Efficacy of peer-led interventions to reduce unprotected anal intercourse among men who have sex with men: a meta-analysis.

OBJECTIVE:To conduct a systematic review and meta-analysis to evaluate the efficacy of peer-led interventions in reducing unprotected anal intercourse (UAI) among men who have sex with men (MSM). METHODS:Randomized clinical trials (RCTs), quasi-experimental studies, pre- and post-intervention studies without control groups, and serial cross-sectional assessments involving peers delivering interventions among MSM and published as of February 2012 were identified by systematically searching 13 electronic databases and cross-referencing. Effect sizes (ES) were calculated as the changes of standardized mean difference (SMD) in UAI between groups or pre-post intervention. RESULTS:A total of 22 studies met the eligibility criteria, including five RCTs, six quasi-experimental studies, six pre-and-post intervention studies, and five serial cross-sectional intervention studies. We used 15 individual studies including 17 interventions for overall ES calculation; peer-led interventions reduced UAI with any sexual partners in meta-analysis (mean ES: -0.27; 95% confidence interval [CI]: -0.41, -0.13; P<0.01). Subgroup analyses demonstrated a statistically significant reduction on UAI in quasi-experimental studies (mean ES: -0.30; 95% CI: -0.50, -0.09; P = 0.01) and serial cross-sectional intervention studies (mean ES: -0.33; 95% CI: -0.57, -0.09; P = 0.01), but non-significant reduction in RCTs (mean ES: -0.15; 95% CI: -0.36, 0.07; P = 0.18) or pre- and post-intervention studies (mean ES: -0.29; 95% CI: -0.69, 0.11; P = 0.15). Heterogeneity was large across these 15 studies (I2 = 77.5%; P<0.01), largely due to pre-and-post intervention studies and serial cross-sectional intervention studies. CONCLUSIONS:Peer-led HIV prevention interventions reduced the overall UAI among MSM, but the efficacy varied by study design. More RCTs are needed to evaluate the effect of peer-led interventions while minimizing potential bias.