HIV risk among substance-using men who have sex with men and women (MSMW): findings from South Florida.

Compared with men who have sex with men only (MSMO), men who have sex with men and women (MSMW) consistently report higher rates of two HIV risk behaviors: transactional sex (TS) and concurrent substance use and sex (CSS). Within MSMW, little is known about how synergistic epidemics ("syndemics") affect TS and CSS. Using a sample of substance-using MSM (n = 515) in South Florida, we compared TS and CSS among MSMO and MSMW; examined whether, within MSMW (n = 86), TS and CSS predict unprotected anal intercourse with partners of serodiscordant/unknown HIV status (SU-UAI); and tested whether syndemics predict TS and CSS. MSMW reported higher rates of engaging in both TS and CSS (AOR = 1.7; 95 % CI 1.0-3.0). Within MSMW, engagement in both TS and CSS predicted SU-UAI (AOR = 3.3; 95 % CI 1.2-9.6); and syndemics predicted TS and CSS involvement (p < 0.01). Substance-using MSMW may benefit from interventions targeting TS, CSS, and background syndemics.