title: Efficacy of peer-led interventions to reduce unprotected anal intercourse among men who have sex with men: a meta-analysis.
abstract: 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.
authors.affiliation: Vanderbilt Institute for Global Health, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America; State Key Laboratory for Infectious Disease Prevention and Control, and National Center for AIDS/STD Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China.
authors.forename: Shaodong
authors.initials: S
authors.lastname: Ye
authors.affiliation: Vanderbilt Institute for Global Health, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America.
authors.forename: Lu
authors.initials: L
authors.lastname: Yin
authors.affiliation: Center for Health, Intervention and Prevention, University of Connecticut, Storrs, Connecticut, United States of America.
authors.forename: Rivet
authors.initials: R
authors.lastname: Amico
authors.affiliation: Department of Psychology, University of Washington, Seattle, Washington, United States of America.
authors.forename: Jane
authors.initials: J
authors.lastname: Simoni
authors.affiliation: Vanderbilt Institute for Global Health, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America; Departments of Pediatrics, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America.
authors.forename: Sten
authors.initials: S
authors.lastname: Vermund
authors.affiliation: State Key Laboratory for Infectious Disease Prevention and Control, and National Center for AIDS/STD Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China.
authors.forename: Yuhua
authors.initials: Y
authors.lastname: Ruan
authors.affiliation: State Key Laboratory for Infectious Disease Prevention and Control, and National Center for AIDS/STD Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China.
authors.forename: Yiming
authors.initials: Y
authors.lastname: Shao
authors.affiliation: Vanderbilt Institute for Global Health, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America; Division of Epidemiology, Departments of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America.
authors.forename: Han-Zhu
authors.initials: HZ
authors.lastname: Qian
mesh_terms: D006801:Humans; D008297:Male; D001003:Anal Canal / Q000502:physiology; D003075:Coitus / Q000502:physiology; D018451:Homosexuality, Male; D010379:Peer Group; D017594:Publication Bias; D047568:Unsafe Sex / Q000517:prevention & control; D002986:Clinical Trials as Topic