School-Based Substance Use Interventions: An Overview of Systematic Reviews and Meta-analysis

Schools offer a strategic setting for substance use prevention; however, program effectiveness remains uncertain. The objective of this study was to evaluate the efficacy of school-based approaches to preventing and reducing substance use for children and adolescents, while incorporating school ecosystem considerations. The data sources were from systematic reviews and RCTs published January 1, 2013, to September 1, 2024. The study selection was based on systematic reviews with clear inclusion/exclusion criteria, searches of >= 2 electronic databases, comprehensive evidence synthesis, and primary RCTs published after 2013 from included systematic reviews or an updated literature search. Eligible studies focused on children and adolescents (5-18 years) and school-based programs targeting the prevention or reduction of substance use compared to education as usual or no intervention. Two reviewers independently screened abstracts and full texts, extracted data, and evaluated risk of bias. Forty-three systematic reviews and 60 RCTs met inclusion criteria. Tobacco (n = 18 trials): moderate-quality evidence showed reduced short-term prevalence with teaching and learning interventions (RR, 0.89; [0.86,0.94]); multicomponent interventions demonstrated similar reductions up to 12 months (RR, 0.89 [0.80,0.99]). Alcohol (n = 9 trials): low-quality evidence indicated minimal effect of teaching and learning interventions (RR, 0.96 [0.87,1.06]). Cannabis (n = 11 trials): no significant effects (RR, 1.00 [0.84,1.19]). Illicit drug use (n = 8 trials): ineffective (RR, 1.00 [0.89,1.11]). Most reviews (62.8%) were of critically low quality. Low-quality evidence and heterogeneous outcome measures necessitate cautious interpretation. Programs demonstrated limited effectiveness in preventing or reducing substance use, suggesting a need to revise approaches toward more comprehensive whole-school strategies.