifyȱ theȱ absenceȱ ofȱ aȱ conditionȱ(224).ȱ ȱ

ȱ 6 Introductionȱ

INTRODUCTIONȱ

Theȱ startingȱ pointȱ ofȱ thisȱ thesisȱ wasȱ basedȱ onȱ theȱ historiesȱ ofȱ manyȱ womenȱ whoȱ sufferedȱ fromȱ lowȱ backȱ painȱ (LBP)ȱ inȱ relationȱ toȱ theirȱ pregnancy.ȱ Womenȱ whoȱ previouslyȱhadȱexperiencedȱofȱLBPȱrecurrentlyȱstatedȱthatȱtheyȱexperiencedȱaȱ“new”ȱ formȱofȱLBPȱwhileȱpregnant.ȱTheȱ“new”ȱLBPȱwasȱdifferentȱinȱtermsȱofȱlocationȱandȱ characterȱasȱwellȱasȱincludedȱnewȱsymptoms.ȱItȱcouldȱoccurȱinsteadȱofȱorȱinȱadditionȱtoȱ theȱ previouslyȱ experiencedȱ intermittentȱ LBP.ȱ Descriptionsȱ suchȱ asȱ “aȱ veryȱ strongȱ trainingȱ acheȱ thatȱ spread”,ȱ “Iȱ feelȱ likeȱ myȱ bodyȱ isȱ fallingȱ apart”,ȱ andȱ “myȱ hipȱ isȱ locking”ȱ wereȱ descriptionsȱ notȱ typicallyȱ heardȱ inȱ relationȱ toȱ nonpregnancyȬrelatedȱ LBP.ȱ ȱ LBPȱ inȱpregnancyȱ isȱ sometimesȱ lookedȱ uponȱ asȱ aȱnormalȱ consequenceȱ ofȱ pregnancyȱ thatȱtheȱwomanȱmustȱendure.ȱTheȱquestionȱhasȱarisenȱasȱtoȱwhatȱimpactȱpregnancyȬ relatedȱLBPȱhasȱonȱdailyȱlife.ȱPreviousȱdescriptionsȱofȱtheȱimpactȱofȱpregnancyȬrelatedȱ LBPȱ onȱ functioningȱ haveȱ mostlyȱ beenȱ obtainedȱ fromȱ selfȬreportedȱ painȱ increasingȱ activitiesȱ orȱ sickȱ leaveȱ reports.ȱ Thereforeȱ itȱ isȱ difficultȱ toȱ compareȱ resultsȱ betweenȱ studiesȱandȱtoȱcompareȱwithȱstudiesȱonȱnonpregnancyȬrelatedȱLBP.ȱ ȱ Throughoutȱ theȱ years,ȱ oneȱ clinicalȱ opinionȱ hasȱ beenȱ thatȱ womenȱ withȱ pregnancyȬ relatedȱ LBPȱ areȱ owomenȱ wh ȱ areȱ lessȱ tolerantȱ toȱ pregnancy,ȱ eitherȱ physicallyȱ orȱ mentally.ȱTheȱquestionȱhasȱarisenȱasȱtoȱwhetherȱthereȱisȱaȱdifferenceȱinȱmuscleȱfunctionȱ inȱ womenȱ whoȱ haveȱ pregnancyȬrelatedȱ LBPȱ comparedȱ toȱ pregnantȱ womenȱ withoutȱ LBP.ȱAdditionally,ȱisȱthereȱanȱassociationȱbetweenȱpersistentȱLBPȱandȱmentalȱhealth,ȱ whichȱshouldȱbeȱconsideredȱbyȱtheȱcaregiverȱwhenȱplanningȱtheȱtreatmentȱstrategies?ȱ ȱ Afterȱdelivery,ȱtheȱmajorityȱofȱwomenȱreportȱthatȱtheȱ“new”ȱtypeȱofȱLBPȱdisappearsȱ whereasȱ theȱ “old”ȱ badȱ backȱ remains.ȱ Howeverȱ whatȱ happensȱ whenȱ theȱ “new”ȱ LBPȱ persistsȱbeyondȱdelivery?ȱFurthermore,ȱisȱitȱpossibleȱtoȱpredictȱearlyȱonȱwhoȱisȱatȱriskȱ forȱpersistentȱLBPȱpostpartum?ȱ ȱ

ȱ 7 Backgroundȱ ȱ

BACKGROUNDȱ

TERMINOLOGYȱ Painȱlocalisationȱisȱoneȱwayȱofȱclassifyingȱlowȱbackȱpainȱ(LBP).ȱLBPȱhasȱbeenȱ definedȱasȱpainȱlocatedȱbetweenȱtheȱtwelfthȱribȱandȱtheȱglutealȱfoldsȱ(89,ȱ242).ȱ Inȱthisȱthesisȱtheȱtermsȱlowȱbackȱpain,ȱpelvicȱgirdleȱpainȱandȱlumbarȱpainȱareȱ used.ȱ ȱ LowȱBackȱPainȱisȱconsideredȱasȱanȱumbrellaȱtermȱforȱpainȱlocalisedȱinȱtheȱpelvicȱ andȱ lumbarȱ regions.ȱ Theȱ numerousȱ termsȱ forȱ pregnancyȬrelatedȱ LBPȱ inȱ theȱ pelvisȱ(267)ȱreflectȱtheȱuncertaintyȱofȱtheȱetiologyȱandȱtoȱdate,ȱitȱisȱconsideredȱaȱ syndrome,ȱ i.e.ȱ aȱ groupȱ ofȱ signsȱ orȱ symptomsȱ whoseȱ appearanceȱ togetherȱ usuallyȱ indicatesȱ theȱ presenceȱ ofȱ aȱ particularȱ diseaseȱ orȱ disorderȱ (Chambersȱ Referenceȱ Online).ȱ Thereȱ existedȱ aȱ needȱ forȱ aȱ termȱ thatȱ describedȱ theȱ pregnancyȬrelatedȱ LBPȱ syndromeȱ andȱ includedȱ theȱ ligaments,ȱ jointȱ capsulesȱ andȱmusclesȱinȱtheȱpelvis,ȱasȱwellȱasȱtheȱsacroiliacȱjointȱ(SIJ)ȱandȱthatȱexcludedȱ gynecologicalȱ and/orȱ urologicalȱ disorders.ȱ Theȱ termȱ Pelvicȱ Girdleȱ Painȱ (PGP)ȱ wasȱproposed,ȱwithȱtheȱfollowingȱdefinition:ȱ“Pelvicȱgirdleȱpainȱ(PGP)ȱgenerallyȱ arisesȱ inȱ relationȱ toȱ pregnancy,ȱ traumaȱ orȱ reactiveȱ arthritis.ȱ Painȱ isȱ experiencedȱ betweenȱtheȱposteriorȱiliacȱcrestȱandȱtheȱglutealȱfold,ȱparticularȱinȱtheȱvicinityȱofȱtheȱ sacroiliacȱjointsȱ(SIJ).ȱTheȱpainȱmayȱradiateȱinȱtheȱposteriorȱthighȱandȱcanȱalsoȱoccurȱ inȱ conjunctionȱ with/orȱ separatelyȱ inȱ theȱ symphysis.ȱ Theȱ enduranceȱ capacityȱ forȱ standing,ȱwalkingȱandȱsittingȱisȱdiminished.ȱTheȱdiagnosisȱofȱPGPȱcanȱbeȱreachedȱafterȱ exclusionȱ ofȱ lumbarȱ causes.ȱ Theȱ painȱ orȱ functionalȱ disturbancesȱ inȱ relationȱ toȱ PGPȱ mustȱbeȱreproducibleȱbyȱspecificȱclinicalȱtests.”(258).ȱ Inȱthisȱthesis,ȱtheȱPGPȱthatȱarisesȱinȱrelationȱtoȱpregnancyȱisȱstudied.ȱ ȱ TheȱtermȱLumbarȱPainȱisȱusedȱforȱpainȱthatȱisȱofȱlumbarȱoriginȱ(151),ȱwithȱorȱ withoutȱradiationȱinȱtheȱleg,ȱandȱwithoutȱaȱspecificallyȱdefinedȱpainȱstructure.ȱ

ȱ 8 Backgroundȱ

EPIDEMIOLOGYȱ

Prevalenceȱofȱlowȱbackȱpainȱinȱwomenȱ Inȱgeneral,ȱwomenȱreportȱmoreȱmusculoskeletalȱpainȱthanȱmenȱ(15,ȱ114,ȱ257).ȱ Amongȱ allȱ musculoskeletalȱ disorders,ȱ LBPȱ isȱ theȱ largestȱ entityȱ (195).ȱ Inȱ aȱ generalȱpopulation,ȱitȱhasȱbeenȱfoundȱthatȱ10Ȭ28%ȱofȱwomenȱrelateȱtheirȱdebutȱ ofȱLBPȱtoȱaȱpregnancyȱ(20,ȱ229).ȱ ȱ PregnancyȬrelatedȱbackȱpainȱhasȱbeenȱreportedȱfromȱallȱoverȱtheȱworldȱ(2,ȱ24,ȱ 55,ȱ 61,ȱ 72,ȱ 128,ȱ 137,ȱ 138,ȱ 150,ȱ 157,ȱ 169,ȱ 174,ȱ 185,ȱ 235,ȱ 236,ȱ 241,ȱ 245,ȱ 263).ȱ Theȱ incidenceȱ ofȱ backȱ painȱ inȱ pregnancyȱ isȱ rarelyȱ reported,ȱ andȱ theȱ 2ȱ studiesȱ identifiedȱshowedȱaȱlargeȱvariationȱ(27Ȭ61%)ȱ(116,ȱ177).ȱInȱaȱrecentȱreview,ȱtheȱ periodȱprevalenceȱofȱanyȱtypeȱofȱLBPȱwasȱestimatedȱtoȱ45%ȱ(rangeȱ3.9Ȭ89.9%)ȱ inȱ pregnancyȱ andȱ 25%ȱ (rangeȱ 0.3Ȭ67%)ȱ postpartumȱ (267).ȱ Althoughȱ notȱ directlyȱinȱassociationȱwithȱtheȱpregnancyȱterm,ȱaȱselfȬreportedȱ1Ȭyearȱperiodȱ prevalenceȱofȱLBPȱofȱ45Ȭ54%ȱwasȱfoundȱinȱgeneralȱNordicȱpopulationsȱofȱ30ȱtoȱ 50ȱ yearȱ oldȱ femalesȱ (126).ȱ Theȱ pointȱ prevalenceȱ ofȱ LBPȱ inȱ theȱ femaleȱ reproductiveȱyearsȱhasȱbeenȱselfȬreportedȱasȱ26%ȱinȱtheȱ25Ȭ44ȱyearȱageȱbandȱ (195),ȱandȱ20%ȱinȱtheȱ16Ȭ44ȱyearȱageȱbandȱ(237).ȱTheȱpointȱprevalenceȱofȱLBPȱinȱ pregnantȱ womenȱ isȱ increasedȱ (rangeȱ 22Ȭ63.4%)ȱ comparedȱ toȱ womenȱ ofȱ theȱ sameȱmeanȱageȱ(6.3%)ȱinȱaȱgeneralȱpopulationȱ(19,ȱ116,ȱ177).ȱSixteenȱpercentȱofȱ womenȱ withȱ pregnancyȬrelatedȱ LBPȱ reportedȱ persistentȱ painȱ 6ȱ yearsȱ afterȱ childbirthȱ(182).ȱPregnancyȱisȱtherebyȱaȱspecificȱsituationȱthatȱincreasesȱtheȱriskȱ ofȱLBP,ȱasȱwellȱasȱtheȱriskȱofȱpersistentȱLBP.ȱ ȱ Theȱ prevalenceȱ ofȱ LBPȱ inȱ pregnancyȱ andȱ postpartumȱ isȱ mostlyȱ basedȱ uponȱ selfȬreportsȱthroughȱquestionnairesȱorȱinterviewsȱ(24,ȱ61,ȱ66,ȱ128,ȱ138,ȱ154,ȱ169,ȱ 176,ȱ177,ȱ185,ȱ211,ȱ235,ȱ236)ȱandȱrarelyȱconfirmedȱandȱclassifiedȱwithȱclinicalȱ evaluationȱ (3,ȱ 14,ȱ 116,ȱ 121,ȱ 183).ȱ Differencesȱ inȱ terminology,ȱ methodology,ȱ includingȱ differentȱ classificationȱ criteriaȱ forȱ theȱ studiedȱ syndrome,ȱ andȱ theȱ samplesȱunderȱstudy,ȱe.g.ȱonlyȱthoseȱwithȱpainȱwarrantingȱmedicalȱhelp,ȱareȱ plausibleȱcausesȱforȱtheȱwideȱrangeȱinȱreportedȱprevalence.ȱ ȱ Inȱaȱfewȱstudies,ȱPGPȱwasȱclinicallyȱdifferentiatedȱfromȱpainȱofȱlumbarȱorigin.ȱ TheȱreportedȱprevalenceȱofȱPGPȱduringȱpregnancyȱwasȱfoundȱtoȱbeȱ14Ȭ28%ȱ(2,ȱ 121,ȱ157)ȱandȱ4Ȭ5%ȱ2Ȭ3ȱmonthsȱpostpartum.ȱTheȱprevalenceȱofȱlowerȱlumbarȱ painȱinȱpregnancyȱwasȱreportedȱasȱ6.5%ȱbyȱAlbertȱetȱal.ȱ(2000)ȱ(2)ȱandȱasȱ13.2%ȱ

ȱ 9 Backgroundȱ ȱ byȱMousaviȱetȱal.ȱ(2007)ȱ(157),ȱhoweverȱtheȱpostpartumȱprevalenceȱofȱlumbarȱ painȱisȱunknown.ȱ ȱ ItȱisȱcomplicatedȱtoȱcompareȱtheȱprevalenceȱofȱpregnancyȬrelatedȱLBPȱwithȱtheȱ epidemiologyȱ ofȱ LBPȱ inȱ generalȱ populations.ȱ Besidesȱ methodologicalȱ differences,ȱ generalȱ populationsȱ usuallyȱ haveȱ broaderȱ ageȱ ranges,ȱ olderȱ ageȱ bands,ȱLBPȱofȱlongerȱduration,ȱandȱareȱnotȱgenderȱdifferentiated.ȱHowever,ȱitȱ doesȱ appearȱ thatȱ theȱ 9Ȭmonthȱ prevalence,ȱ asȱ wellȱ asȱ theȱ pointȱ prevalenceȱ ofȱ LBPȱinȱaȱpregnancyȱisȱhigherȱcomparedȱtoȱwomenȱofȱtheȱsameȱageȱinȱaȱgeneralȱ population.ȱ

Courseȱandȱpredictorsȱofȱlowȱbackȱpainȱ Moreȱ thanȱ 70%ȱ ofȱ theȱ industrializedȱ populationȱ hasȱ LBPȱ sometimeȱ duringȱ theirȱ lifetime.ȱ Amongȱ patientsȱ withȱ acuteȱ LBP,ȱ 76Ȭ90%ȱ improvedȱ withinȱ 1ȱ monthȱ(8,ȱ44,ȱ79),ȱregardlessȱofȱtheȱtypeȱofȱtreatmentȱreceivedȱ(99).ȱHoweverȱ theseȱnumbersȱdoȱnotȱreferȱtoȱcompleteȱrecovery.ȱTheȱmajorityȱcontinueȱtoȱbeȱ symptomaticȱafterȱ1ȱyear,ȱwithȱonlyȱ21%ȱhavingȱrecoveredȱwithȱregardȱtoȱpainȱ andȱ25%ȱwithȱregardȱtoȱdisabilityȱ(48).ȱWithinȱaȱyear,ȱrelapsesȱareȱseenȱinȱ60%ȱ (rangeȱ44Ȭ78%)ȱofȱtheȱpatientsȱ(89).ȱNonspecificȱLBPȱisȱincreasinglyȱregardedȱ asȱhavingȱaȱpersistent,ȱfluctuatingȱsymptomȱcourseȱwithȱintermittentȱflaresȱ(48,ȱ 262).ȱ ȱ MostȱwomenȱrecoverȱfromȱpregnancyȬrelatedȱLBP,ȱalthoughȱtheȱriskȱofȱLBPȱinȱ aȱsubsequentȱpregnancyȱisȱhighȱ(36).ȱImprovementȱisȱapparentȱuntilȱaboutȱ3Ȭ6ȱ monthsȱpostpartumȱ(112,ȱ176,ȱ182).ȱForȱthoseȱwomenȱwithȱpersistentȱpainȱatȱ3ȱ monthsȱpostpartum,ȱtheȱriskȱofȱlongȬtermȱproblemsȱisȱgreatȱ(176,ȱ182),ȱwhichȱisȱ similarȱ toȱ nonpregnancyȬrelatedȱ LBPȱ ofȱ durationȱ longerȱ thanȱ 3ȱ monthsȱ (89).ȱ Theȱ timeȱ pointȱ mayȱ haveȱ anȱ associationȱ withȱ theȱ earlyȱ findingsȱ ofȱ theȱ remissionȱ ofȱ jointȱ relaxation,ȱ whichȱ terminatesȱ 6ȱ monthsȱ postpartumȱ atȱ theȱ latestȱ(90).ȱInȱaȱ12ȬyearȱfollowȬupȱstudyȱofȱwomenȱwithȱLBPȱsevereȱenoughȱtoȱ requireȱ sickȱ leaveȱ whileȱ pregnant,ȱ 92%ȱ reportedȱ LBPȱ duringȱ aȱ subsequentȱ pregnancyȱandȱ86%ȱhadȱrecurrentȱLBPȱwhileȱnotȱpregnantȱ(36).ȱ ȱ Oneȱ ofȱ theȱ mostȱ frequentlyȱ reportedȱ predictorsȱ forȱ eitherȱ developingȱ LBPȱ duringȱ pregnancyȱ orȱ havingȱ persistentȱ LBPȱ postpartumȱ isȱ theȱ previousȱ experienceȱ ofȱ LBP,ȱ eitherȱ inȱ anȱ earlierȱ pregnancyȱ orȱ outsideȱ theȱ pregnancyȱ (11).ȱ Reportedȱ premorbidȱ riskȱ factorsȱ areȱ traumaȱ ofȱ theȱ backȱ orȱ pelvis,ȱ (5),ȱ previousȱ lowerȱ abdominalȱ painȱ (121),ȱ andȱ multiparityȱ (5,ȱ 177).ȱ Aȱ greaterȱ

ȱ 10 Backgroundȱ numberȱ ofȱ yearsȱ ofȱ previousȱ regularȱ leisureȱ physicalȱ activityȱ decreasedȱ theȱ riskȱ ofȱ developingȱ pregnancyȬrelatedȱ LBPȱ (153).ȱ Reportedȱ episodeȬrelatedȱ factorsȱ forȱ LBPȱ inȱ pregnancyȱ areȱ lackȱ ofȱ exerciseȱ (121),ȱ youngerȱ ageȱ (177),ȱ higherȱ levelsȱ ofȱ stress,ȱ workȱ dissatisfactionȱ (5),ȱ uncomfortableȱ workingȱ conditionsȱ(121,ȱ177),ȱoccupationsȱdescribedȱasȱmainlyȱphysicallyȱgdemandin ȱ (153),ȱandȱhigherȱBMIȱ(116).ȱ ȱ EpisodeȬrelatedȱ factorsȱ associatedȱ withȱ persistentȱ LBPȱ andȱ PGPȱ includeȱ featuresȱ specificȱ toȱ theȱ painȱ episodeȱ (severityȱ ofȱ complaints,ȱ earlierȱ onsetȱ ofȱ pain,ȱ highȱ painȱ intensity,ȱ andȱ walkingȱ deficiency),ȱ andȱ maternalȱ factorsȱ (higherȱ BMI,ȱ age,ȱ andȱ jointȱ hypermobility)(11,ȱ 154,ȱ 211).ȱ Lumbarȱ painȱ hasȱ shownȱ aȱ strongerȱ associationȱ toȱ preȬpregnancyȱ LBPȱ (14,ȱ 183),ȱ whileȱ PGPȱ isȱ moreȱ closelyȱ relatedȱ toȱ aȱ pregnancyȱ inȱ occurrenceȱ andȱ recurrence.ȱ Theȱ selfȬ reportedȱ predictorsȱ andȱ courseȱ ofȱ pregnancyȬrelatedȱ LBPȱ postpartumȱ areȱ partlyȱ known,ȱ butȱ notȱ forȱ clinicallyȱ classifiedȱ subgroupsȱ ofȱ patientsȱ withȱ pregnancyȬrelatedȱ LBP.ȱ Thusȱ itȱ isȱ notȱ knownȱ whetherȱ orȱ notȱ aȱ specificȱ subgroupȱ ofȱ patientsȱ withȱ pregnancyȬrelatedȱ LBPȱ hasȱ anȱ increasedȱ riskȱ forȱ persistency.ȱ

PREGNANCYȬRELATEDȱPELVICȱGIRDLEȱPAINȱANDȱ LUMBARȱPAINȱ SeveralȱauthorsȱhaveȱidentifiedȱPGPȱandȱlumbarȱpainȱasȱ2ȱmajorȱsubtypesȱofȱ painȱinȱtheȱlowerȱpartȱofȱtheȱspineȱandȱinȱtheȱpelvisȱduringȱpregnancyȱ(38,ȱ40,ȱ 61,ȱ 116,ȱ 157,ȱ 183,ȱ 189,ȱ 228,ȱ 238).ȱ Womenȱ withȱ PGPȱ haveȱ aȱ differentȱ clinicalȱ presentationȱ thanȱ womenȱ withȱ lumbarȱ painȱ (Tableȱ 1)(183,ȱ 228).ȱ Clinicalȱ experience,ȱasȱwellȱasȱpreviousȱresearch,ȱsuggestȱdifferentȱtreatmentȱstrategiesȱ forȱPGPȱandȱlumbarȱpainȱinȱrelationȱtoȱpregnancyȱ(183,ȱ189).ȱItȱhasȱbeenȱstatedȱ thatȱPGPȱcanȱworsenȱifȱtreatedȱasȱgeneralȱnonpregnancyȬrelatedȱLBPȱ(183).ȱItȱ hasȱ furtherȱ beenȱ reportedȱ thatȱ PGPȱ andȱ PGPȱ combinedȱ withȱ lumbarȱ painȱ (combinedȱpain)ȱhaveȱaȱgreaterȱimpactȱonȱdailyȱactivityȱsuchȱasȱwalkingȱandȱ houseworkȱthanȱlumbarȱpainȱaloneȱ3ȱyearsȱafterȱpregnancyȱ(168).ȱ ȱ ȱ ȱ ȱ ȱ

ȱ 11 Backgroundȱ ȱ Tableȱ1.ȱCharacteristicȱfeaturesȱofȱpregnancyȬrelatedȱPelvicȱGirdleȱPainȱandȱLumbarȱPainȱ fromȱclinicalȱexperience.ȱ ȱ

Featuresȱ PelvicȱGirdleȱPainȱ LumbarȱPainȱ Painȱ Deepȱuni/bilateralȱpainȱinȱbuttocksȱbetweenȱiliacȱcrestȱandȱ Painȱoriginȱinȱandȱbesideȱtheȱ Locationȱ glutealȱfold,ȱdistalȱtoȱlumbarȱspineȱorȱinȱtheȱsymphysis.ȱ lumbarȱspine,ȱwithȱorȱwithoutȱ Mayȱradiateȱtoȱposterolateralȱthigh,ȱtoȱknee,ȱrarelyȱtoȱcalf,ȱ radiationȱtoȱlegȱorȱfoot.ȱ neverȱtoȱfoot.ȱ Functionalȱ Prolongedȱpositionsȱorȱactivities,ȱaboveȱallȱsitting,ȱ Someȱpositionsȱorȱactivitiesȱ Limitationsȱ standing,ȱwalking.ȱActivitiesȱinvolvingȱabductionȬexternalȱ decreaseȱpain;ȱothersȱincrease.ȱ rotationȱofȱhipȱorȱasymmetricalȱloadingȱofȱtheȱpelvisȱ Clinicalȱ Catchingȱofȱtheȱleg*.ȱDelayȱinȱpainȱresponse.ȱPainȱdebutȱinȱ Restrictedȱspinalȱrangeȱofȱ Featuresȱ relationȱtoȱpregnancy.ȱNoȱpositiveȱnerveȱrootȱtest.ȱ motion.ȱRecurrentȱpainȱ episodesȱbeforeȱpregnancy.ȱ Mayȱhaveȱpositiveȱnerveȱrootȱ test.ȱȱ *Catchingȱofȱtheȱleg:ȱdifficultyȱinȱmovingȱoneȱorȱbothȱlegsȱforwardȱwhenȱwalkingȱ(228).ȱ ȱ Mostȱ studiesȱ doȱ notȱ differentiateȱ betweenȱ PGPȱ andȱ lumbarȱ pain,ȱ neitherȱ duringȱpregnancyȱnorȱpostpartumȱ(12,ȱ66,ȱ128,ȱ138,ȱ154,ȱ169,ȱ174,ȱ176,ȱ182,ȱ185,ȱ 235,ȱ 236,ȱ 263),ȱ orȱ excludeȱ womenȱ withȱ lumbarȱ painȱ (3,ȱ 121,ȱ 165).ȱ However,ȱ clinicalȱclassificationȱisȱimportantȱinȱorderȱtoȱevaluateȱpossibleȱdifferencesȱinȱ subgroupȱ prevalence,ȱ course,ȱ cause,ȱ consequences,ȱ andȱ predictorsȱ ofȱ persistency,ȱandȱtherebyȱpossibleȱdifferencesȱinȱmanagement.ȱPregnancyȱitselfȱ mayȱ interfereȱ withȱ studiedȱ factors.ȱ Thereforeȱ itȱ isȱ importantȱ toȱ followȱ allȱ pregnantȱwomenȱofȱaȱcohort,ȱincludingȱwomenȱwithȱallȱtypesȱofȱnonspecificȱ LBP,ȱasȱwellȱasȱwomenȱwithoutȱLBP.ȱ

Classificationȱofȱlowȱbackȱpainȱ Healthcareȱ planningȱ andȱ clinicalȱ professionalsȱ needȱ informationȱ sufficientȱ enoughȱ toȱ decideȱ onȱ theȱ choiceȱ ofȱ treatmentȱ andȱ preventiveȱ measures.ȱ Theȱ goalȱofȱclassificationȱisȱtoȱhaveȱaȱdiagnosisȱthatȱmayȱexplainȱtheȱcauseȱofȱtheȱ syndrome/disease,ȱgiveȱaȱprognosis,ȱassistȱinȱtheȱchoiceȱofȱtherapy,ȱandȱpredictȱ theȱoutcomeȱofȱaȱ specificȱtherapy.ȱ ȱ Theȱ onlyȱ acceptedȱ classificationȱ ofȱ nonspecificȱ LBPȱ isȱ theȱ durationȱ ofȱ pain.ȱ AcuteȱLBPȱisȱwhenȱtheȱdurationȱisȱlessȱthanȱ6ȱweeks,ȱsubacuteȱLBPȱisȱwhenȱtheȱ painȱ durationȱ isȱ 6Ȭ12ȱ weeks,ȱ andȱ persistentȱ LBPȱ isȱ classifiedȱ whenȱ painȱ durationȱ isȱ moreȱ thanȱ 12ȱ weeksȱ (242).ȱ Thisȱ classificationȱ isȱ notȱ enoughȱ forȱ guidingȱ managementȱ andȱ itȱ mayȱ notȱ beȱ relevantȱ forȱ classificationȱ ofȱ LBPȱ inȱ pregnancy.ȱ Anotherȱ wayȱ toȱ classifyȱ LBPȱ isȱ accordingȱ toȱ theȱ severityȱ ofȱ theȱ complaintsȱthatȱmayȱbeȱofȱimportanceȱforȱunderstandingȱtheȱcourseȱ(58).ȱThisȱ

ȱ 12 Backgroundȱ appearsȱ toȱ beȱ anȱ importantȱ classification,ȱ butȱ fromȱ aȱ clinicalȱ perspective,ȱ itȱ shouldȱbeȱmadeȱwithinȱtheȱsubgroupsȱofȱpatientsȱwithȱLBP.ȱ ȱ Thereȱ isȱ noȱ anatomicallyȬspecificȱ diagnosticȱ toolȱ forȱ possibleȱ painȱ sourcesȱ ofȱ PGP.ȱAdditionally,ȱnoȱobjectiveȱfindingsȱforȱPGPȱonȱXȬray,ȱMRI,ȱorȱinȱbloodȱ samplesȱhaveȱbeen ȱidentifiedȱ(84).ȱFromȱaȱclinicalȱpointȱofȱview,ȱaȱdiagnosticȱ triageȱ thatȱ differentiatesȱ betweenȱ seriousȱ pathologyȱ (redȱ flags),ȱ nerveȱ rootȱ problems,ȱandȱnonspecificȱLBPȱisȱtheȱfirstȱstepȱtoȱtakeȱforȱpatientsȱwithȱLBPȱ (111,ȱ 242).ȱ Theȱ majorityȱ ofȱ patientsȱ withȱ LBPȱ fallȱ intoȱ theȱ categoryȱ ofȱ nonspecificȱ LBPȱ andȱ aȱ furtherȱ classificationȱ isȱ neededȱ inȱ orderȱ toȱ chooseȱ treatmentȱ strategies.ȱ Thisȱ classificationȱ doesȱ notȱ necessarilyȱ needȱ toȱ includeȱ explanationȱofȱtheȱcause.ȱ ȱ Basedȱ onȱ currentȱ knowledgeȱ andȱ existingȱ guidelinesȱ forȱ PGPȱ (258)ȱ andȱ LBPȱ (242),ȱclinicalȱevaluationȱofȱpregnancyȬrelatedȱLBPȱshouldȱincludeȱpelvicȱpainȱ provocationȱ tests,ȱ aȱ neurologicalȱ examination,ȱ takeȱ knownȱ characteristicsȱ ofȱ PGPȱ andȱ lumbarȱ painȱ intoȱ account,ȱ andȱ beȱ sufficientȱ enoughȱ toȱ identifyȱ discogenicȱpainȱandȱredȱflagȱconditions.ȱ ȱ Manyȱdifferentȱpelvicȱpainȱprovocationȱtestsȱandȱcriteriaȱhaveȱbeenȱusedȱforȱ classifyingȱ PGPȱ (2,ȱ 14,ȱ 115,ȱ 164,ȱ 165,ȱ 180,ȱ 181,ȱ 226,ȱ 228,ȱ 264).ȱ Noȱ conclusionsȱ canȱ beȱ drawnȱ asȱ toȱ whichȱ criteriaȱ orȱ clinicalȱ testsȱ shouldȱ beȱ usedȱ forȱ PGP.ȱ Regardingȱcriteriaȱforȱtheȱnumberȱofȱpositiveȱpelvicȱpainȱprovocationȱtests,ȱ1ȱ (2,ȱ 183),ȱ 2ȱ (164,ȱ 264),ȱ andȱ 3ȱ (165)ȱ positiveȱ pelvicȱ painȱ provocationȱ testsȱ haveȱ beenȱ suggestedȱ orȱ usedȱ asȱ diagnosticȱ criteriaȱ forȱ PGP.ȱ Inȱ anotherȱ study,ȱ theȱ bestȱ discriminatoryȱ abilityȱ wasȱ achievedȱ byȱ theȱ combinationȱ ofȱ 5ȱ painȱ provocationȱtests,ȱwhichȱwasȱreportedȱtoȱhaveȱaȱsensitivityȱofȱ67%,ȱspecificityȱ ofȱ84%,ȱandȱpredictiveȱvalueȱofȱ57%ȱwhenȱidentifyingȱwomenȱwithȱLBPȱinȱtheȱ lumbosacralȱ regionȱ (115).ȱ Furthermore,ȱ itȱ wasȱ shownȱ thatȱ pregnantȱ womenȱ withoutȱ PGPȱ mostlyȱ hadȱ negativeȱ painȱ provocationȱ testsȱ (0Ȭ15%)ȱ despiteȱ ligamentȱ laxityȱ dueȱ toȱ theȱ pregnancy.ȱ Despiteȱ noȱ LBPȱ thereȱ wasȱ palpableȱ tendernessȱ overȱ theȱ symphysisȱ inȱ 35%ȱ ofȱ theȱ womenȱ whichȱ makesȱ theȱ testȱ questionable.ȱ ȱ ClassificationȱofȱPGPȱrequiresȱexclusionȱofȱlumbarȱcausesȱ(258).ȱSeveralȱtestsȱ forȱexaminationȱofȱtheȱlumbarȱspineȱinȱpregnancyȱhaveȱbeenȱdescribedȱ(115,ȱ 183,ȱ228).ȱHoweverȱtheȱtestȱreactionȱinȱtermsȱofȱpainȱorȱstiffnessȱisȱnotȱspecificȱ enoughȱtoȱexcludeȱintervertebralȱdiscȱpathology,ȱwhichȱisȱprobablyȱtheȱmostȱ commonȱstructuralȱsourceȱofȱnonspecificȱLBPȱ(26,ȱ215).ȱThereȱisȱnoȱdifferenceȱ

ȱ 13 Backgroundȱ ȱ inȱ discȱ abnormalityȱ prevalenceȱ betweenȱ pregnantȱ andȱ nonpregnantȱ populationsȱ(250).ȱItȱisȱthereforeȱimportantȱtoȱalsoȱexamineȱpossibleȱdiscogenicȱ problemsȱinȱaȱpregnantȱpopulationȱwithȱLBP.ȱ ȱ Manyȱ classificationȱ systemsȱ existȱ forȱ patientsȱ withȱ LBP;ȱ theȱ strengthsȱ andȱ weaknessesȱhaveȱbeenȱdiscussedȱinȱreviewsȱ(22,ȱ192,ȱ205).ȱSeveralȱclassificationȱ systemsȱ forȱ LBPȱ patientsȱ haveȱ beenȱ identified,ȱ whichȱ areȱ relevantȱ forȱ physiotherapistsȱ(53,ȱ69,ȱ142,ȱ191,ȱ218).ȱTheȱMechanicalȱDiagnosisȱandȱTherapyȱ (MDT)(142)ȱhasȱbeenȱidentifiedȱasȱaȱwellȱdescribedȱclassificationȱsystem.ȱItȱisȱ commonlyȱ usedȱ (13,ȱ 77)ȱ andȱ includesȱ aȱ standardisedȱ history,ȱ neurologicalȱ examination,ȱ andȱ evaluationȱ ofȱ redȱ flags.ȱ Withinȱ theȱ protocol,ȱ symptomȱ responseȱ duringȱ andȱ afterȱ repeatedȱ movementsȱ isȱ evaluated,ȱ andȱ thisȱ procedureȱhasȱshownȱpromisingȱresultsȱinȱreliabilityȱstudiesȱ(110,ȱ141,ȱ201).ȱIf,ȱ asȱ aȱ resultȱ ofȱ repeatedȱ movementsȱ orȱ positions,ȱ theȱ radiatingȱ symptomsȱ regressȱ proximallyȱ (centralisation)ȱ orȱ theȱ opposite,ȱ progressȱ distallyȱ (peripheralisation),ȱtheȱsymptomsȱareȱconsideredȱdiscogenicȱandȱ haveȱshownȱ aȱ highȱ prognosticȱ valueȱ (56,ȱ 57,ȱ 252).ȱ Furthermore,ȱ pelvicȱ painȱ provocationȱ testsȱwereȱevaluatedȱwithinȱtheȱMDTȱprotocol,ȱwithȱaȱreportedȱsensitivityȱtoȱ detectȱ SIJȱ syndromeȱ ofȱ 0.91ȱ andȱ specificityȱ ofȱ 0.83ȱ (124).ȱ Itȱ wasȱ arguedȱ thatȱ positiveȱSIJȱtests,ȱinȱtheȱabsenceȱofȱcentralisation,ȱareȱsaferȱinȱdiagnosticȱtriageȱ thanȱpelvicȱpainȱprovocationȱtestsȱalone.ȱ

CAUSESȱOFȱPREGNANCYȬRELATEDȱPELVICȱGIRDLEȱPAINȱ DiscussedȱcausesȱofȱpregnancyȬrelatedȱLBPȱinȱtheȱpelvisȱareȱmainlyȱbasedȱonȱ biomechanicalȱandȱhormonalȱchangesȱduringȱpregnancy.ȱHippocratesȱ(cȱ460Ȭcȱ 377ȱBC)ȱhadȱalreadyȱhypothesisedȱthatȱanȱirreversibleȱrelaxationȱofȱtheȱpelvisȱ occursȱ duringȱ pregnancy.ȱ Radiologicalȱ studiesȱ inȱ theȱ earlyȱ 20thȱ centuryȱ confirmedȱ relaxationȱ ofȱ theȱ pelvicȱ joints,ȱ andȱ showedȱ thatȱ itȱ wasȱ dependentȱ uponȱnormalȱbiologicalȱprocessesȱthatȱbeganȱinȱtheȱearlyȱstagesȱofȱpregnancyȱ (90,ȱ268).ȱTowardsȱtheȱendȱofȱtheȱ1920s,ȱitȱbecameȱmethodologicallyȱpossibleȱtoȱ studyȱtheȱroleȱhormonesȱplayedȱwithȱregardȱtoȱincreasedȱmobility.ȱRelaxinȱisȱ oneȱ pregnancyȬrelatedȱ hormoneȱ studied,ȱ consideredȱ toȱ playȱ aȱ roleȱ inȱ theȱ mobilityȱ ofȱ theȱ pelvicȱ joints.ȱ Theȱ hypothesisȱ thatȱ aȱ highȱ levelȱ ofȱ relaxinȱ correlatesȱwithȱPGPȱhasȱbeenȱconfirmedȱinȱsomeȱstudiesȱ(117,ȱ135),ȱbutȱnotȱinȱ othersȱ(4,ȱ190).ȱ ȱ Theȱ earlyȱ reportsȱ ofȱ increasedȱ mobilityȱ inȱ theȱ symphysis,ȱ asȱ wellȱ asȱ inȱ theȱ posteriorȱ pelvicȱ joints,ȱ areȱ probablyȱ theȱ basisȱ forȱ theȱ hypothesisȱ thatȱ PGPȱ isȱ

ȱ 14 Backgroundȱ mainlyȱdueȱtoȱhypermobility.ȱYet,ȱinȱtheȱmidȬ1990s,ȱatȱtheȱtimeȱofȱtheȱplanningȱ ofȱ theȱ presentȱ thesis,ȱ thisȱ wasȱ anȱ establishedȱ beliefȱ amongȱ caregivers.ȱ However,ȱ itȱ hadȱ alreadyȱ beenȱ shownȱ withȱ roentgenȱ stereophotogrammetryȱ thatȱ theȱ quantityȱ ofȱ SIJȱ mobilityȱ wasȱ theȱ sameȱ inȱ womenȱ withȱ andȱ withoutȱ PGPȱ (227).ȱ Aȱ pregnancyȬinducedȱ physiologicalȱ increaseȱ inȱ laxityȱ ofȱ theȱ symphysealȱsoftȱtissueȱhadȱbeenȱreported.ȱHowever,ȱnoȱevidenceȱwasȱfoundȱ thatȱ theȱ degreeȱ ofȱ symphysealȱ distensionȱ determinesȱ theȱ severityȱ ofȱ pelvicȱ painȱinȱpregnancyȱorȱpostpartumȱ(25).ȱItȱhasȱbeenȱsuggestedȱthatȱasymmetricȱ laxityȱofȱtheȱrightȱandȱleftȱSIJȱduringȱpregnancyȱisȱaȱpredictorȱforȱpersistenceȱofȱ moderateȬtoȬsevereȱpregnancyȬrelatedȱPGPȱpostpartumȱ(51).ȱ

Muscleȱfunctionȱinȱrelationȱtoȱlumbopelvicȱstabilityȱ Onlyȱ inȱ moreȱ recentȱ yearsȱ hasȱ theȱ contributionȱ ofȱ muscleȱ functionȱ towardsȱ lumbopelvicȱ stabilityȱ beenȱ discussed.ȱ Accordingȱ toȱ Bastiaanssenȱ etȱal.ȱ (2005)ȱ (11)ȱLehmannȱetȱal.ȱ(1861)ȱandȱSnellingȱetȱal.ȱ(1870)ȱwereȱtheȱfirstȱtoȱmentionȱ thatȱ greatȱ physicalȱ and/orȱ muscularȱ weaknessȱ wereȱ causesȱ ofȱ theȱ painfulȱ “sensations”ȱ inȱ theȱ pelvis.ȱ Overȱ theȱ 100ȱ yearsȱ followingȱ theseȱ earlyȱ studies,ȱ veryȱfewȱauthorsȱhaveȱdiscussedȱtheȱimportanceȱofȱmuscles.ȱ“ReȬeducation”ȱofȱ theȱbackȱmuscles,ȱafterȱdaysȱofȱtreatmentȱwithȱcompleteȱbedȱrest,ȱhasȱbrieflyȱ beenȱ mentionedȱ (268).ȱ Genellȱ (1949)ȱ discussedȱ theȱ causeȱ ofȱ aȱ positiveȱ Trendelenburg’sȱtestȱinȱsevereȱcasesȱandȱconsideredȱlooseningȱofȱtheȱSIJȱandȱ symphysisȱ toȱ beȱ soȱ extremeȱ thatȱ theȱ musclesȱ couldȱ notȱ holdȱ upȱ theȱ nonsupportedȱhalfȱofȱtheȱpelvisȱ(75).ȱFarbrotȱ(1952)ȱdiscussedȱtheȱimportanceȱ ofȱ theȱ longȱ hipȱ extensorsȱ andȱ theȱ abdominalȱ musclesȱ whichȱ preventȱ aȱ horizontalȱpositionȱofȱtheȱsacrumȱ(65).ȱLikewise,ȱtheȱgwastin ȱofȱtheȱabdominalȱ wallȱ musclesȱ wasȱ mentionedȱ asȱ aȱ probableȱ causeȱ ofȱ PGP.ȱ Furthermore,ȱ theȱ valueȱ ofȱ “systematicȱ exercise”ȱ wasȱ discussedȱ asȱ aȱ prophylacticȱ measure.ȱ Inȱ anotherȱ study,ȱ itȱ wasȱ statedȱ thatȱ “aȱ moreȱ orȱ lessȱ functionalȱ insufficiencyȱ ofȱ musculatureȱofȱtheȱpelvicȱgirdleȱhasȱitsȱplaceȱinȱtheȱsymptomatology”ȱ(238).ȱ ȱ Theȱ lumbopelvicȱ regionȱ needsȱ toȱ beȱ stableȱ inȱ orderȱ toȱ permitȱ loadȱ transferȱ fromȱ theȱ trunkȱ toȱ theȱ lowerȱ extremities.ȱ Atȱ theȱ sameȱ time,ȱ thereȱ mustȱ beȱ aȱ certainȱamountȱofȱmobilityȱinȱorderȱtoȱachieveȱlocomotion.ȱStaticȱandȱdynamicȱ stabilityȱ areȱ achievedȱ whenȱ theȱ active,ȱ passiveȱ andȱ controlȱ systemsȱ workȱ togetherȱ (188).ȱ Aȱ biomechanicalȱ modelȱ ofȱ aȱ selfȬlockingȱ mechanismȱ ofȱ theȱ pelvicȱ joints,ȱ basedȱ onȱ theȱ principlesȱ ofȱ formȱ andȱ forceȱ closure,ȱ hasȱ beenȱ describedȱ (221,ȱ 260).ȱ Formȱ closureȱ refersȱ toȱ theȱ closelyȱ fittingȱ sacroiliacȱ jointȱ surfaces.ȱForceȱclosureȱrefersȱtoȱtheȱcompressiveȱforcesȱneededȱinȱadditionȱtoȱ

ȱ 15 Backgroundȱ ȱ theȱformȱclosureȱinȱorderȱtoȱwithstandȱtheȱverticalȱloadȱonȱtheȱrelativelyȱflatȱ surfacesȱofȱtheȱSIJ.ȱTheȱmusculoligamentousȱsystem,ȱgovernedȱbyȱtheȱnervousȱ system,ȱ isȱ responsibleȱ forȱ forceȱ closure.ȱ Theȱ musclesȱ mayȱ beȱ dividedȱ intoȱ 2ȱ functionalȱ muscleȱ systems:ȱ aȱ deep/localȱ andȱ aȱ superficial/globalȱ systemȱ (16).ȱ Theȱ localȱ musclesȱ areȱ thoughtȱ toȱ provideȱ controlȱ andȱ fineȬtuningȱ ofȱ intersegmentalȱmotionȱthatȱisȱnotȱspecificȱtoȱtheȱdirectionȱofȱforceȱwhereasȱtheȱ globalȱmusclesȱcontrolȱtheȱorientationȱofȱtheȱspineȱandȱdirectȱmovements.ȱTheȱ conceptȱofȱmotorȱcontrol,ȱwhereȱtheȱdeepȱmuscleȱcorsetȱandȱtheȱglobalȱmusclesȱ workȱinȱconcert,ȱdetermineȱtheȱlumbopelvicȱstabilityȱ(92,ȱ203,ȱ220).ȱ ȱ Severalȱ studiesȱ suggestȱ anȱ associationȱ betweenȱ nonpregnancyȬrelatedȱ PGPȱ andȱ decreasedȱ stabilityȱ ofȱ theȱ pelvis,ȱ probablyȱ dueȱ toȱ dysfunctionȱ ofȱ theȱ musclesȱwhichȱcontributeȱtoȱforceȱclosureȱofȱtheȱpelvicȱjointsȱ(96,ȱ184,ȱ198,ȱ204,ȱ 243).ȱ Whenȱ theȱ muscularȱ capacityȱ andȱ theȱ tensionȱ ofȱ theȱ ligamentsȱ areȱ inadequate,ȱ decreasedȱ compressionȱ acrossȱ theȱ SIJȱ willȱ occur,ȱ insufficientȱ stabilityȱ willȱ follow,ȱ andȱ optimalȱ loadȱ transferȱ betweenȱ theȱ backȱ andȱ legsȱ becomesȱcompromisedȱ(198).ȱȱ ȱ Theȱerectorȱspinae,ȱtheȱbicepsȱfemorisȱandȱtheȱgluteusȱmaximusȱareȱimportantȱ musclesȱforȱforceȱclosureȱofȱtheȱSIJȱ(243,ȱ259).ȱOtherȱmusclesȱofȱimportanceȱinȱ stabilizationȱofȱtheȱlumbopelvicȱareaȱareȱtheȱtransverseȱabdominalsȱ(204)ȱandȱ theȱ pelvicȱ floorȱ musclesȱ (212).ȱ Strengthȱ andȱ enduranceȱ ofȱ musclesȱ inȱ theȱ lumbopelvicȱareaȱhaveȱnotȱbeenȱtestedȱinȱpregnantȱwomen.ȱHowever,ȱitȱhasȱ beenȱ reportedȱ that,ȱ comparedȱ toȱ healthyȱ controls,ȱ patientsȱ withȱ LBPȱ haveȱ lowerȱenduranceȱinȱtheȱbackȱextensorsȱ(1,ȱ95)ȱandȱhipȱextensorsȱ(middleȬagedȱ women)ȱ(106),ȱdeficiencyȱinȱtrunkȱmusclesȱstrengthȱ(233),ȱandȱpoorerȱabilityȱtoȱ senseȱaȱchangeȱinȱlumbarȱposition,ȱespeciallyȱafterȱfatigueȱ(232).ȱ ȱ Muscleȱ functionȱ inȱ pregnancyȱ hasȱ beenȱ investigatedȱ inȱ 1ȱ studyȱ usingȱ electromyographyȱ (217).ȱ Theȱ resultsȱ indicatedȱ thatȱ reducedȱ backȱ muscleȱ activityȱ atȱ theȱ beginningȱ ofȱ pregnancyȱ leadsȱ toȱ moreȱ painȱ andȱ disabilityȱ throughoutȱtheȱpregnancy.ȱLowȱenduranceȱofȱbackȱandȱhipȱmusclesȱhasȱbeenȱ reportedȱinȱwomenȱwithȱlongstandingȱPGPȱandȱlumbarȱpainȱafterȱpregnancyȱ (168).ȱItȱwasȱindicatedȱthatȱmuscularȱinsufficiencyȱmayȱbeȱanȱimportantȱfactorȱ regardingȱ persistentȱ problems.ȱ Itȱ isȱ unknownȱ ifȱ theȱ reportedȱ insufficiencyȱ developedȱ dueȱ toȱ longstandingȱ problemsȱ orȱ ifȱ theȱ womenȱ alreadyȱ hadȱ muscularȱinsufficiencyȱearlyȱonȱinȱtheȱpregnancy.ȱ ȱ

ȱ 16 Backgroundȱ

Pregnancyȱ causesȱ biomechanicalȱ andȱ hormonalȱ changesȱ toȱ theȱ stabilisingȱ systemȱofȱtheȱlumbopelvicȱareaȱforȱallȱwomen,ȱhoweverȱnotȱallȱgetȱLBP.ȱTheȱ previouslyȱsuggestedȱ“hypermobilityȱhypothesis,”ȱasȱaȱcauseȱofȱPGP,ȱcanȱbeȱ translatedȱintoȱtheȱinabilityȱofȱtheȱmusculoligamentousȱsystemȱtoȱcompensateȱ forȱtheȱincreasedȱlaxityȱofȱtheȱpelvicȱjointsȱthroughȱdynamicȱstabilization.ȱItȱisȱ possibleȱ thatȱ theȱ relationsȱ areȱ notȱ linear,ȱ butȱ ratherȱ areȱ relatedȱ toȱ aȱ certainȱ threshold.ȱ

Gaitȱ Gait,ȱwithȱitsȱunilateralȱloading,ȱrequiresȱlumbopelvicȱstability.ȱAȱprerequisiteȱ forȱstabilityȱisȱadequateȱmuscleȱfunctionȱandȱthereȱareȱindicationsȱthatȱmusclesȱ andȱ theirȱ biomechanicalȱ conditionsȱ changeȱ duringȱ pregnancy.ȱ Pregnantȱ womenȱ areȱ sometimesȱ describedȱ asȱ havingȱ anȱ alteredȱ gaitȱ pattern,ȱ “aȱ waddlingȱ gait,”(150)ȱ definedȱ asȱ anȱ increasedȱ baseȱ ofȱ supportȱ (23).ȱ Byȱ waddling,ȱ theȱ womenȱ avoidȱ rotationȱ ofȱ theȱ lumbopelvicȱ regionȱ andȱ therebyȱ decreaseȱdemandsȱonȱstability.ȱȱ ȱ Theȱnaturalȱcustomaryȱwalkingȱspeedȱforȱadultsȱisȱfromȱ1.0ȱtoȱ1.67ȱm/sȱ(248).ȱ Inȱhealthyȱpregnantȱwomen,ȱcomfortableȱwalkingȱspeedȱhasȱbeenȱreportedȱinȱ someȱstudiesȱtoȱbeȱlowerȱcomparedȱtoȱnonpregnantȱwomenȱ(161,ȱ266),ȱandȱnotȱ changedȱinȱanotherȱ(68).ȱ ȱ WomenȱwithȱPGPȱreportȱactivityȱlimitationȱinȱwalkingȱ(66,ȱ85,ȱ136,ȱ150,ȱ264).ȱ Maximumȱ gaitȱ velocityȱ duringȱ walkingȱ wasȱ studiedȱ onȱ aȱ treadmillȱ inȱ 9ȱ womenȱwithȱpersistentȱPGPȱpostpartumȱ(265).ȱMaximumȱattainableȱwalkingȱ speedȱ variedȱ greatlyȱ inȱ womenȱ withȱ PGPȱ (0.17ȱȬ1.50ȱ m/s)ȱ asȱ comparedȱ toȱ healthyȱ controls,ȱ whereȱ allȱ womenȱ reachedȱ theȱ highestȱ levelȱ (1.50ȱ m/s).ȱ Theȱ authorȱ speculatedȱ thatȱ muscleȱ coordinationȱ parametersȱ wereȱ perhapsȱ responsibleȱforȱtheȱdifference.ȱ

CONSEQUENCESȱOFȱPREGNANCYȬRELATEDȱLOWȱBACKȱ PAINȱ Inȱ backȱ painȱ research,ȱ recommendedȱ studyȱ domainsȱ includeȱ genericȱ healthȱ status,ȱ pain,ȱ backȬspecificȱ function,ȱ workȱ disability,ȱ andȱ patientȱ satisfactionȱ (29).ȱ

ȱ 17 Backgroundȱ ȱ HealthȬrelatedȱqualityȱofȱlifeȱ Accordingȱ toȱ theȱ Worldȱ Healthȱ Organisationȱ (WHO),ȱ healthȱ isȱ “aȱ stateȱ ofȱ completeȱphysical,ȱmentalȱandȱsocialȱwellȬbeing,ȱandȱnotȱmerelyȱtheȱabsenceȱofȱ disease”ȱ (254).ȱ Healthȱ outcomeȱ researchȱ hasȱ restrictedȱ toȱ usingȱ theȱ conceptȱ “healthȬrelatedȱ qualityȱ ofȱ life”ȱ (HRQL)ȱ thatȱ addressesȱ theȱ consequencesȱ ofȱ diseaseȱ and/orȱ impairment,ȱ ratherȱ thanȱ aȱ specificȱ assessmentȱ ofȱ pathology,ȱ diseaseȱorȱimpairmentȱthatȱisȱatȱtheȱorganȱorȱbodyȱsystemȱlevelȱ(102).ȱHRQLȱ includesȱ theȱ perceptionȱ ofȱ anȱ individualȱ ofȱ hisȱ orȱ herȱ degreeȱ ofȱ physical,ȱ psychologicalȱandȱsocialȱwellȬbeingȱandȱtheȱimpactȱtheȱillnessȱhasȱonȱdailyȱlifeȱ (87,ȱ102).ȱ ȱ InȱaȱSwedishȱpopulationȱsurvey,ȱwomenȱreportedȱaȱsignificantlyȱlowerȱHRQLȱ thanȱ men;ȱ specificallyȱ inȱ theȱ ageȱ groupsȱ 20Ȭ29,ȱ 30Ȭ39ȱ andȱ 60Ȭ69ȱ yearsȱ (37).ȱ Duringȱnormalȱpregnancy,ȱHRQLȱisȱreportedlyȱdecreasedȱ(94).ȱWellȬbeingȱinȱ pregnancyȱ isȱ affectedȱ byȱ severalȱ symptomsȱ suchȱ asȱ nauseaȱ (33),ȱ sleepingȱ disordersȱ (209)ȱ andȱ LBP.ȱ Onlyȱ 2ȱ pregnancyȬrelatedȱ LBPȱ studiesȱ wereȱ identifiedȱ thatȱ measuredȱ HRQL.ȱ Inȱ lateȱ pregnancy,ȱ womenȱ reportedȱ lowerȱ HRQLȱ thanȱ nonpregnantȱ healthyȱ womenȱ (173).ȱ Womenȱ withȱ backȱ painȱ reportedȱ theȱ mostȱ impairedȱ HRQL.ȱ Inȱ aȱ 2Ȭyearȱ followȬupȱ ofȱ aȱ randomisedȱ controlledȱ trialȱ withȱ treatmentȱ forȱ persistentȱ PGP,ȱ womenȱ whoȱ improvedȱ inȱ painȱandȱdisabilityȱreportedȱcomparableȱHRQLȱscoresȱonȱtheȱShortȱFormȱ36ȱ HealthȱSurveyȱ(SFȬ36)ȱtoȱnormalȱscoresȱfromȱaȱgeneralȱNorwegianȱpopulationȱ (226).ȱ Onȱ theȱ contrary,ȱ theȱ controlȱ groupȱ demonstratedȱ lowerȱ scoresȱ ofȱ physicalȱhealthȱbutȱnormalȱscoresȱofȱmentalȱhealthȱonȱtheȱSFȬ36.ȱItȱwouldȱbeȱ interestingȱ toȱ evaluateȱ howȱ pregnantȱ womenȱ estimateȱ theirȱ HRQLȱ inȱ earlyȱ pregnancyȱ andȱ compareȱ theȱ impactȱ onȱ healthȱ forȱ differentȱ typesȱ ofȱ LBPȱ experiencedȱ duringȱ pregnancy.ȱ Sinceȱ economicȱ analysisȱ ofȱ PGPȱ hithertoȱ isȱ limitedȱtoȱsickȱleaveȱcosts,ȱthereȱisȱaȱneedȱforȱanȱinstrumentȱthatȱcanȱbeȱusedȱinȱ formalȱ decisionȱ analysisȱ andȱ costȬeffectivenessȱ analysis,ȱ whereȱ PGPȱ canȱ beȱ relatedȱtoȱotherȱconditions.ȱThereȱisȱaȱlackȱofȱknowledgeȱregardingȱHRQLȱinȱ earlyȱpregnancyȱinȱwomenȱwithȱdifferentȱtypesȱofȱLBP.ȱ

Painȱ Painȱ isȱ aȱ subjectiveȱ experienceȱ andȱ includesȱ severalȱ components.ȱ Painȱ intensity,ȱdurationȱandȱlocalisationȱareȱincludedȱinȱtheȱsensoryȬdiscriminativeȱ component,ȱ andȱ itȱ isȱ influencedȱ byȱ emotionsȱ (affectiveȬmotivationalȱ component)ȱ asȱ wellȱ asȱ thoughts,ȱ beliefsȱ andȱ previousȱ experiencesȱ inȱ lifeȱ (evaluativeȬcognitiveȱ component)(147,ȱ 148).ȱ Measuresȱ ofȱ painȱ severityȱ areȱ

ȱ 18 Backgroundȱ differentȱfromȱmeasuresȱofȱpainȱaffectȱ(261).ȱPainȱseverityȱisȱaȱglobalȱconstructȱ measuredȱbyȱpainȱintensityȱandȱinterferenceȱwithȱactivities.ȱPainȱaffectȱisȱtheȱ degreeȱ ofȱ emotionalȱ arousalȱ orȱ changesȱ inȱ actionȱ readinessȱ causedȱ byȱ theȱ sensoryȱexperienceȱofȱpain.ȱPainȱisȱthusȱaȱmultidimensionalȱconstructȱandȱnoȱ consensusȱexistsȱasȱtoȱhowȱtoȱmeasureȱorȱclassifyȱpain.ȱChronicȱpainȱhasȱbeenȱ definedȱ asȱ “…thatȱ whichȱ persistsȱ beyondȱ theȱ normalȱ timeȱ ofȱ healing”(98).ȱ Persistentȱbackȱpainȱhasȱbeenȱdefinedȱasȱpainȱthatȱisȱpresentȱmostȱofȱtheȱtimeȱ forȱ aȱ periodȱ ofȱ 6ȱ monthsȱ orȱ moreȱ duringȱ theȱ priorȱ yearȱ (81).ȱ However,ȱ recurrentȱ painȱ episodesȱ thatȱ lastȱ lessȱ thanȱ 6ȱ monthsȱ mayȱ beȱ aȱ formȱ ofȱ persistentȱpainȱ(261).ȱThroughoutȱthisȱthesis,ȱtheȱtermȱpersistentȱpainȱisȱusedȱ insteadȱ ofȱ chronicȱ painȱ andȱ isȱ definedȱ asȱ recurrentȱ episodesȱ orȱ painȱ presentȱ mostȱofȱtheȱtimeȱǃ12ȱweeks.ȱ ȱ Theȱ frequencyȱ inȱ whichȱ painȱ shouldȱ beȱ measuredȱ inȱ orderȱ toȱ obtainȱ anȱ accurateȱpictureȱofȱtheȱpainȱexperienceȱisȱaȱmatterȱofȱdiscussion.ȱMeanȱpresentȱ painȱintensityȱscoresȱhaveȱbeenȱshownȱtoȱcorrelateȱ(ǃ0.80)ȱwithȱaverageȱpainȱ intensityȱscoresȱfromȱtheȱpreviousȱweekȱ(52).ȱHowever,ȱitȱisȱstillȱcontroversialȱ asȱ toȱ whetherȱ orȱ notȱ theȱ useȱ ofȱ aȱ singleȱ ratingȱ ofȱ currentȱ painȱ isȱ moreȱ appropriateȱthanȱtheȱuseȱofȱanȱaverageȱpainȱratingȱoverȱaȱspecificȱperiodȱ(28,ȱ 52).ȱAȱpainȱdrawingȱisȱanȱoutlineȱofȱtheȱbodyȱonȱwhichȱtoȱmarkȱpainȱlocationsȱ (200).ȱItȱisȱcommonlyȱusedȱtoȱevaluateȱ andȱdescribeȱpainȱlocations,ȱwhichȱhaveȱ beenȱshownȱtoȱbeȱrelatedȱtoȱdisabilityȱ(172).ȱ ȱ Painȱintensityȱinȱpregnantȱwomenȱwithȱbackȱpainȱhasȱbeenȱevaluatedȱatȱoneȱorȱ severalȱtimeȱpointsȱduringȱpregnancyȱ(85,ȱ116,ȱ175,ȱ228),ȱasȱwellȱasȱpostpartumȱ (166,ȱ 176,ȱ 182).ȱ Fewȱ authorsȱ haveȱ classifiedȱ backȱ painȱ andȱ reportedȱ painȱ intensityȱamongȱpatientsȱsubgroupedȱforȱdifferentȱtypesȱofȱpain.ȱInȱpregnantȱ women,ȱnoȱdifferenceȱinȱpainȱintensityȱwasȱidentifiedȱamongȱtheȱthreeȱpatientȱ painȱ subgroups:ȱ thoracicȱ pain,ȱ lumbarȱ painȱ andȱ posteriorȱ pelvicȱ painȱ (228).ȱ However,ȱsomeȱwomenȱbelongedȱtoȱ2ȱsubgroupsȱandȱthereȱwasȱlargeȱspreadȱ inȱtheȱnumberȱofȱgestationalȱweeksȱ(12Ȭ40),ȱwhichȱmakesȱtheȱresultsȱdifficultȱtoȱ interpret.ȱ Inȱ anotherȱ study,ȱ atȱ 7ȱ monthsȱ postpartumȱ noȱ differenceȱ inȱ painȱ intensityȱ wasȱ foundȱ betweenȱ patientsȱ groupedȱ accordingȱ toȱ theȱ followingȱ typesȱ ofȱ pain:ȱ posteriorȱ pelvicȱ pain,ȱ lumbarȱ pain,ȱ mixedȱ painȱ andȱ noȱ painȱ localisationȱ (166).ȱ Thereȱ isȱ aȱ lackȱ ofȱ knowledgeȱ regardingȱ painȱ intensityȱ inȱ earlyȱpregnancyȱinȱwomenȱwithȱdifferentȱtypesȱofȱLBP.ȱ

ȱ 19 Backgroundȱ ȱ Disabilityȱ Theȱ consequencesȱ ofȱ LBPȱ areȱ relatedȱ toȱ theȱ functioningȱ ofȱ patients.ȱ Functioningȱ isȱ aȱ generalȱ termȱ forȱ allȱ bodyȱ functions,ȱ activities,ȱ andȱ participationȱ fromȱ theȱ healthyȱ perspectiveȱ accordingȱ toȱ theȱ Internationalȱ Classificationȱ ofȱ Functioning,ȱ Disabilityȱ andȱ Healthȱ (ICF)ȱ (ICFȱ 2001)(255).ȱ Disabilityȱ isȱ aȱ generalȱ termȱ forȱ impairment,ȱ activityȱ limitations,ȱ andȱ participationȱrestrictionsȱfromȱtheȱproblematicȱaspect.ȱ ȱ Evaluationȱ ofȱ consequencesȱ ofȱ LBPȱ inȱ termsȱ ofȱ disabilityȱ isȱ importantȱ inȱ theȱ rehabilitationȱ processȱ forȱ identifyingȱ targetȱ areasȱ inȱ treatmentȱ strategies.ȱ Inȱ oneȱ ofȱ theȱ mostȱ commonlyȱ usedȱ backȬspecificȱ measuresȱ ofȱ selfȬreportedȱ functioning,ȱtheȱOswestryȱDisabilityȱIndexȱ(ODI)ȱ(29),ȱdisabilityȱisȱdefinedȱasȱ “theȱlimitationsȱofȱaȱpatient’sȱperformanceȱcomparedȱwithȱthatȱofȱaȱfitȱperson”ȱ (accordingȱ toȱ Garradȱ andȱ Bennettȱ (1971)ȱ inȱ Fairbank’sȱ article)(64).ȱ Thisȱ definitionȱ isȱ reasonablyȱ confinedȱ toȱ disabilityȱ accordingȱ toȱ theȱ WHOȱ definition.ȱ ȱ Pregnantȱ womenȱ reportedȱ restrictionsȱ inȱ activitiesȱ ofȱ dailyȱ life,ȱ howeverȱ pregnantȱ womenȱ withȱ backȱ painȱ reportedȱ significantlyȱ moreȱ restrictionsȱ inȱ physicalȱ abilitiesȱ (173).ȱ LBPȱ inȱ pregnancyȱ isȱ sometimesȱ lookedȱ uponȱ asȱ aȱ normalȱconsequenceȱofȱpregnancyȱ(72,ȱ134).ȱYet,ȱaȱthirdȱofȱpregnantȱwomenȱ reportȱ LBPȱ asȱ aȱ severeȱ problemȱ whichȱ interferesȱ withȱ activitiesȱ ofȱ dailyȱ lifeȱ andȱcompromisesȱtheirȱabilityȱtoȱworkȱ(116,ȱ138,ȱ177).ȱPregnantȱwomenȱwhoȱ consultedȱphysicalȱtherapistsȱbecauseȱofȱPGP,ȱreportedȱaȱconsiderableȱlevelȱofȱ complaintsȱinȱactivitiesȱofȱdailyȱlivingȱsuchȱasȱwalking,ȱstanding,ȱsitting,ȱlyingȱ down,ȱ andȱ changingȱ positionsȱ (210).ȱ Inȱ anotherȱ study,ȱ aȱ highȱ proportionȱ ofȱ womenȱwithȱPGPȱcouldȱnoȱlongerȱcarryȱoutȱactivitiesȱsuchȱasȱlifting, ȱcarrying,ȱ andȱvacuumȬcleaningȱbyȱthemselvesȱ(121).ȱOnȱtheȱcontrary,ȱinȱaȱsmallȱstudy,ȱ lowȬgradeȱdisabilityȱwasȱreportedȱbyȱtheȱmajorityȱofȱwomenȱwithȱbackȱpainȱinȱ lateȱpregnancyȱ(186).ȱ ȱ ConsequencesȱofȱpregnancyȬrelatedȱLBPȱhaveȱthusȱprimarilyȱbeenȱreportedȱinȱ termsȱofȱactivitiesȱthatȱproduceȱorȱincreaseȱpain ȱ(66,ȱ85,ȱ136,ȱ138,ȱ177,ȱ210)ȱasȱ wellȱasȱinȱtermsȱofȱpainȱintensityȱandȱsickȱleaveȱ(109,ȱ183,ȱ231).ȱAccordingly,ȱ consequencesȱ onȱ disabilityȱ andȱ HRQLȱ wereȱ mainlyȱ notȱ describedȱ withȱ establishedȱ measurementȱ toolsȱ atȱ theȱ planningȱ ofȱ theȱ presentȱ study.ȱ Furthermore,ȱthereȱisȱaȱlackȱofȱknowledgeȱregardingȱdisabilityȱandȱHRQLȱinȱ earlyȱpregnancyȱinȱwomenȱwithȱdifferentȱtypesȱofȱLBP.ȱ

ȱ 20 Backgroundȱ

DEPRESSIONȱ Fromȱ researchȱ onȱ nonpregnancyȬrelatedȱ LBP,ȱ itȱ hasȱ beenȱ shownȱ thatȱ psychosocialȱ factorsȱ playȱ aȱ roleȱ inȱ LBPȱ (8,ȱ 79,ȱ 114).ȱ Inȱ aȱ generalȱ Swedishȱ community,ȱ theȱ annualȱ incidenceȱ ofȱ firstȱ timeȱ depressionȱ inȱ womenȱ wasȱ reportedȱasȱ7.6ȱperȱ1000ȱpersonȱyearsȱ(208).ȱAmongȱfemaleȱpatientsȱinȱprimaryȱ healthcareȱinȱtheȱNordicȱcountries,ȱtheȱreportedȱprevalenceȱofȱdepressionȱwasȱ 9.9Ȭ14.2%ȱ(158).ȱAlthoughȱitȱisȱnotȱclearȱwhichȱcomesȱfirst,ȱdepressionȱorȱLBP,ȱ itȱhasȱbeenȱshownȱthatȱaȱdepressedȱmoodȱincreasesȱtheȱriskȱforȱpainȱproblemsȱ andȱthatȱpsychosocialȱvariablesȱareȱclearlyȱlinkedȱtoȱtheȱtransitionȱfromȱacuteȱ toȱpersistentȱpainȱdisabilityȱ(129).ȱTheȱriskȱofȱsufferingȱfromȱdepressionȱwhenȱ havingȱ backȱ painȱ hasȱ beenȱ reportedȱ toȱ increaseȱ byȱ 1.40ȱ toȱ 2.06ȱ inȱ aȱ generalȱ populationȱ(144).ȱOneȱaimȱofȱtheȱphysicalȱtherapyȱexaminationȱisȱtoȱidentifyȱorȱ excludeȱ conditionsȱ thatȱ canȱ contraindicateȱ treatmentȱ orȱ reduceȱ theȱ effectivenessȱofȱinterventionȱ (83).ȱItȱhasȱbeenȱreportedȱthatȱprimaryȱhealthȱcareȱ physiciansȱ (196),ȱ asȱ wellȱ asȱ physiotherapistsȱ (83),ȱ doȱ notȱ accuratelyȱ identifyȱ symptomsȱofȱdepression.ȱ ȱ Accordingȱ toȱ theȱ Diagnosticȱ andȱ Statisticalȱ Manualȱ ofȱ Mentalȱ DisordersȬIVȱ classificationsȱ (7),ȱ depressiveȱ symptomsȱ areȱ definedȱ asȱ theȱ following:ȱ depressedȱmood,ȱlossȱofȱinterestȱorȱpleasure,ȱalteredȱappetite,ȱweightȱorȱsleepȱ patterns,ȱpsychomotorȱagitation/retardation,ȱfatigue/lossȱofȱenergy,ȱfeelingsȱofȱ worthlessness,ȱ selfȬreproachȱ orȱ inappropriateȱ guilt,ȱ diminishedȱ abilityȱ toȱ think,ȱ concentrateȱ orȱ indecisivenessȱ andȱ recurrentȱ thoughtsȱ ofȱ deathȱ orȱ suicidalȱideation.ȱAȱmajorȱdepressionȱisȱdefinedȱasȱ5ȱorȱmoreȱofȱtheȱdepressiveȱ symptomsȱthatȱhaveȱbeenȱpresentȱduringȱaȱ2Ȭweekȱperiodȱandȱincludeȱatȱleastȱ depressedȱmoodȱorȱlossȱofȱinterestȱorȱpleasure.ȱ

Postpartumȱdepressionȱ Depressionȱisȱapproximatelyȱtwiceȱasȱcommonȱinȱwomenȱasȱitȱisȱinȱmen,ȱandȱ thereȱ isȱ aȱ peakȱ inȱ depressionȱ debutȱ duringȱ theȱ childbearingȱ yearsȱ (251).ȱ Emotionalȱ problemsȱ inȱ relationȱ toȱ pregnancyȱ mayȱ fallȱ intoȱ 3ȱ categoriesȱ thatȱ rangeȱ fromȱ theȱ lighterȱ maternalȱ blues,ȱ overȱ postpartumȱ depression,ȱ intoȱ theȱ moreȱsevereȱpsychosis.ȱMaternalȱbluesȱareȱconsideredȱaȱrelativelyȱmild,ȱselfȬ limitingȱ moodȱ stateȱ thatȱ occursȱ inȱ theȱ earlyȱ postpartumȱ period,ȱ andȱ affectsȱ betweenȱ50Ȭ80%ȱofȱmothers.ȱPostpartumȱpsychosisȱis,ȱonȱtheȱcontrary,ȱaȱrareȱ conditionȱaffectingȱ0.1Ȭ0.4%ȱofȱmothersȱ(223,ȱ251).ȱAroundȱ10–20%ȱofȱwomenȱ sufferȱfromȱdepressiveȱillnessȱ duringȱpregnancyȱorȱtheȱfirstȱyearȱpostpartumȱ (46,ȱ 76,ȱ 104).ȱ Mostȱ womenȱ experienceȱ theȱ depressionȱ onsetȱ withinȱ 6ȱ weeksȱ

ȱ 21 Backgroundȱ ȱ postpartum,ȱandȱtheȱdurationȱisȱtypicallyȱ2ȱtoȱ6ȱmonthsȱ(43).ȱIfȱleftȱuntreated,ȱitȱ mayȱstillȱpersistȱforȱ1ȱyearȱafterȱdeliveryȱinȱupȱtoȱ25%ȱofȱwomenȱ(32).ȱ ȱ Whenȱ studyingȱ postpartumȱ depression,ȱ itȱ isȱ essentialȱ toȱ excludeȱ itemsȱ thatȱ mightȱ reflectȱ physicalȱ discomfortȱ andȱ therebyȱ confuseȱ depressionȱ withȱ theȱ somaticȱeffectsȱofȱpregnancyȱandȱchildbirth.ȱThisȱisȱaȱprimaryȱfeatureȱwithȱtheȱ EdinburghȱPostnatalȱDepressionȱScaleȱ(EPDS)(45,ȱ104).ȱAlthoughȱtheȱEPDSȱisȱ notȱdiagnostic,ȱitȱisȱaȱvalidȱscreeningȱmeasureȱ(86).ȱFiveȱofȱtheȱitemsȱinȱEPDSȱ areȱ concernedȱ withȱ dysphoricȱ moodȱ itself,ȱ twoȱ withȱ anxiety,ȱ andȱ oneȱ eachȱ withȱguilt,ȱsuicidalȱideasȱandȱnoncoping.ȱ ȱ InȱaȱpostalȱsurveyȱinȱAustralia,ȱpregnancyȬrelatedȱbackȱpainȱwasȱfoundȱtoȱbeȱ associatedȱ withȱ aȱ 2.2ȱ increasedȱ riskȱ ofȱ postpartumȱ depressionȱ (35).ȱ Inȱ aȱ treatmentȱ studyȱ forȱ postpartumȱ PGP,ȱ noȱ differenceȱ inȱ mentalȱ disordersȱ wasȱ foundȱ betweenȱ womenȱ whoȱ hadȱ receivedȱ specificȱ orȱ nonspecificȱ treatmentȱ strategiesȱ forȱ PGPȱ (226).ȱ Furthermore,ȱ postpartumȱ depressionȱ hasȱ beenȱ associatedȱ withȱ sickȱ leaveȱ inȱ pregnancyȱ dueȱ toȱ pregnancyȬrelatedȱ complicationsȱ (103).ȱ Inȱ theȱ Scandinavianȱ countries,ȱ backȱ painȱ isȱ theȱ mostȱ frequentȱreasonȱforȱsickȱleaveȱduringȱpregnancyȱ(230,ȱ264).ȱThereforeȱitȱisȱalsoȱ relevantȱ toȱ evaluateȱ theȱ associationȱ betweenȱ LBPȱ andȱ depression.ȱ Clinicalȱ classificationȱ ofȱ theȱ experiencedȱ LBPȱ wouldȱ giveȱ additionalȱ informationȱ regardingȱpossibleȱdifferencesȱinȱdepressiveȱsymptomsȱbetweenȱtypesȱofȱLBP.ȱ ȱ Inȱ conclusionȱ LBPȱ isȱ oneȱ ofȱ theȱ mostȱ commonȱ complicationsȱ ofȱ pregnancy,ȱ withȱnegativeȱconsequencesȱforȱtheȱaffectedȱwoman,ȱasȱwellȱasȱforȱsociety.ȱTheȱ consequencesȱ needȱ toȱ beȱ betterȱ describedȱ forȱ theȱ differentȱ subtypesȱ ofȱ LBP.ȱ Thereȱareȱbiomechanicalȱ changesȱthatȱ influenceȱ lumbopelvicȱ stabilityȱ duringȱ pregnancyȱandȱsomeȱindicationsȱthatȱthereȱmayȱbeȱinterindividualȱdifferencesȱ inȱmuscularȱadaptationȱtoȱtheȱchanges.ȱIdentificationȱofȱwomenȱwhoȱareȱatȱriskȱ forȱpersistentȱpostpartumȱLBPȱisȱof ȱvalueȱforȱclinicalȱmanagement.ȱLikewise,ȱ evaluationȱofȱpossibleȱinfluencesȱonȱcomorbidityȱisȱimportant.ȱ

ȱ 22 Backgroundȱ

AIMSȱOFȱTHEȱTHESISȱ

Theȱoverallȱaimsȱofȱthisȱthesisȱwereȱtheȱfollowing:ȱ ȱ x toȱinvestigateȱifȱthereȱwereȱdifferencesȱinȱhealthȬrelatedȱqualityȱofȱlife,ȱ painȱintensity,ȱdisability,ȱdepressiveȱsymptomsȱorȱmuscleȱfunction,ȱinȱ subgroupsȱofȱlowȱbackȱpainȱinȱrelationȱtoȱpregnancy,ȱ ȱ x toȱidentifyȱpredictorsȱforȱpersistentȱpregnancyȬrelatedȱpelvicȱgirdleȱpainȱ orȱcombinedȱpainȱpostpartum.ȱ ȱ ȱ ȱ Theȱspecificȱaimsȱofȱthisȱthesisȱwereȱtheȱfollowing:ȱ ȱ x toȱdescribeȱtheȱprevalenceȱofȱclinicallyȱclassifiedȱsubgroupsȱofȱlowȱbackȱ painȱinȱaȱcohortȱofȱwomenȱduringȱpregnancyȱandȱpostpartumȱ(Iȱ&ȱIV),ȱ ȱ x toȱevaluateȱifȱthereȱwasȱaȱdisparityȱinȱtheȱcourseȱofȱclinicallyȱclassifiedȱ subgroupsȱ ofȱ lowȱ backȱ painȱ inȱ pregnancyȱ andȱ postpartum,ȱ andȱ toȱ predictȱearlyȱonȱinȱpregnancyȱwhoȱwasȱatȱriskȱforȱpersistentȱpregnancyȬ relatedȱpelvicȱgirdleȱpainȱorȱcombinedȱpainȱ(IV),ȱ ȱ x toȱ evaluateȱ theȱ consequencesȱ ofȱ pregnancyȬrelatedȱ lowȱ backȱ painȱ inȱ termsȱofȱhealthȬrelatedȱqualityȱofȱlife,ȱpainȱintensity,ȱandȱdisabilityȱforȱ differentȱsubgroupsȱofȱlowȱbackȱpainȱduringȱpregnancyȱ(I),ȱ ȱ x toȱ evaluateȱ ifȱ thereȱ wasȱ anȱ associationȱ betweenȱ lowȱ backȱ painȱ postpartumȱ andȱ depressiveȱ symptomsȱ andȱ toȱ evaluateȱ ifȱ thereȱ wasȱ aȱ differenceȱ inȱ theȱ prevalenceȱ ofȱ depressiveȱ symptomsȱ amongȱ differentȱ subgroupsȱofȱlowȱbackȱpainȱ(II),ȱ ȱ x toȱ evaluateȱ muscleȱ functionȱ duringȱ pregnancyȱ andȱ postpartumȱ inȱ womenȱ withoutȱ lowȱ backȱ painȱ andȱ inȱ subgroupsȱ ofȱ womenȱ withȱ lowȱ backȱpainȱ(III).ȱ ȱ

ȱ 23 MaterialsȱandȱMethodsȱ ȱ

MATERIALSȱANDȱMETHODSȱ

DESIGNȱ Theȱstudyȱconsistedȱofȱ2ȱparts:ȱaȱprospectiveȱcohortȱstudyȱandȱaȱRCTȱwhereȱ womenȱwithȱpersistentȱpostpartumȱPGPȱorȱcombinedȱpainȱwereȱfollowedȱforȱ2ȱ yearsȱafterȱpregnancy.ȱThisȱthesisȱcomprisesȱdataȱcollectedȱinȱtheȱprospectiveȱ cohortȱ studyȱ atȱ theȱ evaluationȱ duringȱ gestationalȱ weeksȱ 12Ȭ18ȱ andȱ atȱ theȱ evaluationȱ3ȱmonthsȱpostpartumȱ(Figureȱ1).ȱ ȱ Evenȱ thoughȱ PGPȱmayȱstart,ȱ onȱ averageȱ inȱ theȱ18thȱ gestationalȱ weekȱ (267)ȱitȱ wasȱtheȱintentionȱtoȱevaluateȱasȱearlyȱasȱpossibleȱduringȱpregnancyȱbutȱpastȱ theȱpointȱofȱhighestȱriskȱforȱmiscarriage.ȱAnotherȱlimitingȱfactorȱforȱtheȱtimeȱ pointȱ ofȱ inclusionȱ wasȱ thatȱ theȱ womenȱ neededȱ toȱ beȱ ableȱ toȱ performȱ theȱ muscleȱtestsȱbeforeȱtheȱgrowingȱabdomenȱhinderedȱtheȱtesting.ȱAdditionally,ȱitȱ wasȱdesiredȱtoȱstudyȱpotentialȱpredictiveȱfactorsȱearlyȱonȱinȱpregnancyȱwhenȱ symptomsȱwereȱlessȱestablished.ȱTheȱsecondȱevaluationȱwasȱatȱthreeȱmonthsȱ postpartumȱsinceȱlittleȱimprovementȱfromȱpregnancyȬrelatedȱPGPȱoccursȱafterȱ 3ȱmonthsȱ(112,ȱ176,ȱ182).ȱ

ȱ 24 MaterialsȱandȱMethodsȱ

THE PART OF THE STUDY INCLUDED IN THE THESIS

CLASSIFICATIONȱ CLASSIFICATIONȱ CLASSIFICATION EQ-5D NO LBP EQ-5D EQ-5D SPECIFIC PAIN VAS STABILISATION PAIN VAS PAIN VAS LUMBAR ODI ODI ODI E EPDS ȱ P PGP PREGNANTȱ D MUSCLEȱ COMBINED MUSCLE MUSCLE S CLINICAL FUNCTION PAIN FUNCTION FUNCTION ȱ NATURAL ȱ COURSE GAIT GAIT GAIT

TIME

GESTATIONAL 3 MONTHS AFTER 3, 6, 12, 24 MONTHS WEEKS 12-18 DELIVERY AFTER INCLUSION

ȱ Figureȱ1. Flow chart of the study.ȱ

ȱ 25 MaterialsȱandȱMethodsȱ ȱ

STUDYȱPOPULATIONȱ TheȱprenatalȱhealthcareȱsystemȱinȱSwedenȱservesȱalmostȱ100%ȱofȱtheȱcountry’sȱ pregnantȱwomen,ȱprovidingȱregularȱphysicalȱandȱpsychologicalȱhealthȱcheckȬ upsȱduringȱpregnancyȱandȱpostpartum.ȱSixȱmidwifesȱatȱ2ȱprenatalȱhealthcareȱ clinics,ȱhousedȱinȱaȱsociodemographicallyȱdiverseȱcommunityȱofȱ26000ȱpeople,ȱ wereȱ involvedȱ inȱ theȱ recruitmentȱ processȱ thatȱ lastedȱ 2ȱ years.ȱ Theȱ studiedȱ cohortȱwasȱcomprisedȱofȱallȱpregnantȱwomenȱconsecutivelyȱregisteredȱatȱtheȱ2ȱ prenatalȱ healthcareȱ clinics.ȱ SwedishȬspeakingȱ womenȱ withȱ anȱ expectedȱ normalȱ pregnancyȱ (asȱ determinedȱ byȱ theȱ midwives)ȱ wereȱ approachedȱ forȱ participationȱ duringȱ gestationalȱ weeksȱ 12Ȭ18.ȱ Womenȱ wereȱ excludedȱ ifȱ theyȱ hadȱ aȱ systemicȱ locomotorȱ disease,ȱ aȱ verifiedȱ diagnosisȱ ofȱ aȱ spinalȱ problemȱ duringȱtheȱpreviousȱ2ȱmonths,ȱorȱaȱhistoryȱofȱfracture,ȱneoplasm,ȱorȱpreviousȱ spinal,ȱpelvicȱorȱfemurȱsurgery.ȱ

MEASUREMENTSȱANDȱPROCEDURESȱ Oneȱphysiotherapist,ȱ(AG)ȱscheduledȱtheȱparticipantsȱforȱassessmentȱandȱdidȱ allȱtheȱevaluationsȱatȱ1ȱprimaryȱhealthȱcareȱclinic.ȱAllȱparticipantsȱcompletedȱ questionnairesȱandȱwereȱphysicallyȱevaluatedȱduringȱgestationalȱweeksȱ12Ȭ18ȱ andȱ3ȱmonthsȱpostpartum.ȱEachȱfullȱassessmentȱtookȱapproximatelyȱ1.5ȱhoursȱ toȱcomplete.ȱ

SelfȬreportedȱquestionnairesȱ First,ȱwhenȱchoosingȱaȱmeasurementȱtool,ȱitȱisȱnecessaryȱtoȱassessȱwhetherȱorȱ notȱtheȱinstrumentȱmeasuresȱtheȱappropriateȱconstructȱunderȱstudyȱandȱifȱitȱisȱ appropriateȱforȱtheȱparticularȱpopulationȱ(faceȱvalidity).ȱPriorȱtoȱtheȱstudy,ȱtheȱ questionnaireȱ wasȱ examinedȱ byȱ anȱ expertȱ inȱ PGPȱ andȱ filledȱ inȱ byȱ 5ȱ womenȱ withȱPGP,ȱwhoȱconfirmedȱtheȱfaceȱvalidity.ȱ ȱ Theȱquestionnaireȱincludedȱbackgroundȱdata,ȱasȱwellȱasȱquestionsȱregardingȱ urinaryȱ incontinence,ȱ activityȱ levelȱ (71),ȱ employmentȱ status,ȱ workȱ dissatisfaction,ȱ andȱ HRQL.ȱ Participantsȱ whoȱ hadȱ previouslyȱ experiencedȱ nonspecificȱLBPȱalsoȱansweredȱquestionsȱaboutȱsickȱleaveȱdueȱtoȱLBP,ȱwhetherȱ LBPȱhadȱhinderedȱtheirȱworkȱduringȱtheȱpastȱ5ȱyears,ȱpresentȱpainȱintensity,ȱ andȱ disability.ȱ Theȱ postpartumȱ questionnaireȱ wasȱ theȱ sameȱ asȱ theȱ questionnaireȱ inȱ gestationalȱ weeksȱ 12Ȭ18ȱ exceptȱ forȱ specificȱ questionsȱ

ȱ 26 MaterialsȱandȱMethodsȱ regardingȱdelivery,ȱsuchȱasȱmodeȱofȱdelivery,ȱdeliveryȱposition,ȱvaginalȱcutsȱatȱ delivery,ȱbabyȱweight,ȱbreastȱfeedingȱasȱwellȱasȱquestionsȱaboutȱtreatmentȱandȱ treatmentȱeffectȱinȱtheȱcaseȱofȱLBP.ȱAlso,ȱpostpartum,ȱaȱdepressionȱscaleȱwasȱ added.ȱ Theȱ participantsȱ hadȱ theȱ opportunityȱ toȱ askȱ questionsȱ regardingȱ theȱ questionnaire,ȱifȱneeded.ȱ

HealthȬrelatedȱqualityȱofȱlifeȱ TheȱEuropeanȱQualityȱofȱLifeȱ5ȱDimensionsȱQuestionnaireȱ(EQȬ5D)ȱ(199,ȱ234)ȱ wasȱusedȱforȱmeasuringȱHRQL.ȱTheȱdevelopmentȱofȱEQȬ5Dȱforȱtheȱassessmentȱ ofȱ HRQLȱ withinȱ populationȱ surveys,ȱ aimedȱ atȱ creatingȱ aȱ healthȱ stateȱ classificationȱ throughȱ whichȱ anȱ overallȱ indexȱ couldȱ beȱ derivedȱ usingȱ preferencesȱfromȱtheȱgeneralȱpopulation,ȱandȱtherebyȱenablingȱcalculationȱofȱ Qualityȱ Adjustedȱ Lifeȱ Yearsȱ (QALYs).ȱ QUALYsȱ areȱ quantitativeȱ estimatesȱ reflectingȱhowȱindividualsȱvalueȱhealthȱstates,ȱandȱareȱtypicallyȱscaledȱfromȱ0ȱ toȱ1.ȱQUALYsȱcanȱbeȱusedȱinȱeconomicȱanalysesȱ(42).ȱ ȱ TheȱEQȬ5DȱconsistsȱofȱtwoȱpartsȱthatȱmonitorȱHRQL.ȱTheȱfirstȱpartȱinvolvesȱaȱ healthȱstateȱclassificationȱschemeȱofȱ5ȱitemsȱwithȱ3ȱresponseȱcategoriesȱ(1ȱ=ȱnoȱ problems,ȱ 2ȱ =ȱ moderateȱ problems,ȱ andȱ 3ȱ =ȱ severeȱ problems).ȱ Theȱ questionsȱ involveȱ theȱ followingȱ dimensions:ȱ mobility,ȱ selfȱ care,ȱ usualȱ activities,ȱ pain/discomfort,ȱ andȱ anxiety/depression.ȱ Thereȱ areȱ 243ȱ (35)ȱ possibleȱ distinctȱ healthȱ states.ȱ Eachȱ healthȱ stateȱ hasȱ aȱ preferenceȱ valueȱ attachedȱ toȱ itȱ andȱ possibleȱvaluesȱrangeȱfromȱȬ0.59ȱtoȱ1.0ȱwhereȱ1.0ȱisȱoptimalȱhealth.ȱTheȱsecondȱ partȱofȱEQȬ5Dȱisȱaȱverticalȱ20ȱcmȱVASȱrangingȱfromȱ0ȱ(worstȱpossibleȱhealthȱ state)ȱ toȱ 100ȱ (bestȱ possibleȱ healthȱ state),ȱ onȱ whichȱ theȱ respondentsȱ rateȱ howȱ theyȱperceiveȱtheirȱhealthȱonȱthatȱparticularȱday.ȱTheȱVASȱisȱnotȱusedȱwhenȱ derivingȱtheȱpreferenceȱvalue.ȱTheȱminimalȱimportantȱdifferenceȱ(MID)ȱforȱtheȱ EQȬ5Dȱscoreȱhasȱbeenȱreportedȱtoȱrangeȱbetweenȱ0.09Ȭ0.22ȱandȱforȱtheȱEQȬ5Dȱ VAS,ȱtheȱestimatesȱrangeȱfromȱ3.82ȱtoȱ8.43ȱ(216).ȱ

Painȱ Painȱ intensityȱ wasȱ measuredȱ inȱ theȱ questionnairesȱ onȱ 2ȱ separateȱ 100ȱ mmȱ horizontalȱVAS,ȱwithȱtheȱendsȱlabeledȱasȱtheȱextremesȱofȱpainȱi.e.ȱ“noȱpain”ȱtoȱ “worstȱimaginableȱpain”ȱ(97).ȱTheȱfirstȱVASȱwasȱusedȱtoȱassessȱpresentȱpainȱ intensityȱandȱtheȱsecondȱVASȱwasȱusedȱtoȱassessȱaverageȱpainȱintensityȱduringȱ theȱpastȱweekȱ(52).ȱPainȱintensityȱwasȱalsoȱmeasuredȱwithȱaȱplasticȱVASȱrulerȱ withȱ aȱ slidingȱ marker,ȱ beforeȱ andȱ afterȱ eachȱ physicalȱ functioningȱ test.ȱ Aȱ previousȱstudyȱhasȱshownȱthatȱtheȱscoreȱchangesȱwithȱtheȱbestȱcutȬoffȱpointsȱ

ȱ 27 MaterialsȱandȱMethodsȱ ȱ forȱ discriminatingȱ betweenȱ improvedȱ andȱ nonimprovedȱ patientsȱ wasȱ 10Ȭ18ȱ mmȱonȱtheȱVASȱ(17).ȱInȱanotherȱstudy,ȱaȱpainȱscoreȱofȱatȱleastȱ7ȱmmȱlessȱthanȱ theȱprecedingȱassessmentȱwasȱreportedȱasȱdecreasedȱpainȱ(39).ȱ ȱ InȱourȱstudyȱpainȱlocationȱwasȱselfȬassessedȱbyȱtheȱwomenȱonȱaȱpainȱdrawingȱ inȱtheȱquestionnaireȱ(200).ȱTheȱextentȱandȱdistributionȱofȱpainȱreportedȱonȱpainȱ drawingsȱhaveȱbeenȱfoundȱtoȱbeȱreasonablyȱstableȱoverȱtimeȱ(139)ȱandȱtoȱhaveȱ highȱcriterion,ȱconstruct,ȱandȱcontentȱvalidityȱ(171).ȱ

Disabilityȱ TheȱOswestryȱLowȱBackȱPainȱDisabilityȱQuestionnaireȱ(ODI)(63)ȱwasȱusedȱtoȱ measureȱbackȬspecificȱfunctioning,ȱthatȱisȱactivitiesȱofȱdailyȱlivingȱthatȱmightȱ beȱ disruptedȱ byȱ LBP.ȱ Theȱ revisedȱ versionȱ (2.0)ȱ (145)ȱ wasȱ usedȱ inȱ thisȱ studyȱ sinceȱ theȱ itemsȱ regardingȱ sexualȱ lifeȱ andȱ painȱ intensity,ȱ ratherȱ thanȱ painȱ medication,ȱwereȱ consideredȱimportantȱinȱtheȱstudiedȱpopulation.ȱTheȱwomenȱ rateȱ theirȱ perceivedȱ disabilityȱ onȱ 10ȱ differentȱ items:ȱ painȱ intensity,ȱ personalȱ care,ȱ lifting,ȱ walking,ȱ sitting,ȱ standing,ȱ sleeping,ȱ sexualȱ life,ȱ socialȱ lifeȱ andȱ travelling.ȱTheȱitemsȱareȱscoredȱfromȱ0ȱtoȱ5.ȱTheȱscoresȱofȱallȱitemsȱareȱaddedȱ up,ȱgivingȱaȱpossibleȱtotalȱscoreȱofȱ50.ȱTheȱtotalȱscoreȱisȱdoubledȱandȱexpressedȱ asȱaȱpercentage,ȱwhereȱ0%ȱrepresentsȱnoȱdisability.ȱTheȱODIȱscoresȱofȱpatientsȱ canȱ beȱ dividedȱ intoȱ categories:ȱ havingȱ minimalȱ orȱ noȱ disabilityȱ (0Ȭ20%),ȱ moderateȱdisabilityȱ(20Ȭ40%),ȱsevereȱdisabilityȱ(40Ȭ60%),ȱcrippledȱ(60Ȭ80%),ȱorȱ bedȬboundȱorȱexaggeratingȱtheȱsymptomsȱ(80Ȭ100%)ȱ(63).ȱ ȱ TwoȱexpertsȱinȱtheȱfieldȱofȱpregnancyȬrelatedȱLBPȱconsideredȱtheȱODIȱtoȱbeȱ suitableȱ forȱ measuringȱ theȱ desiredȱ qualitiesȱ ofȱ PGP.ȱ Aȱ pilotȱ studyȱ wasȱ performedȱ onȱ 5ȱ patientsȱ withȱ PGP.ȱ Theȱ suitabilityȱ ofȱ theȱ instrumentȱ wasȱ confirmed,ȱtherebyȱjustifyingȱtheȱfaceȱvalidityȱofȱtheȱODI.ȱAȱgoldȱstandardȱforȱ measuringȱ statusȱ inȱ LBPȱ patientsȱ isȱ notȱ available,ȱ thereforeȱ validityȱ ofȱ aȱ measurementȱinstrumentȱmustȱbeȱjudgedȱbyȱdirectȱcomparison.ȱTheȱpurposeȱ ofȱ functionalȱ statusȱ questionnairesȱ isȱ toȱ assessȱ limitationsȱ inȱ performingȱ movementsȱandȱactions.ȱItȱisȱimportantȱtoȱevaluateȱwhetherȱtheȱquestionsȱareȱ capacityȬorȱ performanceȬbased.ȱ Theȱ correlationȱ ofȱ ODIȱ toȱ physicalȱ signsȱ showedȱaȱwideȱrangeȱ(0.12Ȭ0.74)ȱ(18).ȱWhenȱrelatingȱpatientȱbehaviourȱtoȱtheȱ ODI,ȱ2ȱitemsȱ(sittingȱandȱwalking)ȱshowedȱgoodȱcorrelationȱwithȱperformance,ȱ whereasȱ liftingȱ correlatedȱ weaklyȱ (67).ȱ Aȱ laterȱ study,ȱ reportedȱ moderateȱ correlationȱ betweenȱ theȱ selfȬreportȱ ofȱ ODIȱ andȱ performanceȬbasedȱ measuresȱ (202).ȱ Goodȱ reliabilityȱ ofȱ theȱ ODIȱ hasȱ beenȱ reportedȱ (64,ȱ 78).ȱ Theȱ minimalȱ importantȱ changeȱ inȱ scoreȱ ofȱ ODIȱ hasȱ beenȱ reportedȱ toȱ 4Ȭ6%ȱ (17).ȱ Ifȱ oneȱ orȱ

ȱ 28 Materials and Methods more items of ODI were missing, the recommendation to calculate a percentage with a smaller denominator was followed.

VAS and ODI scores were used for group comparisons, as well as for dividing the cohort into women exhibiting or not exhibiting consequences due to their syndromes. A score of 0‐10 mm on the VAS and an ODI disability score of 0‐ 10% were defined as no consequence (269). Three groups were compared using the above cut‐offs; 1) those participants having neither pain nor disability, 2) those participants having either pain or disability, and 3) those participants having both pain and disability.

Postpartum depression The EPDS is a 10‐item self‐reported scale specifically designed to screen for postpartum depression in community samples. Each item is scored on a 4‐ point scale (0‐3) with a total score ranging from 0 to 30 where 0 is no depressive symptoms. The scale rates the intensity of depressive symptoms (7) present within the previous 7 days. Cox et al. (1987) proposed a cut‐off score of ≥10 if the test was to be used for screening purposes in primary healthcare, as in the present study (45). A cut‐off score of ≥13 was recommended for evaluating probable depression. Although the scale cannot confirm a diagnosis of depression, when using the threshold of ≥10, the sensitivity for detecting major depression has been reported to be 100%, with a specificity of 82% (86). The sensitivity of the Swedish version of the EPDS (cut‐off score of 11.5) has been reported to be 96%, with a specificity of 49% (256). In our study internal missing values of items excluded the EPDS measure. Good reliability has been reported for the EPDS (45). Four points on the EPDS is considered a clinically significant change in postnatal depression (140).

Classification of the cohort The description of the evaluation procedure is presented in table 2. Participants were assigned to 1 of the 4 following groups based on the type of pain experienced: no LBP, lumbar pain, PGP, or combined PGP and lumbar pain (combined pain). Assignment to 1 of the 3 LBP groups was made following examination by a specialised physiotherapist (AG). Only women who experienced some type of LBP were examined. The examination started with a standard history that focused on known characteristics of lumbar pain (142), as well as PGP (150, 180, 228), and the responses/tolerance to different

29 Materials and Methods positions and activities of daily life such as bending, sitting, standing, walking, and lying. Range of motion of the back was evaluated during standing flexion, extension, and lateral flexion. Five pelvic pain provocation tests were done in the sequence described below. In order to consider a pelvic pain provocation test positive, the test must reproduce the participant’s familiar pain regarding location and quality.

1. Distraction test. The participant lies supine. The examiner applies a posteriorly directed force to both anterior superior iliac spines (123). 2. Posterior pelvic pain provocation test. The participant lies supine with 90 degrees of flexion at the hip and knee on the tested side. The examiner stabilizes the contralateral side of the pelvis over the superior anterior iliac spine. A light manual pressure is applied on the patient’s flexed knee, along the longitudinal axis of the femur. The test is performed bilaterally (181). 3. Gaenslen’s test. The participant lies supine near the edge of the table. One leg hangs over the edge of the table and the hip and knee of the other leg are flexed towards the patient’s chest. The examiner applies a pressure to the flexed knee towards the chest and a counter pressure to the knee of the hanging leg towards the floor. The test is performed bilaterally (123). 4. Compression test. The participant is sidelying with the hip and knee flexed to approximately a right angle. The examiner kneels behind the participant on the table. The examiner applies a pressure vertically downward on the upper iliac crest (123). 5. Sacral thrust. The participant is prone. The examiner applies a light pressure vertically downward on the sacrum (123).

In order to exclude problems from the hip, a rotation range of motion test was performed in prone. The active straight leg raising test (149) was performed followed by a neurological examination (muscle testing, reflex testing in the lower extremities, sensation, and the straight leg raising test). The mechanical assessment of the lumbar spine was based on the MDT protocol (142). The participant performed flexion and extension in standing and in the lying position in sets of 5‐10 repetitions. If needed, lateral flexion was added to the protocol. Baseline symptoms were noted, as were the effects on symptoms during and immediately following the movements. The MDT classification relies on the patients reported response to the movements. This has shown promising results for classification of pain (141) and is reliable in the hands of experienced testers (110, 201, 206). Separate pain provocation tests used in the present study have shown high specificity (0.81‐1.00), but a wide range for

30 Materials and Methods sensitivity (0.04‐0.93) in pregnant women (2, 181). Incorporating pain provocation tests into standardized mechanical assessment of the lumbar spine is of greater diagnostic value than pain provocation tests alone (124).

Criteria for the cohort classification Participants were assigned to the “no LBP” group if they had no subjective LBP or fewer than 2 positive pelvic pain provocation tests, and no lumbar pain or change in range of motion from repeated movements, according to the MDT classification.

Criteria for being assigned to the PGP group were pain experienced between the posterior iliac crest and the gluteal fold, with or without radiation in the posterior thigh and calf, and with or without pain in the symphysis. The pain needed to be reproducible for at least 2 out of the 7 pelvic pain provocation tests performed. No centralisation or peripheralisation during repeated movement assessment could be experienced as well as no lumbar pain or change in range of motion from repeated movements, according to the MDT classification. PGP onset needed to be during pregnancy or within 3 weeks after delivery (150).

The criterion for being assigned to the lumbar pain group was pain experienced in the lumbar region, with or without radiation to the leg. Additionally, reproducible pain and/or change in range of motion from repeated movements or different positions of the lumbar spine, or experience of centralisation and/or peripheralisation during examination, and fewer than 2 positive pelvic pain provocation tests needed to occur.

Participants in the combined pain group experienced pain in the lumbar region, as well as between the posterior iliac crest and the gluteal fold, with or without radiation in the posterior thigh and calf, and with or without pain in the symphysis. They had 2 or more positive pain provocation tests, as well as pain and/or a change in range of motion from repeated movements or different positions of the lumbar spine, or experienced centralisation and/or peripheralisation.

31 Materials and Methods

Table 2. The description of the evaluation procedure.

1. Participants filled in questionnaire 2. Standard history by the physiotherapist according to MDT protocol 3. Standing flexion, extension, lateral flexion of the back 4. Pelvic pain provocation tests 5. Hip range of motion test (at evaluation during pregnancy) 6. Active straight leg raising test (ASLR test) 7. Neurological examinations (muscle testing, reflex in the lower extremities, sensation and the straight leg raising test) 8. Mechanical assessment of the lumbar spine according to the MDT protocol 9. Gait test 10. Isometric hip extension test 11. Isometric endurance of back flexor muscles 12. Isometric endurance of back extensor muscles (only 3 months postpartum)

Reliability of the classification procedure In a nonpublished study, 31 pregnant women (mean age 28 years, range 20‐36; median gestational week 26, range 13‐38; median pain intensity VAS 38 mm, range 0‐87) with some type of LBP were examined according to above protocol by 2 independent examiners, specialised in LBP. The physiotherapists’ years of clinical experience in management of LBP ranged from 17 to 19 years. Agreement between examiners for the 3 syndromes (lumbar pain, PGP, combined pain) was 87% (27/31), giving a substantial kappa coefficient of 0.79 (120). Reliability depends on the experience of the observer. Interpretation of the kappa value is dependent on the number of categories (i.e. more categories give lower kappa values), on the prevalence of scores (i.e. skewed distributions give lower kappa values), and finally, on the presence of systematic differences (i.e. slightly increases kappa values). No systematic differences were seen, however, 16/31 women were classified with PGP, 6 with lumbar pain, and 9 with combined pain.

Physical functioning No study was identified that described test of endurance or strength for the muscles of the lower back, hip or pelvis in a pregnant population. The choice of test included several considerations. For the hip test, a nonweight‐bearing

32 MaterialsȱandȱMethodsȱ ofȱtestȱincludedȱseveralȱconsiderations.ȱForȱtheȱhipȱtest,ȱaȱnonweightȬbearingȱ positionȱwasȱchosenȱinȱorderȱtoȱdecreaseȱtheȱriskȱofȱpainȱprovocation.ȱAȱpilotȱ studyȱonȱ12ȱhealthyȱwomenȱinȱfertileȱageȱwasȱundertaken.ȱTwoȱwomenȱwithȱ PGPȱwereȱtestedȱandȱtheȱpositionsȱwereȱfoundȱtoȱbeȱappropriate.ȱPriorȱtoȱallȱ testing,ȱ itȱ wasȱ emphasizedȱ thatȱ theȱ subjectsȱ couldȱ discontinueȱ eachȱ testȱ atȱ anytimeȱ orȱ declineȱ aȱ testȱ completely.ȱ Duringȱ testing,ȱ 2ȱ correctionsȱ forȱ techniqueȱorȱpositionȱwereȱallowedȱbeforeȱtheȱtesterȱdiscontinuedȱtheȱtest.ȱTheȱ participantsȱratedȱtheirȱpainȱintensityȱonȱaȱ100ȱmmȱhorizontalȱVASȱrulerȱwithȱ gaȱ slidin ȱ marker,ȱ beforeȱ theȱ physicalȱ performanceȱ test,ȱ afterȱ eachȱ completedȱ test,ȱandȱaȱcoupleȱofȱminutesȱafterȱallȱtests.ȱ

Backȱflexorȱmusclesȱenduranceȱ Toȱtestȱisometricȱenduranceȱofȱtheȱbackȱflexorȱmuscles,ȱparticipantsȱlaidȱsupineȱ withȱarmsȱcrossedȱoverȱtheȱchest,ȱhandsȱonȱtheȱoppositeȱshoulders,ȱhipsȱbent,ȱ andȱ kneesȱ andȱ feetȱ apart.ȱ Participantsȱ wereȱ askedȱ toȱ nodȱ forwardȱ andȱ continueȱtoȱliftȱtheirȱheadȱandȱshouldersȱuntilȱtheȱinferiorȱangleȱofȱtheȱscapulaȱ wasȱliftedȱfromȱtheȱtable,ȱandȱtoȱthenȱmaintainȱtheȱpositionȱasȱlongȱasȱpossible,ȱ modifiedȱ fromȱ McQuadeȱ etȱ al.ȱ (1988)(143).ȱ Theȱ numberȱ ofȱ secondsȱ thatȱ theȱ positionȱ wasȱ maintainedȱ wasȱ recordedȱ upȱ toȱ aȱ maximumȱ ofȱ 120ȱ s.ȱ Noȱ referenceȱ valueȱ forȱ pregnantȱ womenȱ wasȱ available.ȱ Thereforeȱ theȱ knownȱ valuesȱforȱhealthyȱwomenȱandȱwomenȱwithȱnonspecificȱLBPȱ(131,ȱ132)ȱwereȱ usedȱ toȱ setȱ maximalȱ timesȱ basedȱ onȱ clinicalȱ judgementȱ andȱ takingȱ intoȱ considerationȱtheirȱpregnancy/3Ȭmonthȱpostpartumȱstatus.ȱReportedȱreliabilityȱ forȱstaticȱabdominalȱenduranceȱwasȱlow/poorȱ(ICCȱ0.51)ȱinȱsomeȱstudiesȱ(132,ȱ 156)ȱandȱhighȱinȱanotherȱ(0.90Ȭ0.95)(100).ȱ

Backȱextensorȱmusclesȱenduranceȱ Toȱ measureȱ isometricȱ enduranceȱ ofȱ backȱ extensorȱ muscles,ȱ participantsȱ laidȱ proneȱwithȱarmsȱcrossedȱandȱtheȱtrunkȱhorizontalȱoutsideȱtheȱtable.ȱTheȱpelvisȱ wasȱ fixedȱ toȱ theȱ tableȱ byȱ strapsȱ andȱ theȱ lowerȱ legsȱ wereȱfixedȱ byȱ theȱ tester,ȱ modifiedȱ fromȱ BieringȬSörensenȱ (1984)ȱ (21).ȱ Theȱ timeȱ inȱ secondsȱ thatȱ thisȱ positionȱwasȱmaintainedȱwasȱrecordedȱandȱtheȱtestȱwasȱdiscontinuedȱafterȱaȱ maximumȱofȱ120ȱs.ȱSinceȱthereȱwasȱnoȱreferenceȱvalueȱforȱpostpartumȱwomen,ȱ knownȱ valuesȱ forȱ healthyȱ womenȱ andȱ womenȱ withȱ nonspecificȱ LBPȱ wereȱ adaptedȱ (1,ȱ 21,ȱ 131,ȱ 132,ȱ 167)ȱ andȱ maximalȱ timesȱ wereȱ setȱ basedȱ onȱ clinicalȱ experienceȱandȱtheȱparticipantsȱpostpartumȱstatus.ȱTheȱbackȱextensorȱtestȱwasȱ inappropriateȱ toȱ performȱ duringȱ pregnancyȱ dueȱ toȱ pressureȱ onȱ theȱ lowerȱ abdomen.ȱ Theȱ testȱ canȱ discriminateȱ betweenȱ subjectsȱ withȱ andȱ withoutȱ

ȱ 33 MaterialsȱandȱMethodsȱ ȱ nonspecificȱ LBPȱ (125).ȱ Reportedȱ ICCsȱ forȱ subjectsȱ withȱ currentȱ orȱ previousȱ LBPȱ andȱ asymptomaticȱ wereȱ 0.88,ȱ 0.77,ȱ andȱ 0.83ȱ respectively.ȱ Otherȱ authorsȱ haveȱfoundȱtheȱtestȱtoȱbeȱunreliableȱforȱhealthyȱsubjectsȱ(107).ȱ

Maximalȱvoluntaryȱisometricȱhipȱextensionȱ Maximalȱ voluntaryȱ isometricȱ hipȱ extensionȱ (Figureȱ 2)ȱ wasȱ measuredȱ withȱ aȱ dynamometerȱwithȱaȱfixedȱsensorȱ(ChatillonȱCSDȱ500ȱstrengthȱdynamometer,ȱ Ametek,ȱLargo,ȱFL).ȱEachȱparticipantȱheldȱaȱslingȱaroundȱtheȱthighȱatȱtheȱdistalȱ endȱofȱtheȱfemurȱandȱpulledȱinȱhipȱextension.ȱParticipantsȱwereȱinstructedȱtoȱ “pullȱtheȱhardestȱyouȱcanȱuntilȱIȱstopȱyouȱafterȱ5ȱs”.ȱNoȱencouragementȱwasȱ givenȱ duringȱ theȱ tests.ȱ Participantȱ startedȱ withȱ theȱ rightȱ leg.ȱ Twoȱ trainingȱ repetitionsȱ wereȱ doneȱ andȱ theȱ meanȱ ofȱ theȱ nextȱ 3ȱ repetitionsȱ wasȱ analysed.ȱ Eachȱ repetitionȱ consistedȱ ofȱ 5ȱ sȱ ofȱ activityȱ andȱ 5Ȭ10ȱ sȱ ofȱ erest.ȱ ȱ Th sameȱ procedureȱ wasȱ repeatedȱ onȱ theȱ leftȱ side.ȱ Theȱ reliabilityȱ ofȱ theȱ hipȱ muscleȱ extensionȱtestȱwasȱinvestigatedȱinȱaȱpilotȱtestȬretestȱstudyȱ(n=20).ȱSpearman’sȱrȱ wasȱ0.82ȱforȱtheȱrightȱlegȱandȱ0.88ȱforȱtheȱleftȱleg;ȱtheȱICCȱ(modelȱ2)ȱwasȱ0.87ȱ forȱtheȱrightȱlegȱandȱ0.85ȱforȱtheȱleftȱleg.ȱTheȱmeasurementȱerrorȱwasȱ53ȱNȱonȱ theȱrightȱlegȱandȱ50ȱNȱonȱtheȱleftȱleg.ȱTheȱmeasurementȱerrorȱwasȱ15%ȱofȱtheȱ rangeȱofȱhipȱextensionȱvalues.ȱ ȱ ȱ

ȱ ȱ Figureȱ2.ȱTheȱhipȱextensionȱtestȱleftȱside.ȱ

Gaitȱspeedȱ Activityȱ limitationȱ withȱ walkingȱ wasȱ studiedȱ inȱ aȱ gaitȱ test,ȱ modifiedȱ fromȱ Ljungquistȱ etȱ al.ȱ (1999)ȱ (131).ȱ Inȱ theȱ studyȱ byȱ Ljungquistȱ etȱ al.ȱ (1999)ȱ theȱ participantsȱ walkedȱ 20ȱ m,ȱ turnedȱ around,ȱ andȱ walkedȱ back.ȱ Clinicalȱ experienceȱ hasȱ shownȱ thatȱ womenȱ withȱ PGPȱ oftenȱ haveȱ increasedȱ painȱ andȱ stabsȱ ofȱ painȱ whileȱ turning.ȱ Sinceȱ itȱ wasȱ theȱ intentionȱ toȱ eliminateȱ painȱ

ȱ 34 MaterialsȱandȱMethodsȱ provocation,ȱ theȱ womenȱ inȱ theȱ presentȱ studyȱ stoppedȱ afterȱ 20ȱ m.ȱ Theȱ participantsȱ wereȱ askedȱ toȱ walkȱ barefootȱ “atȱ aȱ comfortableȱ speed”ȱ onȱ aȱ horizontalȱindoorȱfloor.ȱTheȱ“naturalȱcustomaryȱwalkingȱspeed”ȱisȱconsideredȱ toȱ resultȱ inȱ theȱ leastȱ mechanicalȱ andȱ physiologicalȱ expenditureȱ (247).ȱ Theȱ numberȱ ofȱ secondsȱ itȱ tookȱ toȱ traverseȱ 20ȱ mȱ wasȱ recorded.ȱ Reliabilityȱ forȱ comfortableȱgaitȱspeedȱhasȱbeenȱreportedȱtoȱbeȱgoodȱ(r=0.90)ȱ(27).ȱ

STATISTICALȱANALYSESȱ Allȱ dataȱwereȱ computerizedȱandȱ analyzedȱ usingȱ theȱ SPSSȱ(versionȱ11.0Ȭ14.0;ȱ SPSSȱ Inc.,ȱ Chicago,ȱ IL).ȱ Statisticalȱ significanceȱ wasȱ setȱ atȱ 0.05,ȱ andȱ reportedȱ confidenceȱ intervalsȱ (CI)ȱ wereȱ 95%.ȱ Theȱ statisticalȱ methodsȱ usedȱ forȱ theȱ 4ȱ papersȱareȱdescribedȱinȱTableȱ3.ȱ ȱ Descriptiveȱstatisticsȱwereȱusedȱforȱdemographicȱdataȱandȱpresentedȱasȱmeanȱ andȱstandardȱdeviationȱwhenȱtheȱassumptionsȱofȱnormalityȱandȱhomogeneityȱ ofȱvarianceȱwereȱmetȱandȱtheȱstudiedȱvariablesȱwereȱonȱtheȱratioȱlevel.ȱDataȱonȱ theȱ interval,ȱ ordinal,ȱ orȱ nominalȱ levelsȱ wereȱ analyzedȱ withȱ nonparametricȱ testsȱandȱpresentedȱasȱmedianȱvaluesȱwithȱquartilesȱorȱrange.ȱ ȱ Differenceȱ betweenȱ 2ȱ independentȱ groupsȱ wasȱ measuredȱ withȱ theȱ independentȱsamplesȱtȬtestȱwhenȱtheȱvariableȱwasȱnormallyȱdistributed,ȱhadȱ anȱequalȱvariance,ȱandȱwasȱonȱtheȱratioȱlevel.ȱForȱanalysisȱofȱnonparametricȱ dataȱ onȱ theȱ ordinalȱ level,ȱ theȱ Mannȱ Whitneyȱ UȬtestȱ wasȱ usedȱ forȱ groupȱ comparisons.ȱ Forȱ dataȱ onȱ theȱ nominalȱ level,ȱ theȱ chiȬsquaredȱ testȱ orȱ Fisher’sȱ exactȱtestȱwasȱperformedȱwhenȱappropriate.ȱ ȱ Forȱmultigroupȱcomparisonsȱinȱanalysesȱofȱcontinuousȱparametricȱvariables,ȱaȱ oneȬwayȱ ANOVAȱ wasȱ performed.ȱ Inȱ analysesȱ ofȱ nonparametricȱ dataȱ onȱ aȱ nominalȱlevel,ȱtheȱchiȬsquaredȱtestȱwasȱused,ȱandȱforȱdataȱonȱanȱordinalȱlevel,ȱ theȱKruskalȬWallisȱtestȱwasȱused.ȱCorrectionȱforȱmultipleȱanalysesȱwasȱmadeȱ usingȱtheȱadjustedȱBonferroniȱtest,ȱorȱBonferroniȱcorrection.ȱ ȱ Generalȱ Linearȱ Modelȱ analysesȱ wereȱ performedȱ toȱ evaluateȱ theȱ associationȱ betweenȱ muscleȱ testȱ resultsȱ andȱ cohortȱ subgroupsȱ ofȱ LBP,ȱ whenȱ controllingȱ forȱpainȱintensity.ȱ ȱ InȱPaperȱIIȱlogisticȱregressionȱanalysisȱ(enterȱmethod)ȱwasȱusedȱtoȱexamineȱtheȱ associationȱ betweenȱ depressiveȱ symptoms,ȱ cohortȱ subgroupsȱ ofȱ LBP,ȱ andȱ

ȱ 35 MaterialsȱandȱMethodsȱ ȱ possiblyȱ confoundingȱ descriptiveȱ variables.ȱ Theȱ dependentȱ variableȱ wasȱ depressiveȱ symptoms,ȱ withȱ aȱ cutȬoffȱ scoreȱ ofȱǃ10.ȱ Theȱ cohortȱ subgroupsȱ ofȱ LBPȱwereȱenteredȱasȱcategoricalȱindependentȱvariablesȱ(noȱLBPȱasȱreference).ȱ Theȱ covariatesȱ wereȱ parityȱ (continuous),ȱ urinaryȱ incontinenceȱ (no/yes)ȱ andȱ bodyȱ massȱ indexȱ (BMI)ȱ (continuous).ȱ Theȱ covariatesȱ wereȱ selectedȱ basedȱ onȱ theȱliteratureȱandȱpreviousȱassociationȱwithȱbothȱbackȱpainȱandȱdepressionȱ(88,ȱ 154,ȱ 197,ȱ 214,ȱ 223,ȱ 267).ȱ Selectionȱ wasȱ alsoȱ constrainedȱ byȱ theȱ numberȱ ofȱ possibleȱ independentȱ variablesȱ (4Ȭ5),ȱ givenȱ theȱ leastȱ groupȱ ofȱ theȱdependentȱ wasȱnȱ=ȱ44.ȱ ȱ InȱPaperȱIV,ȱforwardȱstepwiseȱlogisticȱregressionȱanalysisȱwasȱperformedȱonȱ someȱ ofȱ theȱ measuresȱ takenȱ duringȱ gestationalȱ weeksȱ 12Ȭ18ȱ andȱ usedȱ toȱ determineȱ predictorsȱ ofȱ persistentȱ PGPȱ orȱ combinedȱ painȱ 3Ȭmonthsȱ postpartum.ȱ Theȱ initialȱ choiceȱ ofȱ independentȱ variablesȱ wasȱ basedȱ onȱ theȱ hypothesisȱofȱanȱassociationȱbetweenȱmuscleȱdysfunctionȱandȱPGP,ȱasȱwellȱasȱ theȱPGPȱliteratureȱ(5,ȱ11,ȱ121,ȱ154,ȱ245).ȱTwoȱvariablesȱwereȱexcludedȱdueȱtoȱ lowȱ responseȱ rateȱ (exerciseȱ frequencyȱ priorȱ toȱ LBP,ȱ similarȱ LBPȱ duringȱ theȱ previousȱ5ȱyears).ȱWithȱlogisticȱregressionȱanalysisȱitȱisȱcrucialȱthatȱallȱsubjectsȱ includedȱrespondȱtoȱallȱtheȱquestionsȱinȱtheȱmodel,ȱandȱinȱthisȱstudy,ȱperformȱ allȱ theȱ physicalȱ tests.ȱ Theseȱ requirementsȱ reducedȱ theȱ modelȱ toȱ 154ȱ participants.ȱ Civilianȱ statusȱwasȱ excludedȱ becauseȱ onlyȱ 3ȱofȱ 154ȱ participantsȱ wereȱ single.ȱ Inȱ orderȱ toȱ minimizeȱ theȱ riskȱ ofȱ multicollinearity,ȱ aȱ correlationȱ matrixȱ wasȱ analysed.ȱ Univariateȱ analysesȱ forȱ eachȱ independentȱ andȱ dependentȱ variableȱ wereȱ carriedȱ outȱ toȱ computeȱ crudeȱ estimates.ȱ Fourteenȱ independentȱvariablesȱwereȱenteredȱintoȱaȱforwardȱstepwiseȱlogisticȱregressionȱ analysis.ȱ Theȱ finalȱ modelȱ includedȱ significantȱ predictorsȱ withȱ anȱ acceptedȱ statisticalȱsignificanceȱlevelȱofȱp<0.05.ȱTheȱforwardȱstepwiseȱlogisticȱregressionȱ analysisȱwasȱconfirmedȱbyȱaȱbackwardȱstepwiseȱlogisticȱregression.ȱ ȱ

ȱ 36 MaterialsȱandȱMethodsȱ

ȱ Tableȱ3.ȱStatisticalȱmethodsȱusedȱinȱtheȱdifferentȱpapersȱinȱtheȱthesis.ȱ ȱ

Statistical method Paper Paper Paper Paper I II III IV Kruskal-Wallis test x x x

Mann-Whitney U-test x x

Chi-squared test x x x x

Fischer’s exact test x x x

Independent samples t-test x

One way ANOVA x x

General Linear Model Analysis x

Logistic Regression x x

ȱ 37 MaterialsȱandȱMethodsȱ ȱ

ETHICALȱCONSIDERATIONSȱ

Theȱ womenȱ receivedȱ writtenȱ andȱ verbalȱ informationȱ aboutȱ theȱ studyȱ fromȱ theirȱ midwifeȱ beforeȱ givingȱ oralȱ consentȱ toȱ allowȱ theȱ projectȱ leaderȱ (AG)ȱ toȱ contactȱthemȱbyȱtelephone.ȱThereby,ȱtheȱwomenȱwereȱgivenȱtimeȱtoȱconsiderȱ theirȱparticipation.ȱWhenȱcontactedȱbyȱtheȱprojectȱleaderȱtheȱwomenȱhadȱtheȱ opportunityȱtoȱfurtherȱkas ȱquestionsȱaboutȱtheȱstudy.ȱItȱwasȱemphasizedȱthatȱ theirȱparticipationȱwasȱpurelyȱvoluntaryȱandȱthatȱtheyȱcouldȱdiscontinueȱtheirȱ participationȱatȱanyȱpointȱwithoutȱexplanationȱandȱwithoutȱconsequencesȱonȱ theirȱ management.ȱ Theȱ womenȱ gaveȱ theirȱ oralȱ consentȱ toȱ theȱ projectȱ leader.ȱ Theȱ projectȱ leaderȱ wasȱ notȱ involvedȱ inȱ theȱ healthcareȱ managementȱ ofȱ theȱ participants.ȱ ȱ Theȱwomenȱwereȱpregnantȱatȱtheȱfirstȱevaluationȱinȱtheȱstudy.ȱThisȱrequiredȱ someȱspecialȱconsiderationsȱwithȱregardȱtoȱsafetyȱforȱtheȱunbornȱchildȱandȱtheȱ motherȱinȱtheȱmuscleȱtests.ȱTheȱmidwivesȱexcludedȱwomenȱwithȱcomplicatedȱ orȱ riskȱ pregnancies.ȱ Inȱ orderȱ toȱ makeȱ sureȱ thatȱ allȱ includedȱ measurementsȱ wereȱappropriateȱforȱpregnantȱwomenȱwithȱanȱexpectedȱnormalȱpregnancy,ȱ2ȱ obstetriciansȱwereȱinitiallyȱconsultedȱtoȱreviewȱandȱapproveȱtheȱstudyȱdesign.ȱ Likewise,ȱ atȱ theȱ secondȱ evaluationȱ theȱ womenȱ wereȱ onlyȱ 3ȱ monthsȱ postpartum.ȱ Temporaryȱ discomfortȱ couldȱ ariseȱ duringȱ theȱ classificationȱ procedure,ȱ however,ȱ itȱ wasȱ explainedȱ toȱ theȱ participantȱ thatȱ theȱ painȱ provocationȱ wasȱ neededȱ inȱ orderȱ toȱ classifyȱ theȱ symptoms.ȱ Duringȱ physicalȱ functioningȱtests,ȱpainȱprovocationȱwasȱpossible,ȱthereforeȱitȱwasȱemphasisedȱ duringȱtheȱevaluationȱthatȱtheȱwomanȱcouldȱdeclineȱanyȱtestȱorȱterminateȱherȱ participationȱ atȱ anyȱ point.ȱ Anȱ advantageȱ withȱ theȱ participationȱ inȱ theȱ studyȱ wasȱ thatȱ theȱ women,ȱ atȱ anȱ earlyȱ stageȱ inȱ pregnancy,ȱ asȱwellȱ asȱ postpartum,ȱ receivedȱaȱthoroughȱexaminationȱbyȱaȱspecialistȱinȱLBPȱandȱPGP.ȱ TheȱregionalȱEthicalȱCommitteeȱinȱGothenburgȱapprovedȱtheȱstudyȱ(öȱ414Ȭ00).ȱ Anȱ amendmentȱ wasȱ approvedȱ forȱ theȱ reliabilityȱ studyȱ ofȱ theȱ classificationȱ procedureȱ(Tȱ352Ȭ06).ȱ ȱ

ȱ 38 Results

RESULTS

PREVALENCE OF LOW BACK PAIN IN PREGNANCY AND POSTPARTUM A cohort of 457 pregnant women attended the 2 maternity care units between August 2001 and September 2003, of whom 313 were included in the study (17% declined participation) (Figure 3). The studied cohort was a representative community for Sweden, although the parity was somewhat higher than for Sweden in general (1.8 children per women vs. 1.6 in general), and there was a lower degree of higher education among the women (21% versus 30%).

At the evaluation between gestational weeks 12‐18, 119 participants were assigned to the “no LBP” group and 194 to 1 of the 3 LBP groups: PGP (n=104, 54%), lumbar pain (n=33, 17%), and combined pain (n=57, 29%). In order to analyse the physical performance tests in pregnancy, 12 participants were excluded (3 participants were diagnosed with exclusion criteria, 2 participants were ≥18 gestational weeks at inclusion, 7 participants were not able to perform the muscle tests). Thus, there remained 301 participants for the muscle analysis (Paper III) and 308 for analysis of predictors (Paper IV). The PGP group reported a significantly higher level of sick leave at baseline than the group with no LBP group (p=0.001) whereas the groups with lumbar pain and combined pain did not (Table 4). With regard to the demographic data, women with lumbar pain and women with combined pain reported having had significantly more experience of back pain before their first pregnancy than women in the “no LBP” group (p<0.001). Women with lumbar pain had significantly more previous experience of back pain than those with PGP (p=0.001, Table 4).

39 Results

Table 4. Characteristics of the cohort in gestational weeks 12‐18.

Total No LBP Lumbar pain PGP Combined pain Variables in pregnancy weeks 12‐18 n=308 n=118 n=33 n=101 n=56

Age (yr) median (range) 29 (17‐44) 29 (20‐40) 30 (19‐37) 28 (18‐44) 28 (17‐41)

Gestation week at inclusion median (25,75 quartile) 15 (14‐16) 15 (14‐16) 15 (14‐16) 15 (14‐16) 15 (14‐16)

BMI median (25,75 quartile) 24.5 (22.6‐27.4) 24.6 (21.7‐27.4) 23.6 (21.6‐26.3) 24.4 (22.9‐27.6) 25.0 (23.0‐27.9)

Parity median (range) 1 (0‐4) 1 (0‐4) 1 (0‐2) 1 (0‐4) 1 (0‐3)

Urinary incontinence n (%) yes 63 (20) 23 (20) 1 (3) 20 (20) 19 (34) no 244 (80) 95 (80) 32 (97) 80 (80) 37 (66) Full time employment n (%) yes 155 (49) 65 (55) 20 (62) 45 (45) 25 (46) no 150 (51) 53 (45) 12 (38) 55 (55) 30 (54) Work dissatisfaction n (%)yes 19 (7) 4 (4) 2 (7) 8 (8) 5 (10) no 270 (93) 110 (96) 27 (93) 87 (92)) 46 (90) Sick leave at inclusion due to back pain n (%) yes 19 (8) 0 (0) 1 (3) 14 (15) 4 (7) no 231 (92) 67 (100) 31 (97) 81 (85) 52 (93) LBP before 1st pregnancy n (%) yes 124 (40) 30 (26) 25 (76) 38 (38) 31 (55) no 183 (60) 87 (74) 8 (24) 63 (62) 25 (45) Previous pregnancy‐related LBP n (%) Never pregnant before 123 (41) 50 (43) 15 (47) 41 (42) 17 (31) No LBP in a pregnancy 70 (23) 39 (33) 8 (25) 10 (10) 13 (23) LBP in a previous pregnancy, recovered completely 82 (27) 27 (23) 7 (22) 30 (30) 18 (33) LBP in a previous pregnancy that persists 28 (9) 1 (1) 2 (6) 18 (18) 7 (13) LBP hindered work during the last 5 years n (%) yes 94 (55) 29 (63) 17 (68) 28 (45) 20 (53) no 77 (45) 17 (37) 8 (32) 34 (55) 18 (47) Activity level last 6 months n (%) 1‐3 210 (68) 78 (67) 26 (79) 68 (67) 38 (68) 4‐6 97 (32) 39 (33) 7 (21) 33 (33) 18 (32)

40 Results

Variables Postpartum Total No LBP Lumbar pain PGP Combined pain n=272 n=183 n=29 n=46 n=14 Weight of newborn (g) mean (sd) 3683 (548) 3672 (528) 3780 (459) 3635 (650) 3777 (624)

Delivery method n (%) caesarean 22 (8) 12 (7) 2 (7) 5 (11) 3 (21) vaginal 250 (92) 171 (93) 27 (93) 41 (89) 11 (79) Breast feeding n (%) yes 212 (81) 144 (83) 22 (79) 35 (76) 11 (85) no 49 (19) 30 (17) 6 (21) 11 (24) 2 (15) BMI median (25,75 quartile) 25.5 (22.3‐24.8) 24.4 (21.9‐27.5) 25.8 (23.9‐27.7) 26.3 (23.5‐29.9) 24.6 (23.6‐26.6)

41 Resultsȱ ȱ Threeȱmonthsȱ afterȱgivingȱ birth,ȱ 89/272ȱ participantsȱ (33%)ȱexperiencedȱ someȱ formȱofȱLBP:ȱ46/272ȱ(17%)ȱhadȱPGP,ȱ29/272ȱ(11%)ȱhadȱlumbarȱpain,ȱandȱ14/272ȱ (5%)ȱhadȱcombinedȱpain.ȱFiveȱparticipantsȱhadȱinternalȱmissingȱvaluesȱofȱtheȱ EPDSȱ andȱ consequentlyȱ 267ȱ wereȱ analysedȱ forȱ depressiveȱ symptomsȱ postpartum.ȱ Fourȱ participantsȱ wereȱ notȱ ableȱ toȱ performȱ anyȱ muscleȱ testȱ postpartumȱ andȱ 6ȱ participantsȱ withoutȱ anyȱ LBPȱ filledȱ inȱ questionnairesȱ atȱ home,ȱwhichȱreducedȱtheȱpostpartumȱevaluationȱofȱmuscleȱassessmentȱtoȱ262ȱ women.ȱ ȱ PaperȱIȱincludedȱ313ȱpregnantȱwomenȱduringȱgestationalȱweeksȱ12Ȭ18.ȱȱ PaperȱIIȱincludedȱ267ȱwomenȱpostpartum.ȱ PaperȱIIIȱincludedȱ301ȱpregnantȱwomenȱandȱ262ȱwomenȱpostpartum.ȱ PaperȱIVȱincludedȱ308ȱpregnantȱwomenȱandȱ272ȱwomenȱpostpartum.ȱInȱtheȱ predictiveȱmodel,ȱ154ȱparticipantsȱwereȱincluded.ȱ

DropȬoutȱanalysisȱ Fiveȱparticipantsȱmiscarriedȱorȱhadȱanȱinterruptedȱpregnancyȱdueȱtoȱdiseaseȱofȱ theȱ fetus.ȱ ThirtyȬoneȱ participantsȱ deliveredȱ butȱ wereȱ notȱ includedȱ inȱ theȱ postpartumȱanalysis.ȱOfȱtheseȱ31ȱparticipants,ȱ19ȱ(6.5%)ȱdeclinedȱtoȱparticipateȱ dueȱ toȱ lackȱ ofȱ time,ȱ fatigue,ȱ orȱ noȱ givenȱ reason.ȱ Also,ȱ theseȱ 31ȱ participantsȱ differedȱ fromȱ theȱ otherȱ participantsȱ withȱ regardȱ toȱ 4ȱ variables.ȱ Theȱ civilianȱ statusȱwasȱtoȱaȱhigherȱdegreeȱsingleȱ(p<0.02),ȱtheyȱhadȱlowerȱenduranceȱofȱtheȱ backȱflexorȱmusclesȱ(21ȱsȱvs.ȱ33ȱsȱp=0.009),ȱlowerȱHRQLȱ(EQȬ5Dȱscoreȱ0.74ȱvs.ȱ 0.80,ȱ p=0.03),ȱ andȱ higherȱ painȱ intensityȱ (36ȱ mmȱ vs.ȱ 22ȱ mm,ȱ p=0.03)ȱ inȱ gestationalȱweeksȱ12Ȭ18.ȱ

ȱ 42 Resultsȱ

n=457ȱpregnantȱ ȱ ȱ n=73ȱnotȱfulfillingȱinclusionȱ 20ȱobstetricȱreasonsȱ ȱ criteriaȱ 22ȱmiscarriagesȱ 13ȱinsufficientȱSwedishȱ ȱ 18ȱ>18ȱgestationalȱweeksȱ n=384ȱpregnantȱ ȱ ȱ n=9ȱexclusionȱcriteriaȱ 1ȱrheumatoidȱarthritisȱ ȱ n=62ȱnoȱconsentȱ(62/370=17%)ȱ 1ȱpelvospondylitisȱ Paperȱ ȱ 1ȱarthrosisȱ ȱ ȱ n=313ȱpregnantȱ 1ȱSchauermannȱ Iȱ 1ȱfracturedȱspineȱ ȱ 1ȱfracturedȱpelvisȱ n=3ȱexclusionȱcriteriaȱ ȱ 1ȱcoccyxȱsurgeryȱ n=2ȱgestationalȱweeksȱ>18ȱ ȱ 1ȱdiscȱsurgeryȱ Paperȱ 1ȱcongenitalȱhipȱluxationȱ ȱ ȱ n=308ȱpregnantȱ ȱ ȱ IVȱ 1ȱpelvospondylitisȱ ȱ 1ȱspondylolisthesisȱ ȱ n=7ȱnotȱableȱtoȱdoȱphysicalȱ 1ȱCrohn’sȱdiseaseȱ performanceȱtestȱ Paperȱ ȱ ȱ ȱ n=301ȱpregnantȱ IIIȱ ȱ ȱ

ȱ n=308ȱ ȱ postpartumȱ ȱ ȱ n=17ȱexclusionȱcriteriaȱ 2ȱmiscarriagesȱ n=19ȱnoȱconsentȱ(19/291=6.5ȱ%)ȱ 3ȱinterruptedȱpregnanciesȱ ȱ Paperȱ ȱ ȱ ȱ n=272ȱ 8ȱmovedȱoutȱofȱareaȱ ȱ IVȱ postpartumȱ 1ȱtravellingȱ 1ȱcouldȱnotȱbeȱreachedȱ ȱ n=5ȱmissing values inȱEPDS 1ȱaorticȱsurgeryȱ ȱ 1ȱpretermȱdeliveryȱ ȱ Paperȱ ȱ ȱ n=267ȱ ȱ IIȱ postpartumȱ ȱ ȱ n=4ȱnotȱableȱtoȱdoȱphysicalȱperformanceȱtestȱ n=6ȱwithoutȱLBPȱfilledȱinȱquestionnaireȱatȱhome;Ȭnoȱphysicalȱ Paperȱ ȱ performanceȱtestȱ ȱ ȱ n=262ȱ IIIȱ postpartumȱ ȱȱ ȱ ȱ Figureȱ3.ȱEnrolmentȱofȱtheȱstudy.ȱ ȱ

ȱ 43 Resultsȱ ȱ THEȱCOURSEȱOFȱLOWȱBACKȱPAINȱ Theȱ cohortȱ subgroupsȱ duringȱ gestationalȱ weeksȱ 12Ȭ18ȱ andȱ 3ȱ monthsȱ postpartumȱareȱpresentedȱinȱTableȱ5.ȱȱ ȱ ȱ Tableȱ5.ȱCohortȱsubgroupsȱatȱgestationalȱweeksȱ12ȱtoȱ18ȱandȱ3ȱmonthsȱpostpartum.ȱ

ȱ

nȱ SubgroupsȱofȱLBPȱ3ȱmonthsȱpostpartumȱ ȱ ȱ Subgroupsȱ ofȱ LBPȱ inȱ NoȱLBPȱ Lumbarȱpainȱ PGPȱ Combinedȱ ȱ gestationalȱweeksȱ12Ȭ18ȱ painȱ NoȱLBPȱ 89ȱ 9ȱ 9ȱ 0ȱ 107ȱ Lumbarȱpainȱ 21ȱ 1ȱ 4ȱ 3ȱ 29ȱ PGPȱ 56ȱ 8ȱ 18ȱ 3ȱ 85ȱ Combinedȱpainȱ 17ȱ 11ȱ 15ȱ 8ȱ 51ȱ Totalȱ 183ȱ 29ȱ 46ȱ 14ȱ 272ȱ ȱ Ofȱtheȱ85ȱparticipantsȱwithȱPGPȱduringȱgestationalȱweeksȱ12Ȭ18,ȱ18ȱ(21%)ȱhadȱ PGPȱ3ȱmonthsȱpostpartum.ȱWomenȱwithȱPGPȱrecoveredȱfromȱtheirȱLBPȱtoȱaȱ higherȱ degreeȱ (56/85,ȱ 66%),ȱ asȱ comparedȱ toȱ 17/51ȱ (33%)ȱ ofȱ theȱ womenȱ withȱ combinedȱpain.ȱOnlyȱ1ȱparticipantȱwithȱlumbarȱpainȱduringȱgestationalȱweeksȱ 12Ȭ18ȱ hadȱ lumbarȱ painȱ 3ȱ monthsȱ postpartum.ȱ Theȱ majorityȱ ofȱ participantsȱ (21/29,ȱ72%)ȱwhoȱexperiencedȱlumbarȱpainȱduringȱgestationalȱweeksȱ12Ȭ18ȱdidȱ notȱhaveȱLBPȱpostpartum.ȱEighteenȱ(7%)ȱparticipantsȱwhoȱdidȱnotȱhaveȱLBPȱ duringȱ gestationalȱ weeksȱ 12Ȭ18ȱ hadȱ LBPȱ (9ȱ PGP,ȱ 9ȱ lumbarȱ pain)ȱ 3ȱ monthsȱ postpartum.ȱ Althoughȱ aȱ smallȱ group,ȱ theȱ 18ȱ participantsȱ hadȱ aȱ higherȱ BMIȱ (27.4ȱvs.ȱ24.7,ȱp=0.04)ȱinȱgestationalȱweeksȱ12Ȭ18ȱthanȱparticipantsȱwhoȱwhereȱ withoutȱLBPȱinȱgestationalȱweeksȱ12Ȭ18,ȱasȱwellȱasȱ3ȱmonthsȱpostpartum.ȱTwoȱ ofȱ theȱ 9ȱ womenȱ whoȱ hadȱ PGPȱ postpartum,ȱ developedȱ itȱ afterȱ givingȱ birth.ȱ Noneȱofȱtheȱparticipantsȱinȱtheȱ“noȱLBP”ȱgroupȱinȱgestationalȱweeksȱ12Ȭ18ȱhadȱ combinedȱpainȱ3ȱmonthsȱpostpartum,ȱbutȱ3ȱparticipantsȱinȱtheȱPGPȱgroupȱandȱ 3ȱparticipantsȱinȱtheȱlumbarȱpainȱgroupȱhadȱcombinedȱpainȱpostpartum.ȱ Comparedȱ toȱ participantsȱ whoȱ hadȱ LBPȱ atȱ gestationalȱ weeksȱ 12Ȭd18ȱ ȱ an recoveredȱ postpartumȱ (n=94),ȱwomenȱ withȱ persistentȱ LBPȱ (n=71)ȱ hadȱ higherȱ disabilityȱ scoresȱ onȱ ODIȱ (18ȱ vs.ȱ 12,ȱ p=0.02),ȱ lowerȱ selfȬratedȱ HRQLȱ (EQȬ5Dȱ scoreȱ0.73ȱvs.ȱ0.80,ȱp=0.001),ȱmoreȱsickȱleaveȱduringȱtheȱprecedingȱ12ȱmonthsȱ (24%ȱ vs.ȱ 13%,ȱ p=0.03)ȱ andȱ aȱ greaterȱ numberȱ ofȱ positiveȱ pelvicȱ painȱ provocationȱtestsȱ(3.4ȱvs.ȱ2.9,ȱp=0.04)ȱduringȱgestationalȱweeksȱ12Ȭ18.ȱTheyȱalsoȱ tendedȱ toȱ haveȱ lowerȱ enduranceȱ ofȱ theȱ backȱ flexorȱ musclesȱ (27ȱ sȱ vs.ȱ 36ȱ sȱ p=0.07).ȱ

ȱ 44 Resultsȱ

PREDICTORSȱFORȱPELVICȱGIRDLEȱPAINȱORȱCOMBINEDȱ PAINȱ Theȱlogisticȱregressionȱmodelȱincludedȱ154ȱparticipants,ȱ122ȱofȱwhichȱhadȱnoȱ LBPȱ andȱ 32ȱ ofȱ whichȱ hadȱ PGPȱ orȱ combinedȱ pain.ȱ Theȱ 4ȱ factorsȱ thatȱ wereȱ significantlyȱ associatedȱ withȱ PGPȱ orȱ combinedȱ painȱ postpartumȱ wereȱ theȱ following:ȱ1)ȱworkȱdissatisfaction,ȱ2)ȱcombinedȱpainȱinȱgestationalȱweeksȱ12Ȭ 18,ȱ 3)ȱ olderȱ ageȱ (i.e.ȱ forȱ everyȱ yearȱ older,ȱ theȱ riskȱ ofȱ PGPȱ orȱ combinedȱ painȱ postpartumȱ increasedȱ byȱ 1.20),ȱ andȱ 4)ȱ lowȱ enduranceȱ ofȱ theȱ backȱ flexorȱ musclesȱ(i.e.ȱforȱeveryȱ10ȱsȱlostȱinȱendurance,ȱtheȱriskȱofȱPGPȱorȱcombinedȱpainȱ postpartumȱincreasedȱbyȱ1.18)ȱ(Tableȱ6).ȱTheseȱvariablesȱaccountedȱforȱ30%ȱofȱ theȱvarianceȱ(Nagelkerkeȱr2).ȱTheȱ154ȱparticipantsȱincludedȱinȱtheȱregressionȱ analysisȱdidȱnotȱdifferȱfromȱtheȱ89ȱparticipantsȱwhoȱwereȱnotȱincluded,ȱexceptȱ inȱ3ȱvariables.ȱTheȱ89ȱexcludedȱwomenȱwereȱatȱaȱlaterȱgestationalȱweekȱofȱtheirȱ pregnancyȱatȱtheȱtimeȱofȱinclusionȱinȱtheȱstudyȱ(p<0.001),ȱhadȱmoreȱproblemsȱ withȱurinaryȱincontinenceȱ(p=0.03),ȱandȱhadȱhigherȱBMIȱ(p=0.04)ȱthanȱtheȱ154ȱ participantsȱwhoȱwereȱincludedȱinȱtheȱregressionȱanalysis.ȱ ȱ ȱ Tableȱ6.ȱPredictorsȱforȱpersistentȱPGPȱorȱcombinedȱpainȱpostpartumȱ ȱ ȱ Dependentȱvariable:ȱPGP andȱcombinedȱpainȱ3ȱ ȱ Independentȱvariablesȱ monthsȱpostpartumȱ oddsȱratiosȱ 95%ȱCIȱ pȬvalueȱ ȱ Lowȱenduranceȱofȱbackȱflexorsȱ 1.18ȱ 1.01Ȭ1.37ȱ 0.04ȱ ȱ Olderȱageȱ 1.20ȱ 1.07Ȭ1.36ȱ 0.002ȱ ȱ NoȱLBPȱ(ref)ȱ 1ȱ ȱ 0.02ȱ ȱ Lumbarȱpainȱ 1.51ȱ 0.32Ȭ7.20ȱ 0.61ȱ ȱ

PGPȱ 2.17ȱ 0.69Ȭ6.81ȱ 0.19ȱ ȱ Combinedȱpainȱ 7.70ȱ 2.16Ȭ27.44ȱ 0.002ȱ ȱ Workȱdissatisfactionȱ 10.06ȱ 2.16Ȭ46.91ȱ 0.003ȱ ȱ ȱ ȱ

HEALTHȬRELATEDȱQUALITYȱOFȱLIFEȱINȱEARLYȱ PREGNANCYȱ Inȱ gestationalȱ weeksȱ 12Ȭ18,ȱ theȱ womenȱ withȱ someȱ typeȱ ofȱ LBPȱ reportedȱ significantlyȱ lowerȱ weightedȱ healthȱ statusȱ indexȱ asȱ comparedȱ toȱ theȱ womenȱ

ȱ 45 Resultsȱ ȱ withoutȱLBPȱ(EQȬ5Dȱscoreȱ0.73Ȭ0.80ȱvs.ȱ1.0,ȱp<0.001).ȱConcerningȱtheȱselfȬratedȱ healthȱ statusȱ (EQȬ5Dȱ VAS),ȱ theȱ womenȱ withȱ PGPȱ andȱ theȱ womenȱ withȱ combinedȱ painȱ reportedȱ significantlyȱ lowerȱ valuesȱ thanȱ theȱ womenȱ withoutȱ LBPȱ(EQȬ5DȱVASȱ71Ȭ80ȱvs.ȱ87,ȱp<0.001,ȱTableȱ7).ȱHowever,ȱtheȱselfȬratedȱhealthȱ statusȱshowedȱnoȱsignificantȱdifferenceȱbetweenȱtheȱwomenȱwithoutȱLBPȱandȱ theȱwomenȱwithȱlumbarȱpain.ȱTheȱwomenȱwithȱcombinedȱpainȱreportedȱtheȱ lowestȱ weightedȱ healthȱ statusȱ indexȱ andȱ theȱ lowestȱ selfȬratedȱ healthȱ status.ȱ Womenȱwithȱlumbarȱpainȱreportedȱtheȱhighestȱhealthȱstatusȱ(EQȬ5Dȱscoreȱandȱ EQȬ5Dȱ VAS)ȱ ofȱ thoseȱ sufferingȱ fromȱ anyȱ typeȱ ofȱ LBP.ȱ Theȱ womenȱ withȱ combinedȱ painȱ exhibitedȱ significantlyȱ lowerȱ healthȱ statusȱ comparedȱ toȱ theȱ womenȱ withȱ lumbarȱ painȱ (EQȬ5Dȱ scoreȱ andȱ EQȬ5Dȱ VASȱ p=0.02Ȭ0.008).ȱ Twoȱ womenȱhadȱinternalȱmissingȱvaluesȱonȱtheȱEQȬ5Dȱandȱwereȱwithdrawnȱfromȱ theȱanalysis.ȱ ȱ ȱ Tableȱ7.ȱPainȱVAS,ȱODI,ȱandȱEQȱinȱpregnancyȱweeksȱ12Ȭ18.ȱ ȱ

Variableȱmedianȱ 1=ȱ 2=ȱ 3=ȱ 4=ȱ Groupȱ (25,ȱ75ȱ NoȱLBPȱ LumbarȱPainȱ PGPȱ Combinedȱ comparisonsȱ percentile)ȱ ȱ ȱ ȱ painȱ pȬvalueȱ VASȱn=69ȱ n=32ȱ n=100ȱ n=57ȱ correctedȱforȱ ODIȱn=64ȱ n=33ȱ n=101ȱ n=ȱ57ȱ multipleȱtestȱwithȱ EQȱȱȱȱn=116ȱ n=33ȱ n=103ȱ n=ȱ56ȱ adjustedȱ Bonferroniȱ Painȱintensityȱ ȱȱ0ȱ(0Ȭ21)ȱȱȱȱ23ȱ(4Ȭ36)ȱȱȱȱ26ȱ(7Ȭ46)ȱȱȱȱ36ȱ(22Ȭ62)ȱ 1ȱvs.ȱ2,3,4ȱ<0.001ȱ VASȱ(mm)ȱatȱ 2ȱvs.ȱ3ȱnsȱ presentȱȱ 2ȱvs.ȱ4ȱ0.007ȱ 3ȱvs.ȱ4ȱ0.017ȱ Averageȱpainȱ ȱȱ3ȱ(0Ȭ22)ȱ ȱȱȱ20ȱ(8Ȭ37)ȱ ȱȱȱ28ȱ(11Ȭ52)ȱ ȱȱȱ43ȱ(28Ȭ62)ȱ 1ȱvs.ȱ2,3,4ȱ<0.001ȱ intensityȱVASȱ 2ȱvs.ȱ3ȱnsȱ (mm)ȱpreviousȱ 2ȱvs.ȱ4ȱ0.002ȱ weekȱ 3ȱvs.ȱ4ȱ0.003ȱ ODIȱscoreȱ(%)ȱȱ ȱȱ4ȱ(0Ȭ8)ȱȱȱȱ10ȱ(6Ȭ20)ȱȱ ȱȱȱ14ȱ(8Ȭ26)ȱȱȱȱ18ȱ(11Ȭ30)ȱ 1ȱvs.ȱ2,3,4ȱ<0.001ȱ 2ȱvs.ȱ3ȱnsȱ 2ȱvs.ȱ4ȱ0.007ȱ 3ȱvs.ȱ4ȱnsȱ EQȬ5Dȱscoreȱ ȱȱ1ȱ(0,80Ȭ1)ȱ 0.80ȱ(0,73Ȭ0,80)ȱ 0.76ȱ(0,69Ȭ0,80)ȱ 0.73ȱ(0,62Ȭ0,80)ȱ 1ȱvs.ȱ2,3,4ȱ<0.001ȱ 2ȱvs.ȱ3ȱnsȱ 2ȱvs.ȱ4ȱ0.016ȱ 3ȱvs.ȱ4ȱnsȱ EQȬ5DȱVASȱ 87ȱ(80Ȭ91)ȱȱȱȱ80ȱ(68Ȭ94)ȱȱȱȱ75ȱ(65Ȭ85)ȱȱȱȱ71ȱ(51Ȭ80)ȱ 1ȱvs.ȱ2ȱnsȱ 1ȱvs.ȱ3ȱ<0.001ȱ 1ȱvs.ȱ4ȱ<0.001ȱ 2ȱvs.ȱ3ȱnsȱ 2ȱvs.ȱ4ȱ0.008ȱȱ 3ȱvs.ȱ4ȱnsȱ ȱ

ȱ 46 Resultsȱ

PAINȱANDȱDISABILITYȱINȱEARLYȱPREGNANCYȱ Inȱ gestationalȱ weeksȱ 12Ȭ18,ȱ theȱ womenȱ withȱ someȱ typeȱ ofȱ LBPȱ reportedȱ significantlyȱhigherȱpainȱintensityȱ(medianȱ23Ȭ36ȱmmȱvs.ȱ0ȱmm,ȱp<0.001)ȱandȱ higherȱ disabilityȱ (medianȱ ODIȱ 10Ȭ18%ȱ vs.ȱ 4%,ȱ p<0.001)ȱ comparedȱ toȱ theȱ womenȱwithoutȱLBPȱ(Tableȱ7).ȱTheȱwomenȱwithȱcombinedȱpainȱreportedȱtheȱ highestȱpainȱintensityȱandȱtheȱhighestȱlevelȱofȱdisabilityȱandȱtheȱwomenȱwithȱ lumbarȱpainȱreportedȱtheȱlowestȱofȱthoseȱsufferingȱfromȱLBP.ȱTheȱwomenȱwithȱ combinedȱpainȱexhibitedȱsignificantlyȱhigherȱpainȱintensityȱandȱaȱhigherȱlevelsȱ ofȱdisabilityȱcomparedȱtoȱthoseȱwithȱlumbarȱpainȱ(pȬvaluesȱrangingȱfromȱ0.007ȱ toȱ0.002,ȱTableȱ7).ȱTwelveȱwomenȱreportedȱ“moderateȱdisability”ȱ(ODI>ȱ40%),ȱ 7ȱofȱwhomȱhadȱPGPȱandȱ4ȱofȱwhomȱhadȱcombinedȱpain.ȱ ȱ Dividingȱ theȱ cohortȱ accordingȱ toȱ bothȱ painȱ intensityȱ andȱ levelȱ ofȱ disabilityȱ revealedȱ thatȱ 15%ȱ ofȱ womenȱ withȱ PGPȱ and/orȱ lumbarȱ painȱ reportedȱ noȱ consequencesȱdueȱtoȱtheirȱsyndromesȱ(Tableȱ8).ȱInȱtheȱPGPȱandȱcombinedȱpainȱ groups,ȱ2/3ȱ(PGPȱ57%,ȱcombinedȱpainȱ70ȱ%)ȱreportedȱdisabilityȱ>10%ȱonȱtheȱ ODI,ȱ asȱ wellȱ asȱ painȱ >10ȱ mmȱ (VAS)ȱ comparedȱ toȱ theȱ lumbarȱ painȱ group,ȱ whereȱonlyȱaȱ1/3ȱ(30%)ȱreportedȱpainȱandȱdisabilityȱ(Tableȱ8).ȱ ȱ

ȱ Tableȱ8.ȱConsequencesȱofȱhavingȱlumbarȱpain,ȱPGPȱorȱcombinedȱpainȱonȱpainȱandȱdisability.ȱ

Subgroupingȱȱ Painǂ10ȱmmȱȱ ȱ Pain>10ȱmmȱ ȱ Pain>10ȱmmȱ ȱ Totalȱ accordingȱtoȱ ȱ ȱ ORȱ ȱ ANDȱ ȱ ȱ consequenceȱ ODIǂ10%ȱ ȱ ODI>ȱ10%ȱ ȱ ODI>10%ȱ ȱ ȱ nȱ %ȱ nȱ %ȱ nȱ %ȱ nȱ Lumbarȱpainȱ ȱȱȱ7ȱ 21ȱ 16ȱ 48ȱ 10ȱ 30ȱ 33ȱ

PGPȱ 18ȱ 18ȱ 25ȱ 25ȱ 56ȱ 57ȱ 99ȱ Combinedȱpainȱ ȱȱȱ3ȱȱȱȱ5ȱ 14ȱ 25ȱ 40ȱ 70ȱ 57ȱ Totalȱȱ 28ȱ 15ȱ 55ȱ 29ȱ 106ȱ 56ȱ 189ȱ

POSTPARTUMȱDEPRESSIVEȱSYMPTOMSȱ Afterȱ delivery,ȱ 267ȱ womenȱ respondedȱ toȱ theȱ EPDS.ȱ Usingȱ aȱ cutȬoffȱ scoreȱ ofȱ ǃ10,ȱ44/267ȱwomenȱ(16%)ȱexperiencedȱdepressiveȱsymptomsȱpostpartum.ȱOutȱ ofȱ theseȱ 44ȱ women,ȱ 27ȱ (61%)ȱ wereȱ classifiedȱ withȱ LBP.ȱ Thusȱ 27/267ȱ women,ȱ 10%ȱofȱtheȱcohort,ȱhadȱbothȱLBPȱandȱaȱtotalȱscoreȱǃ10ȱonȱtheȱEPDS.ȱWomenȱ withȱLBPȱhadȱhigherȱprevalenceȱofȱdepressiveȱsymptomsȱthanȱthoseȱwithoutȱ LBPȱ(pȱ<ȱ0.001,ȱTableȱ9).ȱTwentyȬtwoȱwomenȱ(8%ȱofȱtheȱcohort)ȱscoredȱǃ13ȱonȱ theȱ EPDSȱ (Tableȱ 9).ȱ Theȱ prevalenceȱ ofȱ depressiveȱ symptomsȱ wasȱ higherȱ

ȱ 47 Resultsȱ ȱ amongȱ womenȱ withȱ lumbarȱ painȱ comparedȱ toȱ womenȱ withoutȱ LBPȱ whenȱ applyingȱaȱcutȬoffȱscoreȱofȱǃ10ȱ(p=0.002)ȱorȱǃ13ȱ(p=0.001).ȱThereȱwasȱaȱhigherȱ prevalenceȱ ofȱ depressiveȱ symptomsȱ amongȱ womenȱ withȱ PGPȱ comparedȱ toȱ womenȱ withoutȱ LBPȱ onlyȱ whenȱ usingȱ aȱ cutȬoffȱ scoreȱ ofȱǃ10ȱ (p=0.01).ȱ Theȱ strongestȱ associationsȱ wereȱ foundȱ betweenȱ depressiveȱ symptomsȱ andȱ theȱ 3ȱ subgroupsȱ ofȱ LBP.ȱ Theȱ associationsȱ remainedȱ significantȱ afterȱ adjustingȱ forȱ parity,ȱurinaryȱincontinence,ȱandȱBMIȱ(oddsȱratioȱ3.58ȱtoȱ5.98,ȱTableȱ10).ȱFiveȱ womenȱ hadȱ internalȱ missingȱ valuesȱ ofȱ itemsȱ andȱ wereȱ excludedȱ fromȱ theȱ analyses.ȱ ȱ ȱ Tableȱ9.ȱDepressiveȱsymptomsȱevaluatedȱ3ȱmonthsȱpostpartumȱusingȱtheȱEPDSȱwithȱcutȬoffȱ scoresȱofȱǃ10ȱandȱǃ13,ȱrespectively.ȱTheȱsignificantȱgroupȱcomparisonsȱareȱshown.ȱ ȱ

EPDSȱ Totalȱ 1ȱ 2+3+4ȱ 2ȱȱ 3ȱ 4ȱ Groupȱ cohortȱ NoȱLBPȱ LBPȱ Lumbarȱ PGPȱ Combinedȱ comparisonsȱ ȱ ȱ ȱ painȱ ȱ painȱ pȬvalueȱ n=267ȱ n=180ȱ n=87ȱ n=29ȱ n=44ȱ n=14ȱ ȱ

EPDSȱǃ10ȱ ȱ ȱ ȱ ȱ ȱ ȱ EPDSȱǃ10ȱ nȱ(%)ȱ 44ȱ(16)ȱ 17ȱ(9)ȱ 27ȱ(31)ȱ 11ȱ(38)ȱ 12ȱ(27)ȱ 4ȱ(29)ȱ pȱ<0.001ȱ (95%ȱCI)ȱ (12ȱtoȱ20)ȱ (5ȱtoȱ13)ȱ (26ȱtoȱ36)ȱ (20ȱtoȱ56)ȱ (14ȱtoȱ40)ȱ (5ȱtoȱ53)ȱ 1ȱvs.ȱ2ȱ0.002ȱ 1ȱvs.ȱ3ȱ0.01ȱ 1ȱvs.ȱ(2,3,4)<0.001ȱ

EPDSȱǃ13ȱ ȱ ȱ ȱ ȱ ȱ ȱ EPDSȱǃ13ȱ nȱ(%)ȱ 22ȱ(8)ȱ 7ȱ(4)ȱ 15ȱ(17)ȱ 8ȱ(28)ȱ 5ȱ(11)ȱ 2ȱ(14)ȱ pȱ<0.001ȱ (95%ȱCI)ȱ (5ȱtoȱ11)ȱ (1ȱtoȱ7)ȱ (9ȱtoȱ25)ȱ (12ȱtoȱ44)ȱ (2ȱtoȱ20)ȱ (5ȱtoȱ23)ȱ 1ȱvs.2ȱ0.001ȱ 1ȱvs.ȱ(2,3,4)<0.001ȱ

ȱ

ȱ

ȱ

ȱ

ȱ 48 Resultsȱ

Tableȱ10.ȱResultsȱfromȱtheȱlogisticȱregressionȱanalysesȱ(enterȱmethod).ȱTheȱdependentȱvariableȱ wasȱ theȱ resultȱ fromȱ theȱ EPDSȱ withȱ aȱ cutȬoffȱ scoreȱ ofȱǃ10.ȱ Theȱ classificationsȱ ofȱ LBPȱ wereȱ enteredȱasȱcategoricalȱindependentȱvariablesȱ(noȱLBPȱgroupȱasȱreference).ȱTheȱcovariatesȱwereȱ parityȱ(continuous),ȱurinaryȱincontinenceȱ(yesȬno),ȱandȱbodyȱmassȱindexȱ(BMI)ȱ(continuous).ȱ

DependentȱEPDSȱwithȱcutȬoffȱscoresȱǃ10ȱ df pȬvalue oddsȱratioȱ 95%ȱCIȱ

Independentȱvariablesȱ ȱȱ ȱ ȱ NoȱLBPȱ(reference)ȱ 3ȱ 0.001ȱ 1ȱ ȱ ȱLumbarȱpainȱ 1ȱ <0.001ȱ 5.81ȱ 2.16Ȭ15.63ȱ ȱPGPȱ 1ȱ 0.008ȱ 3.58ȱ 1.39Ȭ9.22ȱ ȱCombinedȱpainȱ 1ȱ 0.009ȱ 5.98ȱ 1.56Ȭ22.97ȱ Parityȱ 1ȱ 0.05ȱ 1.49ȱ 1.00Ȭ2.22ȱ Urinaryȱincontinenceȱ 1ȱ 0.56ȱ 0.74ȱ 0.27–2.22ȱ BMIȱ 1ȱ 0.70ȱ 1.02ȱ 0.94Ȭ1.11ȱ ȱ

PHYSICALȱMEASURESȱINȱPREGNANCYȱANDȱ POSTPARTUMȱ

Backȱflexorȱmusclesȱenduranceȱȱ Inȱgestationalȱweeksȱ12Ȭ18,ȱtheȱwomenȱwithȱPGPȱhadȱlowerȱenduranceȱofȱtheȱ backȱflexorȱmusclesȱasȱcomparedȱtoȱtheȱwomenȱwithoutȱLBPȱ(meanȱdifferenceȱ 17.9ȱ sȱ p=0.001,ȱ Tableȱ 11).ȱ Postpartum,ȱ theȱ womenȱ withȱ combinedȱ painȱ hadȱ lowerȱ enduranceȱ ofȱ theȱ backȱ flexorȱ musclesȱ asȱ comparedȱ toȱ theȱ womenȱ withoutȱLBPȱ(meanȱdifferenceȱ33ȱsȱp=0.01,ȱTableȱ12.ȱ

Backȱextensorȱmusclesȱenduranceȱ Postpartum,ȱtheȱwomenȱwithȱPGPȱhadȱlowerȱenduranceȱofȱtheȱbackȱextensorȱ musclesȱ asȱ comparedȱ toȱ theȱ womenȱ withoutȱ LBPȱ (meanȱ differenceȱ 28.3ȱ sȱ p<0.001,ȱTableȱ12.ȱ ȱ ȱ ȱ ȱ ȱ ȱ

ȱ 49 Resultsȱ ȱ Tableȱ11.ȱMuscleȱtestȱresultsȱinȱpregnancyȱinȱtheȱ4ȱgroupsȱbasedȱonȱtypeȱofȱLBP:ȱnoȱLBP,ȱ lumbarȱpain,ȱPGPȱandȱcombinedȱpain.ȱ ȱ ȱ 1ȱ 2ȱ 3ȱ 4ȱ ȱ NoȱLBPȱ Lumbarȱpainȱ PGPȱ Combinedȱ Groupȱ meanȱ(95%ȱconfidenceȱ ȱ ȱ ȱ painȱ comparison intervals)ȱ n=116ȱ n=32ȱ n=99ȱ n=54ȱ pȬvalueȱ Backȱflexorȱenduranceȱȱ n=100ȱ n=27ȱ n=83ȱ n=40ȱȱ (s)ȱ 52.6ȱ(45.9Ȭ59.3)ȱ 40.1ȱ(28.4Ȭ51.9)ȱ 34.7ȱ(28.9Ȭ40.5)ȱ 41.0ȱ(30.7Ȭ51.4)ȱ 1ȱvs.ȱ3ȱ0.001ȱ

Rightȱhipȱextensionȱ n=112ȱ n=31ȱ n=91ȱ n=49ȱȱ

(N)ȱ 275ȱ(254Ȭ295)ȱ 220ȱ(186Ȭ253)ȱ 221ȱ(200Ȭ242)ȱ 216ȱ(188Ȭ244)ȱ 1ȱvs.ȱ3ȱ0.001 1ȱvs.ȱ4ȱ0.006ȱ

Leftȱhipȱextensionȱȱ n=111ȱ n=31ȱ n=90ȱ n=49ȱȱ (N)ȱ 254ȱ(233Ȭ275)ȱ 217ȱ(182Ȭ251)ȱ 209ȱ(187Ȭ230)ȱ 204ȱ(177Ȭ232)ȱ 1ȱvs.ȱ3ȱ0.02ȱ 1ȱvs.ȱ4ȱ0.04ȱ

Gaitȱspeedȱ n=112ȱ n=31ȱ n=92ȱ n=53ȱȱ

(m/s)ȱ 1.33ȱ(1.30Ȭ1.36)ȱ 1.31ȱ(1.24Ȭ1.39)ȱ 1.24ȱ(1.20Ȭ1.29)ȱ 1.25ȱ(1.20Ȭ1.30)ȱ 1ȱvs.ȱ3ȱ0.008ȱ

ȱ ȱ Tableȱ12.ȱMuscleȱtestȱresultsȱpostpartumȱinȱtheȱ4ȱgroupsȱbasedȱonȱtypeȱofȱLBP:ȱnoȱLBP,ȱ lumbarȱpain,ȱPGP,ȱandȱcombinedȱpain.ȱ ȱ

ȱ 1ȱ 2 3 4ȱ ȱ NoȱLBPȱ Lumbarȱpainȱ PGPȱ Combinedȱ Groupȱ meanȱ(95%ȱconfidenceȱ ȱ ȱ ȱ painȱ comparisonȱ intervals)ȱ n=176ȱ n=27ȱ n=45ȱ n=14ȱ pȬvalueȱ Backȱflexorȱenduranceȱ n=166ȱ n=20ȱ n=44ȱ n=12ȱȱ (s)ȱ 53.0ȱ(47.4Ȭ58.6)ȱ 56.5ȱ(38.1Ȭ74.9)ȱ 41.8ȱ(30.9Ȭ52.7)ȱ 20.0ȱ(9.7Ȭ30.3)ȱ 1ȱvs.ȱ4ȱ0.01ȱ 2ȱvs.ȱ4ȱ0.03ȱ

Backȱextensorȱenduranceȱ n=162ȱ n=17ȱ n=36ȱ n=9ȱȱ (s)ȱ 79.0ȱ(73.7Ȭ84.4)ȱ 59.8ȱ(42.9Ȭ76.7)ȱ 50.7ȱ(39.1Ȭ62.3)ȱ 56.3ȱ(30.9Ȭ81.7)ȱ 1ȱvs.ȱ3ȱ<0.001ȱ

Rightȱhipȱextensionȱȱ n=172ȱ n=24ȱ n=44ȱ n=14ȱȱ (N)ȱ 256ȱ(242Ȭ270)ȱ 265ȱ(219Ȭ311)ȱ 211ȱ(186Ȭ237)ȱ 183ȱ(156Ȭ210)ȱ 1ȱvs.ȱ3ȱ0.03ȱ 1ȱvs.ȱ4ȱ0.03ȱ

Leftȱhipȱextensionȱȱ n=173ȱ n=24ȱ n=44ȱ n=14ȱȱ (N)ȱ 239ȱ(224Ȭ254)ȱ 261ȱ(209Ȭ313)ȱ 217ȱ(189Ȭ244)ȱ 185ȱ(148Ȭ222)ȱ nsȱ

Gaitȱspeedȱ n=171ȱ n=21ȱ n=44ȱ n=12ȱȱ (m/s)ȱ 1.33ȱ(1.31Ȭ1.36)ȱ 1.27ȱ(1.18Ȭ1.36)ȱ 1.26ȱ(1.21Ȭ1.30)ȱ 1.28ȱ(1.21Ȭ1.36)ȱ 1ȱvs.ȱ3ȱ0.03ȱ ȱ

ȱ 50 Resultsȱ

Maximalȱvoluntaryȱisometricȱhipȱextensionȱ Theȱ womenȱ withȱ PGPȱ andȱ thoseȱ withȱ combinedȱ painȱ hadȱ lowerȱ valuesȱ forȱ maximalȱvoluntaryȱisometricȱhipȱextensionȱmuscleȱstrengthȱ(theȱrangeȱofȱtheȱ meanȱ differenceȱ 45Ȭ59ȱ Nȱ forȱ bothȱ legsȱ inȱ pregnancy,ȱ p=0.001Ȭ0.04,ȱ Tableȱ 11)ȱ andȱforȱtheȱrightȱlegȱpostpartumȱ(meanȱdifferenceȱ45Ȭ73ȱN,ȱp=0.03,ȱTableȱ12)ȱasȱ comparedȱ toȱ theȱ womenȱ withoutȱ LBP.ȱ Noȱ patternȱ wasȱ foundȱ regardingȱ dominantȱpainȱsideȱandȱhipȱmuscleȱresults.ȱ

Gaitȱspeedȱ TheȱwomenȱwithȱPGPȱwalkedȱatȱaȱslowerȱspeedȱasȱcomparedȱtoȱtheȱwomenȱ withoutȱLBPȱbothȱinȱpregnancyȱ(meanȱdifferenceȱ0.09ȱm/s,ȱp=0.008,ȱTableȱ11)ȱ andȱpostpartumȱ(meanȱdifferenceȱ0.07ȱm/s,ȱp=0.03,ȱTableȱ12).ȱ

Painȱintensityȱinȱrelationȱtoȱphysicalȱmeasuresȱ Thereȱ wasȱ noȱ significantȱ differenceȱ inȱ painȱ intensityȱ beforeȱ andȱ afterȱ theȱ physicalȱmeasures,ȱwhichȱimpliesȱthatȱtheȱtestsȱdidȱnotȱcauseȱincreasedȱpain.ȱ Theȱgeneralȱlinearȱmodelȱanalysesȱshowedȱanȱassociationȱbetweenȱsubgroupsȱ ofȱLBPȱandȱtrunkȱmuscleȱendurance,ȱhipȱextensionȱmuscleȱstrengthȱ(bilateralȱ inȱ pregnancyȱ andȱ rightȱ legȱ postpartum), ȱ andȱ gaitȱ speedȱ (Tableȱ 13ȱ andȱ 14).ȱ Whenȱ controllingȱ forȱ painȱ differencesȱ beforeȱ andȱ afterȱ eachȱ test,ȱ theȱ explanationȱofȱtheȱassociationȱbetweenȱmuscleȱfunctionȱandȱsubgroupsȱdidȱnotȱ improve.ȱ Thus,ȱ theȱ lowerȱ valuesȱ inȱ theȱ physicalȱ measuresȱ ofȱ thoseȱ womenȱ withȱsomeȱtypeȱofȱLBPȱcouldȱnotȱbeȱexplainedȱbyȱanȱincreaseȱinȱpainȱduringȱ testing.ȱWhenȱcontrollingȱforȱpretestȱpainȱintensity,ȱagain,ȱnoȱimprovementȱinȱ theȱexplanationȱwasȱachieved.ȱ

ȱ 51 Resultsȱ ȱ Tableȱ13.ȱResultsȱfromȱtheȱgeneralȱlinearȱmodelȱanalysesȱinȱpregnancy.ȱTheȱindependentȱ fixedȱfactorȱwasȱtheȱsubgroupsȱofȱtheȱcohort.ȱInȱcrudeȱmodelȱ1,ȱtheȱassociationȱbetweenȱ muscleȱtestȱresultsȱandȱtheȱsubgroupsȱwasȱanalysed.ȱInȱadjustedȱmodelȱ2,ȱtheȱdifferenceȱinȱ painȱbeforeȱandȱafterȱeachȱtestȱwasȱaddedȱasȱaȱcovariate.ȱInȱadjustedȱmodelȱ3,ȱtheȱpretestȱ painȱintensityȱwasȱaddedȱasȱaȱcovariate.ȱTheȱsignificantȱassociationsȱareȱshown.ȱ ȱ

Pregnancyȱ Crudeȱmodelȱ1ȱ Adjustedȱmodelȱ2ȱ Adjustedȱmodelȱ3ȱ Dependent:ȱBackȱflexorsȱ ȱȱ ȱ Fixedȱfactor:ȱsubgroupsȱofȱtheȱcohortȱ 0.002ȱ 0.001ȱ 0.014ȱ Dependent:ȱHipȱextensionȱ(right)ȱ ȱȱ ȱ Fixedȱfactor:ȱsubgroupsȱofȱtheȱcohortȱ <0.001ȱ <0.001ȱ 0.014ȱ

Dependent:ȱHipȱextensionȱ(left)ȱ ȱȱ ȱ Fixedȱfactor:ȱsubgroupsȱofȱtheȱcohortȱ 0.006ȱ 0.006ȱ nsȱ

Dependent:ȱGaitȱȱ ȱȱ ȱ Fixedȱfactor:ȱsubgroupsȱofȱtheȱcohortȱ 0.004ȱ 0.005ȱ nsȱ

ȱ ȱ Tableȱ14.ȱResultsȱfromȱtheȱgeneralȱlinearȱmodelȱanalysesȱpostpartum.ȱTheȱindependentȱ fixedȱfactorȱwasȱtheȱsubgroupsȱofȱtheȱcohort.ȱInȱcrudeȱmodelȱ1,ȱtheȱassociationȱbetweenȱ muscleȱtestȱresultsȱandȱtheȱclassificationȱwasȱanalysed.ȱInȱadjustedȱmodelȱ2,ȱtheȱdifferenceȱ inȱ painȱ beforeȱ andȱ afterȱ eachȱ testȱ wasȱ addedȱ asȱ aȱ covariate.ȱ Inȱ adjustedȱ modelȱ 3,ȱ theȱ pretestȱpainȱintensityȱwasȱaddedȱasȱaȱcovariate.ȱTheȱsignificantȱassociationsȱareȱshown.ȱ ȱ

Postpartumȱ Crudeȱmodelȱ1ȱ Adjustedȱmodelȱ2ȱ Adjustedȱmodelȱ3ȱ Dependent:ȱBackȱflexorsȱ ȱȱ ȱ Fixedȱfactor:ȱsubgroupsȱofȱtheȱcohortȱ 0.007ȱ 0.008ȱ 0.017ȱ

Dependent:ȱBackȱextensorsȱ ȱȱ ȱ Fixedȱfactor:ȱsubgroupsȱofȱtheȱcohortȱ <0.001ȱ <0.001ȱ nsȱ

Dependent:ȱHipȱextensionȱ(right)ȱ ȱȱ ȱ Fixedȱfactor:ȱsubgroupsȱofȱtheȱcohortȱ 0.002ȱ 0.004ȱ 0.031ȱ

Dependent:ȱGaitȱȱ ȱȱ ȱ Fixedȱfactor:ȱsubgroupsȱofȱtheȱcohortȱ 0.019ȱ 0.020ȱ nsȱ

ȱ

ȱ

ȱ 52 Discussionȱ

DISCUSSIONȱ

PREVALENCEȱOFȱLOWȱBACKȱPAINȱINȱPREGNANCYȱANDȱ POSTPARTUMȱ Whenȱ allȱ formsȱ ofȱ nonspecificȱ LBPȱ wereȱ considered,ȱ 2ȱ outȱ ofȱ 3ȱ womenȱ hadȱ someȱ typeȱ ofȱ LBPȱ inȱ pregnancyȱ andȱ 1ȱ outȱ ofȱ 3ȱ hadȱ LBPȱ postpartum.ȱ Consideringȱtheȱfactȱthatȱwomenȱwhoȱhadȱmildȱsymptomsȱwereȱincludedȱinȱ theȱstudy,ȱtheȱprevalenceȱfoundȱisȱcomparableȱtoȱ3ȱidentifiedȱcohortȱstudiesȱofȱ pregnantȱwomen,ȱinȱwhichȱclinicalȱclassificationȱofȱallȱLBPȱwasȱperformedȱandȱ theȱ wholeȱ cohortȱ ofȱ pregnantȱ womenȱ wasȱ reportedȱ (2,ȱ 116,ȱ 183).ȱ Theȱ onlyȱ cohortȱ studyȱ thatȱ clinicallyȱ reȬevaluatedȱ allȱ womenȱ postpartumȱ reportedȱ anȱ almostȱ identicalȱ overallȱ pointȱ prevalenceȱ asȱ inȱ theȱ presentȱ studyȱ (31.6%ȱ vs.ȱ 33%)(116).ȱItȱhasȱbeenȱestimatedȱthatȱtheȱprevalenceȱofȱpregnancyȬrelatedȱLBPȱ increasesȱbyȱ20%ȱwhenȱwomenȱwithȱmildȱsymptomsȱareȱincludedȱ(267).ȱTheȱ 15%ȱofȱwomenȱinȱtheȱpresentȱstudyȱwhoȱreportedȱnoȱconsequenceȱasȱaȱresultȱ ofȱtheirȱsyndromesȱisȱcomparableȱtoȱtheȱ20%ȱpreviouslyȱdescribedȱasȱafflictedȱ byȱ“aȱnormalȱdiscomfortȱofȱpregnancy”.ȱTheȱnoȱconsentȱrateȱwasȱlowȱinȱtheȱ presentȱ study,ȱ however,ȱ itȱ isȱ possibleȱ thatȱ womenȱ withoutȱ LBPȱ wereȱ lessȱ interestedȱinȱparticipating,ȱwhichȱmayȱhaveȱresultedȱinȱaȱhigherȱprevalenceȱofȱ LBP.ȱ ȱ MostȱprevalenceȱstudiesȱdoȱnotȱdifferentiateȱbetweenȱPGPȱandȱlumbarȱpain,ȱ neitherȱinȱpregnancyȱnorȱpostpartumȱ(12,ȱ66,ȱ128,ȱ138,ȱ154,ȱ169,ȱ174,ȱ176,ȱ182,ȱ 185,ȱ235,ȱ236,ȱ263).ȱWhenȱclassificationȱwasȱperformed,ȱPGPȱwasȱtheȱdominantȱ subgroupȱ ofȱ LBPȱ inȱ theȱ presentȱ study,ȱ asȱ wellȱ asȱ inȱ 2ȱ cohortȱ studiesȱ ofȱ pregnantȱwomenȱthatȱcategorizedȱintoȱsubgroupsȱcomparableȱtoȱtheȱPGPȱandȱ lumbarȱpainȱgroupsȱ(2,ȱ183).ȱClinicalȱexaminationȱwasȱperformedȱinȱanotherȱ cohortȱ ofȱ pregnantȱ women,ȱ butȱ onlyȱ subgroupȱ prevalenceȱ ofȱ “symptomȬ givingȱ pelvicȱ girdleȱ relaxation”ȱ wasȱ reportedȱ (14%)ȱ (121).ȱ Additionally,ȱ inȱ 1ȱ cohortȱstudy,ȱsevereȱLBPȱrequiringȱsickȱleaveȱ(9.2%)ȱwasȱexaminedȱandȱ2/3ȱofȱ theȱ womenȱ wereȱ reportedȱ asȱ havingȱ SIJȱ dysfunctionȱ (14).ȱ Theȱ lowerȱ prevalenceȱ fromȱ theseȱ studiesȱ comparedȱ toȱ theȱ presentȱ studyȱ isȱ consistentȱ sinceȱtheȱcriteriaȱareȱnarrowerȱand,ȱthereby,ȱaȱmoreȱaffectedȱsampleȱisȱstudied.ȱ ȱ

ȱ 53 Discussionȱ ȱ Inȱcontrast,ȱtheȱpostpartumȱdistributionȱofȱsubgroupȱprevalenceȱofȱLBPȱisȱnotȱ consistent.ȱ Theȱ presentȱ studyȱ showedȱ theȱ largestȱ subgroupȱ forȱ PGPȱ andȱ theȱ smallestȱ forȱ combinedȱ pain,ȱ whichȱ isȱ consistentȱ withȱ oneȱ studyȱ thatȱ usedȱ similarȱcriteriaȱ(168),ȱhowever,ȱnearlyȱoppositeȱtoȱanotherȱ(166).ȱClassificationȱ basedȱonȱpainȱdrawingsȱhasȱshownȱtheȱlargestȱgroupȱforȱlumbarȱpainȱ(180).ȱAȱ clinicalȱ observationȱ isȱ thatȱ womenȱ haveȱ difficultiesȱ locatingȱ theȱ pelvisȱ onȱ aȱ painȱdrawing,ȱwhichȱmightȱhaveȱimplicationsȱforȱstudiesȱwhichȱclassifyȱLBPȱ subgroupsȱ basedȱ onȱ painȱ drawings.ȱ Regardingȱ prevalenceȱ ofȱ subgroupsȱ ofȱ LBPȱpostpartum,ȱitȱisȱtooȱearlyȱtoȱdrawȱconclusionsȱsinceȱtheȱpresentȱstudyȱisȱ theȱ onlyȱ identifiedȱ studyȱ thatȱ clinicallyȱ classifiesȱ andȱ reportsȱ prevalenceȱ ofȱ subgroupsȱpostpartumȱfromȱaȱcohortȱofȱpregnantȱwomen.ȱ ȱ Fromȱ cohort/crossȬsectionalȱ studies,ȱ selfȬreportedȱ prevalenceȱ ofȱ backȱ painȱ duringȱ pregnancyȱ showsȱ aȱ wideȱ rangeȱ (48Ȭ89.9%)(267).ȱ Studiesȱ withȱ smallȱ samplesȱ tendȱ toȱ reportȱ higherȱ prevalenceȱ ofȱ LBP,ȱ probablyȱ dueȱ toȱ selectionȱ bias.ȱTheȱselfȬreportedȱoverallȱprevalenceȱofȱLBPȱinȱpregnancyȱisȱhigherȱthanȱ inȱstudiesȱwithȱaȱclinicalȱexamination,ȱpossiblyȱdueȱtoȱtheȱfactȱthatȱevenȱmilderȱ formsȱareȱreported.ȱ ȱ TheȱselfȬreportedȱpointȱprevalenceȱofȱbackȱpainȱinȱpostpartumȱcohortsȱ rangesȱ betweenȱ44%ȱatȱdeliveryȱtoȱ16%ȱatȱ6ȱyearsȱpostpartumȱ(128,ȱ176,ȱ182).ȱForȱtheȱ presentȱstudy,ȱtheȱpointȱprevalenceȱforȱallȱtypesȱofȱLBPȱ3ȱmonthsȱpostpartumȱ (33%)ȱ isȱ similarȱ toȱ theȱ selfȬreportedȱ pointȱ prevalenceȱ atȱ theȱ sameȱ timeȱ pointȱ afterȱ deliveryȱ (26%Ȭ33%)ȱ (112,ȱ 182).ȱ Fromȱ aȱ largeȱ cohortȱ ofȱ 7526ȱ pregnantȱ women,ȱaȱlowȱprevalenceȱforȱPGPȱand/orȱLBPȱ(1.7%)ȱwasȱreportedȱpostpartumȱ (12).ȱHowever,ȱtheȱevaluationȱwasȱundertakenȱ2Ȭ3ȱweeksȱpostpartumȱandȱitȱisȱ questionableȱ asȱ toȱ whetherȱ theȱ womenȱ hadȱ fullyȱ recuperatedȱ normalȱ dailyȱ activity,ȱ whichȱ mayȱ haveȱ provokedȱ someȱ typeȱ ofȱ LBP.ȱ Apartȱ fromȱ theȱ low,ȱ unsureȱpostpartumȱprevalenceȱinȱthisȱlatterȱstudy,ȱtheȱselfȬreportedȱprevalenceȱ postpartumȱisȱsimilarȱtoȱthatȱclinicallyȱevaluated.ȱComparedȱtoȱnonpregnancyȬ relatedȱLBPȱstudies,ȱtheȱprevalenceȱofȱLBPȱpostpartumȱinȱtheȱpresentȱstudyȱisȱ higherȱthanȱthatȱselfȬreportedȱ(26%)ȱinȱtheȱ25Ȭ44ȱyearȱageȱbandȱ(195).ȱ

Powerȱ Aȱ powerȱ calculationȱ wasȱ madeȱ forȱ theȱ plannedȱ RCTȱ study.ȱ Initialȱ powerȱ analysisȱwasȱbasedȱonȱprimaryȱhealthȱcareȱdataȱofȱnonpregnancyȬrelatedȱLBPȱ patients.ȱWithȱaȱbetaȱlevelȱofȱ80%ȱandȱaȱdifferenceȱbetweenȱsubgroupsȱinȱODIȱ ofȱ10%,ȱ62ȱpatientsȱwereȱrequiredȱperȱgroupȱinȱtheȱRCT.ȱWhenȱdataȱnhadȱbee ȱ

ȱ 54 Discussionȱ collectedȱ forȱ approximatelyȱ halfȱ ofȱ theȱ cohort,ȱ aȱ retrospectiveȱ powerȱ calculationȱwasȱperformed,ȱwhichȱrevealedȱthatȱ21ȱparticipantsȱwereȱneededȱ perȱ group.ȱ Estimatedȱ prevalenceȱ ofȱ LBPȱ 3ȱ monthsȱ postȱ partumȱ wasȱ 25%,ȱ accordingȱ toȱ publishedȱ reportsȱ fromȱ 1997ȱ whenȱ theȱ presentȱ studyȱ wasȱ planned.ȱThusȱitȱwasȱappropriateȱtoȱincludeȱ400ȱpregnantȱwomenȱinȱorderȱtoȱ obtainȱ 100ȱ womenȱ withȱ LBPȱ postpartumȱ forȱ theȱ RCTȱ study.ȱ Aȱ retrospectiveȱ analysisȱwasȱdoneȱforȱtheȱphysicalȱperformanceȱtestsȱatȱtheȱendȱofȱtheȱstudy.ȱ Theȱ powerȱ toȱ detectȱ aȱ 20%ȱ differenceȱ inȱ theȱ backȱ flexorȱ musclesȱ wasȱ 52%ȱ (pregnant)ȱandȱ39%ȱ(postpartum);ȱforȱbackȱextensorȱmusclesȱitȱwasȱ69%ȱandȱ forȱhipȱextensors,ȱitȱwasȱ94%.ȱ

Classificationȱofȱlowȱbackȱpainȱ Whenȱ examiningȱ pregnantȱ womenȱ withȱ LBP,ȱ itȱ isȱ notȱ sufficientȱ toȱ onlyȱ identifyȱ redȱ flagȱ conditionsȱ andȱ thoseȱ withȱ nerveȱ rootȱ syndromeȱ andȱ thenȱ considerȱ theȱ remainderȱ asȱ aȱ heterogeneousȱ groupȱ ofȱ nonȬspecificȱ LBP.ȱ PGPȱ andȱ discogenicȱ problemsȱ alsoȱ needȱ toȱ beȱ identifiedȱ sinceȱ clinicalȱ experienceȱ andȱ previousȱ researchȱ suggestȱ differentȱ treatmentȱ strategiesȱ forȱ PGPȱ andȱ lumbarȱpainȱinȱrelationȱtoȱpregnancyȱ(180,ȱ189).ȱTheȱheterogeneousȱnonspecificȱ LBPȱinȱpregnancyȱisȱdivisibleȱintoȱatȱleastȱ3ȱsubgroups;ȱlumbarȱpain,ȱPGP,ȱandȱ combinedȱpain.ȱ ȱ Theȱclassificationȱinȱtheȱpresentȱstudyȱwasȱbasedȱonȱhistory,ȱpainȱlocationȱandȱ clinicalȱtests.ȱTheȱnumbersȱofȱpositiveȱpelvicȱpainȱprovocationȱtestsȱareȱseenȱinȱ Figureȱ4ȱandȱFigureȱ5.ȱTheȱcriteriaȱofȱ2ȱpositiveȱpelvicȱpainȱprovocationȱtestsȱ forȱ PGPȱ wasȱ chosenȱ basedȱ onȱ theȱ studyȱ thatȱ evaluatedȱ theȱ 5ȱ pelvicȱ painȱ provocationȱ testsȱ usedȱ inȱ theȱ presentȱ studyȱ withinȱ theȱ MDTȱ protocolȱ (122).ȱ Usingȱeitherȱ2ȱorȱ3ȱpositiveȱtestsȱforȱclassificationȱofȱSIJȱpainȱreportedlyȱmadeȱ noȱ largeȱ difference,ȱ butȱ 2ȱ isȱ recommended.ȱ Ifȱ 3ȱ positiveȱ pelvicȱ painȱ provocationȱ testsȱ hadȱ beenȱ usedȱ insteadȱ ofȱ 2,ȱ theȱ consequencesȱ forȱ theȱ subgroupȱ distributionȱ areȱ seenȱ inȱ Tablesȱ 15ȱ andȱ 16.ȱ Threeȱ positiveȱ testsȱ forȱ PGPȱprobablyȱselectȱaȱmoreȱaffectedȱgroup.ȱWomenȱwithȱonlyȱ2ȱpositiveȱtestsȱ areȱ thenȱ classifiedȱ asȱ “noȱ LBP”ȱ orȱ asȱ lumbarȱ painȱ ifȱ thereȱ isȱ aȱ positiveȱ examinationȱ ofȱ theȱ lumbarȱ spine,ȱ insteadȱ ofȱ combinedȱ pain.ȱ Onȱ theȱ otherȱ hand,ȱtheȱcriteriaȱofȱ2ȱpositiveȱtests,ȱasȱusedȱinȱtheȱpresentȱstudy,ȱmightȱimplyȱ thatȱtheȱPGPȱgroupȱisȱ“healthier”.ȱvanȱderȱWurffȱetȱal.ȱ(2006)ȱrecommendedȱ3ȱ positiveȱtestsȱoutȱofȱ5ȱbasedȱonȱaȱreceiverȱoperatingȱcharacteristicȱ(ROC)ȱcurveȱ withȱaȱreportedȱmaximalȱareaȱunderȱtheȱcurveȱofȱ0.799ȱ(239).ȱSinceȱbothȱofȱtheȱ

ȱ 55 Discussionȱ ȱ aboveȱmentionedȱstudiesȱwereȱdoneȱonȱnonpregnantȱsamples,ȱtheȱimplicationsȱ onȱtheȱpresentȱevaluationȱinȱpregnancyȱareȱnotȱfullyȱconvincing.ȱ ȱ Comparingȱ theȱ classificationȱ ofȱ 2ȱ versusȱ 3ȱ positiveȱ testsȱ inȱ pregnancyȱ andȱ postpartumȱ showsȱaȱ higherȱdiscrepancyȱ inȱ pregnancy.ȱ Thisȱ mightȱ beȱ dueȱ toȱ higherȱ sensitivityȱ ofȱ structuresȱ inȱ andȱ aroundȱ theȱ pelvisȱ inȱ pregnancy.ȱ Lowȱ rateȱofȱfalseȱpositiveȱpainȱprovocationȱtestsȱ(0Ȭ15%ȱ(115)ȱandȱ16Ȭ21%ȱ(n=2Ȭ3ȱoutȱ ofȱ19)(164))ȱhasȱbeenȱreportedȱinȱpregnantȱwomenȱwithoutȱPGP.ȱAdditionallyȱ whenȱcalculatingȱtheȱprevalenceȱbasedȱonȱ3ȱpositiveȱtests,ȱweȱhaveȱtheȱsameȱ prevalenceȱasȱstudiesȱnotȱincludingȱwomenȱwithȱmildȱsymptoms.ȱ ȱ ȱ

120 120

100 100

80 80

60 60

40 40

20 20

0 0 Cumul ati ve Per cent Cumulati ve Per cent

0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 ȱ ȱ Figureȱ4.ȱNumberȱofȱpositiveȱpelvicȱpainȱ Figureȱ5.ȱNumberȱofȱpositiveȱpelvicȱpainȱ provocationȱtestsȱinȱgestationalȱweeksȱ12Ȭ provocationȱtestsȱpostpartum.ȱ 18.ȱ ȱ ȱ

Tableȱ15.ȱPrevalenceȱofȱsubgroupsȱofȱLBPȱ Tableȱ16.ȱPrevalenceȱofȱsubgroupsȱofȱLBPȱ whenȱusingȱ2ȱversusȱ3ȱpositiveȱpelvicȱpainȱ whenȱusingȱ2ȱversusȱ3ȱpositiveȱpelvicȱpainȱ provocationȱtestsȱinȱpregnancy.ȱ provocationȱtestsȱpostpartum.ȱ ȱ ȱ

Subgroupȱ 2ȱpositiveȱ 3ȱpositiveȱ Subgroupȱ 2ȱpositiveȱ 3ȱpositiveȱ testsȱnȱ(%)ȱ testsȱnȱ(%)ȱ testsȱnȱ(%)ȱ testsȱnȱ(%)ȱ NoȱLBPȱ 118ȱ(38)ȱ 144ȱ(47)ȱ NoȱLBPȱ 183ȱ(67)ȱ 190ȱ(70)ȱ

Lumbarȱpainȱ 29ȱ(11)ȱ 29ȱ(11)ȱ Lumbarȱ 33ȱ(11)ȱ 43ȱ(14)ȱ painȱ PGPȱ 46ȱ(17)ȱ 39ȱ(14)ȱ PGPȱ 101ȱ(33)ȱ 75ȱ(24)ȱ Combinedȱ 14ȱ(5)ȱ 14ȱ(5)ȱ Combinedȱ 56ȱ(18)ȱ 46ȱ(15)ȱ painȱ painȱ ȱ

ȱ 56 Discussionȱ

Kokmeyerȱetȱal.ȱ(2002)ȱdiscussedȱtheȱpreferenceȱofȱaȱmultipleȱtestȱregimeȱoverȱ aȱ singleȱ testȱ forȱ theȱ thighȱ thrustȱ testȱ thatȱ hadȱ shownȱ theȱ highestȱ sensitivityȱ (113).ȱTheȱthighȱthrustȱtestȱisȱsimilarȱtoȱtheȱposteriorȱpelvicȱpainȱprovocationȱ test,ȱwithȱtheȱdifferenceȱbeingȱthatȱtheȱthighȱthrustȱtestȱincludesȱanȱadductionȱ ofȱtheȱhipȱandȱaȱthrust,ȱratherȱthanȱaȱlightȱpressure,ȱasȱinȱtheȱposteriorȱpelvicȱ painȱprovocationȱtest.ȱAȱthighȱthrustȱtestȱachievedȱaȱkappaȱcoefficientȱofȱ0.67,ȱ whileȱwithȱ3/5ȱpositiveȱtestsȱachievedȱaȱkappaȱcoefficientȱofȱ0.70.ȱHowever,ȱtheȱ thighȱ trustȱ testȱ wasȱ positiveȱ inȱ 5ȱ asymptomaticȱ subjects,ȱ whereasȱ aȱ multipleȱ testȱ scoreȱ ofȱ 3/5ȱ testsȱ wasȱ foundȱ negativeȱ byȱ bothȱ examinersȱ forȱ everyȱ asymptomaticȱ subject.ȱ Consequently,ȱ theȱ authorsȱ recommendedȱ aȱ multipleȱ testȱscore.ȱ ȱ Accordingȱ toȱ guidelines,ȱ classificationȱ ofȱ PGPȱ requiresȱ exclusionȱ ofȱ lumbarȱ causesȱ(258).ȱItȱhasȱbeenȱdiscussedȱthatȱSIJȱpainȱclassificationȱshouldȱonlyȱbeȱ consideredȱafterȱexclusionȱofȱpatientsȱwithȱdiscogenicȱpain,ȱdueȱtoȱriskȱofȱfalseȱ positiveȱ painȱ provocationȱ testsȱ (124).ȱ Inȱ theȱ presentȱ study,ȱ womenȱ withȱ centralisation/peripheralisationȱ andȱ positiveȱ pelvicȱ painȱ provocationȱ testsȱ wereȱ classifiedȱ asȱ combinedȱ pain.ȱ Theȱ riskȱ forȱ aȱ falseȱ positiveȱ testȱ isȱ contradictedȱ byȱ resultsȱ fromȱ aȱ nonpublishedȱ studyȱ thatȱ showedȱ thatȱ theȱ posteriorȱ pelvicȱ painȱ provocationȱ testȱ wasȱ negativeȱ inȱ patientsȱ withȱ wellȬ definedȱ lumbarȱ diagnosesȱ (n=53),ȱ whichȱ strengthensȱ theȱ classificationȱ ofȱ theȱ presentȱ study.ȱ Theȱ posteriorȱ pelvicȱ painȱ provocationȱ testȱ wasȱ performedȱ onȱ patientsȱ withȱ computedȱ tomographyȬverifiedȱ discȱ herniation(s)ȱ waitingȱ forȱ surgeryȱorȱpatientsȱ6ȱweeksȱafterȱdiscȱherniationȱsurgery.ȱTheȱsensitivityȱofȱtheȱ posteriorȱ pelvicȱ painȱ provocationȱ testȱ wasȱ 0.88ȱ andȱ theȱ specificityȱ wasȱ 0.89.ȱ Altogether,ȱitȱseemsȱimportantȱtoȱuseȱclassificationsȱforȱbothȱpelvicȱandȱlumbarȱ painȱ sinceȱ womenȱ withȱ positiveȱ painȱ provocationȱ testsȱ inȱ theȱ pelvisȱ andȱ centralisation/peripheralisationȱ canȱ beȱ aȱ targetȱ groupȱ thatȱ isȱ atȱ riskȱ forȱ persistency,ȱirrespectiveȱofȱtheȱcauseȱtoȱtheirȱpain.ȱ ȱ Aȱstrengthȱinȱtheȱpresentȱstudyȱwasȱthatȱtheȱsameȱinvestigatorȱexaminedȱallȱ theȱpatients,ȱwhichȱdecreasedȱtheȱriskȱofȱbias.ȱAlso,ȱtheȱreliabilityȱstudyȱofȱtheȱ classificationȱ intoȱ subgroupsȱ showedȱ aȱ substantialȱ agreementȱ betweenȱ examiners.ȱ Accordingȱ toȱ aȱ recentȱ review,ȱ evaluationȱ ofȱ symptomȱ responseȱ duringȱrepeatedȱmovementsȱwasȱ1ȱofȱfewȱexaminationȱproceduresȱusedȱinȱtheȱ assessmentȱ ofȱ nonspecificȱ LBPȱ thatȱ showedȱ promisingȱ resultsȱ regardingȱ reliabilityȱ (141),ȱ againȱ supportingȱ theȱ proceduresȱ usedȱ inȱ theȱ presentȱ study.ȱ However,ȱtheȱwomanȱwasȱonlyȱexaminedȱonȱ1ȱoccasion,ȱwhichȱmayȱhaveȱbeenȱ insufficientȱtoȱidentifyȱsomeȱwomenȱwhereȱtheȱsymptomsȱcentralizedȱoverȱtheȱ

ȱ 57 Discussionȱ ȱ courseȱ ofȱ severalȱ examinationsȱ (253).ȱ Inȱ regularȱ clinicalȱ practice,ȱ theȱ centralisationȱ phenomenonȱ mightȱ haveȱ beenȱ detectedȱ atȱ aȱ secondȱ visit,ȱ forȱ exampleȱasȱaȱresultȱofȱsendingȱtheȱpatientȱhomeȱwithȱaȱconfirmatoryȱexercise,ȱ whichȱ isȱ aȱ commonȱ procedureȱ withinȱ MDT.ȱ Aȱ consequenceȱ ofȱ thisȱ possibleȱ weaknessȱofȱtheȱclassificationȱmightȱbeȱthatȱtheȱexaminerȱclassifiedȱPGPȱtoȱaȱ higherȱ degree,ȱ insteadȱ ofȱ combinedȱ pain.ȱ Theȱ consequentialȱ subgroupȱ differenceȱwouldȱnotȱhaveȱchangedȱtheȱresultsȱforȱtheȱanalysisȱofȱHRQL,ȱpainȱ intensity,ȱ disability,ȱ theȱ depressiveȱ symptoms,ȱ andȱ theȱ muscleȱ tests.ȱ Itȱ isȱ unsureȱ ifȱ theȱ identificationȱ ofȱ predictorsȱ wouldȱ beȱ differentȱ byȱ thisȱ possibleȱ weaknessȱofȱclassification.ȱInȱconclusion,ȱtheȱclassificationȱofȱLBP,ȱasȱdoneȱinȱ theȱ presentȱ study,ȱ isȱ possibleȱ toȱ doȱ throughoutȱ pregnancy,ȱ andȱ theȱ resultsȱ showȱgroupȱdifferencesȱthatȱareȱimportantȱtoȱidentify.ȱTheȱcauseȱofȱLBPȱisȱstillȱ unknownȱ inȱ theȱ majorityȱ ofȱ patients,ȱ pregnantȱ asȱ wellȱ asȱ nonpregnant.ȱ Physicalȱexaminationȱproceduresȱthatȱshowȱpromisingȱresultsȱforȱidentifyingȱ differentȱhomogenousȱsubgroupsȱthatȱrequireȱspecificȱguidanceȱforȱpreventionȱ andȱmanagementȱ(70,ȱ133)ȱareȱimportantȱandȱofȱgreatestȱinterestȱforȱprimaryȱ healthȱcareȱresearchersȱ(30).ȱ

COURSEȱANDȱPREDICTORSȱ Theȱpresentȱstudyȱshowedȱtheȱclinicalȱnaturalȱcourseȱofȱsubgroupsȱofȱwomenȱ withȱLBPȱevaluatedȱinȱearlyȱpregnancyȱandȱ3ȱmonthsȱpostpartum.ȱTheȱcourseȱ differedȱamongȱtheȱsubgroupsȱandȱtheȱstudyȱconfirmedȱsubgroupȱpersistencyȱ ofȱLBP.ȱWomenȱwithȱcombinedȱpainȱwereȱidentifiedȱtoȱbeȱaȱtargetȱgroupȱsinceȱ theyȱhadȱtheȱlowestȱrecoveryȱrateȱandȱsinceȱtheȱclassificationȱofȱcombinedȱpainȱ wasȱfoundȱtoȱbeȱaȱpredictorȱforȱpersistentȱPGPȱorȱcombinedȱpainȱpostpartum,ȱ withȱ possibleȱ identificationȱ earlyȱ onȱ inȱ pregnancy.ȱ Theȱ prevalenceȱ ofȱ persistentȱPGPȱandȱcombinedȱpainȱ3ȱmonthsȱpostpartumȱwasȱ16Ȭ21%ȱinȱthisȱ study.ȱSinceȱitȱhasȱbeenȱreportedȱthatȱimprovementȱgenerallyȱlevelsȱoffȱaroundȱ 3ȱmonthsȱpostpartumȱ(116,ȱ182),ȱtheseȱwomenȱmayȱhaveȱaȱpoorȱprognosis.ȱTheȱ previouslyȱreportedȱlongȬtermȱpersistencyȱofȱLBPȱinȱ20Ȭ21%ȱofȱwomenȱatȱ2Ȭ3ȱ yearsȱ afterȱ delivery/postpartumȱ (168,ȱ 235),ȱ emphasisesȱ theȱ persistency.ȱ Additionally,ȱwomenȱwithȱPGPȱorȱcombinedȱpainȱinȱtheȱpresentȱstudyȱwereȱ thoseȱwithȱtheȱgreatestȱconsequencesȱofȱtheirȱsyndromeȱinȱtermsȱofȱpainȱandȱ disabilityȱinȱearlyȱpregnancy.ȱSeverityȱofȱcomplaintsȱatȱbaselineȱinȱpregnancyȱ hasȱ beenȱ reportedȱ toȱ correlateȱ withȱ persistentȱ symptomsȱ postpartumȱ (211).ȱ Likewise,ȱ itȱ hasȱ beenȱ shownȱ thatȱ womenȱ withȱ LBPȱ inȱ pregnancy,ȱ severeȱ enoughȱtoȱrequireȱsickȱleave,ȱareȱatȱhighȱriskȱforȱpersistentȱandȱrecurrentȱLBPȱ

ȱ 58 Discussionȱ manyȱyearsȱafterȱpregnancyȱ(36),ȱwhichȱagainȱemphasisesȱtheȱneedȱforȱspecialȱ attentionȱtoȱtheseȱwomen.ȱ ȱ Theȱ prevalenceȱ ofȱ PGPȱ decreasedȱ fromȱ pregnancyȱ toȱ 3ȱ monthsȱ postpartumȱ andȱtheȱproportionȱofȱlumbarȱpainȱremainedȱstable.ȱThisȱconfirmsȱresultsȱfromȱ aȱ followȬupȱ questionnaireȱ whereȱ itȱ wasȱ shownȱ thatȱ lumbarȱ painȱ duringȱ pregnancyȱisȱsimilarȱtoȱlumbarȱpainȱreportedȱbyȱnonȬpregnantȱwomen,ȱwhileȱ PGPȱisȱprimarilyȱrelatedȱtoȱpregnancyȱ(180).ȱTheȱresultsȱofȱtheȱpresentȱstudyȱ suggestȱ thatȱ pregnancyȱ doesȱ notȱ alterȱ theȱ courseȱ ofȱ lumbarȱ pain.ȱ Mostȱ previousȱ studiesȱ ofȱ pregnancyȬrelatedȱ LBPȱ didȱ notȱ identifyȱ womenȱ withȱ lumbarȱ painȱ orȱ excludedȱ theseȱ women,ȱ andȱ therebyȱ womenȱ withȱ combinedȱ painȱ wereȱ notȱ studiedȱ either.ȱ Consequently,ȱ ifȱ theyȱ hadȱ notȱ beenȱ identifiedȱ andȱincludedȱinȱtheȱpresentȱstudy,ȱtheseȱwomenȱwouldȱhaveȱbeenȱmissed;ȱtheȱ combinedȱpain,ȱasȱwellȱasȱtheȱlumbarȱpainȱgroup.ȱItȱisȱimportantȱtoȱstudyȱallȱ typesȱofȱLBPȱinȱpregnancy,ȱnotȱjustȱwomenȱwithȱPGP,ȱwhoȱgenerallyȱhaveȱaȱ goodȱprognosis.ȱ ȱ Itȱhasȱbeenȱreportedȱthatȱmultipleȱpainȱlocalisationȱisȱpredictiveȱofȱpersistentȱ painȱ (49,ȱ 62,ȱ 162).ȱ Inȱ theȱ presentȱ study,ȱ painȱ drawingsȱ madeȱ byȱ theȱ womenȱ withȱcombinedȱpainȱwereȱcomparedȱwithȱanȱageȬmatchedȱsampleȱofȱwomenȱ withȱLBPȱinȱprimaryȱhealthȱcareȱ(n=78,ȱunpublishedȱdata).ȱLowerȱdegreesȱofȱ bothȱ cervicalȱ andȱ lumbarȱ painȱ localisationȱ wereȱ foundȱ inȱ theȱ womenȱ withȱ combinedȱ painȱ andȱ noneȱ hadȱ drawnȱ painȱ marksȱ outsideȱ theȱ outlineȱ ofȱ theȱ bodyȱonȱtheȱpainȱdrawing.ȱThisȱindicatesȱthatȱtheȱwomenȱwithȱcombinedȱpainȱ doȱnotȱpresentȱasȱaȱgroupȱwithȱwidespreadȱpain.ȱ ȱ Mostȱ postpartumȱ studiesȱ haveȱ onlyȱ followedȱ thoseȱ whoȱ hadȱ LBP/PGPȱ inȱ pregnancy.ȱ Womenȱ withoutȱ LBPȱ inȱ pregnancyȱ sometimesȱ haveȱ aȱ debutȱ inȱ relationȱtoȱdeliveryȱandȱthusȱareȱmissedȱinȱtheȱprevalenceȱreport,ȱasȱwellȱasȱinȱ followȬupȱstudies.ȱStudiesȱthatȱfollowedȱnonclassifiedȱLBPȱinȱpregnancyȱandȱ reportedȱpersistentȱLBPȱpostpartumȱshowedȱaȱprevalenceȱofȱ43Ȭ54%ȱatȱ3ȱtoȱ6ȱ monthsȱ postpartumȱ (128,ȱ 154,ȱ 180,ȱ 236).ȱ Inȱ theȱ presentȱ study,ȱ theȱ lowerȱ persistencyȱrateȱatȱ3ȱmonthsȱpostpartumȱwasȱprobablyȱdueȱtoȱtheȱsampleȱinȱ pregnancyȱincludingȱwomenȱwithȱmildȱsymptoms.ȱ ȱ Studiesȱ thatȱ haveȱ onlyȱ followedȱ womenȱ withȱ PGPȱ reportedȱaȱ wideȱ rangeȱ ofȱ persistentȱPGPȱ1Ȭ2ȱyearsȱpostpartumȱ(8.5Ȭ68%)ȱ(3,ȱ121,ȱ165).ȱTheȱwideȱrangeȱisȱ probablyȱ dueȱ toȱ moreȱ specific,ȱ yetȱ diverseȱ criteriaȱ forȱ PGP.ȱ Anȱ additionalȱ explanationȱforȱtheȱlowerȱprevalenceȱfoundȱinȱtheȱstudyȱbyȱAlbertȱetȱal.ȱ(2001),ȱ

ȱ 59 Discussionȱ ȱ isȱ thatȱ womenȱ withȱ painȱ ofȱ theȱ sameȱ intensityȱ orȱ lowerȱ thanȱ previouslyȱ experiencedȱ beforeȱ indexȱ pregnancy,ȱ wereȱ consideredȱ healthyȱ andȱ excludedȱ fromȱfollowȬupȱ(3).ȱ ȱ OneȱofȱtheȱaimsȱofȱthisȱthesisȱwasȱtoȱidentifyȱpredictorsȱofȱpersistentȱPGPȱorȱ combinedȱ painȱ postpartum.ȱ Theȱ mainȱ outcomeȱ inȱ theȱ predictiveȱ modelȱ wasȱ classificationȱofȱPGPȱorȱcombinedȱpainȱatȱtheȱ3ȱmonthȱpostpartumȱevaluation.ȱ Onlyȱ 1ȱ womanȱ hadȱ theȱ classificationȱ ofȱ lumbarȱ painȱ bothȱ inȱ pregnancyȱ andȱ postpartumȱandȱaȱhighȱproportionȱofȱwomenȱwithȱlumbarȱpainȱrecovered.ȱTheȱ resultsȱshowedȱthatȱwomenȱwhoȱwereȱdissatisfiedȱatȱwork,ȱwhoȱhadȱcombinedȱ painȱ inȱ earlyȱ pregnancy,ȱ whoȱ wereȱ relativelyȱ older,ȱ andȱ whoȱ hadȱ lowȱ enduranceȱofȱtheȱbackȱflexorȱmuscles,ȱhadȱanȱincreasedȱriskȱofȱpersistency.ȱTheȱ predictiveȱmodelȱwasȱbasedȱonȱ154ȱwomen.ȱTheȱ154ȱparticipantsȱincludedȱinȱ theȱregressionȱanalysisȱdidȱnotȱdifferȱfromȱtheȱ89ȱparticipantsȱwhoȱwereȱnotȱ included,ȱ exceptȱ forȱ 3ȱ variables.ȱ Theȱ 89ȱ excludedȱ womenȱ wereȱ atȱ aȱ laterȱ gestationalȱweekȱofȱtheirȱpregnancyȱatȱtheȱtimeȱofȱinclusionȱinȱtheȱstudy,ȱhadȱ moreȱproblemsȱwithȱurinaryȱincontinenceȱandȱhadȱhigherȱBMI.ȱAnȱassociationȱ betweenȱBMIȱandȱLBPȱinȱrelationȱtoȱpregnancyȱhasȱpreviouslyȱbeenȱreportedȱ (116,ȱ154,ȱ174).ȱStudyingȱtheȱunivariateȱassociations,ȱtheȱconsequencesȱmightȱ beȱ thatȱ theȱ importanceȱ ofȱ BMIȱ isȱ underestimatedȱ inȱ theȱ presentȱ study.ȱ Multivariateȱ analysesȱ haveȱ drawbacks.ȱ Correlationȱ andȱ theȱ multivariateȱ modelsȱassumeȱlinearity,ȱwhichȱisȱoftenȱnotȱrealistic,ȱandȱmultivariateȱanalysisȱ isȱ sensitiveȱ toȱ smallȱ deviationsȱ inȱ theȱ data,ȱ andȱ thusȱ toȱ samplingȱ error.ȱ Nevertheless,ȱ multivariateȱanalysisȱ isȱaȱ powerfulȱ toolȱ toȱ identifyȱ factorsȱ thatȱ codetermine.ȱ ȱ Itȱ hasȱ beenȱ reportedȱ thatȱ subjectȱ characteristicsȱ influenceȱ theȱ lumbarȱ paraspinalȱfatigabilityȱmoreȱstronglyȱatȱtheȱL4ȬL5ȱlevelȱthanȱatȱL1ȬL2,ȱandȱthatȱ theȱeffectȱofȱageȱandȱBMIȱareȱmoreȱpronouncedȱinȱwomenȱthanȱinȱmenȱ(105).ȱ WomenȱwithȱhighȱBMIȱfatiguedȱfasterȱthanȱwomenȱwithȱnormalȱorȱlowȱBMI.ȱ Oneȱwouldȱhaveȱpresumedȱthatȱbackȱmusclesȱofȱheavyȱandȱlightȱindividualsȱ wouldȱhaveȱadaptedȱtoȱtheȱdemands.ȱHowever,ȱtheȱresultsȱsuggestedȱthatȱtheȱ lowȱ backȱ musclesȱ inȱ womenȱ didȱ notȱ undergoȱ adaptiveȱ changesȱ toȱ maintainȱ enduranceȱ capacityȱ relativeȱ toȱ BMI.ȱ Thisȱ isȱ interestingȱ toȱ consider,ȱ bothȱ inȱ pregnancyȱ andȱ postpartum,ȱ whenȱ manyȱ womenȱ doȱ notȱ resumeȱ theirȱ prepregnancyȱweightȱ(118).ȱ ȱ Thereȱmayȱbeȱaȱsubgroupȱdifferenceȱregardingȱpredictorsȱthatȱisȱgenerallyȱnotȱ identifiedȱwhenȱnoȱclassificationȱofȱLBPȱisȱmade.ȱPreviousȱexperienceȱofȱLBPȱisȱ

ȱ 60 Discussionȱ oneȱofȱtheȱmostȱfrequentlyȱreportedȱriskȱfactorsȱforȱeitherȱdevelopingȱLBPȱinȱ pregnancyȱ(14,ȱ121,ȱ174,ȱ175,ȱ235)ȱorȱhavingȱpersistentȱLBPȱpostpartumȱ(211,ȱ 235,ȱ236).ȱInȱtheȱpresentȱstudy,ȱpreviousȱLBPȱwasȱnotȱanȱidentifiedȱpredictorȱ forȱ persistentȱ pain.ȱ NonpregnancyȬrelatedȱ LBP,ȱ reportedȱ inȱ primaryȱ healthȱ careȱtoȱhaveȱaȱrecurrentȱcourseȱ(219,ȱ262),ȱmayȱpartlyȱexplainȱtheȱriskȱfactor.ȱAȱ greaterȱ numberȱ ofȱ womenȱ withȱ lumbarȱ painȱ hadȱ previousȱ experienceȱ ofȱ nonpregnancyȬrelatedȱ LBP,ȱ butȱ sinceȱ theȱ outcomeȱ variableȱ wasȱ pregnancyȬ relatedȱ PGPȱ orȱ combinedȱ pain,ȱ thisȱ factorȱ didȱ notȱ present.ȱ Furthermore,ȱ theȱ identifiedȱ predictorȱ ofȱ lowȱ enduranceȱ ofȱ theȱ backȱ flexorȱ musclesȱ mayȱ beȱ aȱ covariantȱfactorȱthatȱpartiallyȱexplainsȱpreviousȱpregnancyȬrelatedȱLBP.ȱAtȱtheȱ 12Ȭ18ȱ gestationalȱ weekȱ evaluation,ȱ mostȱ womenȱ withȱ PGPȱ hadȱ aȱ shortȱ durationȱ ofȱ symptoms,ȱ suggestingȱ thatȱ lowȱ enduranceȱ ofȱ theȱ backȱ flexorȱ musclesȱ wasȱ presentȱ beforeȱ pregnancy.ȱ Oneȱ hypothesisȱ isȱ thatȱ pregnancyȬ relatedȱ hormoneȬinducedȱ ligamentȱ laxity,ȱ inȱ combinationȱ withȱ lowȱ muscleȱ endurance,ȱimpairsȱdynamicȱstabilityȱofȱtheȱpelvisȱandȱpartiallyȱexplainsȱwhyȱ womenȱhaveȱpregnancyȬrelatedȱPGP.ȱ ȱ Inȱ theȱ presentȱ study,ȱ olderȱ ageȱ wasȱ anotherȱ predictorȱ forȱ persistentȱ PGPȱ orȱ combinedȱpain.ȱBothȱyoungerȱ(236)ȱandȱolderȱ(235)ȱageȱhaveȱbeenȱreportedȱtoȱ beȱriskȱfactorsȱforȱpersistentȱLBP.ȱTheȱmeanȱageȱofȱtheȱwomenȱwasȱlowerȱinȱaȱ studyȱthatȱreportedȱyoungȱageȱasȱaȱhigherȱriskȱ(25.6)ȱcomparedȱtoȱstudiesȱthatȱ reportedȱ olderȱ ageȱ (29Ȭ31.8).ȱ Theȱ associationȱ mightȱ beȱ bimodal,ȱ withȱ theȱ youngestȱandȱtheȱoldestȱwomenȱbeingȱatȱaȱhigherȱriskȱ(267).ȱAlthoughȱmeanȱ ageȱwasȱratherȱlowȱinȱcomparisonȱtoȱthatȱinȱprimaryȱhealthȱcare,ȱitȱturnedȱoutȱ toȱbeȱaȱpredictor.ȱThereȱisȱlittleȱevidenceȱthatȱearlyȱtreatmentȱcanȱchangeȱtheȱ longȬtermȱcourseȱ(244),ȱhowever,ȱtheȱpregnantȱwomenȱareȱaȱpossibleȱgroupȱtoȱ targetȱforȱtrialsȱofȱprevention.ȱ ȱ Dissatisfactionȱ withȱ workȱ wasȱ identifiedȱ asȱ aȱ predictorȱ ofȱ persistentȱ PGPȱ orȱ combinedȱ pain.ȱ Likewiseȱ dissatisfactionȱ withȱ workȱ hasȱ beenȱ identifiedȱ asȱ aȱ predictorȱofȱfutureȱnonpregnancyȬrelatedȱbackȱpainȱ(130)ȱandȱfutureȱbackȱpainȱ inȱpregnancyȱ(5,ȱ177).ȱBackȱflexorȱmuscleȱenduranceȱhasȱnotȱbeenȱreportedȱasȱaȱ predictor,ȱ butȱ thereȱ areȱ reportsȱ suggestingȱ anȱ associationȱ betweenȱ muscleȱ functionȱandȱLBPȱ(96,ȱ184,ȱ198,ȱ204,ȱ243).ȱTheȱpredictorsȱforȱpersistentȱPGPȱorȱ combinedȱ painȱ thatȱ wereȱ identifiedȱ inȱ theȱ presentȱ studyȱ areȱ notȱ uniqueȱ forȱ pregnantȱwomen,ȱbutȱratherȱhaveȱalsoȱbeenȱreportedȱinȱotherȱsgroupȱ ofȱLBPȱ (47,ȱ62,ȱ130).ȱ

ȱ 61 Discussionȱ ȱ HEALTHȬRELATEDȱQUALITYȱOFȱLIFE,ȱPAINȱANDȱ DISABILITYȱ Pregnantȱ womenȱ withȱ bothȱ PGPȱ andȱ lumbarȱ painȱ i.e.ȱ combinedȱ painȱ wereȱ greatestȱ affected,ȱ asȱ measuredȱ byȱ selfȬratedȱ HRQL,ȱ painȱ intensity,ȱ andȱ disability.ȱ Thereȱ isȱ aȱ riskȱ thatȱ highlyȱ affectedȱ womenȱ withinȱ theȱ subgroupsȱ (illustratedȱbyȱwideȱconfidenceȱintervals)ȱremainedȱunnoticedȱdueȱtoȱrelativelyȱ lowȱ medianȱ ratings.ȱ Furthermore,ȱ inȱ evaluationsȱ ofȱ pregnantȱ womenȱ withȱ LBP,ȱwhereȱnoȱdistinctionȱwasȱmadeȱbetweenȱPGPȱandȱlumbarȱpain,ȱ“seriousȱ pain”ȱwasȱreportedȱbyȱ25%ȱ(116,ȱ186)ȱandȱ“severeȱdisability”ȱbyȱ30Ȭ36%ȱ(116,ȱ 177).ȱInȱtheȱpresentȱstudy,ȱinȱtheȱgroupsȱwithȱPGP,ȱ2/3ȱofȱtheȱwomenȱexhibitedȱ bothȱpainȱandȱdisabilityȱ(PGPȱ57ȱ%,ȱcombinedȱpainȱ70ȱ%),ȱi.e.ȱtwiceȱasȱmanyȱasȱ inȱtheȱlumbarȱpainȱgroupȱ(30%).ȱTheȱPGPȱgroupsȱreportedȱaȱhigherȱproportionȱ ofȱpainȱandȱdisabilityȱcomparedȱtoȱclinicalȱnaturalȱcourseȱstudiesȱofȱcohortsȱofȱ primaryȱhealthȱcareȱpatientsȱwithȱLBP,ȱofȱwhomȱ50%ȱstillȱreportedȱpainȱandȱ disabilityȱ afterȱ 3ȱ monthsȱ (48,ȱ 269).ȱ Theȱ resultsȱ ofȱ theȱ presentȱ studyȱ areȱ inȱ accordanceȱ withȱ studiesȱ showingȱ that,ȱ withȱ anȱ increasingȱ numberȱ ofȱ musculoskeletalȱconditions,ȱtheȱHRQLȱdeterioratesȱ(194).ȱ ȱ Sensitivityȱcanȱbeȱdefinedȱasȱtheȱabilityȱofȱanȱinstrumentȱtoȱmeasureȱchangeȱinȱ aȱ state,ȱ irrespectiveȱ ofȱ whetherȱ itȱ isȱt relevan ȱ orȱ meaningful,ȱ whereasȱ responsivenessȱ canȱ beȱ viewedȱ asȱ theȱ abilityȱ ofȱ anȱ instrumentȱ toȱ measureȱ aȱ meaningfulȱ importantȱ change.ȱ Responsiveness,ȱ orȱ theȱ minimalȱ importantȱ changeȱ (MIC)ȱ ofȱ anȱ instrument,ȱ hasȱ beenȱ definedȱ asȱ aȱ changeȱ orȱ minimallyȱ clinicallyȱ importantȱ differenceȱ (MID)ȱ whereȱ theȱ changeȱ isȱ valuatedȱ fromȱ aȱ clinicalȱpointȱofȱviewȱ(17,ȱ101).ȱThereȱisȱnoȱconsensusȱonȱtheȱmostȱappropriateȱ strategyȱ forȱ quantifyingȱ responsiveness,ȱ butȱ effectȱ sizeȱ calculationȱ andȱ ROCȱ curvesȱhaveȱbeenȱproposedȱ(17,ȱ54,ȱ82).ȱ ȱ Theȱ MIDȱ forȱ theȱ EQȬ5Dȱ scoreȱ hasȱ beenȱ reportedȱ toȱ rangeȱ betweenȱ 0.09Ȭ0.22ȱ andȱforȱtheȱEQȬ5DȱVAS,ȱtheȱestimatesȱrangedȱfromȱ3.82ȱtoȱ8.43ȱ(74,ȱ216).ȱTheȱ reportedȱMIDȱofȱEQȬ5DȱsuggestȱthatȱtheȱgroupȱwithȱPGPȱandȱtheȱgroupȱwithȱ combinedȱpainȱhadȱaȱclinicallyȱimportantȱdifferenceȱcomparedȱtoȱtheȱwomenȱ withoutȱLBP,ȱalreadyȱearlyȱonȱinȱpregnancy.ȱ ȱ AȱrelevantȱMIDȱinȱODIȱscoreȱbetweenȱgroupsȱhasȱnotȱbeenȱreported,ȱbutȱMICȱ inȱdisabilityȱhasȱbeenȱproposedȱtoȱ4Ȭ10%ȱonȱtheȱODIȱ(17,ȱ146)ȱandȱaȱmeanȱODIȱ ofȱ 10%ȱ isȱ reportedȱ fromȱ normalȱ populationsȱ (64).ȱ Theȱ MICȱ ofȱ ODIȱ andȱ theȱ previouslyȱreportedȱdifferencesȱbetweenȱimprovedȱandȱnonimprovedȱpatientsȱ onȱtheȱVASȱ(10 Ȭ18ȱmm)(17),ȱsuggestȱthatȱtheȱgroupȱwithȱPGPȱandȱtheȱgroupȱ

ȱ 62 Discussionȱ withȱ combinedȱ painȱ hadȱ aȱ clinicallyȱ importantȱ differenceȱ onȱ disabilityȱ andȱ painȱ comparedȱ toȱ theȱ womenȱ withoutȱ LBP,ȱ alreadyȱ earlyȱ onȱ inȱ pregnancy,ȱ althoughȱ theirȱ medianȱ groupȱ levelȱ wasȱ low.ȱ Theȱ lumbarȱ painȱ groupȱ hadȱ valuesȱcloserȱtoȱhealthyȱwomen.ȱ

MeasuresȱofȱhealthȬrelatedȱqualityȱofȱlifeȱandȱdisabilityȱ Theȱ EQȬ5Dȱ asȱ wellȱ asȱ theȱ SFȬ36ȱ (246)ȱ areȱ examplesȱ ofȱ commonȱ genericȱ instrumentsȱ usedȱ toȱ quantifyȱ theȱ HRQLȱ inȱ peopleȱ withȱ musculoskeletalȱ disordersȱ(73).ȱTheȱSFȬ36ȱisȱaȱselfȬreportedȱscaleȱwithȱtheȱaimȱtoȱcaptureȱhealthȱ inȱitsȱbroadestȱsense.ȱItȱisȱaȱprofileȱinstrumentȱdescribingȱ healthȱstatusȱalongȱ severalȱdimensions.ȱSinceȱeconomicȱanalysisȱofȱPGPȱhithertoȱisȱlimitedȱtoȱsickȱ leaveȱcosts,ȱthereȱwasȱaȱneedȱforȱanȱinstrumentȱthatȱcouldȱbeȱusedȱinȱformalȱ decisionȱanalysisȱandȱcostȬeffectivenessȱanalysisȱandȱthereforeȱtheȱEQȬ5Dȱwasȱ chosenȱ forȱ thisȱ study.ȱ Recently,ȱ preferenceȬbasedȱ measuresȱ haveȱ alsoȱ beenȱ derivedȱfromȱSFȬ36ȱ(31)ȱhoweverȱinconsistentȱestimatesȱandȱoverȱpredictionȱofȱ theȱvalueȱofȱtheȱpoorestȱhealthȱstatesȱwereȱreported.ȱOnȱtheȱotherȱhand,ȱceilingȱ effectsȱofȱEQȬ5Dȱinȱmoreȱhealthyȱpopulationsȱhasȱbeenȱcriticizedȱ(10,ȱ160).ȱ ȱ TheȱmostȱcommonlyȱusedȱbackȬspecificȱmeasuresȱofȱselfȬreportedȱfunctioningȱ (29)ȱareȱtheȱODIȱandȱtheȱRDQȱ(207).ȱTheȱODIȱisȱdevelopedȱforȱtheȱlowerȱbackȱ whereasȱ RDQȱ isȱ backȱ specific,ȱ i.e.ȱ includingȱ atȱ leastȱ theȱ thoracicȱ andȱ lumbarȱ regions,ȱwhichȱsuggestsȱtheȱbetterȱsuitabilityȱofȱODIȱforȱPGP.ȱSeveralȱitemsȱofȱ ODIȱ andȱ RDQȱ evaluateȱ theȱ sameȱ activity,ȱ butȱ inȱ addition,ȱ theȱ ODIȱ includesȱ itemsȱonȱtravelȱandȱsexualȱactivityȱwhichȱareȱknownȱtoȱincreaseȱPGPȱ(85,ȱ150).ȱ Whenȱ theȱ ODIȱ wasȱ comparedȱ withȱ theȱ RDQ,ȱ theȱ formerȱ wasȱ consideredȱ suitableȱ forȱ aȱ populationȱ withȱ aȱ higherȱ degreeȱ ofȱ disabilityȱ (64).ȱ Givenȱ theȱ findingsȱthatȱsomeȱwomenȱwithȱPGPȱdoȱbecomeȱquiteȱdisabled,ȱtheȱODIȱseemsȱ moreȱ appropriateȱ forȱ thisȱ group.ȱ Eachȱ itemȱ onȱ theȱ ODIȱ isȱ scoredȱ onȱ aȱ hierarchicalȱ6Ȭpointȱscale,ȱwhereasȱtheȱRDQȱusesȱyes/noȱanswers.ȱAsȱaȱresult,ȱifȱ thereȱ areȱ onlyȱ smallȱ changesȱ inȱ function,ȱ theȱ ODIȱ isȱ arguedȱ toȱ beȱ moreȱ responsiveȱ (18).ȱ Inȱ aȱ laterȱ study,ȱ theȱ responsivenessȱ ofȱ ODIȱ wasȱ lowerȱ comparedȱtoȱRDQ,ȱwhereasȱtheȱspecificityȱtoȱchangeȱwasȱhigherȱinȱODIȱ(17).ȱ However,ȱ theȱ responsivenessȱ forȱ ODIȱ hasȱ notȱ beenȱ calculatedȱ inȱ aȱ groupȱ ofȱ moreȱseverelyȱaffectedȱpatients.ȱForȱtheȱassessmentȱofȱwomenȱwithȱpregnancyȬ relatedȱLBP,ȱwhoȱseemȱtoȱhaveȱaȱwideȱrangeȱofȱdegreesȱofȱdisability,ȱitȱmayȱbeȱ usefulȱtoȱemployȱbothȱODIȱandȱRDQ,ȱsinceȱtheyȱcomplementȱeachȱother.ȱ ȱ

ȱ 63 Discussionȱ ȱ Inȱ conclusion,ȱ theȱ populationȱ underȱ studyȱ needsȱ toȱ beȱ consideredȱ whenȱ choosingȱanȱinstrumentȱforȱmeasuresȱofȱHRQLȱandȱdisability.ȱȱ

POSTPARTUMȱDEPRESSIONȱ Clinicalȱ experienceȱ hasȱ shownȱ thatȱ treatmentȱ strategiesȱ targetȱ eitherȱ LBPȱ orȱ postpartumȱ depression.ȱ Basedȱ onȱ theȱ findingȱ ofȱ highȱ comorbidityȱ ofȱ theseȱ complicationsȱofȱpregnancy,ȱitȱseemsȱimportantȱtoȱscreenȱforȱbothȱdepressiveȱ symptomsȱandȱLBPȱatȱpostpartumȱfollowȬupȱorȱinȱprimaryȱhealthȱcare,ȱandȱtoȱ considerȱ treatmentȱ strategiesȱ forȱ bothȱ symptoms.ȱ Postpartumȱ depressionȱ isȱ commonlyȱ overlookedȱ byȱ primaryȱ healthȱ careȱ (43).ȱ Studiesȱ haveȱ shownȱ thatȱ 25%ȱ ofȱ womenȱ withȱ morbidityȱ postpartumȱ didȱ notȱ seekȱ professionalȱ help,ȱ althoughȱ 49%ȱ wouldȱ haveȱ likedȱ moreȱ helpȱ orȱ adviceȱ (34).ȱ Fromȱ aȱ physicalȱ therapyȱ perspective,ȱ womenȱ withȱ depressionȱ inȱ additionȱ toȱ LBPȱ needȱ toȱ beȱ identifiedȱ inȱ orderȱ toȱ receiveȱ anȱ optimalȱ treatmentȱ result.ȱ Althoughȱ itȱ isȱ notȱ clearȱwhichȱcomesȱfirst,ȱdepressionȱorȱLBP,ȱitȱhasȱbeenȱshownȱinȱnonpregnantȱ populationsȱthatȱtheȱpresenceȱofȱdepressionȱisȱassociatedȱwithȱpoorȱoutcomesȱ (129).ȱInȱprimaryȱhealthȱcare,ȱitȱhasȱalsoȱbeenȱshownȱthatȱpainȱandȱdepressionȱ predictȱ eachȱ otherȱ symmetrically,ȱ whichȱ suggestsȱ aȱ possibleȱ meansȱ ofȱ earlyȱ identificationȱofȱwomenȱatȱriskȱforȱeitherȱofȱtheȱsymptomsȱ(80).ȱAlthoughȱnotȱ evaluatedȱ inȱ theȱ presentȱ studyȱ forȱ itsȱ accuracy,ȱ theȱ EPDSȱ seemsȱ toȱ beȱ anȱ adequateȱ andȱ simpleȱ screeningȱ toolȱ forȱ caregiversȱ whoȱ treatȱ womenȱ postpartum.ȱHighȱscoresȱdoȱnotȱbyȱthemselvesȱconfirmȱdepressiveȱillnessȱbutȱ ratherȱindicateȱtheȱneedȱforȱfurtherȱassessment.ȱ ȱ Inȱtheȱcohort,ȱtheȱoverallȱprevalenceȱofȱdepressiveȱsymptomsȱ(cutȬoffȱǃ10)ȱwasȱ 16%,ȱcomparableȱtoȱthatȱwhichȱhasȱbeenȱreportedȱ(13–20%)ȱinȱsimilarȱstudiesȱ (46,ȱ 76,ȱ 104).ȱ Theȱ prevalenceȱ ofȱ depressionȱ didȱ notȱ differȱ inȱ studiesȱ ofȱ postpartumȱ womenȱ whenȱ comparedȱ toȱ aȱ controlȱ groupȱ ofȱ nonpostpartumȱ womenȱ fromȱ theȱ sameȱ populationȱ (9,ȱ 46,ȱ 170).ȱ Inȱ aȱ largerȱ populationȬbasedȱ study,ȱhowever,ȱtheȱriskȱofȱdepressionȱwasȱhigherȱforȱpostpartumȱwomenȱthanȱ amongȱcontrols,ȱwhenȱcontrollingȱforȱunevenȱdistributionȱofȱriskȱfactorsȱ(priorȱ depression,ȱ highȱ scoreȱ onȱ theȱ lifeȱ eventȱ scale,ȱ andȱ poorȱ relationshipȱ toȱ partner)(59).ȱ ȱ Theȱprevalenceȱofȱprobableȱdepressionȱ(cutȬoffȱǃȱ13)ȱinȱtheȱpostpartumȱcohortȱ wasȱ similarȱ toȱ otherȱ Scandinavianȱ samplesȱ (163,ȱ 256),ȱ butȱ higherȱ thanȱ inȱ EnglandȱorȱAustraliaȱ(35,ȱ46).ȱOneȱpostalȱsurveyȱthatȱreportedȱcomorbidityȱofȱ postpartumȱ depressionȱ andȱ LBPȱ wasȱ identifiedȱ (35).ȱ Forȱ comparison,ȱ theȱ

ȱ 64 Discussionȱ resultsȱofȱtheȱpresentȱstudyȱwereȱanalyzedȱwithȱaȱcutȬoffȱǃ13.ȱUsingȱthisȱcutȬ off,ȱtheȱriskȱforȱhavingȱdepressiveȱsymptomsȱwhenȱclassifiedȱwithȱlumbarȱpainȱ (ORȱ8.44)ȱorȱwithȱcombinedȱpainȱ(ORȱ6.76)ȱatȱ3ȱmonthsȱpostpartumȱwasȱhigherȱ comparedȱtoȱ6Ȭ7ȱmonthsȱpostpartumȱinȱtheȱpostalȱsurveyȱfromȱAustraliaȱ(ORȱ 2.2).ȱTheȱprevalenceȱofȱdepressiveȱsymptomsȱ(159)ȱandȱtheȱprevalenceȱofȱPGPȱ (180)ȱ haveȱ beenȱ shownȱ toȱ decreaseȱ aȱ coupleȱ ofȱ monthsȱ afterȱ delivery.ȱ Theȱ higherȱ oddsȱ mayȱ partlyȱ beȱ dueȱ toȱ theȱ factȱ thatȱ theȱ studyȱ wasȱ undertakenȱ 3ȱ monthsȱ afterȱ delivery,ȱ comparedȱ toȱ 6Ȭ7ȱ monthsȱ inȱ theȱ studyȱ byȱ Brownȱ andȱ Lumleyȱ (2000).ȱ Furthermore,ȱ theȱ differenceȱ inȱ methodologyȱ (postalȱ surveyȱ versusȱ clinicalȱ evaluation),ȱ asȱ wellȱ asȱ culturalȱ differences,ȱ mightȱ explainȱ theȱ disparity.ȱ ȱ Theȱ childbearingȱ yearsȱ areȱ aȱ periodȱ ofȱ greatȱ adjustmentȱ forȱ women.ȱ Itȱ isȱ importantȱtoȱidentifyȱtheȱwomenȱatȱriskȱofȱpostpartumȱdepressionȱsince,ȱifȱleftȱ untreated,ȱ inȱ upȱ toȱ 25%ȱ ofȱ women,ȱ itȱ mayȱ persistȱ forȱ atȱ leastȱ 1ȱ yearȱ afterȱ deliveryȱ (32).ȱ Depressionȱ hasȱ beenȱ reportedȱ toȱ haveȱ aȱ negativeȱ impactȱ onȱ women’sȱsocialȱadjustmentȱandȱmotherȬinfantȱinteraction,ȱasȱwellȱasȱproduceȱ longȬtermȱ effectsȱ suchȱ asȱ behavioralȱ problemsȱ inȱ theȱ childȱ (159).ȱ Sleepȱ disturbancesȱ dueȱ toȱ pregnancyȱ and/orȱ childcareȱ postpartumȱ compoundȱ theȱ riskȱforȱdepressionȱ(35,ȱ209)ȱandȱpossiblyȱtheȱriskȱofȱLBP,ȱsinceȱdisturbedȱsleepȱ hasȱbeenȱshownȱtoȱresultȱinȱincreasedȱmusculoskeletalȱpain,ȱtenderness,ȱandȱ fatigueȱinȱhealthyȱpersonsȱ(155).ȱTheseȱreportsȱdemonstrateȱtheȱvulnerabilityȱ ofȱwomenȱtodȱȱpainȱan depressionȱinȱtheȱchildbearingȱyears.ȱ ȱ Additionally,ȱtheȱextentȱofȱphysicalȱfunctionalȱimpairmentȱmayȱnotȱdependȱonȱ theȱ severityȱ ofȱ theȱ postpartumȱ depressiveȱ symptomsȱ (50).ȱ Daȱ Costaȱ etȱ al.ȱ (2005)ȱreportedȱthatȱtheȱexperienceȱofȱevenȱmilderȱformsȱofȱdepressedȱmoodȱ (i.e.ȱEPDSȱ10Ȭ12)ȱresultedȱinȱsignificantȱimpairmentȱtoȱphysicalȱhealthȱstatus.ȱ Thus,ȱ treatmentȱ ofȱ evenȱ milderȱ formsȱ ofȱ depressiveȱ symptomsȱ shouldȱ beȱ considered.ȱ ȱ Itȱ mightȱ haveȱ beenȱ interestingȱ toȱ evaluateȱ depressiveȱ symptomsȱ duringȱ pregnancy.ȱHowever,ȱtheȱEPDSȱwasȱnotȱvalidatedȱforȱprenatalȱuseȱatȱtheȱstartȱ ofȱtheȱstudy.ȱAlsoȱfocusȱonȱdepressiveȱsymptomsȱwasȱavoidedȱsinceȱitȱmightȱ haveȱ influencedȱ theȱ postpartumȱ evaluation.ȱ Inȱ conclusion,ȱ evenȱ thoughȱ theȱ riskȱforȱdepressionȱmayȱnotȱbeȱhigherȱinȱpostpartumȱwomenȱcomparedȱtoȱnonȬ postpartum,ȱ theȱ prevalenceȱ ofȱ depressiveȱ symptomsȱ isȱ 3ȱ timesȱ higherȱ whenȱ havingȱLBP.ȱ

ȱ 65 Discussion

MUSCLE FUNCTION The results of the present study indicate an association between muscle function and pregnancy‐related LBP that is stronger for PGP and combined pain than for lumbar pain, although the syndromes may have partly the same etiology. The retrospective power calculation showed that the power to detect a difference was low in some of the muscle tests. No statistically significant difference could be found between subgroups of LBP, therefore it is not known if lumbar pain and PGP are different with regard to muscle functioning. Notably, the women with lumbar pain were similar to the healthy group regarding muscle test results postpartum despite high pain intensity. The confidence intervals of the muscle tests strengthen the hypothesis that the PGP groups are different from, at least, the “no LBP” group.

The muscle tests were performed in nonweight‐bearing positions, which might be regarded as nonfunctional. However, the test positions were chosen with respect to the risk of pain increasing in standing positions, the position possible with the dynamometer, and the use of recommended muscle test positions (108). In the theoretical model of the self‐locking mechanism, the pelvis is described as providing a stable base for movement of the limbs in all positions. Likewise, the recommended functional test of load transfer in the lumbopelvic region is the ASLR test, which is a supine test (258). Muscle differences were noted in the study, in spite of the nonweight‐bearing position, which strengthens the hypothesis of an association between muscle dysfunction and, at least, PGP. Additionally, the improvement seen in muscle function, pain, and disability in women with PGP after specific stabilising exercises further supports the hypothesis (60, 225, 226).

The drop‐outs in the separate tests were not expected to influence the results since the reasons for not performing a test were mostly nonrelated to the LBP per se, but rather to the pregnancy itself. In pregnancy, 7 women were unable to do any test due to experiencing palpitations (n=1) or being too far along in pregnancy (n=6). Postpartum, 4 women were unable to do any test due to the risk that discogenic problems would become worse, the woman’s lack of time, fear of pain or possible kidney problems. The most common cause for not doing a test was reported discomfort in the prone position due to pregnancy, being at most 7/99 of the women with PGP. The highest proportion was lack of time (6/27) in the group with lumbar pain.

66 Discussionȱ

Oneȱproblemȱwithȱmuscleȱtestingȱisȱthatȱitȱmightȱbeȱinfluencedȱbyȱperceivedȱ pain.ȱControlȱforȱtheȱinfluenceȱofȱpainȱwasȱsomewhatȱachievedȱbyȱallowingȱtheȱ womenȱ toȱ estimateȱ painȱ levelȱ onȱ aȱ VAS,ȱ beforeȱ andȱ afterȱ eachȱ test.ȱ Noȱ differenceȱinȱpainȱlevelȱbeforeȱandȱafterȱtheȱtestȱwasȱfound.ȱ Likewise,ȱinȱtheȱ generalȱlinearȱmodelȱanalyses,ȱanȱassociationȱwasȱnotedȱbetweenȱsubgroupsȱofȱ LBPȱ andȱ trunkȱ muscleȱ endurance,ȱ hipȱ extensionȱ muscleȱ strength,ȱ andȱ gaitȱ speed.ȱ Whenȱ controllingȱ forȱ painȱ differencesȱ beforeȱ andȱ afterȱ eachȱ test,ȱ theȱ explainedȱvarianceȱofȱtheȱassociationȱbetweenȱmuscleȱfunctionȱandȱsubgroupsȱ ofȱLBPȱdidȱnot ȱimprove.ȱThus,ȱtheȱlowerȱvaluesȱinȱtheȱtestsȱofȱthoseȱwomenȱ withȱsomeȱtypeȱofȱLBPȱcouldȱnotȱbeȱexplainedȱbyȱanȱincreaseȱinȱpainȱduringȱ testing.ȱ Whenȱ controllingȱ forȱ preȬtestȱ painȱ intensity,ȱ noȱ improvementȱ inȱ theȱ explainedȱvarianceȱofȱtheȱassociationȱwasȱachieved.ȱ ȱ Painȱ hasȱ aȱ potentȱ effectȱ onȱ motorȱ activityȱ andȱ probablyȱ playsȱ aȱ roleȱ inȱ theȱ developmentȱ ofȱ persistentȱ problemsȱ (222).ȱ Itȱ hasȱ beenȱ suggestedȱ thatȱ theȱ presenceȱofȱpainȱleadsȱtoȱinhibitionȱorȱdelayedȱactivationȱofȱspecificȱmusclesȱorȱ muscleȱ groupsȱ inȱ atȱ leastȱ someȱ individualsȱ (91).ȱ Alteredȱ muscleȱ recruitmentȱ hasȱbeenȱshownȱinȱsubjectsȱ withȱnonspecificȱLBPȱ(93,ȱ240)ȱandȱinȱsubjectsȱwithȱ nonpregnancyȬrelatedȱPGPȱ(96,ȱ184).ȱ ȱ Performanceȱ motivationȱ isȱ anotherȱ difficultyȱ toȱ copeȱ withȱ inȱ muscleȱ testing.ȱ Noȱencouragementȱwasȱgivenȱduringȱtheȱtestsȱinȱtheȱpresentȱstudyȱinȱorderȱtoȱ haveȱ asȱ farȱ asȱ possibleȱ theȱ sameȱ conditionȱ forȱ allȱ women.ȱ Thereȱ wereȱ largeȱ rangesȱ forȱ theȱ differentȱ muscleȱ tests.ȱ Toȱ ourȱ knowledge,ȱ MIDȱ inȱ muscleȱ testȱ analysisȱisȱnotȱdefined,ȱbutȱaȱ10%ȱdifferenceȱbetweenȱgroupsȱisȱaȱvalueȱusedȱ (119,ȱ 127).ȱ Theȱ statisticallyȱ significantȱ differenceȱ inȱ muscleȱ testsȱ ofȱ theȱ PGPȱ subgroupsȱwasȱ15Ȭ62%ȱofȱtheȱvaluesȱofȱtheȱwomenȱwithoutȱLBP.ȱ ȱ Studyingȱ muscleȱ functionȱ whileȱ walkingȱ confirmedȱ theȱ gaitȱ difficultiesȱ previouslyȱ reportedȱ byȱ womenȱ withȱ PGPȱ (150,ȱ 168).ȱ Evenȱ earlyȱ onȱ inȱ pregnancy,ȱtheȱwomenȱwithȱPGPȱwalkedȱatȱaȱslowerȱspeedȱthanȱtheȱwomenȱ withoutȱ LBP.ȱ Theȱ gaitȱ speedȱ wasȱ belowȱ theȱ cutȬoffȱ levelȱ ofȱ 1.3ȱ m/sȱ thatȱ hasȱ beenȱ proposedȱ toȱ differentiateȱ betweenȱ backȱ patientsȱ andȱ healthyȱ personsȱ (131).ȱ Theȱ statisticallyȱ significantȱ differenceȱ betweenȱ subgroupsȱ mustȱ beȱ regardedȱ withȱ caution,ȱ however.ȱ Aȱ clinicallyȱ importantȱ differenceȱ forȱ improvementȱ inȱ gaitȱ speedȱ afterȱ hipȱ fractureȱ hasȱ beenȱ reportedȱ toȱ 0.1ȱ m/sȱ (187).ȱ Althoughȱ theȱ differenceȱ betweenȱ groups ȱ inȱ theȱ presentȱ studyȱ wasȱ smallerȱ inȱ general,ȱ relevantȱ differenceȱ andȱ changeȱ areȱ notȱ necessarilyȱ equivalent.ȱ

ȱ 67 Discussionȱ ȱ ȱ Gaitȱ speedȱ mightȱ beȱ regardedȱ asȱ aȱ functionalȱ testȱ indicating,ȱ amongȱ otherȱ things,ȱtheȱconditionȱofȱstabilityȱoverȱtheȱpelvis.ȱTheȱ“waddlingȱgait”ȱseenȱinȱ pregnantȱ womenȱ mayȱ beȱ anȱ adaptationȱ inȱ orderȱ toȱ achieveȱ stability.ȱ Peakȱ transverseȱplaneȱlumbopelvicȱrotationȱoccursȱatȱfootȱstrikeȱ(213).ȱByȱwaddling,ȱ theȱ womenȱ avoidȱ rotationȱ ofȱ theȱ lumbopelvicȱ regionȱ andȱ therebyȱ decreaseȱ demandsȱ onȱ stabilityȱ andȱ alsoȱ theȱ riskȱ ofȱ gettingȱ orȱ increasingȱ pain.ȱ Theȱ reportedȱandȱobservedȱshorterȱstrideȱlengthȱisȱperhapsȱdueȱtoȱtheȱsameȱreasonȱ sinceȱ lumbopelvicȱ rangeȱ ofȱ motionȱ increasesȱ withȱ strideȱ lengthȱ (213).ȱ Additionally,ȱwaddlingȱgaitȱplacesȱtheȱcentreȱofȱgravityȱofȱtheȱtrunkȱaboveȱtheȱ weightȬbearingȱ hipȱ andȱ therebyȱ decreasesȱ theȱ demandsȱ onȱ theȱ abductors.ȱ Furthermore,ȱ significantȱ increasesȱ inȱ hipȱ andȱ ankleȱ kineticȱ gaitȱ parametersȱ haveȱbeenȱobservedȱduringȱpregnancy,ȱexplainingȱwhyȱgaitȱmotionȱremainedȱ relativelyȱ unchangedȱ despiteȱ increasesȱ inȱ bodyȱ massȱ andȱ widthȱ asȱ wellȱ asȱ changesȱ inȱ massȱ distributionȱ aboutȱ theȱ trunk.ȱ Thisȱ findingȱ indicatesȱ thatȱ duringȱ pregnancy,ȱ thereȱ mayȱ beȱ anȱ increasedȱ demandȱ placedȱ onȱ theȱ hipȱ abductor,ȱhipȱextensor,ȱandȱankleȱplantarȱflexorȱmusclesȱduringȱwalkingȱ(68).ȱ Inȱconclusion,ȱgaitȱmayȱbeȱanȱindicatorȱofȱtheȱfunctionalȱlimitationȱinȱPGPȱthatȱ probablyȱisȱrelatedȱtoȱlumbopelvicȱstability.ȱ

INTERNATIONALȱCLASSIFICATIONȱOFȱFUNCTIONING,ȱ DISABILITYȱANDȱHEALTHȱ Whenȱ studyingȱ consequencesȱ ofȱ pregnancyȬrelatedȱ LBP,ȱ theȱ Internationalȱ Classificationȱ ofȱ Functioning,ȱ Disabilityȱ andȱ Healthȱ (ICF),ȱ developedȱ byȱ theȱ WHOȱ (255),ȱ isȱ aȱ suitableȱ framework.ȱ Theȱ ICFȱ organizesȱ informationȱ asȱ “functioningȱandȱdisability”ȱandȱ“contextualȱfactors”.ȱWithinȱfunctioningȱandȱ disability,ȱ “bodyȱ functions”ȱ andȱ “bodyȱ structures”ȱ areȱ included.ȱ Bodyȱ functionsȱ areȱ theȱ physiologicalȱ functionsȱ ofȱ bodyȱ systems,ȱ includingȱ psychologicalȱ functions,ȱ whereasȱ bodyȱ structuresȱ areȱ theȱ anatomicalȱ partsȱ suchȱasȱorgans,ȱlimbsȱandȱtheirȱcomponents.ȱProblemsȱ(significantȱdeviationsȱ orȱ loss)ȱ inȱ bodyȱ functionȱ orȱ structureȱ areȱ definedȱ asȱ impairments.ȱ Alsoȱ includedȱwithinȱ functioningȱ andȱ disabilityȱareȱ“activity”ȱandȱ“participation”ȱ components,ȱwhichȱcoverȱdomainsȱofȱfunctioningȱfromȱbothȱanȱindividualȱandȱ aȱ societalȱ perspective.ȱ Theȱ difficultyȱ anȱ individualȱ mayȱ haveȱ toȱ executeȱ anȱ activityȱ isȱ definedȱ asȱ activityȱ limitation.ȱ Theȱ problemȱ anȱ individualȱ mayȱ experienceȱ inȱ lifeȱ situationsȱ isȱ definedȱ asȱ participationȱ restrictions.ȱ Theȱ contextualȱfactorsȱareȱpersonal,ȱasȱwellȱasȱenvironmentalȱfactors.ȱ ȱ

ȱ 68 Discussionȱ

Inȱtheȱpresentȱstudy,ȱtheȱICFȱmodelȱwasȱusedȱforȱstructuringȱvariablesȱstudiedȱ withinȱ researchȱ ofȱ pregnancyȬrelatedȱ LBPȱ (Figureȱ 6).ȱ Theȱ variablesȱ wereȱ identifiedȱinȱtheȱliteratureȱstudiedȱforȱthisȱthesisȱandȱwithinȱreferencesȱlistsȱofȱ thatȱliterature.ȱAtȱtheȱstartȱofȱtheȱstudy,ȱnoȱpublishedȱstudyȱwasȱfoundȱwhereȱ anȱestablishedȱmeasurementȱtoolȱwasȱusedȱforȱevaluatingȱdisabilityȱandȱHRQLȱ inȱ LBPȱ inȱ relationȱ toȱ pregnancy.ȱ Althoughȱ LBPȱ inȱ pregnancyȱ sometimesȱ isȱ lookedȱ uponȱ asȱ transientȱ andȱ unimportant,ȱ theȱ impactȱ ofȱ pregnancyȬrelatedȱ LBP,ȱasȱreportedȱinȱtheȱpresentȱstudyȱandȱotherȱstudiesȱ(36,ȱ116,ȱ121,ȱ152,ȱ168,ȱ 173,ȱ189)ȱsupportsȱtheȱopposite.ȱInȱrecentȱyears,ȱthereȱhasȱbeenȱaȱstrongȱtrendȱ toȱ useȱ establishedȱ measurementȱ toolsȱ whichȱ areȱ importantȱ forȱ comparisonȱ betweenȱstudies.ȱEnvironmentalȱfactorsȱandȱfactorsȱonȱparticipationȱlevel,ȱsuchȱ asȱlifeȱsituation,ȱareȱlessȱstudiedȱwithinȱpregnancyȬrelatedȱLBP.ȱEnvironmentalȱ factorsȱ wereȱ notȱ evaluatedȱ inȱ theȱ presentȱ studyȱ butȱ needȱ toȱ beȱ betterȱ understoodȱ inȱ pregnancyȬrelatedȱ LBP.ȱ Depressiveȱ symptomsȱ wereȱ studiedȱ usingȱ theȱ EPDS.ȱ Theȱ EPDSȱ wasȱ placedȱ onȱ theȱ bodyȱ functionȱ dimension,ȱ howeverȱdepressionȱhasȱshownȱtoȱbeȱdifficultȱtoȱcategoriseȱinȱtheȱICFȱmodelȱ (249),ȱ probablyȱ becauseȱ itȱ mayȱ beȱ seenȱ asȱ aȱ biologicalȱ asl ȱ wel ȱ asȱ anȱ environmentalȱfactor.ȱTheȱcombinationȱofȱaȱpathoȬphysiologicalȱmodelȱandȱaȱ psychosocialȱ modelȱ seemsȱ importantȱ forȱ theȱ understandingȱ ofȱ LBPȱ inȱ pregnancy.ȱ Inȱ conclusion,ȱ researchȱ withinȱ pregnancyȬrelatedȱ LBPȱ hasȱ expandedȱ extensivelyȱ duringȱtheȱ lastȱdecades.ȱ Whenȱ designingȱ newȱstudies,ȱ allȱdimensionsȱofȱtheȱICFȱneedȱto ȱbeȱconsideredȱinȱorderȱtoȱobtainȱaȱcompleteȱ pictureȱofȱtheȱproblem.ȱ

ȱ 69 Discussionȱ ȱ

Low Back Pain in relation to pregnancy

Body function & structure Activity Participation

(61, 116, 154, 174, 235) (266) BMI Gait parameters Sickȱleaveȱ(116,ȱ152,ȱ173,ȱ176,ȱ (3, 150, 154, 174, (179), 211, 235) (265) Delivery factors Gait speed ȱ177,ȱ211,ȱ230,ȱ264) (164, 178) (41) ȱ Sagittal configuration Lifting ȱ(3,ȱ14,ȱ61,ȱ72,ȱ121,ȱ165,ȱ176,ȱ (164) Work Sagittal mobility ODI ȱ177,ȱ235,ȱ236,ȱ263) Relaxin (4, 25, 117, 137, 190) RDQ Pain intensity (3, 85, 60, 109, 116, 128, 154, 157, DRI (116, 165, 166, 173) EQȬ5Dȱ 165, 166, 175, 176, 180, 182, 225, 226, 228, 236, 245) EQ-5D SFȬ36ȱ Pain location (116, 150, 166, 228, 245) SF-36 NHP Pain course (175, 182) NHP ODI Pain character (157, 166, 228) RDQ EQ-5D DRI, SF-36 (225, 226) ODI (225, 226) RDQ (186) EPDS NHP (173)ȱ HSCL (226) Muscle function (168, 225)ȱ

Environmental factors Personal factors

Contraceptives (3, 14, 112, 177, 211, 229, 245) Age see review (267) Education (3, 61, 154, 177, 226, 235, 245) BMI Socioeconomic class (174, 245, 263) Ethnicity (66, 174, 245) Physical exercise (121, 153, 165, 173, 183, 210, 226, 245) Heredity (136) Sick leaveȱ Parity see review (267) Physical exercise Smoking (14, 61, 109, 112, 116, 121, 128, 152, 174, 186, 235, 245) ȱ ȱ SF-36

Figureȱ6.ȱInteractionsȱbetweenȱtheȱcomponentsȱofȱtheȱICFȱ(WHOȱ2001).ȱUnderȱtheȱcomponentsȱareȱlistedȱvariablesȱstudiedȱ withinȱ researchȱ ofȱ pregnancyȬrelatedȱ LBP.ȱ Anȱ instrumentȱ mayȱ haveȱ variablesȱ fromȱ differentȱ componentsȱ andȱ isȱ therebyȱ underȱseveralȱcomponentsȱinȱtheȱICFȱmodel.ȱ ȱ DRIȱȱ DisabilityȱRatingȱIndexȱ HSCLȱ TheȱHopkinsȱSymptomȱCheckȱListȱ NHPȱȱ NottinghamȱHealthȱProfile QBPDSȱ QuebecȱBackȱPainȱDisabilityȱScale

ȱ 70 Discussionȱ

CLINICALȱIMPLICATIONSȱ Oneȱclinicalȱimplicationȱofȱthisȱthesisȱisȱthatȱtheȱwomenȱatȱriskȱforȱpersistentȱ painȱ postpartumȱ mayȱ beȱ identifiedȱ earlyȱ onȱ inȱ pregnancyȱ usingȱ knownȱ andȱ wellȬdescribedȱ classificationȱ methods.ȱ Theȱ identifiedȱ predictorsȱ canȱ beȱ evaluatedȱ byȱ questionsȱ concerningȱ ageȱ andȱ workȱ satisfaction,ȱ andȱ withȱ inexpensiveȱ methodsȱ forȱ measuringȱ enduranceȱ ofȱ theȱ backȱ flexorȱ muscles.ȱ Anotherȱ clinicalȱ implicationȱ isȱ thatȱ theȱ EPDSȱ seemsȱ toȱ beȱ anȱ accurateȱ andȱ simpleȱ instrumentȱ toȱ useȱ inȱ clinicalȱ practiseȱ forȱ screeningȱ forȱ depressiveȱ symptoms.ȱWhenȱidentifiedȱriskȱwomen,ȱpossibleȱneedȱforȱmultipleȱtreatmentȱ strategiesȱshouldȱbeȱconsidered.ȱ ȱ Inȱhasȱbeenȱshownȱthatȱonlyȱ32%ȱofȱwomenȱwithȱLBPȱreportȱtheirȱmorbidityȱtoȱ prenatalȱcaregiversȱ(245).ȱOfȱthoseȱcaregiversȱasked,ȱ75%ȱdidȱnotȱrecommendȱ anyȱ treatment.ȱ Theȱ studyȱ indicatesȱ theȱ needȱ forȱ physiotherapistsȱ whoȱ canȱ classifyȱ theȱ LBP,ȱ directȱ appropriateȱ activityȱ andȱ trainingȱ levels,ȱ andȱ offerȱ treatmentȱwhenȱneeded.ȱ ȱ Theȱ questionȱ canȱ beȱ askedȱ asȱ toȱ whyȱ certainȱ womenȱ experienceȱ PGPȱ whileȱ othersȱdoȱnot.ȱNoȱoneȱstructuralȱcomponent,ȱe.g.ȱjoint,ȱmuscleȱorȱligament,ȱisȱ likelyȱ toȱ beȱ theȱ soleȱ sourceȱ ofȱ pain.ȱ Theȱ LBPȱ thatȱ womenȱ experienceȱ inȱ pregnancyȱisȱlikelyȱtoȱbeȱmultifactorial,ȱwithȱoneȱorȱmoreȱfactorsȱdominating.ȱ Therefore,ȱ itȱ wouldȱ beȱ beneficialȱ toȱ seekȱ commonȱ patternsȱ thatȱ mayȱ beȱ addressedȱ usingȱ focusedȱ treatments.ȱ Attemptsȱ toȱ preventȱ theȱ occurrenceȱ ofȱ LBPȱhaveȱfailedȱ(8)ȱandȱsubsequentlyȱcomorbidityȱandȱnegativeȱconsequencesȱ needȱ toȱ beȱ addressed.ȱ Effectiveȱ treatmentȱ shouldȱ beȱ pursuedȱ sinceȱ evidenceȱ suggestsȱthatȱLBPȱinȱpregnancyȱmayȱleadȱtoȱdisabilityȱasȱwellȱaȱpersistentȱLBPȱ afterȱpregnancy.ȱ

FUTUREȱRESEARCHȱ Furtherȱ studiesȱ onȱ howȱ toȱ preventȱ theȱ developmentȱ ofȱ factorsȱ thatȱ describeȱ persistentȱpregnancyȬrelatedȱPGPȱareȱneeded,ȱparallelȱtoȱstudiesȱonȱcontextualȱ factors,ȱ asȱ wellȱ asȱ psychosocialȱ factorsȱ withinȱ participationȱ dimensions.ȱ Oneȱ canȱonlyȱspeculateȱonȱhowȱpreviousȱexperienceȱofȱLBPȱinȱthisȱpopulationȱmayȱ interfereȱwithȱexpectationsȱofȱrecoveryȱandȱcopingȱstrategies.ȱWomenȱwithȱaȱ LBPȱdebutȱinȱrelationȱtoȱaȱpregnancy,ȱmayȱattributeȱtheȱLBPȱtoȱtheȱpregnancy,ȱ thatȱinȱitselfȱhasȱanȱendȱandȱtherebyȱanȱexpectancyȱofȱpainȱreliefȱwithȱit.ȱOnȱtheȱ contrary,ȱlumbarȱpainȱisȱoftenȱexperiencedȱearlierȱonȱinȱlifeȱandȱhasȱaȱrecurrentȱ course.ȱTheȱroleȱofȱtheȱcognitiveȬevaluativeȱcomponentȱmayȱbeȱdifferentȱforȱaȱ

ȱ 71 Discussionȱ ȱ womanȱwithȱrecurrentȱlumbarȱpainȱwhoȱalsoȱexperiencesȱPGP.ȱSheȱdoesȱnotȱ haveȱtheȱexperienceȱofȱLBPȱthatȱrecoversȱandȱtherebyȱherȱexpectationsȱmightȱ beȱdifferentȱwhenȱfacedȱwithȱ2ȱtypesȱofȱpain.ȱHere,ȱitȱisȱinterestingȱtoȱapplyȱ ideasȱ ofȱ painȱ exacerbationȱ withȱ catastrophisingȱ theoriesȱ andȱ fearȱ ofȱ pain.ȱ Thereȱisȱgrowingȱinformationȱwithȱregardȱtoȱdifferentȱcopingȱstrategies,ȱwhichȱ areȱ probablyȱ applicableȱ toȱ theȱ PGPȱ population,ȱ butȱ stillȱ poorlyȱ understoodȱ (84).ȱTheȱsocialȱaspect,ȱincludingȱfamilyȱandȱworkȱsituations,ȱseemsȱrelevantȱtoȱ evaluate.ȱInȱaddition,ȱthereȱisȱaȱyoungȱandȱgrowingȱresearchȱbranchȱthatȱstudyȱ sexȱandȱgenderȱdifferencesȱofȱbiologicalȱandȱpsychosocialȱfactorsȱinȱrelationȱtoȱ painȱandȱpainȱmechanisms.ȱTheȱresultsȱfromȱthesesȱstudiesȱmayȱbeȱimportantȱ toȱconsiderȱinȱpregnancyȬrelatedȱLBP.ȱ ȱ

ȱ 72 Discussionȱ

CONCLUSIONSȱ

x Theȱclinicalȱclassificationȱshowedȱanȱequalȱprevalenceȱofȱlumbarȱpainȱinȱ pregnancyȱandȱpostpartum,ȱwhileȱtheȱrateȱofȱwomenȱwithȱpelvicȱgirdleȱ painȱorȱcombinedȱpainȱdecreasedȱafterȱpregnancy.ȱ ȱ x Theȱclinicalȱnaturalȱcourseȱofȱwomenȱwithȱcombinedȱpainȱshowedȱtheȱ lowestȱrecoveryȱrateȱamongȱtheȱsubgroupsȱofȱlowȱbackȱpain.ȱ ȱ x Aȱtargetȱgroupȱthatȱisȱatȱriskȱforȱpersistentȱpostpartumȱpelvicȱgirdleȱpainȱ orȱ combinedȱ painȱ isȱ womenȱ whoȱ areȱ dissatisfiedȱ atȱ work,ȱ haveȱ combinedȱpainȱearlyȱonȱinȱpregnancy,ȱareȱrelativelyȱolder,ȱandȱhaveȱlowȱ enduranceȱofȱtheȱbackȱflexorȱmuscles.ȱIdentificationȱofȱthisȱtargetȱgroupȱ appearsȱ possibleȱ withȱ theȱ describedȱ classificationȱ ofȱ lowȱ backȱ painȱ inȱ earlyȱpregnancy.ȱ ȱ x Duringȱ earlyȱ pregnancy,ȱ womenȱ withȱ combinedȱ painȱ experiencedȱ greaterȱ consequencesȱ inȱ termsȱ ofȱ healthȬrelatedȱ qualityȱ ofȱ life,ȱ painȱ intensity,ȱandȱdisability,ȱthanȱwomenȱwithȱlumbarȱpainȱalone.ȱ ȱ x Postpartumȱ depressiveȱ symptomsȱ wereȱ 3ȱ timesȱ moreȱ prevalentȱ inȱ womenȱ withȱ lowȱ backȱ painȱ thanȱ inȱ thoseȱ without,ȱ yieldingȱ aȱ comorbidityȱrateȱofȱ10%ȱinȱtheȱcohort.ȱWomenȱwithȱlumbarȱpainȱtendedȱ toȱhaveȱaȱhigherȱriskȱforȱdepressionȱthanȱwomenȱwithȱpelvicȱgirdleȱpain.ȱ ȱ x Theȱ hypothesisȱ ofȱ theȱ associationȱ betweenȱ theȱ pelvicȱ girdleȱ painȱ subgroupȱandȱmuscleȱdysfunctionȱwasȱsupportedȱbyȱtheȱresultsȱwhichȱ showedȱ lowȱ trunkȱ muscleȱ enduranceȱ duringȱ pregnancyȱ andȱ postpartum.ȱ ȱ x Physicalȱ therapistsȱ treatingȱ womenȱ withȱ postpartumȱ lowȱ backȱ painȱ needȱtoȱscreenȱforȱdepressiveȱsymptoms.ȱ ȱ

ȱ 73 SummaryȱinȱSwedishȱ ȱ

SUMMARYȱINȱSWEDISHȱ

Nedreȱländryggssmärtaȱförekommerȱiȱhögreȱgradȱhosȱgravidaȱkvinnorȱänȱhosȱ kvinnorȱ iȱ sammaȱ ålderȱ iȱ befolkningen.ȱ Graviditetsrelateradȱ nedreȱ ländryggssmärtaȱ kvarstårȱ 6ȱ årȱ efterȱ graviditetȱ hosȱ 16ȱ %ȱ avȱ kvinnorna.ȱ Graviditetȱ representerarȱ därmedȱ enȱ specifikȱ risksituationȱ förȱ såvälȱ nedreȱ ländryggssmärtaȱ somȱ kvarståendeȱ nedreȱ ländryggssmärtaȱ efterȱ graviditet.ȱ Graviditetsrelateradȱ nedreȱ ländryggssmärtaȱ studerasȱ vanligenmȱ so ȱ enȱ enhetȱ trotsȱattȱendastȱenȱundergruppȱavȱnedreȱländryggssmärta,ȱbäckensmärta,ȱtycksȱ varaȱ relateradȱ tillȱ graviditet.ȱ Därmedȱ ärȱ möjligaȱ skillnaderȱ mellanȱ undergrupperȱokända.ȱ ȱ Avhandlingensȱ syftenȱ varȱ följande:ȱ 1)ȱ attȱ beskrivaȱ förekomstȱ avȱ klinisktȱ klassificeradeȱ undergrupperȱ avȱ kvinnorȱ medȱ nedreȱ ländryggssmärtaȱ iȱ enȱ kohortȱ (ingenȱ nedreȱ ländryggssmärta,ȱ lumbalȱ smärta,ȱ bäckensmärta,ȱ kombineradȱ bäckenȬochȱ lumbalsmärtaȱ (kombineradȱ smärta))ȱ iȱ graviditetȱ ochȱ postpartumȱ ochȱ 2)ȱ attȱ undersökaȱ omȱ detȱ fannsȱ enȱ skillnadȱ iȱ förlopp,ȱ hälsoȬ relateradȱ liskvalitet,ȱ smärtintensitet,ȱ funktionsnedsättning,ȱ depressivaȱ symtom,ȱ ellerȱ muskelfunktionȱ iȱ undergrupperȱ avȱ kohortenȱ samtȱ 3)ȱ attȱ identifieraȱprediktorerȱförȱkvarståendeȱgraviditetsrelateradȱbäckensmärtaȱellerȱ kombineradȱsmärtaȱpostpartum.ȱȱ ȱ Konsekutivtȱ inkluderadeȱ gravidarȱ kvinno ȱ klassificeradesȱ iȱ undergrupperȱ genomȱ mekaniskȱ undersökningȱ avȱ lumbalkolumna,ȱ smärtprovokationstesterȱ förȱ bäckenet,ȱ standardiseradȱ anamnesupptagning,ȱ ochȱ smärtteckningar.ȱ Allaȱ kvinnorȱ besvaradeȱ frågeformulärȱ (bakgrundsfrågor,ȱ EQȬ5D).ȱ Kvinnorȱ medȱ nedreȱ ländryggssmärtaȱ fylldeȱ iȱ Oswestryȱ Disabilityȱ Indexȱ ochȱ smärtmått.ȱ EdinburghȱPostnatalȱDepressionȱScaleȱanvändesȱförȱattȱundersökaȱdepressivaȱ symtomȱ 3ȱ månaderȱ postpartumȱ (ǃ10).ȱ Uthållighetstestȱ avȱ bålmuskulaturen,ȱ styrketestȱ avȱ höftmuskulaturȱ ochȱ gånghastighetȱ undersöktes.ȱ Multipelȱ logistiskȱ regressionȱ användesȱ förȱ attȱ identifieraȱ prediktorerȱ frånȱ självrapporteringȱsamtȱfrånȱdenȱkliniskaȱundersökningen.ȱ ȱ Vidȱ undersökningȱ iȱ graviditetsveckaȱ 12Ȭ18,ȱ hadeȱ 118/308ȱ (38%)ȱ kvinnorȱ ingenȱ nedreȱ ländryggssmärta,ȱ 101ȱ (33%)ȱ hadeȱ bäckensmärta,ȱ 33ȱ (11%)ȱ hadeȱ lumbalȱ smärtaȱ ochȱ 56ȱ (18%)ȱ hadeȱ kombineradȱ smärta.ȱ Treȱ månaderȱ postpartum,ȱvarȱ183/272ȱ(67%)ȱkvinnorȱutanȱnedreȱländryggssmärta,ȱ46ȱ(17%)ȱ hadeȱ bäckensmärta,ȱ 29ȱ (11%)ȱ hadeȱ lumbalȱ smärta,ȱ ochȱ 14ȱ (5%)ȱ kombineradȱ smärta.ȱ Gravidaȱ kvinnorȱ medȱ kombineradȱ smärtaȱ rapporteradeȱ högstaȱ påverkanȱ iȱ termerȱ avȱ hälsorelateradȱ livskvalitet,ȱ smärtintensitet,ȱ ochȱ

ȱ 74 Summary in Swedish funktionsnedsättning. Kvinnor med bäckensmärta och/eller kombinerad smärta hade lägre värden för uthållighet i bålmuskulaturen, styrka av höftextensorer och gånghastighet jämfört med kvinnor utan nedre ländryggssmärta. Depressiva symtom förekom i tre gånger så hög grad hos kvinnor med nedre ländryggssmärta (27/87 31%) jämfört med kvinnor utan nedre ländryggssmärta (17/180 9%). Postpartum hade 16‐20% av kvinnor kvarstående bäcken‐och kombinerad smärta medan 1/29 hade lumbal smärta. Identifierade prediktorer för kvarstående bäcken eller kombinerad smärta var otrivsel på arbetet, högre ålder, kombinerad smärta i tidig graviditet, och låg uthållighet i bukmuskulaturen. Sammanfattningsvis identifierades kvinnor med kombinerad smärta som en riskgrupp eftersom de hade det lägsta tillfrisknandet och eftersom klassifikationen kombinerad smärta visade sig vara prediktor för kvarstående bäckensmärta eller kombinerad smärta postpartum. Hypotesen att muskeldysfunktion var relaterad till bäckensmärta stärktes. Baserat på vårt resultat av hög komorbiditet av postpartum depressiva symtom och nedre ländryggssmärta, förefaller det viktigt att screena för och överväga behandling för båda symtomen.

75 Acknowledgementsȱ ȱ

ACKNOWLEDGEMENTSȱ

Iȱwouldȱlikeȱtoȱexpressȱmyȱdeepȱandȱsincereȱgratitudeȱtoȱeachȱandȱeveryȱoneȱwhoȱmadeȱ thisȱworkȱpossible.ȱInȱparticularȱIȱwouldȱlikeȱtoȱthank:ȱ ȱ Professorȱ Birgittaȱ Öberg,ȱ myȱ tutor,ȱ forȱ sharingȱ yourȱ broadȱ knowledgeȱ andȱ sharpȱanalyticȱskills.ȱYourȱcapabilityȱtoȱcaptureȱtheȱessence,ȱtoȱdiscernȱpatternsȱ inȱ chaosȱ neverȱ ceaseȱ toȱ amazeȱ me.ȱ Yourȱ enthusiasmȱ andȱ skilfulȱ guidanceȱ makesȱyouȱtoȱaȱtrueȱtutor.ȱ ȱ AssociateȱprofessorȱHansȱChristianȱÖstgaard,ȱmyȱcoȬtutor,ȱforȱencouragement,ȱ promptȱanswersȱandȱforȱsharingȱyourȱgreatȱknowledgeȱinȱpelvicȱgirdleȱpain.ȱ LastȱbutȱnotȱleastȱforȱyourȱabilityȱtoȱmakeȱmeȱfeelȱIȱwouldȱmanageȱthisȱproject.ȱ ȱ AnnȱJosefssonȱcoȬauthorȱforȱskilfulȱguidanceȱinȱtheȱfieldȱofȱdepression.ȱ ȱ Joanitaȱ Bjursell,ȱ Kristinaȱ Törnkvist,ȱ Barbaraȱ Lyman,ȱ Gunnelȱ Klerfors,ȱ Lottaȱ Krok,ȱ Anetteȱ Granhag,ȱ midwivesȱ atȱ theȱ antenatalȱ healthȱ careȱ clinicsȱ forȱ conscientiouslyȱ includingȱ theȱ pregnantȱ womenȱ toȱ theȱ study.ȱ Margaretaȱ Wennergren,ȱ Margaretaȱ Hellgren,ȱ andȱ Joyȱ Ellisȱ forȱ competentȱ advices.ȱ Allȱ midwivesȱatȱTopasgatanȱantenatalȱhealthȱcareȱclinicȱforȱrecruitmentȱofȱwomenȱ withȱlowȱbackȱpainȱintoȱtheȱreliabilityȱstudy.ȱ ȱ Kerstinȱ Johansson,ȱ Anetteȱ Edsbergerȱ andȱ Gunillaȱ Zetherströmȱ forȱ sharingȱ yourȱ greatȱ knowledgeȱ ofȱ pelvicȱ girdleȱ painȱ atȱ theȱ planningȱ ofȱ theȱ study.ȱ Kerstinȱforȱyourȱpositiveȱattitudeȱandȱfruitfulȱlunchȱdiscussionsȱoverȱtheȱyears.ȱ ȱ Ylvaȱ Almér,ȱ Görelȱ Kjellman,ȱ Lenaȱ OldforsȬEngströmȱ previousȱ colleaguesȱ atȱ PVȬrehabȱ whereȱ itȱ allȱ started,ȱ forȱ providingȱ theȱ openȱ atmosphereȱ ofȱ questioningȱwhatȱweȱdidȱandȱwhy;ȱIȱlearnedȱforȱlife!ȱ ȱ JoannaȱKvistȱforȱintroducingȱmeȱintoȱscience,ȱgforȱsharin ȱyourȱgreatȱscientificȱ knowledge,ȱforȱlateȱtalksȱaboutȱscienceȱandȱlife,ȱandȱforȱyourȱvastȱhospitality.ȱ ȱ Allȱ colleguesȱ atȱ theȱ departmentȱ ofȱ Physiotherapyȱ inȱ Linköpingȱ forȱ supportȱ andȱ constructiveȱ discussionsȱ overȱ theȱ years.ȱ Youȱ wereȱ theȱ reasonȱ forȱ theȱ endlessȱnumberȱofȱtravelsȱbetweenȱGothenburgȱandȱLinköping.ȱÅsaȱFahlstedt,ȱ

ȱ 76 Acknowledgementsȱ

EmmaȱWinquist,ȱandȱAnnaȱMagnussonȱforȱexcellentȱadministrativeȱsupport.ȱ Yourȱhaveȱbeenȱ“myȱeyes,ȱarmsȱandȱfeet”ȱinȱLinköping.ȱ ȱ MariaȱGutkeȱforȱengagementȱinȱrecruitingȱhealthyȱwomenȱtoȱtheȱpilotȱstudy.ȱ ȱ Gunillaȱ KjellbyȬWendtȱ forȱ sharingȱ yourȱ greatȱ knowledgeȱ ofȱ backȱ pain,ȱ forȱ splendidȱ coȬoperation,ȱ andȱ forȱ support,ȱ inspirationȱ andȱ fruitfulȱ discussionsȱ aboutȱeverythingȱthroughȱtheȱyears.ȱ ȱ Mariȱ Lundbergȱ forȱ highlyȱ scientificȱ discussions,ȱ forȱ skilfulȱ reviewȱ ofȱ manuscripts,ȱandȱforȱyourȱwarmȱfriendship.ȱTheȱdaysȱasȱPhDȬstudentȱwouldȱ haveȱbeenȱsoȱlonelyȱwithoutȱyou.ȱ ȱ MariaȱLarssonȱforȱhighȬqualityȱdiscussionsȱaboutȱscienceȱandȱeveryȬdayȱlife.ȱ ȱ MarianneȱNordinȱforȱcoȬoperationȱwhenȱIȱwasȱbusyȱincludingȱwomen.ȱ ȱ “TheȱPhDȱresearchȬgroup”ȱinȱGothenburg:ȱKerstinȱHagberg,ȱGunillaȱLimbäckȬ Svensson,ȱ Annaȱ Danielsson,ȱ Elisabethȱ Hansson,ȱ Piaȱ Thoméeȱ forȱ scienticȱ discussionsȱwithoutȱ“ceilingȱeffect”ȱandȱforȱallȱtheȱlaughterȱthroughȱtheȱyears.ȱ ȱ OlleȱEricsson,ȱJohnȱCarstensen,ȱHenrikȱMagnussonȱforȱstatisticalȱadvice.ȱ ȱ AllisonȱKaigleȱHolmȱforȱexcellentȱrevisionȱofȱtheȱEnglishȱtext.ȱ ȱ Marjutȱ Molénȱ illustratorȱ ofȱ theȱ coverȱ pageȱ andȱ friend,ȱ forȱ capturingȱ theȱ simplicityȱinȱtheȱdiversityȱofȱthisȱwork.ȱ ȱ IngȬBrittȱ andȱ Boȱ Jacobsson,ȱ myȱ parents,ȱ forȱ alwaysȱ believingȱ inȱ meȱ andȱ forȱ supportingȱ meȱ whateverȱ Iȱ setȱ myȱ mindȱ onȱ doing.ȱ IngȬMarieȱ andȱ Tommyȱ Gutke,ȱmyȱparentsȱinȱlaw,ȱforȱalwaysȱbeingȱthereȱforȱmyȱchildren.ȱ ȱ MostȱofȱallȱmyȱbelovedȱJanneȱandȱourȱchildrenȱJuliaȱandȱJanelleȱforȱbeingȱtheȱ spiritȱofȱmyȱlifeȱandȱforȱbringingȱsoȱmuchȱjoyȱtoȱme.ȱ ȱ Thisȱstudyȱwasȱsupportedȱbymȱgrantsȱfro ȱTheȱSwedishȱResearchȱCouncil,ȱtheȱ VardalȱFoundation,ȱtheȱFoundationȱofȱtheȱRegionȱVästraȱGötaland,ȱtheȱTryggȱ Hansaȱ Researchȱ Foundation,ȱ andȱ theȱ Rehabilitationȱ andȱ Medicalȱ Researchȱ Foundation.ȱ

ȱ 77 Referencesȱ

REFERENCESȱ

1.ȱ AlarantaȱH,ȱLuotoȱS,ȱHeliovaaraȱM,ȱHurriȱH.ȱStaticȱbackȱenduranceȱandȱ theȱriskȱofȱlowȬbackȱpain.ȱClinȱBiomechȱ(Bristol,ȱAvon)ȱ1995;ȱ10:323Ȭ324.ȱ 2.ȱ AlbertȱH,ȱGodskesenȱM,ȱWestergaardȱJ.ȱEvaluationȱofȱclinicalȱtestsȱusedȱinȱ classificationȱproceduresȱinȱpregnancyȬrelatedȱpelvicȱjointȱpain.ȱEurȱ SpineȱJȱ2000;ȱ9:161Ȭ166.ȱ 3.ȱ AlbertȱH,ȱGodskesenȱM,ȱWestergaardȱJ.ȱPrognosisȱinȱfourȱsyndromesȱofȱ pregnancyȬrelatedȱpelvicȱpain.ȱActaȱObstetȱGynecolȱScandȱ2001;ȱ80:505Ȭ 510.ȱ 4.ȱ AlbertȱH,ȱGodskesenȱM,ȱWestergaardȱJG,ȱChardȱT,ȱGunnȱL.ȱCirculatingȱ levelsȱofȱrelaxinȱareȱnormalȱinȱpregnantȱwomenȱwithȱpelvicȱpain.ȱEurȱJȱ ObstetȱGynecolȱReprodȱBiolȱ1997;ȱ74:19Ȭ22.ȱ 5.ȱ AlbertȱHB,ȱGodskesenȱM,ȱKorsholmȱL,ȱWestergaardȱJG.ȱRiskȱfactorsȱinȱ developingȱpregnancyȬrelatedȱpelvicȱgirdleȱpain.ȱActaȱObstetȱGynecolȱ Scandȱ2006;ȱ85:539Ȭ544.ȱ 6.ȱ AltmanȱDG.ȱPracticalȱstatisticsȱforȱmedicalȱresearch.ȱLondon:ȱChapmanȱ&ȱ Hall/CRC,ȱ1991.ȱ 7.ȱ AmericanȱPsychiatricȱAssociation,ȱed.ȱDiagnosticȱandȱStatisticalȱManualȱofȱ MentalȱDisorders.ȱWashington,ȱDC,ȱ2000.ȱ 8.ȱ AnderssonȱGB.ȱEpidemiologicalȱfeaturesȱofȱchronicȱlowȬbackȱpain.ȱLancetȱ 1999;ȱ354:581Ȭ585.ȱ 9.ȱ AugustoȱA,ȱKumarȱR,ȱCalheirosȱJM,ȱMatosȱE,ȱFigueiredoȱE.ȱPostȬnatalȱ depressionȱinȱanȱurbanȱareaȱofȱPortugal:ȱcomparisonȱofȱchildbearingȱ womenȱandȱmatchedȱcontrols.ȱPsycholȱMedȱ1996;ȱ26:135Ȭ141.ȱ 10.ȱ BadiaȱX,ȱSchiaffinoȱA,ȱAlonsoȱJ,ȱHerdmanȱM.ȱUsingȱtheȱEuroQoIȱ5ȬDȱinȱtheȱ Catalanȱgeneralȱpopulation:ȱfeasibilityȱandȱconstructȱvalidity.ȱQualȱLifeȱ Resȱ1998;ȱ7:311Ȭ322.ȱ 11.ȱ BastiaanssenȱJM,ȱdeȱBieȱRA,ȱBastiaenenȱCH,ȱEssedȱGG,ȱvanȱdenȱBrandtȱ PA.ȱAȱhistoricalȱperspectiveȱonȱpregnancyȬrelatedȱlowȱbackȱand/orȱ pelvicȱgirdleȱpain.ȱEurȱJȱObstetȱGynecolȱReprodȱBiolȱ2005;ȱ120:3Ȭ14.ȱ 12.ȱ BastiaenenȱCH,ȱdeȱBieȱRA,ȱWoltersȱPM,ȱetȱal.ȱEffectivenessȱofȱaȱtailorȬmadeȱ interventionȱforȱpregnancyȬrelatedȱpelvicȱgirdleȱand/orȱlowȱbackȱpainȱ afterȱdelivery:ȱshortȬtermȱresultsȱofȱaȱrandomizedȱclinicalȱtrialȱ [ISRCTN08477490].ȱBMCȱMusculoskeletȱDisordȱ2006;ȱ7:19.ȱ

ȱ 78 Referencesȱ ȱ 13.ȱ BattieȱMC,ȱCherkinȱDC,ȱDunnȱR,ȱCiolȱMA,ȱWheelerȱKJ.ȱManagingȱlowȱ backȱpain:ȱattitudesȱandȱtreatmentȱpreferencesȱofȱphysicalȱtherapists.ȱ PhysȱTherȱ1994;ȱ74:219Ȭ226.ȱ 14.ȱ BergȱG,ȱHammarȱM,ȱMollerȬNielsenȱJ,ȱLindenȱU,ȱThorbladȱJ.ȱLowȱbackȱ painȱduringȱpregnancy.ȱObstetȱGynecolȱ1988;ȱ71:71Ȭ75.ȱ 15.ȱ BergmanȱS,ȱHerrstromȱP,ȱHogstromȱK,ȱPeterssonȱIF,ȱSvenssonȱB,ȱJacobssonȱ LT.ȱChronicȱmusculoskeletalȱpain,ȱprevalenceȱrates,ȱandȱ sociodemographicȱassociationsȱinȱaȱSwedishȱpopulationȱstudy.ȱJȱ Rheumatolȱ2001;ȱ28:1369Ȭ1377.ȱ 16.ȱ BergmarkȱA.ȱStabilityȱofȱtheȱlumbarȱspine.ȱAȱstudyȱinȱmechanicalȱ engineering.ȱActaȱOrthopȱScandȱSupplȱ1989;ȱ230:1Ȭ54.ȱ 17.ȱ BeurskensȱAJ,ȱdeȱVetȱHC,ȱKokeȱAJ.ȱResponsivenessȱofȱfunctionalȱstatusȱinȱ lowȱbackȱpain:ȱaȱcomparisonȱofȱdifferentȱinstruments.ȱPainȱ1996;ȱ65:71Ȭ 76.ȱ 18.ȱ BeurskensȱAJ,ȱdeȱVetȱHC,ȱKokeȱAJ,ȱvanȱderȱHeijdenȱGJ,ȱKnipschildȱPG.ȱ Measuringȱtheȱfunctionalȱstatusȱofȱpatientsȱwithȱlowȱbackȱpain.ȱ AssessmentȱofȱtheȱqualityȱofȱfourȱdiseaseȬspecificȱquestionnaires.ȱSpineȱ 1995;ȱ20:1017Ȭ1028.ȱ 19.ȱ BieringȬSorensenȱF.ȱLowȱbackȱtroubleȱinȱaȱgeneralȱpopulationȱofȱ30Ȭ,ȱ40Ȭ,ȱ 50Ȭ,ȱandȱ60ȬyearȬoldȱmenȱandȱwomen.ȱStudyȱdesign,ȱrepresentativenessȱ andȱbasicȱresults.ȱDanȱMedȱBullȱ1982;ȱ29:289Ȭ299.ȱ 20.ȱ BieringȬSorensenȱF.ȱAȱprospectiveȱstudyȱofȱlowȱbackȱpainȱinȱaȱgeneralȱ population.ȱI.ȱOccurrence,ȱrecurrenceȱandȱaetiology.ȱScandȱJȱRehabilȱ Medȱ1983;ȱ15:71Ȭ79.ȱ 21.ȱ BieringȬSorensenȱF.ȱPhysicalȱmeasurementsȱasȱriskȱindicatorsȱforȱlowȬbackȱ troubleȱoverȱaȱoneȬyearȱperiod.ȱSpineȱ1984;ȱ9:106Ȭ119.ȱ 22.ȱ BinkleyȱJ,ȱFinchȱE,ȱHallȱJ,ȱBlackȱT,ȱGowlandȱC.ȱDiagnosticȱclassificationȱofȱ patientsȱwithȱlowȱbackȱpain:ȱreportȱonȱaȱsurveyȱofȱphysicalȱtherapyȱ experts.ȱPhysȱTherȱ1993;ȱ73:138Ȭ150;ȱdiscussionȱ150Ȭ135.ȱ 23.ȱ BirdȱAR,ȱMenzȱHB,ȱHydeȱCC.ȱTheȱeffectȱofȱpregnancyȱonȱfootprintȱ parameters.ȱAȱprospectiveȱinvestigation.ȱJȱAmȱPodiatrȱMedȱAssocȱ1999;ȱ 89:405Ȭ409.ȱ 24.ȱ BjorklundȱK,ȱBergstromȱS.ȱIsȱpelvicȱpainȱinȱpregnancyȱaȱwelfareȱ complaint?ȱActaȱObstetȱGynecolȱScandȱ2000;ȱ79:24Ȭ30.ȱ 25.ȱ BjorklundȱK,ȱBergstromȱS,ȱNordstromȱML,ȱUlmstenȱU.ȱSymphysealȱ distentionȱinȱrelationȱtoȱserumȱrelaxinȱlevelsȱandȱpelvicȱpainȱinȱ pregnancy.ȱActaȱObstetȱGynecolȱScandȱ2000;ȱ79:269Ȭ275.ȱ 26.ȱ BogdukȱN.ȱTheȱanatomicalȱbasisȱforȱspinalȱpainȱsyndromes.ȱJȱ ManipulativeȱPhysiolȱTherȱ1995;ȱ18:603Ȭ605.ȱ

ȱ 79 Referencesȱ

27.ȱ BohannonȱRW.ȱComfortableȱandȱmaximumȱwalkingȱspeedȱofȱadultsȱagedȱ 20Ȭ79ȱyears:ȱreferenceȱvaluesȱandȱdeterminants.ȱAgeȱAgeingȱ1997;ȱ26:15Ȭ 19.ȱ 28.ȱ BoltonȱJE.ȱAccuracyȱofȱrecallȱofȱusualȱpainȱintensityȱinȱbackȱpainȱpatients.ȱ Painȱ1999;ȱ83:533Ȭ539.ȱ 29.ȱ BombardierȱC.ȱOutcomeȱassessmentsȱinȱtheȱevaluationȱofȱtreatmentȱofȱ spinalȱdisorders:ȱsummaryȱandȱgeneralȱrecommendations.ȱSpineȱ2000;ȱ 25:3100Ȭ3103.ȱ 30.ȱ BouterȱLM,ȱvanȱTulderȱMW,ȱKoesȱBW.ȱMethodologicȱissuesȱinȱlowȱbackȱ painȱresearchȱinȱprimaryȱcare.ȱSpineȱ1998;ȱ23:2014Ȭ2020.ȱ 31.ȱ BrazierȱJ,ȱRobertsȱJ,ȱDeverillȱM.ȱTheȱestimationȱofȱaȱpreferenceȬbasedȱ measureȱofȱhealthȱfromȱtheȱSFȬ36.ȱJȱHealthȱEconȱ2002;ȱ21:271Ȭ292.ȱ 32.ȱ BrockingtonȱI.ȱMotherhoodȱandȱmentalȱhealth.ȱOxford:ȱOxfordȱUniversityȱ Press,ȱ1996.ȱ 33.ȱ BroussardȱCN,ȱRichterȱJE.ȱNauseaȱandȱvomitingȱofȱpregnancy.ȱ GastroenterolȱClinȱNorthȱAmȱ1998;ȱ27:123Ȭ151.ȱ 34.ȱ BrownȱS,ȱLumleyȱJ.ȱMaternalȱhealthȱafterȱchildbirth:ȱresultsȱofȱanȱ Australianȱpopulationȱbasedȱsurvey.ȱBrȱJȱObstetȱGynaecolȱ1998;ȱ105:156Ȭ 161.ȱ 35.ȱ BrownȱS,ȱLumleyȱJ.ȱPhysicalȱhealthȱproblemsȱafterȱchildbirthȱandȱmaternalȱ depressionȱatȱsixȱtoȱsevenȱmonthsȱpostpartum.ȱBjogȱ2000;ȱ107:1194Ȭ1201.ȱ 36.ȱ BrynhildsenȱJ,ȱHanssonȱA,ȱPerssonȱA,ȱHammarȱM.ȱFollowȬupȱofȱpatientsȱ withȱlowȱbackȱpainȱduringȱpregnancy.ȱObstetȱGynecolȱ1998;ȱ91:182Ȭ186.ȱ 37.ȱ BurstromȱK,ȱJohannessonȱM,ȱDiderichsenȱF.ȱSwedishȱpopulationȱhealthȬ relatedȱqualityȱofȱlifeȱresultsȱusingȱtheȱEQȬ5D.ȱQualȱLifeȱResȱ2001;ȱ 10:621Ȭ635.ȱ 38.ȱ CarlsonȱHL,ȱCarlsonȱNL,ȱPasternakȱBA,ȱBalderstonȱKD.ȱUnderstandingȱ andȱmanagingȱtheȱbackȱpainȱofȱpregnancy.ȱCurrȱWomensȱHealthȱRepȱ 2003;ȱ3:65Ȭ71.ȱ 39.ȱ CarlssonȱAM.ȱAssessmentȱofȱchronicȱpain.ȱI.ȱAspectsȱofȱtheȱreliabilityȱandȱ validityȱofȱtheȱvisualȱanalogueȱscale.ȱPainȱ1983;ȱ16:87Ȭ101.ȱ 40.ȱ CollitonȱJ.ȱManagingȱBackȱPainȱDuringȱPregnancy.ȱMedscapeȱWomensȱ Healthȱ1997;ȱ2:2.ȱ 41.ȱ CommissarisȱDA,ȱNilssonȬWikmarȱLB,ȱVanȱDieenȱJH,ȱHirschfeldȱH.ȱJointȱ coordinationȱduringȱwholeȬbodyȱliftingȱinȱwomenȱwithȱlowȱbackȱpainȱ afterȱpregnancy.ȱArchȱPhysȱMedȱRehabilȱ2002;ȱ83:1279Ȭ1289.ȱ 42.ȱ CoonsȱSJ,ȱRaoȱS,ȱKeiningerȱDL,ȱHaysȱRD.ȱAȱcomparativeȱreviewȱofȱgenericȱ qualityȬofȬlifeȱinstruments.ȱPharmacoeconomicsȱ2000;ȱ17:13Ȭ35.ȱ 43.ȱ CooperȱPJ,ȱMurrayȱL.ȱPostnatal ȱdepression.ȱBmjȱ1998;ȱ316:1884Ȭ1886.ȱ

ȱ 80 Referencesȱ ȱ 44.ȱ CosteȱJ,ȱDelecoeuillerieȱG,ȱCohenȱdeȱLaraȱA,ȱLeȱParcȱJM,ȱPaolaggiȱJB.ȱ Clinicalȱcourseȱandȱprognosticȱfactorsȱinȱacuteȱlowȱbackȱpain:ȱanȱ inceptionȱcohortȱstudyȱinȱprimaryȱcareȱpractice.ȱBmjȱ1994;ȱ308:577Ȭ580.ȱ 45.ȱ CoxȱJL,ȱHoldenȱJM,ȱSagovskyȱR.ȱDetectionȱofȱpostnatalȱdepression.ȱ Developmentȱofȱtheȱ10ȬitemȱEdinburghȱPostnatalȱDepressionȱScale.ȱBrȱJȱ Psychiatryȱ1987;ȱ150:782Ȭ786.ȱ 46.ȱ CoxȱJL,ȱMurrayȱD,ȱChapmanȱG.ȱAȱcontrolledȱstudyȱofȱtheȱonset,ȱdurationȱ andȱprevalenceȱofȱpostnatalȱdepression.ȱBrȱJȱPsychiatryȱ1993;ȱ163:27Ȭ31.ȱ 47.ȱ CroftȱPR,ȱDunnȱKM,ȱRaspeȱH.ȱCourseȱandȱprognosisȱofȱbackȱpainȱinȱ primaryȱcare:ȱtheȱepidemiologicalȱperspective.ȱPainȱ2006;ȱ122:1Ȭ3.ȱ 48.ȱ CroftȱPR,ȱMacfarlaneȱGJ,ȱPapageorgiouȱAC,ȱThomasȱE,ȱSilmanȱAJ.ȱ Outcomeȱofȱlowȱbackȱpainȱinȱgeneralȱpractice:ȱaȱprospectiveȱstudy.ȱBmjȱ 1998;ȱ316:1356Ȭ1359.ȱ 49.ȱ CrookȱJ,ȱMoldofskyȱH.ȱTheȱclinicalȱcourseȱofȱmusculoskeletalȱpainȱinȱ empiricallyȱderivedȱgroupingsȱofȱinjuredȱworkers.ȱPainȱ1996;ȱ67:427Ȭ433.ȱ 50.ȱ DaȱCostaȱD,ȱDritsaȱM,ȱRippenȱN,ȱLowensteynȱI,ȱKhalifeȱS.ȱHealthȬrelatedȱ qualityȱofȱlifeȱinȱpostpartumȱdepressedȱwomen.ȱArchȱWomenȱMentȱ Healthȱ2005.ȱ 51.ȱ DamenȱL,ȱBuyrukȱHM,ȱGulerȬUysalȱF,ȱLotgeringȱFK,ȱSnijdersȱCJ,ȱStamȱHJ.ȱ Theȱprognosticȱvalueȱofȱasymmetricȱlaxityȱofȱtheȱsacroiliacȱjointsȱinȱ pregnancyȬrelatedȱpelvicȱpain.ȱIn:Spine,ȱ2002;ȱ2820Ȭ2824.ȱ 52.ȱ deȱWitȱR,ȱvanȱDamȱF,ȱHannemanȱM,ȱetȱal.ȱEvaluationȱofȱtheȱuseȱofȱaȱpainȱ diaryȱinȱchronicȱcancerȱpainȱpatientsȱatȱhome.ȱPainȱ1999;ȱ79:89Ȭ99.ȱ 53.ȱ DelittoȱA,ȱErhardȱRE,ȱBowlingȱRW.ȱAȱtreatmentȬbasedȱclassificationȱ approachȱtoȱlowȱbackȱsyndrome:ȱidentifyingȱandȱstagingȱpatientsȱforȱ conservativeȱtreatment.ȱPhysȱTherȱ1995;ȱ75:470Ȭ485;ȱdiscussionȱ485Ȭ479.ȱ 54.ȱ DeyoȱRA,ȱCentorȱRM.ȱAssessingȱtheȱresponsivenessȱofȱfunctionalȱscalesȱtoȱ clinicalȱchange:ȱanȱanalogyȱtoȱdiagnosticȱtestȱperformance.ȱJȱChronicȱDisȱ 1986;ȱ39:897Ȭ906.ȱ 55.ȱ DiakowȱPR,ȱGadsbyȱTA,ȱGadsbyȱJB,ȱGleddieȱJG,ȱLeprichȱDJ,ȱScalesȱAM.ȱ Backȱpainȱduringȱpregnancyȱandȱlabor.ȱJȱManipulativeȱPhysiolȱTherȱ 1991;ȱ14:116Ȭ118.ȱ 56.ȱ DonelsonȱR,ȱAprillȱC,ȱMedcalfȱR,ȱGrantȱW.ȱAȱprospectiveȱstudyȱofȱ centralizationȱofȱlumbarȱandȱreferredȱpain.ȱAȱpredictorȱofȱsymptomaticȱ discsȱandȱanularȱcompetence.ȱSpineȱ1997;ȱ22:1115Ȭ1122.ȱ 57.ȱ DonelsonȱR,ȱSilvaȱG,ȱMurphyȱK.ȱCentralizationȱphenomenon.ȱItsȱ usefulnessȱinȱevaluatingȱandȱtreatingȱreferredȱpain.ȱSpineȱ1990;ȱ15:211Ȭ 213.ȱ

ȱ 81 Referencesȱ

58.ȱ DunnȱKM,ȱJordanȱK,ȱCroftȱPR.ȱCharacterizingȱtheȱcourseȱofȱlowȱbackȱpain:ȱ aȱlatentȱclassȱanalysis.ȱAmȱJȱEpidemiolȱ2006;ȱ163:754Ȭ761.ȱ 59.ȱ EberhardȬGranȱM,ȱEskildȱA,ȱTambsȱK,ȱSamuelsenȱSO,ȱOpjordsmoenȱS.ȱ DepressionȱinȱpostpartumȱandȱnonȬpostpartumȱwomen:ȱprevalenceȱandȱ riskȱfactors.ȱActaȱPsychiatrȱScandȱ2002;ȱ 106:426Ȭ433.ȱ 60.ȱ EldenȱH,ȱLadforsȱL,ȱOlsenȱMF,ȱOstgaardȱHC,ȱHagbergȱH.ȱEffectsȱofȱ acupunctureȱandȱstabilisingȱexercisesȱasȱadjunctȱtoȱstandardȱtreatmentȱ inȱpregnantȱwomenȱwithȱpelvicȱgirdleȱpain:ȱrandomisedȱsingleȱblindȱ controlledȱtrial.ȱBmjȱ2005;ȱ330:761.ȱ 61.ȱ EndresenȱEH.ȱPelvicȱpainȱandȱlowȱbackȱpainȱinȱpregnantȱwomenȬȬanȱ epidemiologicalȱstudy.ȱScandȱJȱRheumatolȱ1995;ȱ24:135Ȭ141.ȱ 62.ȱ EnthovenȱP,ȱSkargrenȱE,ȱCarstensenȱJ,ȱObergȱB.ȱPredictiveȱfactorsȱforȱ1Ȭ yearȱandȱ5Ȭyearȱoutcomeȱforȱdisabilityȱinȱaȱworkingȱpopulationȱofȱ patientsȱwithȱlowȱbackȱpainȱtreatedȱinȱprimaryȱcare.ȱPainȱ2006;ȱ122:137Ȭ 144.ȱ 63.ȱ FairbankȱJC,ȱCouperȱJ,ȱDaviesȱJB,ȱOȇBrienȱJP.ȱTheȱOswestryȱlowȱbackȱpainȱ disabilityȱquestionnaire.ȱPhysiotherapyȱ1980;ȱ66:271Ȭ273.ȱ 64.ȱ FairbankȱJC,ȱPynsentȱPB.ȱTheȱOswestryȱDisabilityȱIndex.ȱSpineȱ2000;ȱ 25:2940Ȭ2952;ȱdiscussionȱ2952.ȱ 65.ȱ FarbrotȱE.ȱTheȱrelationshipȱofȱtheȱeffectȱandȱpainȱofȱpregnancyȱtoȱtheȱ anatomyȱofȱtheȱpelvis.ȱActaȱradiolȱ1952;ȱ38:403Ȭ419.ȱ 66.ȱ FastȱA,ȱShapiroȱD,ȱDucommunȱEJ,ȱFriedmannȱLW,ȱBouklasȱT,ȱFlomanȱY.ȱ LowȬbackȱpainȱinȱpregnancy.ȱSpineȱ1987;ȱ12:368Ȭ371.ȱ 67.ȱ FisherȱK,ȱJohnstonȱM.ȱValidationȱofȱtheȱOswestryȱLowȱBackȱPainȱDisabilityȱ Questionnaire,ȱitsȱsensitivityȱasȱaȱmeasureȱofȱchangeȱfollowingȱ treatmentȱandȱitsȱrelationshipȱwithȱotherȱaspectsȱofȱtheȱchronicȱpainȱ experience.ȱPhysiotherapyȱTheoryȱandȱPracticeȱ1997;ȱ13:67Ȭ80.ȱ 68.ȱ FotiȱT,ȱDavidsȱJR,ȱBagleyȱA.ȱAȱbiomechanicalȱanalysisȱofȱgaitȱduringȱ pregnancy.ȱJȱBoneȱJointȱSurgȱAmȱ2000;ȱ82:625Ȭ632.ȱ 69.ȱ FritzȱJM,ȱBrennanȱGP,ȱCliffordȱSN,ȱHunterȱSJ,ȱThackerayȱA.ȱAnȱ examinationȱofȱtheȱreliabilityȱofȱaȱclassificationȱalgorithmȱforȱ subgroupingȱpatientsȱwithȱlowȱbackȱpain.ȱSpineȱ2006;ȱ31:77Ȭ82.ȱ 70.ȱ FritzȱJM,ȱGeorgeȱS.ȱTheȱuseȱofȱaȱclassificationȱapproachȱtoȱidentifyȱ subgroupsȱofȱpatientsȱwithȱacuteȱlowȱbackȱpain.ȱInterraterȱreliabilityȱandȱ shortȬtermȱtreatmentȱoutcomes.ȱSpineȱ2000; ȱ25:106Ȭ114.ȱ 71.ȱ FrändinȱK.ȱPhysicalȱactivityȱandȱfunctionalȱperformanceȱinȱaȱpopulationȱ studiedȱlongitudinallyȱfromȱ70ȱtoȱ75ȱyearsȱofȱage.ȱIn:Sahlgrenskaȱ Academy,ȱDeptȱofȱRehabilitationȱMedicine.ȱGothenburg:ȱGöteborgȱ University,ȱ1995.ȱ

ȱ 82 Referencesȱ ȱ 72.ȱ FungȱBK,ȱKwongȱCM,ȱHoȱES.ȱLowȱbackȱpainȱofȱwomenȱduringȱpregnancyȱ inȱtheȱmountainousȱdistrictȱofȱcentralȱTaiwan.ȱZhonghuaȱYiȱXueȱZaȱZhiȱ (Taipei)ȱ1993;ȱ51:103Ȭ106.ȱ 73.ȱ GarrattȱA,ȱSchmidtȱL,ȱMackintoshȱA,ȱFitzpatrickȱR.ȱQualityȱofȱlifeȱ measurement:ȱbibliographicȱstudyȱofȱpatientȱassessedȱhealthȱoutcomeȱ measures.ȱBmjȱ2002;ȱ324:1417.ȱ 74.ȱ GarrattȱAM,ȱKlaberȱMoffettȱJ,ȱFarrinȱAJ.ȱResponsivenessȱofȱgenericȱandȱ specificȱmeasuresȱofȱhealthȱoutcomeȱinȱlowȱbackȱpain.ȱSpineȱ2001;ȱ26:71Ȭ 77;ȱdiscussionȱ77.ȱ 75.ȱ GenellȱS.ȱStudiesȱonȱInsufficientiaȱpelvisȱ(gravidarumȱetȱpuerperarum).ȱ ActaȱObstetȱetȱGynecolȱScandȱ1949;ȱ28:1Ȭ33.ȱ 76.ȱ GeorgiopoulosȱAM,ȱBryanȱTL,ȱYawnȱBP,ȱHoustonȱMS,ȱRummansȱTA,ȱ TherneauȱTM.ȱPopulationȬbasedȱscreeningȱforȱpostpartumȱdepression.ȱ ObstetȱGynecolȱ1999;ȱ93:653Ȭ657.ȱ 77.ȱ GraceyȱJH,ȱMcDonoughȱSM,ȱBaxterȱGD.ȱPhysiotherapyȱmanagementȱofȱ lowȱbackȱpain:ȱaȱsurveyȱofȱcurrentȱpracticeȱinȱnorthernȱIreland.ȱSpineȱ 2002;ȱ27:406Ȭ411.ȱ 78.ȱ GronbladȱM,ȱHupliȱM,ȱWennerstrandȱP,ȱetȱal.ȱIntercorrelationȱandȱtestȬ retestȱreliabilityȱofȱtheȱPainȱDisabilityȱIndexȱ(PDI)ȱandȱtheȱOswestryȱ DisabilityȱQuestionnaireȱ(ODQ)ȱandȱtheirȱcorrelationȱwithȱpainȱintensityȱ inȱlowȱbackȱpainȱpatients.ȱClinȱJȱPainȱ1993;ȱ9:189Ȭ195.ȱ 79.ȱ GrotleȱM,ȱBroxȱJI,ȱVeierodȱMB,ȱGlomsrodȱB,ȱLonnȱJH,ȱVollestadȱNK.ȱ Clinicalȱcourseȱandȱprognosticȱfactorsȱinȱacuteȱlowȱbackȱpain:ȱpatientsȱ consultingȱprimaryȱcareȱforȱtheȱfirstȱtime.ȱSpineȱ2005;ȱ30:976Ȭ982.ȱ 80.ȱ GurejeȱO,ȱSimonȱGE,ȱVonȱKorffȱM.ȱAȱcrossȬnationalȱstudyȱofȱtheȱcourseȱofȱ persistentȱpainȱinȱprimaryȱcare.ȱPainȱ2001;ȱ92:195Ȭ200.ȱ 81.ȱ GurejeȱO,ȱVonȱKorffȱM,ȱSimonȱGE,ȱGaterȱR.ȱPersistentȱpainȱandȱwellȬbeing:ȱ aȱWorldȱHealthȱOrganizationȱStudyȱinȱPrimaryȱCare.ȱJamaȱ1998;ȱ 280:147Ȭ151.ȱ 82.ȱ GuyattȱG,ȱWalterȱS,ȱNormanȱG.ȱMeasuringȱchangeȱoverȱtime:ȱassessingȱtheȱ usefulnessȱofȱevaluativeȱinstruments.ȱJȱChronicȱDisȱ1987;ȱ40:171Ȭ178.ȱ 83.ȱ HaggmanȱS,ȱMaherȱCG,ȱRefshaugeȱKM.ȱScreeningȱforȱsymptomsȱofȱ depressionȱbyȱphysicalȱtherapistsȱmanagingȱlowȱbackȱpain.ȱPhysȱTherȱ 2004;ȱ84:1157Ȭ1166.ȱ 84.ȱ HansenȱA,ȱJensenȱDV,ȱLarsenȱEC,ȱetȱal.ȱPostpartumȱpelvicȱpainȬȬtheȱ ȈpelvicȱjointȱsyndromeȈ:ȱaȱfollowȬupȱstudyȱwithȱspecialȱreferenceȱtoȱ diagnosticȱmethods.ȱActaȱObstetȱGynecolȱScandȱ2005;ȱ84:170Ȭ176.ȱ

ȱ 83 Referencesȱ

85.ȱ HansenȱA,ȱJensenȱDV,ȱWormslevȱM,ȱetȱal.ȱSymptomȬgivingȱpelvicȱgirdleȱ relaxationȱinȱpregnancy.ȱII:ȱSymptomsȱandȱclinicalȱsigns.ȱActaȱObstetȱ GynecolȱScandȱ1999;ȱ78:111Ȭ115.ȱ 86.ȱ HarrisȱB,ȱHuckleȱP,ȱThomasȱR,ȱJohnsȱS,ȱFungȱH.ȱTheȱuseȱofȱratingȱscalesȱtoȱ identifyȱpostȬnatalȱdepression.ȱBrȱJ ȱPsychiatryȱ1989;ȱ154:813Ȭ817.ȱ 87.ȱ HaysȱRD,ȱMoralesȱLS.ȱTheȱRANDȬ36ȱmeasureȱofȱhealthȬrelatedȱqualityȱofȱ life.ȱAnnȱMedȱ2001;ȱ33:350Ȭ357.ȱ 88.ȱ HervaȱA,ȱLaitinenȱJ,ȱMiettunenȱJ,ȱetȱal.ȱObesityȱandȱdepression:ȱresultsȱ fromȱtheȱlongitudinalȱNorthernȱFinlandȱ1966ȱBirthȱCohortȱStudy.ȱIntȱJȱ Obesȱ(Lond)ȱ2006;ȱ30:520Ȭ527.ȱ 89.ȱ HestbaekȱL,ȱLeboeufȬYdeȱC,ȱMannicheȱC.ȱLowȱbackȱpain:ȱwhatȱisȱtheȱlongȬ termȱcourse?ȱAȱreviewȱofȱstudiesȱofȱgeneralȱpatientȱpopulations.ȱEurȱ SpineȱJȱ2003;ȱ12:149Ȭ165.ȱ 90.ȱ HeymanȱJ,ȱLundqvistȱA.ȱTheȱsymphysisȱpubisȱinȱpregnancyȱandȱ parturition.ȱActaȱObstetȱetȱGynecolȱScand ȱ1932;ȱ12:191Ȭ226.ȱ 91.ȱ HodgesȱPW,ȱMoseleyȱGL.ȱPainȱandȱmotorȱcontrolȱofȱtheȱlumbopelvicȱ region:ȱeffectȱandȱpossibleȱmechanisms.ȱJȱElectromyogrȱKinesiolȱ2003;ȱ 13:361Ȭ370.ȱ 92.ȱ HodgesȱPW,ȱRichardsonȱCA.ȱInefficientȱmuscularȱstabilizationȱofȱtheȱ lumbarȱspineȱassociatedȱwithȱlowȱbackȱpain.ȱAȱmotorȱcontrolȱevaluationȱ ofȱtransversusȱabdominis.ȱSpineȱ1996;ȱ21:2640Ȭ2650.ȱ 93.ȱ HodgesȱPW,ȱRichardsonȱCA.ȱAlteredȱtrunkȱmuscleȱrecruitmentȱinȱpeopleȱ withȱlowȱbackȱpainȱwithȱupperȱlimbȱmovementȱatȱdifferentȱspeeds.ȱArchȱ PhysȱMedȱRehabilȱ1999;ȱ80:1005Ȭ1012.ȱ 94.ȱ HuestonȱWJ,ȱKasikȬMillerȱS.ȱChangesȱinȱfunctionalȱhealthȱstatusȱduringȱ normalȱpregnancy.ȱJȱFamȱPractȱ1998;ȱ47:209Ȭ212.ȱ 95.ȱ HultmanȱG,ȱNordinȱM,ȱSarasteȱH,ȱOhlsenȱH.ȱBodyȱcomposition,ȱ endurance,ȱstrength,ȱcrossȬsectionalȱarea,ȱandȱdensityȱofȱMMȱerectorȱ spinaeȱinȱmenȱwithȱandȱwithoutȱlowȱbackȱpain.ȱJȱSpinalȱDisordȱ1993;ȱ 6:114Ȭ123.ȱ 96.ȱ HungerfordȱB,ȱGilleardȱW,ȱHodgesȱP.ȱEvidenceȱofȱalteredȱlumbopelvicȱ muscleȱrecruitmentȱinȱtheȱpresenceȱofȱsacroiliacȱjointȱpain.ȱSpineȱ2003;ȱ 28:1593Ȭ1600.ȱ 97.ȱ HuskissonȱEC.ȱMeasurementȱofȱpain.ȱLancetȱ1974;ȱ2:1127Ȭ1131.ȱ 98.ȱ IASP.ȱClassificationȱofȱchronicȱpain.ȱIn:IASP.ȱSeattle,ȱWA,ȱ1994.ȱ 99.ȱ IndahlȱA,ȱVelundȱL,ȱReikeraasȱO.ȱGoodȱprognosisȱforȱlowȱbackȱpainȱwhenȱ leftȱuntampered.ȱAȱrandomizedȱclinicalȱtrial.ȱSpineȱ1995;ȱ20:473Ȭ477.ȱ

ȱ 84 Referencesȱ ȱ 100.ȱ ItoȱT,ȱShiradoȱO,ȱSuzukiȱH,ȱTakahashiȱM,ȱKanedaȱK,ȱStraxȱTE.ȱLumbarȱ trunkȱmuscleȱenduranceȱtesting:ȱanȱinexpensiveȱalternativeȱtoȱaȱmachineȱ forȱevaluation.ȱArchȱPhysȱMedȱRehabilȱ1996;ȱ77:75Ȭ79.ȱ 101.ȱ JaeschkeȱR,ȱSingerȱJ,ȱGuyattȱGH.ȱMeasurementȱofȱhealthȱstatus.ȱ Ascertainingȱtheȱminimalȱclinicallyȱimportantȱdifference.ȱControlȱClinȱ Trialsȱ1989;ȱ10:407Ȭ415.ȱ 102.ȱ JetteȱAM.ȱUsingȱhealthȬrelatedȱqualityȱofȱlifeȱmeasuresȱinȱphysicalȱ therapyȱoutcomesȱresearch.ȱPhysȱTherȱ1993;ȱ73:528Ȭ537.ȱ 103.ȱ JosefssonȱA,ȱAngelsiooȱL,ȱBergȱG,ȱetȱal.ȱObstetric,ȱsomatic,ȱandȱ demographicȱriskȱfactorsȱforȱpostpartumȱdepressiveȱsymptoms.ȱObstetȱ Gynecolȱ2002;ȱ99:223Ȭ228.ȱ 104.ȱ JosefssonȱA,ȱBergȱG,ȱNordinȱC,ȱSydsjoȱG.ȱPrevalenceȱofȱdepressiveȱ symptomsȱinȱlateȱpregnancyȱandȱpostpartum.ȱActaȱObstetȱGynecolȱ Scandȱ2001;ȱ80:251Ȭ255.ȱ 105.ȱ KankaanpaaȱM,ȱLaaksonenȱD,ȱTaimelaȱS,ȱKokkoȱSM,ȱAiraksinenȱO,ȱ HanninenȱO.ȱAge,ȱsex,ȱandȱbodyȱmassȱindexȱasȱdeterminantsȱofȱbackȱ andȱhipȱextensorȱfatigueȱinȱtheȱisometricȱSorensenȱbackȱenduranceȱtest.ȱ ArchȱPhysȱMedȱRehabilȱ1998;ȱ79:1069Ȭ1075.ȱ 106.ȱ KankaanpaaȱM,ȱTaimelaȱS,ȱLaaksonenȱD,ȱHanninenȱO,ȱAiraksinenȱO.ȱ Backȱandȱhipȱextensorȱfatigabilityȱinȱchronicȱlowȱbackȱpainȱpatientsȱandȱ controls.ȱArchȱPhysȱMedȱRehabilȱ1998;ȱ79:412Ȭ417.ȱ 107.ȱ KellerȱA,ȱHellesnesȱJ,ȱBroxȱJI.ȱReliabilityȱofȱtheȱisokineticȱtrunkȱextensorȱ test,ȱBieringȬSorensenȱtest,ȱandȱAstrandȱbicycleȱtest:ȱassessmentȱofȱ intraclassȱcorrelationȱcoefficientȱandȱcriticalȱdifferenceȱinȱpatientsȱwithȱ chronicȱlowȱbackȱpainȱandȱhealthyȱindividuals.ȱSpineȱ2001;ȱ26:771Ȭ777.ȱ 108.ȱ KendallȱPetersonȱF,ȱMcCrearyȱKendallȱE.ȱMusclesȱTestingȱandȱFunction.ȱ Baltimore:ȱWilliamsȱ&ȱWilkins,ȱ1983.ȱ 109.ȱ KihlstrandȱM,ȱStenmanȱB,ȱNilssonȱS,ȱAxelssonȱO.ȱWaterȬgymnasticsȱ reducedȱtheȱintensityȱofȱback/lowȱbackȱpainȱinȱpregnantȱwomen.ȱActaȱ ObstetȱGynecolȱScandȱ1999;ȱ78:180Ȭ185.ȱ 110.ȱ KilpikoskiȱS,ȱAiraksinenȱO,ȱKankaanpaaȱM,ȱLeminenȱP,ȱVidemanȱT,ȱ AlenȱM.ȱInterexaminerȱreliabilityȱofȱlowȱbackȱpainȱassessmentȱusingȱtheȱ McKenzieȱmethod.ȱSpineȱ2002;ȱ27:E207Ȭ214.ȱ 111.ȱ KoesȱBW,ȱvanȱTulderȱMW,ȱOsteloȱR,ȱKimȱBurtonȱA,ȱWaddellȱG.ȱClinicalȱ guidelinesȱforȱtheȱmanagementȱofȱlowȱbackȱpainȱinȱprimaryȱcare:ȱanȱ internationalȱcomparison.ȱSpineȱ2001;ȱ26:2504Ȭ2513;ȱdiscussionȱ2513Ȭ 2504.ȱ 112.ȱ KogstadȱO.ȱ[Pelvicȱinstability.ȱAȱcontroversialȱdiagnosis].ȱTidsskrȱNorȱ Laegeforenȱ1988;ȱ108:1115Ȭ1119.ȱ

ȱ 85 Referencesȱ

113.ȱ KokmeyerȱDJ,ȱVanȱderȱWurffȱP,ȱAufdemkampeȱG,ȱFickenscherȱTC.ȱTheȱ reliabilityȱofȱmultitestȱregimensȱwithȱsacroiliacȱpainȱprovocationȱtests.ȱJȱ ManipulativeȱPhysiolȱTherȱ2002;ȱ25:42Ȭ48.ȱ 114.ȱ KopecȱJA,ȱSayreȱEC,ȱEsdaileȱJM.ȱPredictorsȱofȱbackȱpainȱinȱaȱgeneralȱ populationȱcohort.ȱSpineȱ2004;ȱ29:70Ȭ77;ȱdiscussionȱ77Ȭ78.ȱ 115.ȱ KristianssonȱP,ȱSvardsuddȱK.ȱDiscriminatoryȱpowerȱofȱtestsȱappliedȱinȱ backȱpainȱduringȱpregnancy.ȱSpineȱ1996;ȱ21:2337Ȭ2343;ȱdiscussionȱ2343Ȭ 2334.ȱ 116.ȱ KristianssonȱP,ȱSvardsuddȱK,ȱvonȱSchoultzȱB.ȱBackȱpainȱduringȱ pregnancy:ȱaȱprospectiveȱstudy.ȱSpineȱ1996;ȱ21:702Ȭ709.ȱ 117.ȱ KristianssonȱP,ȱSvardsuddȱK,ȱvonȱSchoultzȱB.ȱSerumȱrelaxin,ȱ symphysealȱpain,ȱandȱbackȱpainȱduringȱpregnancy.ȱAmȱJȱObstetȱ Gynecolȱ1996;ȱ175:1342Ȭ1347.ȱ 118.ȱ KrummelȱDA.ȱPostpartumȱweightȱcontrol:ȱaȱviciousȱcycle.ȱJȱAmȱDietȱ Assocȱ2007;ȱ107:37Ȭ40.ȱ 119.ȱ KvistȱJ.ȱRehabilitationȱfollowingȱanteriorȱcruciateȱligamentȱinjury:ȱ currentȱrecommendationsȱforȱsportsȱparticipation.ȱSportsȱMedȱ2004;ȱ 34:269Ȭ280.ȱ 120.ȱ LandisȱJR,ȱKochȱGG.ȱTheȱmeasurementȱofȱobserverȱagreementȱforȱ categoricalȱdata.ȱBiometricsȱ1977;ȱ33:159Ȭ174.ȱ 121.ȱ LarsenȱEC,ȱWilkenȬJensenȱC,ȱHansenȱA,ȱetȱal.ȱSymptomȬgivingȱpelvicȱ girdleȱrelaxationȱinȱpregnancy.ȱI:ȱPrevalenceȱandȱriskȱfactors.ȱActaȱ ObstetȱGynecolȱScandȱ1999;ȱ78:105Ȭ110.ȱ 122.ȱ LaslettȱM,ȱAprillȱCN,ȱMcDonaldȱB,ȱYoungȱSB.ȱDiagnosisȱofȱsacroiliacȱ jointȱpain:ȱvalidityȱofȱindividualȱprovocationȱtestsȱandȱcompositesȱofȱ tests.ȱManȱTherȱ2005;ȱ10:207Ȭ218.ȱ 123.ȱ LaslettȱM,ȱWilliamsȱM.ȱTheȱreliabilityȱofȱselectedȱpainȱprovocationȱtestsȱ forȱsacroiliacȱjointȱpathology.ȱSpineȱ1994;ȱ19:1243Ȭ1249.ȱ 124.ȱ LaslettȱM,ȱYoungȱSB,ȱAprillȱCN,ȱMcDonaldȱ B.ȱDiagnosingȱpainfulȱ sacroiliacȱjoints:ȱAȱvalidityȱstudyȱofȱaȱMcKenzieȱevaluationȱandȱ sacroiliacȱprovocationȱtests.ȱAustȱJȱPhysiotherȱ2003;ȱ49:89Ȭ97.ȱ 125.ȱ LatimerȱJ,ȱMaherȱCG,ȱRefshaugeȱK,ȱColacoȱI.ȱTheȱreliabilityȱandȱvalidityȱ ofȱtheȱBieringȬSorensenȱtestȱinȱasymptomaticȱsubjectsȱandȱsubjectsȱ reportingȱcurrentȱorȱpreviousȱnonspecificȱlowȱbackȱpain.ȱSpineȱ1999;ȱ 24:2085Ȭ2089;ȱdiscussionȱ2090.ȱ 126.ȱ LeboeufȬYdeȱC,ȱKlougartȱN,ȱLauritzenȱT.ȱHowȱcommonȱisȱlowȱbackȱpainȱ inȱtheȱNordicȱpopulation?ȱDataȱfromȱaȱrecentȱstudyȱonȱaȱmiddleȬagedȱ generalȱDanishȱpopulationȱandȱfourȱsurveysȱpreviouslyȱconductedȱinȱ theȱNordicȱcountries.ȱSpineȱ1996;ȱ21:1518Ȭ1525;ȱdiscussionȱ1525Ȭ1516.ȱ

ȱ 86 Referencesȱ ȱ 127.ȱ LewekȱM,ȱRudolphȱK,ȱAxeȱM,ȱSnyderȬMacklerȱL.ȱTheȱeffectȱofȱ insufficientȱquadricepsȱstrengthȱonȱgaitȱafterȱanteriorȱcruciateȱligamentȱ reconstruction.ȱClinȱBiomechȱ(Bristol,ȱAvon)ȱ2002;ȱ17:56Ȭ63.ȱ 128.ȱ LindalȱE,ȱHaukssonȱA,ȱArnardottirȱS,ȱHallgrimssonȱJP.ȱLowȱbackȱpain,ȱ smokingȱandȱemploymentȱduringȱpregnancyȱandȱafterȱdeliveryȱȬȱaȱ3Ȭ monthȱfollowȬupȱstudy.ȱJȱObstetȱGynaecolȱ2000;ȱ20:263Ȭ266.ȱ 129.ȱ LintonȱSJ.ȱAȱreviewȱofȱpsychologicalȱriskȱfactorsȱinȱbackȱandȱneckȱpain.ȱ Spineȱ2000;ȱ25:1148Ȭ1156.ȱ 130.ȱ LintonȱSJ.ȱOccupationalȱpsychologicalȱfactorsȱincreaseȱtheȱriskȱforȱbackȱ pain:ȱaȱsystematicȱreview.ȱJȱOccupȱRehabilȱ2001;ȱ11:53Ȭ66.ȱ 131.ȱ LjungquistȱT,ȱFranssonȱB,ȱHarmsȬRingdahlȱK,ȱBjornhamȱA,ȱNygrenȱA.ȱAȱ physiotherapyȱtestȱpackageȱforȱassessingȱbackȱandȱneckȱdysfunctionȬȬ discriminativeȱabilityȱforȱpatientsȱversusȱhealthyȱcontrolȱsubjects.ȱ PhysiotherȱResȱIntȱ1999;ȱ4:123Ȭ140.ȱ 132.ȱ LjungquistȱT,ȱHarmsȬRingdahlȱK,ȱNygrenȱA,ȱJensenȱI.ȱIntraȬȱandȱinterȬ raterȱreliabilityȱofȱanȱ11Ȭtestȱpackageȱforȱassessingȱdysfunctionȱdueȱtoȱ backȱorȱneckȱpain.ȱPhysiotherȱResȱIntȱ1999;ȱ4:214Ȭ232.ȱ 133.ȱ LongȱA,ȱDonelsonȱR,ȱFungȱT.ȱDoesȱitȱmatterȱwhichȱexercise?ȱAȱ randomizedȱcontrolȱtrialȱofȱexerciseȱforȱlowȱbackȱpain.ȱSpineȱ2004;ȱ 29:2593Ȭ2602.ȱ 134.ȱ MacEvillyȱM,ȱBuggyȱD.ȱBackȱpainȱandȱpregnancy:ȱaȱreview.ȱPainȱ1996;ȱ 64:405Ȭ414.ȱ 135.ȱ MacLennanȱAH.ȱTheȱroleȱofȱtheȱhormoneȱrelaxinȱinȱhumanȱ reproductionȱandȱpelvicȱgirdleȱrelaxation.ȱScandȱJȱRheumatolȱSupplȱ 1991;ȱ88:7Ȭ15.ȱ 136.ȱ MacLennanȱAH,ȱMacLennanȱSC.ȱSymptomȬgivingȱpelvicȱgirdleȱ relaxationȱofȱpregnancy,ȱpostnatalȱpelvicȱjointȱsyndromeȱandȱ developmentalȱdysplasiaȱofȱtheȱhip.ȱTheȱNorwegianȱAssociationȱforȱ WomenȱwithȱPelvicȱGirdleȱRelaxationȱ(LandforeningenȱforȱKvinnerȱMedȱ Bekkenlosningsplager).ȱActaȱObstetȱGynecolȱScandȱ1997;ȱ76:760Ȭ764.ȱ 137.ȱ MacLennanȱAH,ȱNicolsonȱR,ȱGreenȱRC,ȱBathȱM.ȱSerumȱrelaxinȱandȱ pelvicȱpainȱofȱpregnancy.ȱLancetȱ1986;ȱ2:243Ȭ245.ȱ 138.ȱ MantleȱMJ, ȱGreenwoodȱRM,ȱCurreyȱHL.ȱBackacheȱinȱpregnancy.ȱ RheumatolȱRehabilȱ1977;ȱ16:95Ȭ101.ȱ 139.ȱ MargolisȱRB,ȱChibnallȱJT,ȱTaitȱRC,ȱKrauseȱSJ.ȱTestȬretestȱreliabilityȱofȱtheȱ painȱdrawingȱinstrument.Aȱratingȱsystemȱforȱuseȱwithȱpatientȱpainȱ drawings.ȱPainȱ1988;ȱ33:49Ȭ51.ȱ

ȱ 87 Referencesȱ

140.ȱ MattheyȱS.ȱCalculatingȱclinicallyȱsignificantȱchangeȱinȱpostnatalȱ depressionȱstudiesȱusingȱtheȱEdinburghȱPostnatalȱDepressionȱScale.ȱJȱ AffectȱDisordȱ2004;ȱ78:269Ȭ272.ȱ 141.ȱ MayȱS,ȱLittlewoodȱC,ȱBishopȱA.ȱReliabilityȱofȱproceduresȱusedȱinȱtheȱ physicalȱexaminationȱofȱnonȬspecificȱlowȱbackȱpain:ȱaȱsystematicȱreview.ȱ AustȱJȱPhysiotherȱ2006;ȱ 52:91Ȭ102.ȱ 142.ȱ McKenzieȱR,ȱMayȱS.ȱTheȱLumbarȱSpine.ȱMechanicalȱDiagnosisȱ&ȱ Therapy.ȱWaikanae:ȱSpinalȱPublicationsȱNewȱZealandȱLtd,ȱ2003.ȱ 143.ȱ McQuadeȱKJ,ȱTurnerȱJA,ȱBuchnerȱDM.ȱPhysicalȱfitnessȱandȱchronicȱlowȱ backȱpain.ȱAnȱanalysisȱofȱtheȱrelationshipsȱamongȱfitness,ȱfunctionalȱ limitations,ȱandȱdepression.ȱClinȱOrthopȱRelatȱResȱ1988:198Ȭ204.ȱ 144.ȱ McWilliamsȱLA,ȱGoodwinȱRD,ȱCoxȱBJ.ȱDepressionȱandȱanxietyȱ associatedȱwithȱthreeȱpainȱconditions:ȱresultsȱfromȱaȱnationallyȱ representativeȱsample.ȱPainȱ2004;ȱ111:77Ȭ83.ȱ 145.ȱ MeadeȱTW,ȱDyerȱS,ȱBrowneȱW,ȱFrankȱAO.ȱRandomisedȱcomparisonȱofȱ chiropracticȱandȱhospitalȱoutpatientȱmanagementȱforȱlowȱbackȱpain:ȱ resultsȱfromȱextendedȱfollowȱup.ȱBmjȱ1995;ȱ311:349Ȭ351.ȱ 146.ȱ MeadeȱTW,ȱDyerȱS,ȱBrowneȱW,ȱTownsendȱJ,ȱFrankȱAO.ȱLowȱbackȱpainȱ ofȱmechanicalȱorigin:ȱrandomisedȱcomparisonȱofȱchiropracticȱandȱ hospitalȱoutpatientȱtreatment.ȱBmjȱ1990;ȱ300:1431Ȭ1437.ȱ 147.ȱ MelzackȱR.ȱFromȱtheȱgateȱtoȱtheȱneuromatrix.ȱPainȱ1999;ȱSupplȱ6:S121Ȭ 126.ȱ 148.ȱ MelzackȱR,ȱWallȱPD.ȱPainȱmechanisms:ȱaȱnewȱtheory.ȱScienceȱ1965;ȱ 150:971Ȭ979.ȱ 149.ȱ MensȱJM,ȱVleemingȱA,ȱSnijdersȱCJ,ȱStamȱHJ,ȱGinaiȱAZ.ȱTheȱactiveȱ straightȱlegȱraisingȱtestȱandȱmobilityȱofȱtheȱpelvicȱjoints.ȱEurȱSpineȱJȱ 1999;ȱ8:468Ȭ474.ȱ 150.ȱ MensȱJM,ȱVleemingȱA,ȱStoeckartȱR,ȱStamȱHJ,ȱSnijdersȱCJ.ȱUnderstandingȱ peripartumȱpelvicȱpain.ȱImplicationsȱofȱaȱpatientȱsurvey.ȱSpineȱ1996;ȱ 21:1363Ȭ1369;ȱdiscussionȱ1369Ȭ1370.ȱ 151.ȱ MerskeyȱH,ȱBogdukȱN.ȱClassificationȱofȱchronicȱpain:descriptionsȱofȱ chronicȱpainȱsyndromesȱandȱdefinitionsȱofȱpainȱterms.ȱSeattle:ȱIASPȱ Press,ȱ1994.ȱ 152.ȱ MogrenȱI.ȱPerceivedȱhealth,ȱsickȱleave,ȱpsychosocialȱsituation,ȱandȱ sexualȱlifeȱinȱwomenȱwithȱlowȬbackȱpainȱandȱpelvicȱpainȱduringȱ pregnancy.ȱActaȱObstetȱGynecolȱScandȱ2006;ȱ85:647Ȭ656.ȱ 153.ȱ MogrenȱIM.ȱPreviousȱphysicalȱactivityȱdecreasesȱtheȱriskȱofȱlowȱbackȱ painȱandȱpelvicȱpainȱduringȱpregnancy.ȱScandȱJȱPublicȱHealthȱ2005;ȱ 33:300Ȭ306.ȱ

ȱ 88 Referencesȱ ȱ 154.ȱ MogrenȱIM.ȱBMI,ȱpainȱandȱhyperȬmobilityȱareȱdeterminantsȱofȱlongȬ termȱoutcomeȱforȱwomenȱwithȱlowȱbackȱpainȱandȱpelvicȱpainȱduringȱ pregnancy.ȱEurȱSpineȱJȱ2006:1Ȭ10.ȱ 155.ȱ MoldofskyȱH.ȱSleepȱandȱpain.ȱSleepȱMedȱRevȱ2001;ȱ5:385Ȭ396.ȱ 156.ȱ MorelandȱJ,ȱFinchȱE,ȱStratfordȱP,ȱBalsorȱB,ȱGillȱC.ȱInterraterȱreliabilityȱofȱ sixȱtestsȱofȱtrunkȱmuscleȱfunctionȱandȱendurance.ȱJȱOrthopȱSportsȱPhysȱ Therȱ1997;ȱ26:200Ȭ208.ȱ 157.ȱ MousaviȱSJ,ȱParnianpourȱM,ȱVleemingȱA.ȱPregnancyȱrelatedȱpelvicȱ girdleȱpainȱandȱlowȱbackȱpainȱinȱanȱIranianȱpopulation.ȱSpineȱ2007;ȱ 32:E100Ȭ104.ȱ 158.ȱ MunkȬJorgensenȱP,ȱAllgulanderȱC,ȱDahlȱAA,ȱetȱal.ȱPrevalenceȱofȱ generalizedȱanxietyȱdisorderȱinȱgeneralȱpracticeȱinȱDenmark,ȱFinland,ȱ Norway,ȱandȱSweden.ȱPsychiatrȱServȱ2006;ȱ57:1738Ȭ1744.ȱ 159.ȱ MurrayȱL,ȱCooperȱP,ȱHipwellȱA.ȱMentalȱhealthȱofȱparentsȱcaringȱforȱ infants.ȱArchȱWomenȱMentȱHealthȱ2003;ȱ6ȱSupplȱ2:S71Ȭ77.ȱ 160.ȱ MyersȱC,ȱWilksȱD.ȱComparisonȱofȱEuroqolȱEQȬ5DȱandȱSFȬ36ȱinȱpatientsȱ withȱchronicȱfatigueȱsyndrome.ȱQualȱLifeȱResȱ1999;ȱ8:9Ȭ16.ȱ 161.ȱ NagyȱLE,ȱKingȱJC.ȱEnergyȱexpenditureȱofȱpregnantȱwomenȱatȱrestȱorȱ walkingȱselfȬpaced.ȱAmȱJȱClinȱNutrȱ1983;ȱ38:369Ȭ376.ȱ 162.ȱ NatvigȱB,ȱBruusgaardȱD,ȱEriksenȱW.ȱLocalizedȱlowȱbackȱpainȱandȱlowȱ backȱpainȱasȱpartȱofȱwidespreadȱmusculoskeletalȱpain:ȱtwoȱdifferentȱ disorders?ȱAȱcrossȬsectionalȱpopulationȱstudy.ȱJȱRehabilȱMedȱ2001;ȱ 33:21Ȭ25.ȱ 163.ȱ NielsenȱFormanȱD,ȱVidebechȱP,ȱHedegaardȱM,ȱDalbyȱSalvigȱJ,ȱSecherȱNJ.ȱ Postpartumȱdepression:ȱidentificationȱofȱwomenȱatȱrisk.ȱBjogȱ2000;ȱ 107:1210Ȭ1217.ȱ 164.ȱ NilssonȬWikmarȱL,ȱHarmsȬRingdahlȱK,ȱPiloȱC,ȱPahlbackȱM.ȱBackȱpainȱinȱ womenȱpostȬpartumȱisȱnotȱaȱunitaryȱconcept.ȱPhysiotherȱResȱIntȱ1999;ȱ 4:201Ȭ213.ȱ 165.ȱ NilssonȬWikmarȱL,ȱHolmȱK,ȱOijerstedtȱR,ȱHarmsȬRingdahlȱK.ȱEffectȱofȱ threeȱdifferentȱphysicalȱtherapyȱtreatmentsȱonȱpainȱandȱactivityȱinȱ pregnantȱwomenȱwithȱpelvicȱgirdleȱpain:ȱaȱrandomizedȱclinicalȱtrialȱ withȱ3,ȱ6,ȱandȱ12ȱmonthsȱfollowȬupȱpostpartum.ȱSpineȱ2005;ȱ30:850Ȭ856.ȱ 166.ȱ NilssonȬWikmarȱL,ȱPiloȱC,ȱPahlbackȱM,ȱHarmsȬRingdahlȱK.ȱPerceivedȱ painȱandȱselfȬestimatedȱactivityȱlimitationsȱinȱwomenȱwithȱbackȱpainȱ postȬpartum.ȱPhysiotherȱResȱIntȱ2003;ȱ8:23Ȭ35.ȱ 167.ȱ NordinȱM,ȱKahanovitzȱN,ȱVerderameȱR,ȱetȱal.ȱNormalȱtrunkȱmuscleȱ strengthȱandȱenduranceȱinȱwomenȱandȱtheȱeffectȱofȱexercisesȱandȱ

ȱ 89 Referencesȱ

electricalȱstimulation.ȱPartȱ1:ȱNormalȱenduranceȱandȱtrunkȱmuscleȱ strengthȱinȱ101ȱwomen.ȱSpineȱ1987;ȱ12:105Ȭ111.ȱ 168.ȱ NorenȱL,ȱOstgaardȱS,ȱJohanssonȱG,ȱOstgaardȱHC.ȱLumbarȱbackȱandȱ posteriorȱpelvicȱpainȱduringȱpregnancy:ȱaȱ3ȬyearȱfollowȬup.ȱEurȱSpineȱJȱ 2002;ȱ11:267Ȭ271.ȱ 169.ȱ NwugaȱV.ȱPregnancyȱandȱbackȱpainȱamongȱupperȱclassȱNigerianȱ women.ȱAustȱJȱPhysiotherȱ1982;ȱ28:8Ȭ11.ȱ 170.ȱ OȇHaraȱMW,ȱZekoskiȱEM,ȱPhilippsȱLH,ȱWrightȱEJ.ȱControlledȱ prospectiveȱstudyȱofȱpostpartumȱmoodȱdisorders:ȱcomparisonȱofȱ childbearingȱandȱnonchildbearingȱwomen.ȱJȱAbnormȱPsycholȱ1990;ȱ99:3Ȭ 15.ȱ 171.ȱ OhlundȱC,ȱEekȱC,ȱPalmbaldȱS,ȱAreskougȱB,ȱNachemsonȱA.ȱQuantifiedȱ painȱdrawingȱinȱsubacuteȱlowȱbackȱpain.ȱValidationȱinȱaȱnonselectedȱ outpatientȱindustrialȱsample.ȱSpineȱ1996;ȱ21:1021Ȭ1030;ȱdiscussionȱ1031.ȱ 172.ȱ OhnmeissȱDD,ȱVanharantaȱH,ȱEstlanderȱAM,ȱJamsenȱA.ȱTheȱ relationshipȱofȱdisabilityȱ(Oswestry)ȱandȱpainȱdrawingsȱtoȱfunctionalȱ testing.ȱEurȱSpineȱJȱ2000;ȱ9:208Ȭ212.ȱ 173.ȱ OlssonȱC,ȱNilssonȬWikmarȱL.ȱHealthȬrelatedȱqualityȱofȱlifeȱandȱphysicalȱ abilityȱamongȱpregnantȱwomenȱwithȱandȱwithoutȱbackȱpainȱinȱlateȱ pregnancy.ȱActaȱObstetȱGynecolȱScandȱ2004;ȱ83:351Ȭ357.ȱ 174.ȱ OrvietoȱR,ȱAchironȱA,ȱBenȬRafaelȱZ,ȱGelernterȱI,ȱAchironȱR.ȱLowȬbackȱ painȱofȱpregnancy.ȱActaȱObstetȱGynecolȱScandȱ1994;ȱ73:209Ȭ214.ȱ 175.ȱ OstgaardȱHC,ȱAnderssonȱGB.ȱPreviousȱbackȱpainȱandȱriskȱofȱdevelopingȱ backȱpainȱinȱaȱfutureȱpregnancy.ȱSpineȱ1991;ȱ16:432Ȭ436.ȱ 176.ȱ OstgaardȱHC,ȱAnderssonȱGB.ȱPostpartumȱlowȬbackȱpain.ȱSpineȱ1992;ȱ 17:53Ȭ55.ȱ 177.ȱ OstgaardȱHC,ȱAnderssonȱGB,ȱKarlssonȱK.ȱPrevalenceȱofȱbackȱpainȱinȱ pregnancy.ȱSpineȱ1991;ȱ16:549Ȭ552.ȱ 178.ȱ OstgaardȱHC,ȱAnderssonȱGB,ȱSchultzȱAB,ȱMillerȱJA.ȱInfluenceȱofȱsomeȱ biomechanicalȱfactorsȱonȱlowȬbackȱpainȱinȱpregnancy.ȱSpineȱ1993;ȱ18:61Ȭ 65.ȱ 179.ȱ OstgaardȱHC,ȱAnderssonȱGB,ȱWennergrenȱM.ȱTheȱimpactȱofȱlowȱbackȱ andȱpelvicȱpainȱinȱpregnancyȱonȱtheȱpregnancyȱoutcome.ȱActaȱObstetȱ GynecolȱScandȱ1991;ȱ70:21Ȭ24.ȱ 180.ȱ OstgaardȱHC,ȱRoosȬHanssonȱE,ȱZetherstromȱG.ȱRegressionȱofȱbackȱandȱ posteriorȱpelvicȱpainȱafterȱpregnancy.ȱSpineȱ1996;ȱ21:2777Ȭ2780.ȱ 181.ȱ OstgaardȱHC,ȱZetherstromȱG,ȱRoosȬHanssonȱE.ȱTheȱposteriorȱpelvicȱ painȱprovocationȱtestȱinȱpregnantȱwomen.ȱEurȱSpineȱJȱ1994;ȱ3:258Ȭ260.ȱ

ȱ 90 Referencesȱ ȱ 182.ȱ OstgaardȱHC,ȱZetherstromȱG,ȱRoosȬHanssonȱE.ȱBackȱpainȱinȱrelationȱtoȱ pregnancy:ȱaȱ6ȬyearȱfollowȬup.ȱSpineȱ1997;ȱ22:2945Ȭ2950.ȱ 183.ȱ OstgaardȱHC,ȱZetherstromȱG,ȱRoosȬHanssonȱE,ȱSvanbergȱB.ȱReductionȱ ofȱbackȱandȱposteriorȱpelvicȱpainȱinȱpregnancy.ȱSpineȱ1994;ȱ19:894Ȭ900.ȱ 184.ȱ OȇSullivanȱPB, ȱBealesȱDJ,ȱBeethamȱJA,ȱetȱal.ȱAlteredȱmotorȱcontrolȱ strategiesȱinȱsubjectsȱwithȱsacroiliacȱjointȱpainȱduringȱtheȱactiveȱstraightȬ legȬraiseȱtest.ȱSpineȱ2002;ȱ27:E1Ȭ8.ȱ 185.ȱ PaduaȱL,ȱCaliandroȱP,ȱAprileȱI,ȱetȱal.ȱBackȱpainȱinȱpregnancy:ȱ1Ȭyearȱ followȬupȱofȱuntreatedȱcases.ȱEurȱSpineȱJȱ2005;ȱ14:151Ȭ154.ȱ 186.ȱ PaduaȱL,ȱPaduaȱR,ȱBondiȱR,ȱetȱal.ȱPatientȬorientedȱassessmentȱofȱbackȱ painȱinȱpregnancy.ȱEurȱSpineȱJȱ2002;ȱ11:272Ȭ275.ȱ 187.ȱ PalombaroȱKM,ȱCraikȱRL,ȱMangioneȱKK,ȱTomlinsonȱJD.ȱDeterminingȱ meaningfulȱchangesȱinȱgaitȱspeedȱafterȱhipȱfracture.ȱPhysȱTherȱ2006;ȱ 86:809Ȭ816.ȱ 188.ȱ PanjabiȱMM.ȱTheȱstabilizingȱsystemȱofȱtheȱspine.ȱPartȱI.ȱFunction,ȱ dysfunction,ȱadaptation,ȱandȱenhancement.ȱJȱSpinalȱDisordȱ1992;ȱ5:383Ȭ 389;ȱdiscussionȱ397.ȱ 189.ȱ PerkinsȱJ,ȱHammerȱRL,ȱLoubertȱPV.ȱIdentificationȱandȱmanagementȱofȱ pregnancyȬrelatedȱlowȱbackȱpain.ȱJȱNurseȱMidwiferyȱ1998;ȱ43:331Ȭ340.ȱ 190.ȱ PetersenȱLK,ȱHvidmanȱL,ȱUldbjergȱ N.ȱNormalȱserumȱrelaxinȱinȱwomenȱ withȱdisablingȱpelvicȱpainȱduringȱpregnancy.ȱGynecolȱObstetȱInvestȱ 1994;ȱ38:21Ȭ23.ȱ 191.ȱ PetersenȱT,ȱOlsenȱS,ȱLaslettȱM,ȱetȱal.ȱInterȬtesterȱreliabilityȱofȱaȱnewȱ diagnosticȱclassificationȱsystemȱforȱpatientsȱwithȱnonȬspecificȱlowȱbackȱ pain.ȱAustȱJȱPhysiotherȱ2004;ȱ50:85Ȭ94.ȱ 192.ȱ PetersenȱT,ȱThorsenȱH,ȱMannicheȱC,ȱEkdahlȱC.ȱClassificationȱofȱnonȬ specificȱlowȱbackȱpain:ȱaȱreviewȱofȱtheȱliteratureȱonȱclassificationsȱ systemsȱrelevantȱtoȱphysiotherapy.ȱPhysȱTherȱRevȱ1999;ȱ4:265Ȭ281.ȱ 193.ȱ PetrieȱA,ȱSabinȱC.ȱMedicalȱStatisticsȱatȱaȱGlance.ȱMassachusetts,ȱUS:ȱ BlackwellȱScienceȱLtd,ȱ2003.ȱ 194.ȱ PicavetȱHS,ȱHoeymansȱN.ȱHealthȱrelatedȱqualityȱofȱlifeȱinȱmultipleȱ musculoskeletalȱdiseases:ȱSFȬ36ȱandȱEQȬ5DȱinȱtheȱDMC3ȱstudy.ȱAnnȱ RheumȱDisȱ2004;ȱ63:723Ȭ729.ȱ 195.ȱ PicavetȱHS,ȱSchoutenȱJS.ȱMusculoskeletalȱpainȱinȱtheȱNetherlands:ȱ prevalences,ȱconsequencesȱandȱriskȱgroups,ȱtheȱDMC(3)Ȭstudy.ȱPainȱ 2003;ȱ102:167Ȭ178.ȱ 196.ȱ PignoneȱMP,ȱGaynesȱBN,ȱRushtonȱJL,ȱetȱal.ȱScreeningȱforȱdepressionȱinȱ adults:ȱaȱsummaryȱofȱtheȱevidenceȱforȱtheȱU.S.ȱPreventiveȱServicesȱTaskȱ Force.ȱAnnȱInternȱMedȱ2002;ȱ136:765Ȭ776.ȱ

ȱ 91 Referencesȱ

197.ȱ PoolȬGoudzwaardȱAL,ȱSliekerȱTenȱHoveȱMC,ȱVierhoutȱME,ȱetȱal.ȱ RelationsȱbetweenȱpregnancyȬrelatedȱlowȱbackȱpain,ȱpelvicȱfloorȱactivityȱ andȱpelvicȱfloorȱdysfunction.ȱIntȱUrogynecolȱJȱPelvicȱFloorȱDysfunctȱ 2005.ȱ 198.ȱ PoolȬGoudzwaardȱAL,ȱVleemingȱA,ȱStoeckartȱR,ȱSnijdersȱCJ,ȱMensȱJM.ȱ Insufficientȱlumbopelvicȱstability:ȱaȱclinical,ȱanatomicalȱandȱ biomechanicalȱapproachȱtoȱȇaȬspecificȇȱlowȱbackȱpain.ȱManȱTherȱ1998;ȱ 3:12Ȭ20.ȱ 199.ȱ RabinȱR,ȱdeȱCharroȱF.ȱEQȬ5D:ȱaȱmeasureȱofȱhealthȱstatusȱfromȱtheȱ EuroQolȱGroup.ȱAnnȱMedȱ2001;ȱ33:337Ȭ343.ȱ 200.ȱ RansfordȱA,ȱCairnsȱD,ȱMooneyȱV.ȱTheȱpainȱdrawingȱasȱanȱaidȱtoȱtheȱ psychologicalȱevaluationȱofȱpatientsȱwithȱlowȬbackȱpain.ȱSpineȱ1976:127Ȭ 134.ȱ 201.ȱ RazmjouȱH,ȱKramerȱJF,ȱYamadaȱR.ȱIntertesterȱreliabilityȱofȱtheȱ McKenzieȱevaluationȱinȱassessingȱpatientsȱwithȱmechanicalȱlowȬbackȱ pain.ȱJȱOrthopȱSportsȱPhysȱTherȱ2000;ȱ30:368Ȭ383;ȱdiscussionȱ384Ȭ369.ȱ 202.ȱ RenemanȱMF,ȱJorritsmaȱW,ȱSchellekensȱJM,ȱGoekenȱLN.ȱConcurrentȱ validityȱofȱquestionnaireȱandȱperformanceȬbasedȱdisabilityȱ measurementsȱinȱpatientsȱwithȱchronicȱnonspecificȱlowȱbackȱpain.ȱJȱ OccupȱRehabilȱ2002;ȱ12:119Ȭ129.ȱ 203.ȱ RichardsonȱCA.ȱTherapeuticȱexerciseȱforȱspinalȱsegmentalȱstabilizationȱ inȱlowȱbackȱpain.ȱLondon:ȱChurchillȱLivingstone,ȱ1999.ȱ 204.ȱ RichardsonȱCA,ȱSnijdersȱCJ,ȱHidesȱJA,ȱDamenȱsL,ȱPa ȱMS,ȱStormȱJ.ȱTheȱ relationȱbetweenȱtheȱtransversusȱabdominisȱmuscles,ȱsacroiliacȱjointȱ mechanics,ȱandȱlowȱbackȱpain.ȱSpineȱ2002;ȱ27:399Ȭ405.ȱ 205.ȱ RiddleȱDL.ȱClassificationȱandȱlowȱbackȱpain:ȱaȱreviewȱofȱtheȱliteratureȱ andȱcriticalȱanalysisȱofȱselectedȱsystems.ȱPhysȱTherȱ1998;ȱ78:708Ȭ737.ȱ 206.ȱ RiddleȱDL,ȱRothsteinȱJM.ȱIntertesterȱreliabilityȱofȱMcKenzieȇsȱ classificationsȱofȱtheȱsyndromeȱtypesȱpresentȱinȱpatientsȱwithȱlowȱbackȱ pain.ȱSpineȱ1993;ȱ18:1333Ȭ1344.ȱ 207.ȱ RolandȱM,ȱMorrisȱR.ȱAȱstudyȱofȱtheȱnaturalȱhistoryȱofȱbackȱpain.ȱPartȱI:ȱ developmentȱofȱaȱreliableȱandȱsensitiveȱmeasureȱofȱdisabilityȱinȱlowȬ backȱpain.ȱSpineȱ1983;ȱ8:141Ȭ144.ȱ 208.ȱ RorsmanȱB,ȱGrasbeckȱA,ȱHagnellȱO,ȱetȱal.ȱAȱprospectiveȱstudyȱofȱfirstȬ incidenceȱdepression.ȱTheȱLundbyȱstudy,ȱ1957Ȭ72.ȱBrȱJȱPsychiatryȱ1990;ȱ 156:336Ȭ342.ȱ 209.ȱ RossȱLE,ȱMurrayȱBJ,ȱSteinerȱM.ȱSleepȱandȱperinatalȱmoodȱdisorders:ȱaȱ criticalȱreview.ȱJȱPsychiatryȱNeurosciȱ2005;ȱ30:247Ȭ256.ȱ

ȱ 92 Referencesȱ ȱ 210.ȱ RostȱCC,ȱJacquelineȱJ,ȱKaiserȱA,ȱVerhagenȱAP,ȱKoesȱBW.ȱPelvicȱpainȱ duringȱpregnancy:ȱaȱdescriptiveȱstudyȱofȱsignsȱandȱsymptomsȱofȱ870ȱ patientsȱinȱprimaryȱcare.ȱSpineȱ2004;ȱ29:2567Ȭ2572.ȱ 211.ȱ RostȱCC,ȱJacquelineȱJ,ȱKaiserȱA,ȱVerhagenȱAP,ȱKoesȱBW.ȱPrognosisȱofȱ womenȱwithȱpelvicȱpainȱduringȱpregnancy:ȱaȱlongȬtermȱfollowȬupȱ study.ȱActaȱObstetȱGynecolȱScandȱ2006;ȱ85:771Ȭ777.ȱ 212.ȱ SapsfordȱRR,ȱHodgesȱPW,ȱRichardsonȱCA,ȱCooperȱDH,ȱMarkwellȱSJ,ȱ JullȱGA.ȱCoȬactivationȱofȱtheȱabdominalȱandȱpelvicȱfloorȱmusclesȱduringȱ voluntaryȱexercises.ȱNeurourolȱUrodynȱ2001;ȱ20:31Ȭ42.ȱ 213.ȱ SaundersȱSW,ȱSchacheȱA,ȱRathȱD,ȱHodgesȱPW.ȱChangesȱinȱthreeȱ dimensionalȱlumboȬpelvicȱkinematicsȱandȱtrunkȱmuscleȱactivityȱwithȱ speedȱandȱmodeȱofȱlocomotion.ȱClinȱBiomechȱ(Bristol,ȱAvon)ȱ2005;ȱ 20:784Ȭ793.ȱ 214.ȱ SBU.ȱReportsȱfromȱtheȱSwedishȱCouncilȱonȱTechnologyȱAssessmentȱinȱ HealthȱCareȱ(SBU).ȱUrinaryȱincontinence.ȱIntȱJȱTechnolȱAssessȱHealthȱ Careȱ2000;ȱ16:722Ȭ726.ȱ 215.ȱ SchwarzerȱAC,ȱAprillȱCN,ȱDerbyȱR,ȱFortinȱJ,ȱKineȱG,ȱBogdukȱN.ȱTheȱ prevalenceȱandȱclinicalȱfeaturesȱofȱinternalȱdiscȱdisruptionȱinȱpatientsȱ withȱchronicȱlowȱbackȱpain.ȱSpineȱ1995;ȱ20:1878Ȭ1883.ȱ 216.ȱ ShikiarȱR,ȱWillianȱMK,ȱOkunȱMM,ȱThompsonȱCS,ȱRevickiȱDA.ȱTheȱ validityȱandȱresponsivenessȱofȱthreeȱqualityȱofȱlifeȱmeasuresȱinȱtheȱ assessmentȱofȱpsoriasisȱpatients:ȱresultsȱofȱaȱphaseȱIIȱstudy.ȱHealthȱQualȱ LifeȱOutcomesȱ2006;ȱ4:71.ȱ 217.ȱ SihvonenȱT,ȱHuttunenȱM,ȱMakkonenȱM,ȱAiraksinenȱO.ȱFunctionalȱ changesȱinȱbackȱmuscleȱactivityȱcorrelateȱwithȱpainȱintensityȱandȱ predictionȱofȱlowȱbackȱpainȱduringȱpregnancy.ȱArchȱPhysȱMedȱRehabilȱ 1998;ȱ79:1210Ȭ1212.ȱ 218.ȱ SikorskiȱJM.ȱAȱrationalizedȱapproachȱtoȱphysiotherapyȱforȱlowȬbackȱ pain.ȱSpineȱ1985;ȱ10:571Ȭ579.ȱ 219.ȱ SkargrenȱEI,ȱCarlssonȱPG,ȱObergȱBE.ȱOneȬyearȱfollowȬupȱcomparisonȱofȱ theȱcostȱandȱeffectivenessȱofȱchiropracticȱandȱphysiotherapyȱasȱprimaryȱ managementȱforȱbackȱpain.ȱSubgroup ȱanalysis,ȱrecurrence,ȱandȱ additionalȱhealthȱcareȱutilization.ȱSpineȱ1998;ȱ23:1875Ȭ1883;ȱdiscussionȱ 1884.ȱ 220.ȱ SnijdersȱC,ȱVleemingȱA,ȱStoeckartȱR.ȱTransferȱofȱlumbosacralȱloadȱtoȱ iliacȱbonesȱandȱlegs.Partȱ1:ȱBiomechanicsȱofȱselfȬbracingȱofȱtheȱsacroiliacȱ jointsȱandȱitsȱsignificanceȱforȱtreatmentȱandȱexercise.ȱClin.ȱBiomechȱ1993;ȱ 8:285Ȭ294.ȱ

ȱ 93 Referencesȱ

221.ȱ SnijdersȱC,ȱVleemingȱA,ȱStoeckartȱR,ȱMensȱJM,ȱKleinrensinkȱGJ.ȱ Biomechanicsȱofȱtheȱinterfaceȱbetweenȱspineȱandȱpelvisȱinȱdifferentȱ postures.ȱIn:ȱVleemingȱA,ȱMooneyȱV,ȱSnijdersȱC,ȱDormanȱT,ȱStoeckartȱR,ȱ eds.ȱMovement,ȱstabilityȱandȱlowȱbackȱpain.ȱTheȱessentialȱroleȱofȱtheȱ pelvis:ȱChurchillȱLivingstone,ȱ1997;ȱ103Ȭ113.ȱ 222.ȱ SterlingȱM,ȱJullȱG,ȱWrightȱA.ȱTheȱeffectȱofȱmusculoskeletalȱpainȱonȱ motorȱactivityȱandȱcontrol.ȱJȱPainȱ2001;ȱ2:135Ȭ145.ȱ 223.ȱ StoweȱZN,ȱNemeroffȱCB.ȱWomenȱatȱriskȱforȱpostpartumȬonsetȱmajorȱ depression.ȱAmȱJȱObstetȱGynecolȱ1995;ȱ173:639Ȭ645.ȱ 224.ȱ StreinerȱD,ȱNormanȱG.ȱHealthȱmeasurementȱscales:ȱaȱpracticalȱguideȱtoȱ theirȱdevelopmentȱandȱuse.ȱOxford;NewȱYork:ȱOxfordȱUniversityȱPress,ȱ 1995.ȱ 225.ȱ StugeȱB,ȱLaerumȱE,ȱKirkesolaȱG,ȱVollestadȱN.ȱTheȱefficacyȱofȱaȱtreatmentȱ programȱfocusingȱonȱspecificȱstabilizingȱexercisesȱforȱpelvicȱgirdleȱpainȱ afterȱpregnancy:ȱaȱrandomizedȱcontrolledȱtrial.ȱSpineȱ2004;ȱ29:351Ȭ359.ȱ 226.ȱ StugeȱB,ȱVeierodȱMB,ȱLaerumȱE,ȱVollestadȱN.ȱTheȱefficacyȱofȱaȱtreatmentȱ programȱfocusingȱonȱspecificȱstabilizingȱexercisesȱforȱpelvicȱgirdleȱpainȱ afterȱpregnancy:ȱaȱtwoȬyearȱfollowȬupȱofȱaȱrandomizedȱclinicalȱtrial.ȱ Spineȱ2004;ȱ29:E197Ȭ203.ȱ 227.ȱ SturessonȱB,ȱSelvikȱG,ȱUdenȱA.ȱMovementsȱofȱtheȱsacroiliacȱjoints.ȱAȱ roentgenȱstereophotogrammetricȱanalysis.ȱSpineȱ1989;ȱ14:162Ȭ165.ȱ 228.ȱ SturessonȱB,ȱUdenȱG,ȱUdenȱA.ȱPainȱpatternȱinȱpregnancyȱandȱȈcatchingȈȱ ofȱtheȱlegȱinȱpregnantȱwomenȱwithȱposteriorȱpelvicȱpain.ȱSpineȱ1997;ȱ 22:1880Ȭ1883;ȱdiscussionȱ1884.ȱ 229.ȱ SvenssonȱHO,ȱAnderssonȱGB,ȱHagstadȱA,ȱJanssonȱPO.ȱTheȱrelationshipȱ ofȱlowȬbackȱpainȱtoȱpregnancyȱandȱgynecologicȱfactors.ȱSpineȱ1990;ȱ 15:371Ȭ375.ȱ 230.ȱ SydsjoȱA,ȱSydsjoȱG,ȱKjesslerȱB.ȱSickȱleaveȱandȱsocialȱbenefitsȱduringȱ pregnancyȬȬaȱSwedishȬNorwegianȱcomparison.ȱActaȱObstetȱGynecolȱ Scandȱ1997;ȱ76:748Ȭ754.ȱ 231.ȱ SydsjoȱA,ȱSydsjoȱG,ȱWijmaȱB,ȱKjesslerȱB.ȱChangesȱinȱsickȱleaveȱratesȱandȱ theȱuseȱofȱpregnancyȬassociatedȱsocialȱbenefitsȱamongȱpregnantȱ Swedishȱwomen:ȱanȱoutcomesȱstudy.ȱJȱWomensȱHealthȱ1998;ȱ7:249Ȭ260.ȱ 232.ȱ TaimelaȱS,ȱKankaanpaaȱM,ȱLuotoȱS.ȱTheȱeffectȱofȱlumbarȱfatigueȱonȱtheȱ abilityȱtoȱsenseȱaȱchangeȱinȱlumbarȱposition.ȱAȱcontrolledȱstudy.ȱSpineȱ 1999;ȱ24:1322Ȭ1327.ȱ 233.ȱ TakemasaȱR,ȱYamamotoȱH,ȱTaniȱT.ȱTrunkȱmuscleȱstrengthȱinȱandȱeffectȱ ofȱtrunkȱmuscleȱexercisesȱforȱpatientsȱwithȱchronicȱlowȱbackȱpain.ȱTheȱ

ȱ 94 Referencesȱ ȱ differencesȱinȱpatientsȱwithȱandȱwithoutȱorganicȱlumbarȱlesions.ȱSpineȱ 1995;ȱ20:2522Ȭ2530.ȱ 234.ȱ TheȱEuroQolȱG.ȱEuroQolȬaȱnewȱfacilityȱforȱtheȱmeasurementȱofȱhealthȱ relatedȱqualityȱofȱlife.ȱHealthȱPolicyȱ1990;ȱ16:199Ȭ208.ȱ 235.ȱ ToȱWW,ȱWongȱMW.ȱFactorsȱassociatedȱwithȱbackȱpainȱsymptomsȱinȱ pregnancyȱandȱthe ȱpersistenceȱofȱpainȱ2ȱyearsȱafterȱpregnancy.ȱActaȱ ObstetȱGynecolȱScandȱ2003;ȱ82:1086Ȭ1091.ȱ 236.ȱ TurgutȱF,ȱTurgutȱM,ȱCetinsahinȱM.ȱAȱprospectiveȱstudyȱofȱpersistentȱ backȱpainȱafterȱpregnancy.ȱEurȱJȱObstetȱGynecolȱReprodȱBiolȱ1998;ȱ 80:45Ȭ48.ȱ 237.ȱ UrwinȱM,ȱSymmonsȱD,ȱAllisonȱT,ȱetȱal.ȱEstimatingȱtheȱburdenȱofȱ musculoskeletalȱdisordersȱinȱtheȱcommunity:ȱtheȱcomparativeȱ prevalenceȱofȱsymptomsȱatȱdifferentȱanatomicalȱsites,ȱandȱtheȱrelationȱtoȱ socialȱdeprivation.ȱAnnȱRheumȱDisȱ1998;ȱ57:649Ȭ655.ȱ 238.ȱ WaldeȱJ.ȱObstetricalȱandȱgynecologicalȱbackȱandȱpelvicȱpains,ȱespeciallyȱ thoseȱcontractedȱduringȱpregnancy.ȱActaȱObstetȱGynecolȱScandȱSupplȱ 1962;ȱ41(Supplȱ2):11Ȭ53.ȱ 239.ȱ vanȱderȱWurffȱP,ȱBuijsȱEJ,ȱGroenȱGJ.ȱAȱMultitestȱRegimenȱofȱPainȱ ProvocationȱTestsȱasȱanȱAidȱtoȱReduceȱUnnecessaryȱMinimallyȱInvasiveȱ SacroiliacȱJointȱProcedures.ȱArchȱPhysȱMedȱRehabilȱ2006;ȱ87:10Ȭ14.ȱ 240.ȱ vanȱDieenȱJH,ȱCholewickiȱJ,ȱRadeboldȱA.ȱTrunkȱmuscleȱrecruitmentȱ patternsȱinȱpatientsȱwithȱlowȱbackȱpainȱenhanceȱtheȱstabilityȱofȱtheȱ lumbarȱspine.ȱSpineȱ2003;ȱ28:834Ȭ841.ȱ 241.ȱ vanȱDongenȱPW,ȱdeȱBoerȱM,ȱLemmensȱWA,ȱTheronȱGB.ȱHypermobilityȱ andȱperipartumȱpelvicȱpainȱsyndromeȱinȱpregnantȱSouthȱAfricanȱ women.ȱEurȱJȱObstetȱGynecolȱReprodȱBiolȱ1999;ȱ84:77Ȭ82.ȱ 242.ȱ vanȱTulderȱM,ȱBeckerȱA,ȱBekkeringȱT,ȱetȱal.ȱChapterȱ3.ȱEuropeanȱ guidelinesȱforȱtheȱmanagementȱofȱacuteȱnonspecificȱlowȱbackȱpainȱinȱ primaryȱcare.ȱEurȱSpineȱJȱ2006;ȱ15ȱSupplȱ2:S169Ȭ191.ȱ 243.ȱ vanȱWingerdenȱJP,ȱVleemingȱA,ȱBuyrukȱHM,ȱRaissadatȱK.ȱStabilizationȱ ofȱtheȱsacroiliacȱjointȱinȱvivo:ȱverificationȱofȱmuscularȱcontributionȱtoȱ forceȱclosureȱofȱtheȱpelvis.ȱEurȱSpineȱJȱ2004;ȱ13:199Ȭ205.ȱ 244.ȱ WandȱBM,ȱBirdȱC,ȱMcAuleyȱJH,ȱDoreȱCJ,ȱMacDowellȱM,ȱDeȱSouzaȱLH.ȱ Earlyȱinterventionȱforȱtheȱmanagementȱofȱacuteȱlowȱbackȱpain:ȱaȱsingleȬ blindȱrandomizedȱcontrolledȱtrialȱofȱbiopsychosocialȱeducation,ȱmanualȱ therapy,ȱandȱexercise.ȱSpineȱ2004;ȱ29:2350Ȭ2356.ȱ 245.ȱ WangȱSM,ȱDezinnoȱP,ȱMaranetsȱI,ȱBermanȱMR,ȱCaldwellȬAndrewsȱAA,ȱ KainȱZN.ȱLowȱbackȱpainȱduringȱpregnancy:ȱprevalence,ȱriskȱfactors,ȱandȱ outcomes.ȱObstetȱGynecolȱ2004;ȱ104:65Ȭ70.ȱ

ȱ 95 Referencesȱ

246.ȱ WareȱJE,ȱJr.,ȱSherbourneȱCD.ȱTheȱMOSȱ36ȬitemȱshortȬformȱhealthȱsurveyȱ (SFȬ36).ȱI.ȱConceptualȱframeworkȱandȱitemȱselection.ȱMedȱCareȱ1992;ȱ 30:473Ȭ483.ȱ 247.ȱ WatersȱRL,ȱLunsfordȱBR,ȱPerryȱJ,ȱByrdȱR.ȱEnergyȬspeedȱrelationshipȱofȱ walking:ȱstandardȱtables.ȱJȱOrthopȱResȱ1988;ȱ6:215Ȭ222.ȱ 248.ȱ WatersȱRL,ȱMulroyȱS.ȱTheȱenergyȱexpenditureȱofȱnormalȱandȱpathologicȱ gait.ȱGaitȱPostureȱ1999;ȱ9:207Ȭ231.ȱ 249.ȱ WeiglȱM,ȱCiezaȱA,ȱAndersenȱC,ȱKolleritsȱB,ȱAmannȱE,ȱStuckiȱG.ȱ IdentificationȱofȱrelevantȱICFȱcategoriesȱinȱpatientsȱwithȱchronicȱhealthȱ conditions:ȱaȱDelphiȱexercise.ȱJȱRehabilȱMedȱ2004:12Ȭ21.ȱ 250.ȱ WeinrebȱJC,ȱWolbarshtȱLB,ȱCohenȱJM,ȱBrownȱCE,ȱMaravillaȱKR.ȱ PrevalenceȱofȱlumbosacralȱintervertebralȱdiskȱabnormalitiesȱonȱMRȱ imagesȱinȱpregnantȱandȱasymptomaticȱnonpregnantȱwomen.ȱRadiologyȱ 1989;ȱ170:125Ȭ128.ȱ 251.ȱ WeissmanȱMM,ȱOlfsonȱM.ȱDepressionȱinȱwomen:ȱimplicationsȱforȱhealthȱ careȱresearch.ȱScienceȱ1995;ȱ269:799Ȭ801.ȱ 252.ȱ WernekeȱM,ȱHartȱDL.ȱCentralizationȱphenomenonȱasȱaȱprognosticȱfactorȱ forȱchronicȱlowȱbackȱpainȱandȱdisability.ȱSpineȱ2001;ȱ26:758Ȭ764;ȱ discussionȱ765.ȱ 253.ȱ WernekeȱM,ȱHartȱDL,ȱCookȱD.ȱAȱdescriptiveȱstudyȱofȱtheȱcentralizationȱ phenomenon.ȱAȱprospectiveȱanalysis.ȱSpineȱ1999;ȱ24:676Ȭ683.ȱ 254.ȱ WHO.ȱConstitutionȱofȱtheȱWorldȱHelathȱOrganization.ȱIn:WHO.ȱ Geneva,ȱ1978.ȱ 255.ȱ WHO.ȱInternationalȱclassificationȱofȱFunctioning,ȱDisabilityȱandȱHealth.ȱ In:ȱOrganisationȱWH,ȱed.ȱResolutionȱWHAȱ54.21.22,ȱ2001.ȱ 256.ȱ WickbergȱB,ȱHwangȱCP.ȱTheȱEdinburghȱPostnatalȱDepressionȱScale:ȱ validationȱonȱaȱSwedishȱcommunityȱsample.ȱActaȱPsychiatrȱScandȱ1996;ȱ 94:181Ȭ184.ȱ 257.ȱ WijnhovenȱHA,ȱdeȱVetȱHC,ȱPicavetȱHS.ȱPrevalenceȱofȱmusculoskeletalȱ disordersȱisȱsystematicallyȱhigherȱinȱwomenȱthanȱinȱmen.ȱClinȱJȱPainȱ 2006;ȱ22:717Ȭ724.ȱ 258.ȱ VleemingȱA,ȱAlbertȱH,ȱÖstgaardȱH,ȱStugeȱB,ȱSturessonȱB.ȱEuropeanȱ guidelinesȱonȱtheȱdiagnosisȱandȱtreatmentȱofȱpelvicȱgirdleȱpain.ȱIn,ȱ2005.ȱ http://www.backpaineurope.org/web/files/WG4/_Guidelines.pdf 259.ȱ VleemingȱA,ȱPoolȬGoudzwaardȱAL,ȱHammudoghluȱD,ȱStoeckartȱR,ȱ SnijdersȱCJ,ȱMensȱJM.ȱTheȱfunctionȱofȱtheȱlongȱdorsalȱsacroiliacȱ ligament:ȱitsȱimplicationȱforȱunderstandingȱlowȱbackȱpain.ȱSpineȱ1996;ȱ 21:556Ȭ562.ȱ

ȱ 96 Referencesȱ ȱ 260.ȱ VleemingȱA,ȱSnijdersȱC,ȱStoeckartȱR,ȱMensȱJM.ȱTheȱroleȱofȱtheȱsacroiliacȱ jointsȱinȱcouplingȱbetweenȱspine,ȱpelvis,ȱlegsȱandȱarms.ȱIn:ȱVleemingȱA,ȱ MooneyȱV,ȱDormanȱT,ȱSnijdersȱC,ȱStoeckartȱR,ȱeds.ȱMovement,ȱstabilityȱ &ȱlowȱbackȱpain.ȱTheȱessentialȱroleȱofȱtheȱpelvis:ȱChurchillȱLivingstone,ȱ 1997;ȱ53Ȭ71.ȱ 261.ȱ VonȱKorffȱM,ȱJensenȱMP,ȱKarolyȱP.ȱAssessingȱglobalȱpainȱseverityȱbyȱ selfȬreportȱinȱclinicalȱandȱhealthȱservicesȱresearch.ȱSpineȱ2000;ȱ25:3140Ȭ 3151.ȱ 262.ȱ VonȱKorffȱM,ȱSaundersȱK.ȱTheȱcourseȱofȱbackȱpainȱinȱprimaryȱcare.ȱ Spineȱ1996;ȱ21:2833Ȭ2837;ȱdiscussionȱ2838Ȭ2839.ȱ 263.ȱ WorkuȱZ.ȱPrevalenceȱofȱlowȬbackȱpainȱinȱLesothoȱmothers.ȱJȱ ManipulativeȱPhysiolȱTherȱ2000;ȱ23:147Ȭ154.ȱ 264.ȱ WormslevȱM,ȱJuulȱAM,ȱMarquesȱB,ȱMinckȱH,ȱBentzenȱL,ȱHansenȱTM.ȱ Clinicalȱexaminationȱofȱpelvicȱinsufficiencyȱduringȱpregnancy.ȱAnȱ evaluationȱofȱtheȱinterobserverȱvariation,ȱtheȱrelationȱbetweenȱclinicalȱ signsȱandȱpainȱandȱtheȱrelationȱbetweenȱclinicalȱsignsȱandȱphysicalȱ disability.ȱScandȱJȱRheumatolȱ1994;ȱ23:96Ȭ102.ȱ 265.ȱ WuȱW,ȱMeijerȱOG,ȱJutteȱPC,ȱetȱal.ȱGaitȱinȱpatientsȱwithȱpregnancyȬ relatedȱpainȱinȱtheȱpelvis:ȱanȱemphasisȱonȱtheȱcoordinationȱofȱtransverseȱ pelvicȱandȱthoracicȱrotations.ȱClinȱBiomechȱ(Bristol,ȱAvon)ȱ2002;ȱ17:678Ȭ 686.ȱ 266.ȱ WuȱW,ȱMeijerȱOG,ȱLamothȱCJ,ȱetȱal.ȱGaitȱcoordinationȱinȱpregnancy:ȱ transverseȱpelvicȱandȱthoracicȱrotationsȱandȱtheirȱrelativeȱphase.ȱClinȱ Biomechȱ(Bristol,ȱAvon)ȱ2004;ȱ19:480Ȭ488.ȱ 267.ȱ WuȱWH,ȱMeijerȱOG,ȱUegakiȱK,ȱetȱal.ȱPregnancyȬrelatedȱpelvicȱgirdleȱ painȱ(PPP),ȱI:ȱTerminology,ȱclinicalȱpresentation,ȱandȱprevalence.ȱEurȱ SpineȱJȱ2004;ȱ13:575Ȭ589.ȱ 268.ȱ YoungȱJ.ȱRelaxationȱofȱtheȱPelvicȱJointsȱinȱPregnancy:ȱPelvicȱ ArthropathyȱofȱPregnancy.ȱTheȱJournalȱofȱObstetricsȱ&ȱGynaecologyȱofȱ BritishȱEmpireȱ1940;ȱ47:493Ȭ524.ȱ 269.ȱ ÖbergȱB,ȱEnthovenȱP,ȱKjellmanȱG,ȱSkargrenȱE.ȱBackȱPainȱinȱPrimaryȱ Care:ȱaȱProspectiveȱCohortȱStudyȱofȱClinicalȱOutcomeȱandȱHealthcareȱ Consumption.ȱAdvancesȱInȱPhysiotherapyȱ2003;ȱ5:98Ȭ108.ȱ ȱ

ȱ 97