School-based violence prevention programs: systematic review of secondary prevention trials

OBJECTIVE: To quantify the effectiveness of school-based violence prevention programs for children identified as at risk for aggressive behavior. DESIGN: Systematic review and meta-analysis of randomized controlled trials. Electronic databases and bibliographies were systematically searched and authors and organizations were contacted to identify randomized controlled trials. Standardized, weighted mean effect sizes were assessed by meta-analysis. SETTING: Elementary, middle, and high schools. PARTICIPANTS: Children at risk for aggressive behavior. MAIN OUTCOME MEASURES: Violent injuries, observed or reported aggressive or violent behaviors, and school or agency responses to aggressive behaviors. RESULTS: Of the 44 trials identified, none reported data on violent injuries. For the 28 trials that assessed aggressive behaviors, the pooled difference between study groups was -0.36 (95% confidence interval, -0.54 to -0.19) in favor of a reduction in aggression with intervention. For the 9 trials that reported data on school or agency responses to aggression, the pooled difference was -0.59 (95% confidence interval, -1.18 to 0.01). Subgroup analyses suggested greater effectiveness in older students and when administered to mixed-sex groups rather than to boys alone. CONCLUSIONS: School-based violence prevention programs may produce reductions in aggressive and violent behaviors in children who already exhibit such behavior. These results, however, need to be confirmed in large, high-quality trials.