Prevalence of Chlamydia trachomatis in a public colposcopy clinic population.

Background: Chlamydia trachomatis is a major public health issue, with notifications of this sexually transmitted disease continuing to rise in Australia. Women attending colposcopy clinics are referred for treatment of cervical abnormalities often associated with human papilloma virus (HPV) infection. There is evidence that women who have acquired one sexually transmitted infection, such as HPV, are at higher risk of acquiring another. Women attending colposcopy clinics may therefore be at risk of undiagnosed infection with C. trachomatis.

Aim: To determine the prevalence of C. trachomatis in women attending a public metropolitan colposcopy clinic in Victoria.

Methods: A cross-sectional study was performed. Institutional ethics committee approval and informed consent were obtained. Consecutive women attending the colposcopy clinic completed a questionnaire and had a swab collected from the endocervix for analysis by polymerase chain reaction for C. trachomatis. Positive screens were treated in accordance with best practice. Data were analysed with Minitab Version 2004 (Minitab Inc, State College, PA, USA).

Results: Of 581 women approached to participate in the trial, consent was obtained from 568 women (98%) and final outcome data was available on 560 women (99%). The overall rate of chlamydial infection was 2.1% (95% CI 1.5-2.7%). However, in women aged 25 years or less the rate was 5.8% (95% CI 3.8-7.8%) and in women over 25 years it was only 0.9% (95% CI 0.4-1.4%). Apart from age, no other demographic factor was significantly associated with chlamydial infection.

Conclusion: Although the prevalence of chlamydial infection in the colposcopy clinic population as a whole does not warrant a policy for routine screening, screening directed at women aged 25 years or less would gain the greatest yields in terms of cost efficacy. Such a policy should be implemented as standard practice.