Objective: To examine factors that explain the effect of a cognitive-behavioral intervention on reductions in HIV transmission risk among HIV-infected men who have sex with men (MSM).
Method: Of the 1910 HIV-infected MSM screened, 616 participants considered to be at risk of transmitting HIV were randomized to a 15-session, individually delivered cognitive-behavioral intervention (n = 301) or a wait-list control (n = 315).
Results: Consistent with previous intent-to-treat findings, there was an overall reduction in transmission risk acts among MSM in both intervention and control arms, with significant intervention effects observed at the 5-, 10-, 15-, and 20-month assessments (risk ratios = 0.78, 0.62, 0.48, and 0.38, respectively). These intervention-related decreases in HIV transmission risk acts seemed to be partially due to sustained serosorting practices. MSM in the intervention condition reported a significantly greater proportion of sexual partners who were HIV infected at the 5- and 10-month assessments (risk ratios = 1.14 and 1.18).
Conclusions: The Healthy Living Project, a cognitive-behavioral intervention, is efficacious in reducing transmission risk acts among MSM. This seems to have been due in large part to the fact that MSM in the intervention condition reported sustained serosorting practices.