Rate of repeat diagnoses in men who have sex with men for Chlamydia trachomatis and Neisseria gonorrhoeae: a retrospective cohort study.

UNLABELLED Background Sexually transmissible infections (STIs) have increased rapidly among men who have sex with men (MSM). One of the most effective strategies to control STIs is partner notification. Inadequate partner notification may be associated with high rates of repeat diagnoses with STIs. The aim of this study is to estimate and compare the rate of chlamydia and gonorrhoea infection following primary infection to the overall clinic rate. METHODS A retrospective cohort analysis of MSM attending the Melbourne Sexual Health Clinic was conducted. For both infections, the overall incidence and that following diagnosis and treatment was calculated. RESULTS Of the 13053 MSM, the incidence of diagnoses for chlamydia and gonorrhoea was 8.5 (95% CI: 8.2-8.9) and 6.2 (95% CI: 5.9-6.5) per 100 person-years, respectively. Seventy per cent of chlamydia and 64% of gonorrhoea cases were retested at 10-365 days after diagnosis and treatment. Following diagnosis and treatment of chlamydia, the rate ratio in these individuals in the first quarter was 16- and 8-fold higher for chlamydia and gonorrhoea, respectively, compared with the background incidence of diagnoses. Similarly, following diagnosis and treatment of gonorrhoea, the rate ratio in these individuals in the first quarter was 18- and 10-fold higher for gonorrhoea and chlamydia, respectively. CONCLUSIONS These data suggest that approximately half of MSM who test positive for chlamydia or gonorrhoea within 90 days after an initial infection represent contact with either a previous sexual partner or member of the same sexual network, the remainder representing the particularly high STI risk for these MSM.