The incidence of pelvic inflammatory disease in untreated women infected with Chlamydia trachomatis: a structured review.

Because of the long-term consequences of pelvic inflammatory disease (PID), the cost-effectiveness of Chlamydia trachomatis screening depends in part on the incidence of PID in untreated, chlamydia-infected women. The aim of this study was to evaluate the original research assessing the incidence of PID following C. trachomatis infection. We conducted a thorough search of the literature and selected all available prospective cohort studies. Six studies had original data: the incidence of PID varied from 0% (97.5% confidence interval [CI] 0-12%) during one year of follow-up of 30 women to 30% (95% CI 12-54%) during 50 days of follow-up of 20 women. Studies that included asymptomatic women in other settings reported a lower incidence than those that evaluated women in sexually transmitted disease clinics. In conclusion, no study was of a size or quality to answer our research question definitively. Investigators and clinicians planning chlamydia-screening programmes need to be cognizant of the inconclusive incidence data.