Using local sexual network data to characterize concurrency and sexual mixing patterns among men who have sex with men (MSM) enrolled in an HIV Prevention Project

Objectives: Sexual networks play an important role in HIV transmission. Concurrent partnerships facilitate increased rates of transmission, while sexual mixing/partner selection impact HIV transmission patterns, particularly when partnerships serve as a "bridge" from high to low prevalence subgroups leading to broader dissemination of HIV within a community. We estimated the prevalence and correlates of high-risk concurrency and high-risk discordant partnerships among MSM at risk for HIV transmission.;Methods: Sexually active MSM (N = 387) ages 16--72 enrolled from 2002--2004 in Seattle WA and Portland OR provided detailed information on sociodemographics, drug/alcohol use, and sexual behaviors during the prior 90 days via telephone-based interviews. Concurrency and high-risk concurrency (unprotected anal intercourse (UAI) within a concurrent partnership) were assessed. Discordant partnerships based on race/ethnicity, HIV serostatus, and age characteristics of participants and their partners, and high-risk (i.e., UAI within the partnership) discordant partnerships, were also evaluated for N = 995 partnerships reported by participants.;Results: Concurrency prevalence was 54.5% and high-risk concurrency was 15.0%. HIV positive men were more likely to report high-risk concurrency (APR 1.84; 95% CI 1.03-3.28), while those who met a recent partner through media were less likely to (APR 0.41; 0.20-0.83). Sexual mixing patterns revealed that 15.2% of partnerships were high-risk race discordant, 24.0% high-risk HIV serostatus discordant, and 12.7% high-risk age discordant. In multiple variable analysis, substance abusers (APR 1.60; 95% CI 1.09, 2.35) and those in a paid paying partnership (APR 1.77; 95% CI 1.04, 3.01) were more likely to report high-risk race discordant partnerships, while men reporting substance use (APR 1.39; 95% CI 1.05, 1.85) or drug use at last sexual encounter (APR 1.40; 95% CI 1.07, 1.83) were more likely to report high-risk HIV serostatus discordant partnerships.;Conclusions: Concurrency prevalence was high although there were few correlates, suggesting that risk is evenly distributed among MSM. Generalized rather than targeted prevention messages for MSM about risks of concurrent partnerships are most appropriate. Substance use/abuse was correlated with high-risk discordant partnerships and HIV prevention efforts targeting these individuals should be incorporated in all contexts that afford access to these individuals (e.g., HIV testing facilities).