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.