Risk behaviours and HIV infection among men having sexual relations with men: baseline characteristics of participants in the Omega Cohort Study, Montreal, Quebec, Canada

OBJECTIVE: To describe characteristics of men having sex with men (MSM) participating in the Omega Cohort, to describe HIV-positive participants at baseline interview, and to estimate HIV incidence. METHODS: The Omega Cohort is a study on the incidence and psychosocial determinants of HIV infection among MSM living in Montreal. MSM complete a questionnaire and are tested for HIV every six months. RESULTS: During the previous six months, 31% and 12% of 810 participants (mean age = 33 years) reported unprotected anal sex with regular and casual partners, respectively. Eight participants (0.98%) were HIV-infected at baseline. HIV incidence was 0.89 per 100 person-years (7/787 person-years) 95% confidence interval: 0.36-1.83]. CONCLUSION: A significant proportion of participants reported current risk behaviours. Despite this, HIV incidence is relatively low. It is important to target MSM who do not practice safe sex and to encourage those practicing safe sex to sustain these behaviours.