Randomised controlled trial of screening for Chlamydia trachomatis to prevent pelvic inflammatory disease: the POPI (prevention of pelvic infection) trial

Abstract

Objective To determine whether screening and treating women for chlamydial infection reduces the incidence of pelvic inflammatory disease over the subsequent 12 months.Design Randomised controlled trial.Setting Common rooms, lecture theatres, and student bars at universities and further education colleges in London.Participants 2529 sexually active female students, mean age 21 years (range 16-27).Intervention Participants completed a questionnaire and provided self taken vaginal swabs, with follow-up after one year. Samples were randomly allocated to immediate testing and treatment for chlamydial infection, or storage and analysis after a year (deferred screening controls).Main outcome measure Incidence of clinical pelvic inflammatory disease over 12 months.Results Baseline prevalence of chlamydia was 5.4% (68/1254) in screened women and 5.9% (75/1265) in controls. 94% (2377/2529) of women were followed up after 12 months. The incidence of pelvic inflammatory disease was 1.3% (15/1191) in screened women compared with 1.9% (23/1186) in controls (relative risk 0.65, 95% confidence interval 0.34 to 1.22). Seven of 74 control women (9.5%, 95% confidence interval 4.7% to 18.3%) who tested positive for chlamydial infection at baseline developed pelvic inflammatory disease over 12 months compared with one of 63 (1.6%) screened women (relative risk 0.17, 0.03 to 1.01). However, most episodes of pelvic inflammatory disease occurred in women who tested negative for chlamydia at baseline (79%, 30/38). 22% (527/2377) of women reported being tested independently for chlamydia during the trial.Conclusion Although some evidence suggests that screening for chlamydia reduces rates of pelvic inflammatory disease, especially in women with chlamydial infection at baseline, the effectiveness of a single chlamydia test in preventing pelvic inflammatory disease over 12 months may have been overestimated.Trial registration ClinicalTrials.gov NCT00115388.

Chlamydia trachomatis Infection and Reproductive Health Outcomes in Women

“…In contrast, two randomized trials comparing chlamydia screening in young women with a control group not invited for testing found a 50% reduction in PID over the subsequent year (64,82). Finally, in another randomised trial, limited evidence was observed suggesting that screening for chlamydia reduces PID rates: 10% of asymptomatic infected women not treated developed PID within a year, versus 2% of screened and treated women (63). Further studies evaluating the effectiveness of chlamydia screening are clearly needed.…”

“…However, the risk of developing PID among C. trachomatis-infected women is not well known since few prospective studies have been performed and the number of cases included has generally been small. Despite these limitations, the risk seems to be high: the results of a recent randomised controlled trial performed in the UK that included 75 women with untreated, asymptomatic C. trachomatis infection found that 9.5% (95% CI 4.7%-18.3%) developed PID over 1 year (63). Although current data are limited, the risk of developing PID seems to be higher in the first few weeks of infection (41).…”

Tubal Damage, Infertility and Tubal Ectopic Pregnancy: Chlamydia trachomatis and Other Microbial Aetiologies

“…These authors conclude that their study shows that a longer duration of the asymptomatic period results in a more pronounced impact of a screening programme (Althaus et al, 2010). The incidence of PID in untreated women infected with C. trachomatis has been reviewed and widely discussed in the literature in terms of (1) its cost-effectiveness as a screening program and (2) as a predictor of tubal damage in infertile patients (Aghaizu et al, 2008;Althaus et al, 2010;Bakken & Ghaderi 2009;den Hartog et al, 2008;Dietrich et al, 2010;Kalwij et al, 2010;Land et al, 2010;Low et al, 2009;Low & Hocking 2010;Oakeshott et al, 2010;Risser & Risser 2007;Simms & Horner 2008). In a comprehensive study that evaluated all available original research and assessed the incidence of PID following C. trachomatis infection, it was concluded that no study could adequately answer the question and that many studies either had inaccuracies, validition problems or only indirect evidence to support their reported incidences (Risser and Risser, 2007).…”

“…The baseline prevalence of Chlamydia was 5.4% in the screened population of 2529 sexually active female students (mean age 20.9 years) and 5.9% in (deferred screening) controls with the incidences of PID found to be 1.3% and 1.9% respectively in these cohorts. It was reported that after 12 months, most episodes of PID occurred in women who tested negative for Chlamydia at baseline (9.5%) when compared to the intervention group (1.6%) and these authors concluded that the effectiveness of a single Chlamydia test in preventing PID over 12 months may also have been overestimated (Oakeshott et al, 2010). A Danish randomised trial was conducted with 9-year follow-up testing of 4000 asymptomatic women for the presence of urogenital Chlamydia trachomatis.…”

“…Furthermore, it was proposed by these authors that an effective approach when assessing biological outcomes of chlamydial infection currently reuqires multiple rounds of screening in randomized control trials (RCT) (Low et al, 2009). A recent RCT (the POPI-prevention of pelvic infection-trial) was undertaken to determine whether a single screening test and treating a subset of 2529 women for chlamydial infection can in fact reduce the incidence of PID over a 12-month period (Oakeshott et al, 2010). The baseline prevalence of Chlamydia was 5.4% in the screened population of 2529 sexually active female students (mean age 20.9 years) and 5.9% in (deferred screening) controls with the incidences of PID found to be 1.3% and 1.9% respectively in these cohorts.…”