Gay men report high rates of unprotected anal sex with partners of unknown or discordant HIV status.

OBJECTIVE: To examine patterns and factors that correlate with unprotected anal intercourse (UAI) practices among San Francisco gay men, including UAI with partners of unknown or different HIV antibody status. DESIGN: A longitudinal cohort recruited for the San Francisco Young Men's Health Study in 1992; re-assessed annually. Participants and methods: A sample of 510 unmarried gay men who were 18 to 29 years at baseline were originally recruited as part of a larger population and referral-based sample. Subjects participated in four consecutive waves of data collection. RESULTS: The prevalence of reported unprotected anal intercourse (UAI) increased from 37% to 50% between 1993-1994 and 1996-1997. Almost half of all men who reported UAI in 1996-1997 indicated that it occurred with a partner of unknown or discordant HIV antibody status. This high-risk practice correlated with greater numbers of male sex partners, use of nitrite inhalants, sex in commercial sex environments, perceived difficulty controlling sexual risk-taking, and negative emotional reactions following UAI. CONCLUSIONS: These data on increasing rates of sexual risk-taking further confirm trends in sexual behavior previously suggested by rising rates of rectal gonorrhea in this population. Additional and sustained prevention efforts are urgently needed in light of the very high background rates of HIV infection found among gay men in San Francisco.