Network mixing and network influences most linked to HIV infection and risk behavior in the HIV epidemic among black men who have sex with men.

Objectives: We evaluated network mixing and influences by network members upon Black men who have sex with men.

Methods: We conducted separate social and sexual network mixing analyses to determine the degree of mixing on risk behaviors (e.g., unprotected anal intercourse [UAI]). We used logistic regression to assess the association between a network "enabler" (would not disapprove of the respondent's behavior) and respondent behavior.

Results: Across the sample (n = 1187) network mixing on risk behaviors was more assortative (like with like) in the sexual network (r(sex), 0.37-0.54) than in the social network (r(social), 0.21-0.24). Minimal assortativity (heterogeneous mixing) among HIV-infected men on UAI was evident. Black men who have sex with men reporting a social network enabler were more likely to practice UAI (adjusted odds ratio = 4.06; 95% confidence interval = 1.64, 10.05) a finding not observed in the sexual network (adjusted odds ratio = 1.31; 95% confidence interval = 0.44, 3.91).

Conclusions: Different mixing on risk behavior was evident with more disassortativity among social than sexual networks. Enabling effects of social network members may affect risky behavior. Attention to of high-risk populations' social networks is needed for effective and sustained HIV prevention.