Background and objectives: Epidemiologic studies of chlamydial infections may often miss factors associated with the acquisition of infection.
Goal: To evaluate factors associated with risk for initial and recurrent Chlamydia trachomatis infections.
Study design: A retrospective study of patients attending a sexually transmitted disease clinic and, within this retrospective cohort, a nested case-control study.
Results: Among initial-negative subjects the crude incidence rate was 11.5 per 1,000 months of follow-up. Among initial-positive subjects, the crude incidence rate was 28 per 1,000 months of follow-up (RR = 1.8, 95% CI: 1.4-2.2). The increase in risk of infection associated with prior infection was independent of age. In the case-control study, a reduced risk of recurrent infection was associated with tubal ligation, hormonal contraception, and barrier contraception.
Conclusions: As well as targeting sexually active adolescents, prevention programs should recommend repeat testing for all women with prior chlamydial infection, irrespective of age. Furthermore, issues related to personal control of health may modify risk for infection.
PIP: Epidemiologic studies of Chlamydia trachomatis that evaluate women at only one time point may detect infections present for variable durations. To overcome this limitation, a retrospective review was conducted of the medical records of 2476 sexually transmitted disease clinic patients from Jefferson County, Alabama (US), who had been repeatedly tested for C. trachomatis in 1992-95. In addition, a nested case-control evaluation of 98 matched sets was performed of factors associated with recurrent chlamydial infection. The first culture was positive in 457 women (18.4%). Overall, the crude incidence rate of chlamydia was 28/1000 person-months of follow-up in women whose first culture was positive and 11.5/1000 person-months in those with an initially negative result (relative risk, 1.8; 95% confidence interval, 1.4-2.2). The increase in risk of infection associated with prior infection was independent of age. In the case-control study, use of barrier contraception, hormonal methods, and tubal ligation was protective against recurrent chlamydia, suggesting that personal control of health mediates risk. These findings suggest that all women with prior chlamydial infections should be retested, regardless of age.