School-based prevention for illicit drugs use: A systematic review

Objective. To evaluate the effectiveness of school-based interventions in preventing or reducing drug use. Methods. The search strategy was conducted according to the Cochrane Collaboration method, and applied to MEDLINE, EMBASE, ERIC, PSYCHINFO, Cochrane Library, ACP Journal Club, Cochrane Drugs and Alcohol Group Register. RCTs and CCTs evaluating school-based interventions designed to prevent substance use were reviewed. Data were extracted independently by two reviewers. Quality was assessed. Interventions were classified as skills, affective, and knowledge focused. Results. 29 RCTs were included; 28 were conducted in the USA; most were focused on 6th–7th grade students. Compared with usual curricula, skills-based interventions significantly reduce marijuana use (RR = 0.82; 95% CI: 0.73, 0.92) and hard drug use (RR = 0.45; 95% CI: 0.24, 0.85), and improve decision-making skills, self-esteem, peer pressure resistance (RR = 2.05; 95% CI: 1.24, 3.42) and drug knowledge. Compared with usual curricula, affective interventions improve decision-making skills and drug knowledge, and knowledge-focused programs improve drug knowledge. Skills-based interventions are better than affective ones in improved self-efficacy. No differences are evident for skills vs. knowledge-focused programs on drug knowledge. Affective interventions improve decision-making skills and drug knowledge to a higher degree than knowledge-focused programs. Conclusion. Skills-based programs help to deter drug use. Well designed, long-term randomised trials, and evaluation of intervention components are required.