Risk of reproductive complications following chlamydia testing:a population-based retrospective cohort study in Denmark

• Published in: The Lancet Infectious Diseases
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2016
• Subjects: Adolescent; Adult; Chlamydia Infections/complications; Chlamydia trachomatis/isolation & purification; Denmark/epidemiology; Female; Humans; Incidence; Pelvic Inflammatory Disease/etiology; Pregnancy; Ectopic/etiology; Retrospective Studies; Risk; Greenland
• Online Access: https://pure.au.dk/portal/en/publications/c295912b-3604-49c6-864f-9829fadd0385; https://doi.org/10.1016/S1473-3099(16)30092-5

BACKGROUND: Uncertainty in the risk of reproductive complications (pelvic inflammatory disease, ectopic pregnancy, and tubal factor infertility) following chlamydia infection and repeat infection hampers the design of evidence-based chlamydia control programmes. We estimate the association between diagnosed chlamydia and episodes of hospital health care (inpatient, outpatient, and emergency department) for a reproductive complication. METHODS: We constructed and analysed a retrospective population-based cohort of women aged 15-44 years from administrative records in Denmark (1995-2012). We used a subset of the national Danish Chlamydia Study. The master dataset contains all residents of Denmark (including Greenland) who had a positive chlamydia test recorded by a public health microbiology laboratory from Jan 1, 1992, to Nov 2, 2011. Individuals were randomly matched (by age and sex) to four individuals drawn from the population register (Danish Civil Registration System) who did not have a positive chlamydia test during this interval. The outcomes in the study were hospital episodes of health-care (inpatient, outpatient, and emergency department) with a diagnosis of pelvic inflammatory disease, ectopic pregnancy, or tubal factor infertility. FINDINGS: The 516 720 women (103 344 positive, 182 879 negative, 230 497 never-tested) had a mean follow-up of 7·96 years. Compared with women with only negative tests, the risk of each complication was 30% higher in women with one or more positive tests (pelvic inflammatory disease, adjusted hazard ratio [AHR] 1·50 [95% CI 1·43-1·57]; ectopic pregnancy, AHR 1·31 [1·25-1·38]; tubal factor infertility, AHR 1·37 [1·24-1·52]) and 60% lower in women who were never-tested (pelvic inflammatory disease, AHR 0·33 [0·31-0·35]; ectopic pregnancy, AHR 0·42 [0·39-0·44]; tubal factor infertility AHR 0·29 [0·25-0·33]). A positive test had a minor absolute impact on health as the difference in the lifetime incidence of complications was small between women who tested positive and those ...