Predictors of repeat Chlamydia trachomatis infections diagnosed by DNA amplification testing among inner city females.

OBJECTIVE To describe the epidemiology of prevalent and incident chlamydia infection in order to assess the appropriate interval for chlamydia screening; and to identify risk factors predictive of infection and repeat infections. DESIGN Prospective longitudinal study of a consecutive sample of 3860 sexually active females aged 12-60 years tested for C. trachomatis by polymerase chain reaction in Baltimore City clinics during 11,904 patient visits over a 33 month period. RESULTS Chlamydia prevalence, incidence, and frequency to diagnosis of infection varied by age. Among 2073 females < 25 years, chlamydia infection was found in 31.2%. The median times to first and repeat incident infections were 7.0 months and 7.6 months, respectively. Among 1787 females > or = 25 years, chlamydia infection was found in 9.6%. Median times to first and repeat incident infections were 13.8 months and 11.0 months, respectively. Age < 25 years yielded the highest risk of infection. CONCLUSIONS Since a high burden of chlamydia was found among mostly asymptomatic females < 25 years in a spectrum of clinical settings, we recommend chlamydia screening for all sexually active females < 25 years at least twice yearly.