Factors associated with unprotected anal intercourse among men who have sex with men: results from a respondent driven sampling survey in Nanjing, China, 2008.

Unprotected anal intercourse (UAI) is a well-documented risk factor for acquiring HIV, but not well-studied in China. We studied demographic and behavioral correlates for UAI among men who have sex with men (MSM) in a respondent-driven-sampling (RDS) survey in Nanjing, China. Four hundred and thirty MSM (including ten seeds) participated in this study, rendering an adjusted rate of UAI as 62.3 % (95 % CI 56.4-68.4 %). Adjusted HIV and syphilis prevalence rates were 6.6 % (95 % CI 3.0-10.4) and 12.6 % (95 % CI 8.1-18.3), respectively. HIV- and syphilis-positive cases were more likely to have engaged in UAI. Being unwilling to use condoms, meeting partners in non-conventional venues, having multiple male sex-partners in the past 6 months, having sex with regular and casual male partners in the past 6 months, and consumption of alcohol before sex were all positively associated with UAI. Based on the observed high prevalence of UAI among MSM in Nanjing, we can conclude that implementation of strategies to motivate MSM with high-risk behaviors to use condoms is urgently required in Nanjing.