The ChallengesofElectronic Prescription Systems Based on Semantic WebTechnologies
JuhaPuustjärvi, Leena Puustjärvi
Department of InformationTechnology Lappeenranta UniversityofTechnology P.O.Box 20 FIN-53851 Lappeenranta,Finland [email protected] [email protected]
Abstract: Thetechnologydeveloped forinteroperable autonomoussystems has significantly changed duringthe past few years. However, this new technology based on Semantic Webisnot yetdeployed in electronicprescriptions systems. On theother hand, duringthe pastfew yearsseveralorganizationsinthe healthcare sectorhave produced standards andrepresentationformsusing XML. This generalization of XML-technologies sets apromising starting pointfor the interoperabilityofthe various organizations in the healthcare sector. However, the introductionofXML is notenoughbut many other XML-based technologies have to be introduced in order to achieve aseamless interoperability betweenthe electronic prescriptionsystemsand other organizations of thehealth care sector. In this articleweillustratethe querying facilitiesthat thedeployment of the semanticweb technology can provide forelectronicprescriptionssy stems. Furthermore we illustrate thesystem architecture andthe ontologies as wellasthe ontology specification languages that are required in implementing an electronic prescription system based on semanticweb technologies.
1Introduction
Imaginethatyou areonavacationonthe othersideofthe world, andyou become suddenlyill and must be hospitalized. Immediately the physicianinthe hospital queries the Internet, enteringyour universal healthidentification number and within fewseconds the physicianaccessyourcomplete medical history including yourpatient record, medicalchartand bloodanalysis.Thenthe physicianqueries your previous prescriptions suchasthe amountofcertain drugs, andyour digitalX-rayfilms. After this the physician constructs theprescription by theprescription writer which checkswhether the drugs have mutual negative effectswithyourother ongoingmedicaltreatment,and finallythe appropriate treatment is provided.
251 Unfortunatelythisscenario is not possible today. Accessing your complete medical history or previous prescriptions throughInternet is not possible. Themain reasons for this are the isolation of various healthcare systemsand the lack of standardization of medicaldatasuch as patientrecords and electronicprescriptions. By thestandardization we refertothe medicalontologiesthatgive semantics for medicaldata.
Theacademic researchofelectronic prescriptionsisdiscussedinmany practitioner reports andpublicnationalplans,e.g., in [Hy05, Bo05,CM04, SG00, Ke99, Ve06]. These plansshare severalsimilar motivations andreasons for the implementationof electronic prescription systems(EPSs). These include:
• Reduction of medicationerrors
• Speeding up the prescription ordering process
• Better statistical data for researchpurposes
• Financialsavings The technology developedfor interoperableautonomoussystemshas significantly changedduringthe pastfew years. Howeverthe new technology basedonSemantic Web [AH04,DO03, SH05] is not yetdeployed in health care sector. Throughthis technology many of the features of the previous scenario could be achieved. On the other hand,during thepastfew yearsseveral organizations in the healthca re sector have produced standards andrepresentationformsusing XML. Forexample, patientrecords, bloodanalysisand electronicprescriptions are typically representedasXML-documents [Wo01, St01,Li01, Ju05, Ma05]. Thisgeneralization of XML-technologies sets a promising starting point for the interoperability of thevarious organizations in the healthcare sector. However, theintroduction of XML[HS02] itself is notenough but also many otherXML-basedtechnologies [SH05] have to be introduced in order to achieve aseamless interoperabilitybetween the organizationswithinthe healthcare sector.
In this article we illustrate the interoperability withinthe healthcaresectorfrom electronic prescriptionspoint of view. In particular, we illustrate
• how XML-basedtechnologies canbeutilizedinmodeling theconceptsthatare relatedtoprescriptionwriting, and
• how web-service technologycan be usedinimplementing the interoperability of electronicprescription systemand other healthcaresystems.
Themaingoalofthisarticle is to show the gains that theintegrationofthe healthcare systemsand thedeploymentofthe Semantic Webtechnologies can providefor electronic prescription systems.
252 The rest of thepaperisorganizedasfollows. First in Section 2, we give amotivation by illustratinganoverviewofapaper basedprescribing systemand electronicprescribing system.Especially we will illustrate the way thephysician canutilize the new querying facilitiesthe EPS(Electronic Prescription System)may provide. Then,insection 3, we describe our proposed service oriented architecture for EPS. An essentialfeature of the architectureisthatthe componentsinteract throughweb service interfaces. In Section 4, we consider EPSs from conceptualmodeling pointofview. Especiallyweillustrate the role of XML-basedtechnologiesand theappropriate ontologiesinthe developmentof EPSs.Chapter5concludes thepaperbydiscussingthe advantages anddisadvantagesof our approach.
2Motivation
We first shortlydescribe theprocess behindthe paper-basedprescriptionsystem. It goes as follows: first apatent visits aphysician for consultation. Afterthe consultationthe physician writes amedical prescriptionofdrugs forthe patient on apaper prescription form.Then the physiciansignsthisform by hand andgives theprescription form to the patient. Thepatient can then present theprescription form at anypharmacyinthe country. Then, in apharmacy, thepharmacist dispenses theprescribed drugs listedonthe prescription to thepatientand keeps theprescription form.The prescriptions dispensed by apharmacy areperiodicallybatched togetherand sent to agovernmentalauthority whichafter processing theprescriptionssends paymentstothe pharmacy.
We next illustrate howthe electronic prescriptionprocess maydeviate from the paper- basedprescription process. It goesasfollows:firstapatient visits aphysicianfor diagnosis. In prescribing medication thephysician usesthe EPS. The EPSmay provide for examplethe followingqueries
• querying the previousprescriptionsofthe patient,
• querying statistical information aboutprevious prescriptionssuchasthe amount of certain drugs,
• querying patientsrecords,
• querying the physicians givenpreviousprescriptions, or
• querying the digitalX-ray filmsofthe patient. In addition,the physicianmay annotatethe prescriptionbyappropriate information, e.g., by stating that thedrugs arenot allowed to be givenbefore certain date,and that the drugs aregiven in certain portions, e.g., aportiononceamonth. And, on the other way round, thephysician mayexpress queries on the annotationssuchaswhether thedrugs arepreviously givenupinone or several portions.
253 Once thephysicianhas constructedthe prescription the EPSmay automatically
• check in thecaseofmultidrugtreatment whether the drugs have mutual negative effects,
• check whether thedrugs have mutual negative effectswiththe otherongoing medicaltreatment of thepatient,
• check thedose,
• check whethersomeofdrugcan be changed to acheaperdrug. Once the checks and possible changes have been donethe physician signsthe prescription electronically. Then theprescription is encryptedand sent to an electronic prescription holdingstore. Basically theholding store maybecentralized or distributed store.The patient will also receive the prescriptioninthe paper form,whichincludestwo barcodes. The firstidentifiesthe address of theprescription in theholdingstore, and the second is theencryption keywhichallows thepharmacisttodecrypt theprescr iption.
3The architectureofthe serviceorientede-prescription system
We now describethe architecture that canbeusedfor providing theservicesdescribedin Section2.The architecture is basedonthe service orientedcomputingparadigm. Basically, services areameansfor buildingdistributed applicatio ns more efficiently than with previous software approaches.The mainideabehind servicesisthat theyare used formultiple purposes. Services are also used by puttingthemtogetherorcomposing them.Thereforeeveryaspectofservices is designedtohelpthembecomposed.
In thehealthcare sector serviceorientedcomputing providesanelegant approachfor connecting electronic prescription system to theotherrelevant healthcaresystems. For example, electronic prescription writercan interactwith the health care systemthat supports patient records.There mayalso be componentsthatare usedbydifferent healthcare systems.For example, medicaldatabasemay provide services for medical information systemsaswell as for electronic prescription system.
The communication is basedonthe notionofweb services [Ne02].Originallythey provide away for executing business transactionsinthe Internetbut they canbeusedin ehealth sector as well. Technically web servicesare self-describingmodularapplications thatcan be published, locatedand invokedacross the Web. Once aservice is deployed, other applications caninvoke the deployedservice.Ingeneral,awebservice canbe anything from asimplerequest to complicatedbusiness or ehealth processes.
Thecomponents of theelectronic prescription system arepresentedinFigure 1. In reality, each component communicatesthrough aweb service interface, butinFigure 1 in order to keepthe figureclear we have omittedthose interfaces.
254 E-prescription requests Prescription Prescription Pharmacy pricing holding store E-prescription authority Answer Requestson E-prescription patient’s prescriptions Medical Query database Answer Healthcaresystem Prescription Expert Query writer Requests database on patients Answer records
Physician
Figure1.The componentsofane-prescriptionsyst em.
.InFigure 2, we have presentedamore detail structure of the Prescription holding store whichalsoincludesthe webserviceinterface.
e-prescription e-prescription request response
Requestsonpatients’ record webservice Requests on patients’ prescriptions Responsesonpatients’records interface Responsesonpatients prescriptions
Prescription management application
Prescription database
Figure 2. Thecomponents of the prescription holding store.
Note that each message in the Figure 2ispresented as an XML-document. Further, each XML-document is carriedbythe SOAP protocol [SH05]. SOAP is aprotocol specification that defines auniform wayofpassing XML-coded data.
255 4Ontologies for electronicprescription systems
In this sectionwewill firstgiveashort introduction to ontologies. Then we illustrate what kindofontology languages are neededinorder to support the featurespresentedin Section2.
Thetermontology originatesfromphilosophywhere it is used as the name of the study of the natureofexistence [GR93]. In thecontext of computer science, thecommonly used definition is “An ontology is an explicitand formalspecificationofa conceptualization” [AH04]. So it is ageneralvocabularyofacertain domain. Essentially theusedontology must be shared andconsensual terminology as it is used for informationsharingand exchange. On the other hand,ontologytries to capture the meaningofaparticular subject domain that corresponds to what ahumanbeingknows about that domain. It alsotries to characterize that meaning in terms of conceptsand their relationships.
Ontology is typicallyrepresented as classes, properties attributes andvalues. So they also provide asystematic waytostandardize theusedmetadata i tems. Metadata items describe certain important characteristicsoftheir target in acompactform.The metadata describing the content of adocument (e.g.,anelectronic prescription)iscommonly calledsemantic metadata.For example,the keywords attached to many scientific articles represent semantic metadata
Each ontology describes adomainofdiscourse. It consistsofafinite setofconceptsand the relationship betweenthe concepts. Forexample, withinelectronic prescription systemspatient,drug, and e-prescription aretypical concepts. These concepts andtheir relationships aregraphicallypresentedinFigure 3.
drug
includes
prceeds e-prescription
isPrescribedBy isTargetedAt
patient physician
Figure 3. An e-prescriptionontology.
256 In Figure4the ontology of Figure3is extended by instances, i.e., it includes the instancesofthe classes physician, patient and e-prescription
drug
includes
precedes e-prescription
isPrescribedBy isTargetedAt
patient physician type type type type type type type
JackSmith John Taylor isPrescribedBy isPrescribedBy Is TargetedAt
e-prescription e-prescription Id 123 precedes Id 678
Figure4.Anextension of thee-prescription ontology.
The ontology of Figure 4allows awide varietyofqueries including:
• Give me all prescriptions prescribedtoJack Taylor
• Give me all prescriptions prescribedbyphysician John Smith
• Give me all prescriptions includingdrugnamed Panadol. The mostcommonlyusedontologylanguages are XML[HS02], XMLSchema[HS02], RDF[DO03],RDF Schema [DO03] and OWL[SH05].
257
257 XML(Extensible Markup Language)[HS02] is ametamarkuplanguagefor text documents.Itisthe syntactic foundationlayer of the Semantic Web. Allother technologies providingfeatures for theSemanticWeb will be builtontop of XML. Particularly XMLdefines ageneric syntax usedtomarkupdatawithsimple human readabletags. An important feature of XMListhatitdoesnot have afixed setoftags butitallowsusertodefine tags of their own.For example, various communitieshave defined their specializedvocabularies (set of tags) for various domainssuchasMathMl formathematics, BSMLfor bioinformaticsand GovML(GovernmentalMarkup Language) for government.
Forexampleusing XML we can represent an electronic prescription as follows:
Figure 5. AprescriptioninXML
In this illustrative XML-documentwehave usedtags“Prescription”,“Patient”, “Identification”, ”Medicine”,“Disease”, “Quantity”,“Refills”, and “Dose”
XMLSchema [HS02] is alanguagefor restricting thestructure of XMLdocuments. It hastwo roles: Firstitisatemplate for aform generator (e.g., prescriptionwriter)to generate instances of specific document type (e.g., prescription type). Second, it is a validator to ensurethe accuracy of documents such as transmittedelectronic prescriptions.
Onecharacteristic of XMLSchemaisthat itssyntax is basedonXML itself. Anice feature of XML-Schema is alsothatone candefine newXML-Schemebyextending or restrictingalready existing scheme. In additionXML Schema providesasophisticated setofdatatypesthatcan be used in XMLdocuments. So,for example, if there is aneed for extending the prescription by the address of thepatients, we only have to extendthe XML Schemaofthe prescriptiondocument, i.e.,weadd theaddress elementtothe XML-Schema.
258 An XMLdocument is well-formed if it complies with allthe W3Csyntaxrules of XML [HS02]. This requirement guaranteesthat an XMLprocessor can break into identifiable componentsthe document. Further, XML-document is validifitreferences and satisfies an XMLSchema [HS02]. In our architecture (Figure 1), this means that thereissuchan XML processor at each communication unit.Sofor example, whenthe prescription holding storereceives an electronicprescriptionitfirst checks the validityofthe prescription andstoresthe prescription only if it valid.
While XMLdocumentsattach metadata to parts of the documents, one use of RDF (ResourceDescriptionFramework) [DO03] is to createmetadata about thedocument as astandalone entity. To illustrate this we can for example statebyanRDF statementthat aprescription (e.g.,the prescription of Figure 5) is prescribed by physicianJackSmith
The RDFmodel[DO03]iscalledatriplebecause it has three parts: subject, predicate and object. Eachtriple is an RDF-statement.The preceding statementabout JackSmith is such astatement: “ theprescription” is the subject,”isPrescribedBy” is thepredicate, and“Jack Smith” is theobject. In orderthatRDF-statementscan be represented and transmitteditneedssyntax. The syntax hasbeen giveninXML.SoanRDF-statement canberepresented as an XML-document.
RDFSchema[DO03] provides thevocabulary forthe RDF-statements. Forexamplein our case,” isPrecribedBy” is an item of ourvocabulary. In the stackofthe Semantic Web RDF-Schemaisalanguage layered on topofRDF.Itallows creatingclassesof data.Aclass is agroupofthingswith commoncharacteristics. Forexample, we have specified class e-presciption,patient and physician.ThenbyanRDF statementwecan forexample, specify that physician Jack Smith is an instance o fthe class physician ,and by another RDFstatementwecan specifythat prescriptionno. 72543isaninstance of the class e-prescription .
RDFSchema is aweakontology language in thesense that it offers only themodelling concepts class, subclass relations, property, subproperty relation and domain and range restrictions.There are many modelling primitivesthatare useful in modelling documents in health caresectorbut aremissingfrom RDFSchema. Forexample, neither we canspecify that classes(e.g., physicians and patients )are notnecessary disjoint nor canwebuildnew class by setoperations, e.g., class doctors is theunion of the classes physicians and dentists.However,these kindsoffeaturescan be declaredbythe OWL (Web Ontology Language) [SH05].
5Conclusions
Electronic prescriptionisthe electronic transmission of prescriptionsofpharmaceutical products from legallyprofessionally qualifiedhealthcarepractitioners to registered pharmacies. Thescopeofthe prescribedproducts variesfrom country to countryas permitted by governmentauthoritiesorhealth insurance carriers. Forelectronic prescription to be accepted by thephysicians, pharmacies andpatientsitmustprovide addedbenefits to allparticipants.
259 In particular, electronic prescription systems have significantpotentialtoimprove the qualityofmedication prescription andcontributetoreduction of medica tion errors. Therefore, during thepastfew years severalorganizationsinthe healthcare sector have produced standards andrepresentation forms usingXML.For example, patient records, bloodanalysisand electronic prescriptionsare typicallyrepresentedasXML-documents. This generalization of XML-technologies sets apromisingstarting point for the interoperabilityofthe various organizations in the healthcare sector.However,the introductionofXML itself is notenough butalso many otherXML-basedtechnologies have to be introduced in ordertoachieveaseamlessinteroperabilitybetween the organizationswithinthe healthcare sector.
Today, in electronic prescriptionsystemsthere is agreat diversity in technological solutions. The solutions differinmanywaysincludingthe architecture of the EPS, used security policy, how theprescriptionsare storedfor furtheranalysis, andhow XML- based technologies areutilized. We canalsomake thedistinctionbetween electronic prescription systems dependingonwhether their main goal is to reducethe costs of medications or whetherthe main goal improving the qualityofmedications
In this articlewehave illustrated theinteroperability within thehealthcare sectorfrom electronic prescriptions point of view.Inparticular, we illustratedho wXML-based technologies canbeutilizedinmodelling theconceptsthatare relatedtoprescription writing,and how web-service technologycan be used in implementing the interoperabilityofelectronicprescription system and otherhealth caresystems.
AconsequenceofintroducingSemanticWeb technologiesinhealthcare sector is thatit significantly changes the dailyduties of the employees of thehealthcaresector. Therefore the most challengingaspect will notbethe technologybut rather changingthe mind-setofthe employees andthe training of the new technology.
Theintroductionofanewtechnologyisalsoaninvestment. The investment on new Semantic Webtechnologyincludes avariety of costs includingsoftware,hardwareand training costs. Trainingthe staffonSemanticWeb techno logy is abig investment, and hence many organizations like to cutonthiscost as much as p ossible.However, the incorrectusage and implementationofanew technology, duetolack of proper training, mightturn outtobemore expensive in thelongrun.
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