Unplugged, an European school-based programme for drug use prevention among adolescents: mid-term results from the EU-Dap cluster randomized trial

Background The empirical evidence of effectiveness of school-based programs against substance abuse is rather weak. A recent Cochrane review, pointed out that most high quality evaluation studies in this field have been conducted in North America. The main result of the review was that in the school context only skills-based programs seem to be effective in preventing drug use. To assess the generalizability of the US findings in the European context, and to cover the lack of European studies, the European Commission funded in 2002 the EU-Dap project. The study is a multicenter cluster randomized trial designed to conduct a rigorous evaluation of an innovative school-based curriculum for the prevention of substance use in European junior high schools. Methods The “Unplugged” program, based on a Comprehensive Social Influence approach and consisting of 12 one-hour sessions delivered by class teachers, was implemented in seven European countries during the 2004-2005 school year. One hundred and forty-three schools (7th, 8th and 9th grade) were randomised into three intervention arms (basic curriculum, basic plus peer involvement and basic plus parent involvement), and a usual curriculum control arm. A pre-test survey was conducted before the implementation of the program (n=7079), while two post-test surveys were conducted afterwards, the first 3 months after the end of the program (n=6370), and the second at 1 year follow-up (n=5541). Multilevel Analysis was used to investigate the effectiveness of the program in preventing and reducing drug use at the post test and at one year follow-up. Results At the post-test, the program was effective in reducing the prevalence of use in the last 30 days for all the analysed variables. The Prevalence Odds Ratios of use were 0.70 (0.52-0.94) for daily smoking (>20 cigarettes in the last 30 days), 0.72 (0.58-0.90) for sporadic drunkenness (at least once in the last 30 days), 0.69 (0.48-0.99) for regular drunkenness (>3 times) and 0.77 (0.60-1.00) for sporadic use of cannabis (at least once). At one year follow-up, the effectiveness on cigarettes use was not statistically significant anymore, while the effect on drunkenness episodes was maintained, with a Prevalence Odds Ratio of 0.80 (0.67-0.97) for sporadic drunkenness and of 0.62 (0.47-0.81) for regular drunkenness. The effect on cannabis use was slightly significant, with a POR of 0.74 (0.53-1.01) for regular use (>3 times in the last 30 days). Conclusions The EU-Dap project is the first large European evaluation of a comprehensive drug prevention program for adolescents. At the post test, it reduces of 25-30% the daily use of cigarettes, sporadic and regular drunkenness and sporadic use of cannabis. At one year follow-up, it reduces of 20% sporadic drunkenness episodes and of 40% the regular ones and it is likely to reduce of 25% regular use of cannabis. The program can therefore be recommended as an effective tool to prevent drug use among adolescents.