65. CIRCUMCISION STATUS AND RISK OF SEXUALLY TRANSMITTED INFECTIONS IN THE HIM COHORT OF HOMOSEXUAL MEN IN SYDNEY, AUSTRALIA

Abstract

Objectives: To examine circumcision status as an independent risk factor for prevalent and incident sexually transmitted infections (STIs) in the community-based Health in Men (HIM) cohort of homosexual men.

Methods: Between 2001 and 2004, 1427 initially HIV-negative men were enrolled. Circumcision status was self-reported at baseline and was validated by clinical examination in a sub-sample of participants. All participants were tested annually for HIV and offered testing for other STIs including nucleic acid amplification tests (NAAT) for urethral gonorrhoea and chlamydia, and serology for syphilis and herpes simplex virus (HSV). Demographic information and past history of STIs was collected at baseline and detailed information on sexual risk behaviours was collected every 6 months. At annual face-to-face visits, participants reported diagnoses of STIs made in the previous 12 months.

Results: At baseline, 66% of participants reported being circumcised; mostly as infants. Uptake of STI testing was high with over 90% of participants tested each year. On multivariate analysis, controlling for age and sexual risk behaviour, circumcision was not associated with baseline seropositivity to syphilis (p = 0.34), HSV1 (p = 0.33) or HSV2 (p = 0.92), nor with a history of self-reported genital warts (p = 0.18). There was also no association with incident bacterial urethral infections (p = 0.67 & p = 0.89 for gonorrhoea and chlamydia, respectively), self-reported incident genital warts (p = 0.35), incident HSV1 (p = 0.70) or incident HSV2 (p = 0.36). However, circumcision was associated with a significantly reduced risk of incident syphilis after controlling for age, number of casual partners in the previous 6 months and unprotected anal intercourse according to partners' HIV status (HR = 0.35, 95% CI 0.14-0.87, p = 0.024).

Conclusion: Circumcised men had a reduced risk of incident syphilis in this cohort. Although most STIs were not associated with circumcision, these data suggest that circumcision may have an effect on syphilis acquisition in homosexual men.