Utility of risk-based chlamydia testing in primary care: analysis of retrospective surveillance data among women in Melbourne, Australia

Abstract

Background Chlamydia (Chlamydia trachomatis) continues to be a public health challenge in Australia, with some contention as to the best screening approach. In the present study we examined chlamydia testing, positivity and sexual behaviour among women with the aim of informing targeted testing among women aged ≥30 years. Methods: A longitudinal analysis was conducted on retrospective surveillance data collected among women attending general practice, family planning and sexual health clinics participating in sentinel surveillance in Melbourne, Australia. Women were aged ≥16 years and underwent urogenital testing for C. trachomatis (chlamydia) at participating clinics between 2007 and 2014. Chlamydia incidence was calculated as positive chlamydia tests over person-years (PY) among women and reported by 5-year age groups. A Cox regression model examined correlates of a positive chlamydia test among women aged ≥30 years. Results: In all, 36 770 women contributed 46 432 PY and 52 395 chlamydia tests, of which 2895 were positive. The overall chlamydia incidence rate was 6.2 per 100 PY (95% confidence interval (CI) 6.0–6.5). Chlamydia incidence declined with age, plateauing to <5 per 100 PY among women aged ≥30 years. Among women aged ≥30 years, being born in North-East Asia (adjusted hazard ratio (aHR) 2.9; 95% CI 1.9–4.5) and reporting multiple partners (aHR 2.5; 95% CI 1.8–3.5) in the past 12 months were associated with a positive chlamydia test. Conclusions: Chlamydia control remains challenging in Australia and optimising testing in primary care is a key priority. The results of the present study suggest that, at least among women aged ≥30 years, chlamydia testing should be risk-based and informed by appropriate sexual history taking.