PT - JOURNAL ARTICLE AU - Adamma Aghaizu AU - Fiona Reid AU - Sally Kerry AU - Phillip E Hay AU - Harry Mallinson AU - Jorgen S Jensen AU - Sarah Kerry AU - Sheila Kerry AU - Pippa Oakeshott TI - Frequency and risk factors for incident and redetected <em>Chlamydia trachomatis</em> infection in sexually active, young, multi-ethnic women: a community based cohort study AID - 10.1136/sextrans-2014-051607 DP - 2014 Nov 01 TA - Sexually Transmitted Infections PG - 524--528 VI - 90 IP - 7 4099 - http://sti.bmj.com/content/90/7/524.short 4100 - http://sti.bmj.com/content/90/7/524.full SO - Sex Transm Infect2014 Nov 01; 90 AB - Objective To investigate the frequency and risk factors for incident and redetected Chlamydia trachomatis infection in sexually active, young, multi-ethnic women in the community. Design Cohort study. Setting 20 London universities and Further Education colleges. Participants 954 sexually experienced women, mean age 21.5 years (range 16–27), 26% from ethnic minorities, who were recruited to the Prevention of Pelvic Infection (POPI) chlamydia screening trial between 2004 and 2006, and returned repeat postal self-taken vaginal swabs 11–32 (median 16) months after recruitment. Results The estimated annual incidence of chlamydia infection among 907 women who tested negative at baseline was 3.4 per 100 person-years (95% CI 2.5 to 4.6 per 100 person-years), but 6.6 per 100 person-years (95% CI 4.5 to 9.3 per 100 person-years) in the 326 teenagers (&lt;20 years). Predictors of incident chlamydia infection were age &lt;20 years (relative risk (RR) 4.0, 95% CI 2.1 to 7.5), and (after adjusting for age) a new sexual partner during 12 months follow-up (RR 4.4, 95% CI 2.0 to 9.9), smoking (RR 2.2 95% CI 1.2 to 3.9), concurrent bacterial vaginosis (RR 2.0 95% CI 1.1 to 3.9) and high risk carcinogenic human papillomavirus (RR 2.2, 95% CI 1.1 to 4.3). Of 47 women positive for chlamydia at baseline, 12 (25.5%, 95% CI 13.9% to 40.3%) had redetected infection at a median of 16 months follow-up. Taking into account follow-up time (65 person-years), the annual redetection rate was 18.5 per 100 person-years (95% CI 9.9 to 30.0 per 100 person-years). Conclusions One in four women with chlamydia infection at baseline retested positive, supporting recent recommendations to routinely retest chlamydia positives.