Longitudinal patterns of sexual behavior and condom use in a cohort of HIV-negative gay and bisexual men in Vancouver, British Columbia, Canada, 1995-2000

OBJECTIVE: To characterize longitudinal patterns of sexual behavior in a cohort of young gay and bisexual men and determine their reasons for not using condoms. METHODS: Prospective data from a cohort of young gay and bisexual men aged 18 to 30 years were studied. Study participants had completed a baseline questionnaire and HIV test between May 1995 and April 1996 and four annual follow-up questionnaires. RESULTS: A total of 130 HIV-negative Vanguard participants met the eligibility criteria for this analysis. The median age at baseline was 26 years (range, 24-28). Most were white (79%), had completed high school (85%), were currently employed (82%), lived in stable housing (95%), and reported annual incomes of > or =$10,000 (82%). (All dollar amounts are given in Canadian dollars.) Consistently over the 5-year study period, > 70% of study subjects reported having > or =1 regular male sexual partners in the previous year. During each of the five successive 1-year periods, between 34% and 40% of respondents reported having had unprotected receptive anal intercourse with regular partners. Slightly fewer individuals (between 29%-39%) reported having had unprotected insertive anal intercourse with regular partners. Between 13% and 25% of participants reported having had insertive unprotected anal intercourse with casual sexual partners; and between 9% and 18% reported having had unprotected receptive anal intercourse with casual sexual partners. Reasons for engaging in unprotected anal intercourse varied depending on type of sexual partnership. CONCLUSION: High-risk sexual behaviors remained fairly consistent over a 5-year period in this study. This suggests that it is critically important to understand the motivations for unprotected sex when designing and implementing programs aimed at reducing HIV risk among young gay and bisexual men.