HIV prevention research for men who have sex with men: a systematic review and meta-analysis.

A systematic review of HIV prevention reports published or distributed in the United States as of June 1998 yielded 9 rigorous controlled trials reporting intervention effects on unprotected sex for men who have sex with men. A summary measure of these effects was favorable (odds ratio,.69), statistically significant (95% confidence interval, 0.56-0.86), and very homogeneous. This summary value indicates a 26% reduction in the proportion of men engaging in unprotected anal intercourse. The most clearly favorable effects were observed among interventions that promoted interpersonal skills, were delivered in community-level formats, or focused on younger populations or those at higher behavioral risk. These studies demonstrate that interventions can promote risk reduction among men who have sex with men. Yet given the epidemiology of HIV in the United States, the small number of rigorous controlled intervention trials for this population is striking. Many more rigorous evaluations of HIV prevention efforts with men who have sex with men are needed to ascertain with confidence the effects of specific intervention components, population characteristics, and methodologic features.