Chlamydia trachomatis and the Risk of Pelvic Inflammatory Disease, Ectopic Pregnancy, and Female Infertility: A Retrospective Cohort Study Among Primary Care Patients

Abstract

Background: We evaluated the risk of pelvic inflammatory disease (PID), ectopic pregnancy, and infertility in women with a previous Chlamydia trachomatis (CT) diagnosis compared with women who tested negative for CT and CT untested women, considering both targeted and incidental (ie, prescribed for another indication) use of CT-effective antibiotics.

Methods: This was a retrospective study of women aged 12-25 years at start of follow-up within the Clinical Practice Research Datalink GOLD database linked to index of multiple deprivation quintiles, 2000-2013. CT test status and antibiotic use were determined in a time-dependent manner. Risk of PID, ectopic pregnancy, or female infertility were evaluated using of Cox proportional hazard models.

Results: We studied 857 324 women, contributing 6 457 060 person-years. Compared with women who tested CT-negative, women who tested CT-positive had an increased risk of PID (adjusted hazard ratio [aHR], 2.36; 95% confidence interval [CI], 2.01-2.79), ectopic pregnancy (aHR, 1.87; 95% CI, 1.38-2.54), and infertility (aHR, 1.85; 95% CI, 1.27-2.68). The PID risk was higher for women with 2 or more positive CT tests than those with 1 positive test. PID risk increased with the number of previous antibiotic prescriptions, regardless of CT test status.

Conclusions: We showed an association between CT-positive tests and 3 adverse reproductive health outcomes. Moreover, this risk increased with repeat CT infections. CT-effective antibiotic use showed no decreased risks of subsequent PID regardless of CT history. Our results confirm the reproductive health burden of CT, which requires adequate public health interventions.

Keywords: Chlamydia trachomatis; CPRD; adverse reproductive health; antibiotics.

Figure 1.

Flow diagram of women included in the study per exclusion step. Abbreviations: CPRD, Clinical Practice Research Datalink; IMD, index of multiple deprivation; SES, socioeconomic status; UK, United Kingdom. *Numbers add up to more than the total number of women excluded in this step because a woman could have a history of more than 1 of the excluded conditions.

Figure 2.

Classification of follow-up time according to CT test status and antibiotic use. Abbreviations: CT, Chlamydia trachomatis; PID, pelvic inflammatory disease. Never use = no antibiotic prescription was issued during follow-up; current use = the most recently recorded antibiotic prescription was issued in the past 3 months; recent use = the most recently recorded prescription was issued between 4 months and 3 years ago.