Detection of Chlamydia trachomatis in rectal specimens in women and its association with anal intercourse: a systematic review and meta-analysis.

OBJECTIVES: Chlamydia trachomatis is the most commonly diagnosed bacterial STI. Lack of prevalence and risk factor data for rectal chlamydia in women has testing and treatment implications, as azithromycin (a first-line urogenital chlamydia treatment) may be less effective for rectal chlamydia. We conducted a systematic review of studies on women in high-income countries to estimate rectal chlamydia prevalence, concurrency with urogenital chlamydia and associations with reported anal intercourse (AI). DESIGN: Systematic review and four meta-analyses conducted using random-effects modelling. DATA SOURCES: Medline, Embase, Cumulative Index to Nursing and Allied Health Literature, PsycINFO and the Cochrane Database were searched for articles published between January 1997 and October 2017. ELIGIBILITY CRITERIA: Studies reporting rectal chlamydia positivity in heterosexual women aged ≥15 years old in high-income countries were included. Studies must have used nucleic acid amplification tests and reported both the total number of women tested for rectal chlamydia and the number of rectal chlamydia infections detected. Conference abstracts, case reports and studies with self-reported diagnoses were excluded. Data extracted included setting, rectal and urogenital chlamydia testing results, AI history, and demographics. RESULTS: Fourteen eligible studies were identified, all among diverse populations attending sexual health services. Among routine clinic-attending women, summary rectal chlamydia positivity was 6.0% (95% CI 3.2% to 8.9%); summary concurrent rectal chlamydia infection was 68.1% in those who tested positive for urogenital chlamydia (95% CI 56.6% to 79.6%); and of those who tested negative for urogenital chlamydia, 2.2% (95% CI 0% to 5.2%) were positive for rectal chlamydia. Reported AI was not associated with rectal chlamydia (summary risk ratio 0.90; 95% CI 0.75 to 1.10). CONCLUSIONS: High levels of rectal chlamydia infection have been shown in women with urogenital chlamydia infection. The absence of association between reported AI and rectal chlamydia suggests AI is not an adequate indicator for rectal testing. Further work is needed to determine policy and practice for routine rectal testing in women.