The effectiveness of a school-based substance abuse prevention program: 18-month follow-up of the EU-Dap cluster randomized controlled trial

Aim: To evaluate the effectiveness of a school-based substance abuse prevention program developed in the EU-Dap study (EUropean Drug Addiction Prevention trial). Materials and methods: Cluster Randomized Controlled Trial. Seven European countries participated in the study; 170 schools (7079 pupils 12–14 years of age) were randomly assigned to one of three experimental conditions or to a control condition during the school year 2004/2005. The program consisted of a 12-h curriculum based on a comprehensive social influence approach. A pre-test survey assessing past and current substance use was conducted before the implementation of the program, while a post-test survey was carried out about 18 months after the pre-test. The association between program condition and change in substance use at post-test was expressed as adjusted prevalence odds ratio (POR), estimated by multilevel regression models. Results: Persisting beneficial program effects were found for episodes of drunkenness (any, POR = 0.80; 0.67–0.97; frequent, POR = 0.62; 0.47–0.81) and for frequent cannabis use in the past 30 days (POR = 0.74; 0.53–1.00), whereas daily cigarette smoking was not affected by the program as it was at the short-term follow-up. Baseline non-smokers that participated in the program progressed in tobacco consumption to a lower extent than those in the control condition, but no difference was detected in the proportion of quitters or reducers among baseline daily smokers. Conclusion: The experimental evaluation of an innovative school curriculum based on a comprehensive social influence approach, indicated persistent positive effects over 18 months for alcohol abuse and for cannabis use, but not for cigarette smoking.