Postpartum Urinary Tract Infection by Mode of Delivery: a Danish Nationwide Cohort Study
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Open Access Research BMJ Open: first published as 10.1136/bmjopen-2017-018479 on 14 March 2018. Downloaded from Postpartum urinary tract infection by mode of delivery: a Danish nationwide cohort study Tina Djernis Gundersen,1 Lone Krebs,2 Ellen Christine Leth Loekkegaard,1 Steen Christian Rasmussen,3 Julie Glavind,4 Tine Dalsgaard Clausen1 To cite: Gundersen TD, ABSTRACT Strengths and limitations of this study Krebs L, Loekkegaard ECL, Objectives To examine the association between et al. Postpartum urinary postpartum urinary tract infection and intended mode of ► Large nationwide study including data from the tract infection by mode of delivery as well as actual mode of delivery. delivery: a Danish nationwide Danish birth cohort (n=450 856). Design Retrospective cohort study. cohort study. BMJ Open ► High-quality data where prospective collection limits Setting and participants All live births in Denmark 2018;8:e018479. doi:10.1136/ the risk of selection and information bias. between 2004 and 2010 (n=450 856). Births were bmjopen-2017-018479 ► Evaluates the risk of urinary tract infection (UTI) by classified by intended caesarean delivery (n=45 053) or intended as well as actual mode of delivery. ► Prepublication history and intended vaginal delivery (n=405 803), and by actual mode ► The diagnosis of postpartum UTI was not confirmed additional material for this of delivery: spontaneous vaginal delivery, operative vaginal paper are available online. To by urinary cultures. delivery, emergency or planned caesarean delivery in view these files, please visit ► Cohort study without the ability to assess causality. the journal online (http:// dx. doi. labour or prelabour. org/ 10. 1136/ bmjopen- 2017- Primary and secondary outcome measures The 018479). primary outcome measure was postpartum urinary tract infection (n=16 295) within 30 days post partum, defined with discomfort, prolonged hospital stay Received 3 July 2017 as either a diagnosis of urinary tract infection in the and readmission and has been associated Revised 27 January 2018 National Patient Registry or redemption of urinary tract with an increased risk of discontinued Accepted 9 February 2018 infection-specific antibiotics recorded in the Register of breast feeding.1 4 In Denmark and many Medicinal Product Statistics. other countries, most women deliver in Results We found that 4.6% of women with intended hospitals and are discharged a few hours after caesarean delivery and 3.5% of women with intended http://bmjopen.bmj.com/ giving birth,1 5 6 and 79% of all postpartum vaginal delivery were treated for postpartum urinary tract infection. Women with intended caesarean delivery UTIs in Denmark will occur after discharge and are diagnosed and treated by a general had a significantly increased risk of postpartum urinary 3 6 tract infection compared with women with intended practitioner. vaginal delivery (OR 1.33, 95% CI 1.27 to 1.40), after Especially, when counselling women aiming adjustment for age at delivery, smoking, body mass index, for caesarean delivery, on maternal request educational level, gestational diabetes mellitus, infection without obstetric indications, it is essential to during pregnancy, birth weight, preterm delivery, preterm provide information regarding both major prelabour rupture of membranes, pre-eclampsia, parity and minor complications. In several studies, on September 30, 2021 by guest. Protected copyright. and previous caesarean delivery (adjusted OR 1.24, the risk of postpartum UTI and other puer- 95% CI 1.17 to 1.46). Using actual mode of delivery as peral infections has been found to be increased exposure, all types of operative delivery had an equally after caesarean delivery as compared with 1 increased risk of postpartum urinary tract infection Department of Gynecology vaginal delivery.5–7 However, there is a paucity and Obstetrics, Nordsjaellands compared with spontaneous vaginal delivery. Hospital, Hilleroed, Denmark Conclusions Compared with intended vaginal delivery, of data evaluating the risk of postpartum UTI 2Department of Gynecology and intended caesarean delivery was significantly associated by intended mode of delivery. This infor- Obstetrics, Holbaek Sygehus, with a higher risk of postpartum urinary tract infection. mation is useful in the clinical setting when Holbaek, Denmark Future studies should focus on reducing routine counselling the pregnant woman prior to 3 Department of Clinical catheterisation prior to operative vaginal delivery as well delivery about the perceived risks attributed Microbiology, Hvidovre Hospital, as improving procedures related to catheterisation. 8 Hvidovre, Denmark to the various modes of delivery. As the prev- 4Institute for Clinical Medicine, alence of emergency caesarean delivery or Department of Gynecology and operative vaginal delivery among women with Obstetrics, Aarhus University INTRODUCTIOn intended vaginal delivery varies in different Hospital, Aarhus, Denmark Urinary tract infection (UTI) is a common populations, information regarding risks Correspondence to postpartum infection occurring in 2%–4% attributed to the actual mode of delivery is 1–3 Ms. Tina Djernis Gundersen; of all deliveries. Although postpartum UTI also important when using data from other tinadgundersen@ gmail. com is usually a mild infection, it is associated populations. Gundersen TD, et al. BMJ Open 2018;8:e018479. doi:10.1136/bmjopen-2017-018479 1 Open Access BMJ Open: first published as 10.1136/bmjopen-2017-018479 on 14 March 2018. Downloaded from We examined the risk of postpartum UTI by intended restrictive definition of UTI. UTI was defined by a hospital and actual mode of delivery in a Danish national birth discharge diagnosis of lower or upper UTI or redemption cohort. of a prescription for a UTI-specific antibiotic within 30 days post partum, however, women who at any timepoint within the first 30 days post partum redeemed a prescrip- MATERIALS AND METHODS tion for dicloxacillin, benzylpenicillin or metronidazole This study is a nationwide, register-based cohort study (antibiotics not used for UTI treatment) were classified of all live births in Denmark from 1 January 2004 to as not having UTI, as we considered that they had been 31 December 2010 (n=450 856). treated for another kind of infection, that erroneously A database was established based on four popula- had been diagnosed as a UTI (online supplementary tion-based Danish registers: the Medical Birth Registry,9 appendix). the Fertility Database,10 the National Patient Registry,11 the Register of Medicinal Product Statistics12 and addi- Exposure tional data from Statistics Denmark.13 Codes from the Nordic Medico-Statistical Committee 16 No international review board approval was needed for classification of surgical procedures were used to this cohort study in accordance with Danish regulations. define mode of delivery as: planned caesarean delivery By use of the civil registration number, which is a unique prelabour, planned caesarean delivery in labour, personal identification number, linkage between registers emergency caesarean delivery prelabour, emergency was possible.13 After linkage, data were de-identified to caesarean delivery in labour and operative vaginal ensure data safety. delivery. According to Danish guidelines, a caesarean The Medical Birth Registry provided data on date delivery is classified as planned if the decision to deliver of birth, vital status at birth, mode of delivery, parity, by caesarean delivery is made more than 8 hours before multiple gestation, maternal smoking status, body mass delivery. index (BMI), previous caesarean delivery, birth weight The primary exposure was intended mode of delivery. and gestational age at birth. The Fertility Database linked Planned caesarean delivery prelabour and planned children to their mothers and provided date of birth for caesarean delivery in labour were merged to define the mother. The National Patient Registry contributed intended caesarean delivery. Intended vaginal delivery with hospital admission dates, discharge diagnoses for included spontaneous or operative vaginal delivery and complications during pregnancy and codes for surgical emergency caesarean delivery (prelabour or in labour). procedures related to delivery. The Register of Medicinal Spontaneous vaginal delivery was defined as delivery Product Statistics provided data on individual redemp- with no code recorded for an operative procedure at tion of prescriptions for antibiotics, all of which require birth (online supplementary appendix). Secondary http://bmjopen.bmj.com/ a prescription. When a prescription is redeemed, the exposure was actual mode of delivery. buyer’s civil registration number and the Anatomical Therapeutic Chemical code of the drug prescribed Other covariates are automatically linked to the specific date. Statistics Covariates were selected based on theory and knowledge 1 6 17 Denmark provided information on maternal educational from previous studies. Maternal covariates were status. age at delivery (continuous, years), smoking (current smoker, yes or no), pregestational BMI (≥25 or <25 kg/ Variable definitions m2), educational level (measured as highest completed Outcome education at childbirth: elementary school/high on September 30, 2021 by guest. Protected copyright. The primary outcome was defined as a hospital discharge school, short education/skilled worker, medium/long diagnosis of lower or upper UTI or redemption of a education) and previous caesarean delivery (yes or no). prescription