A cluster randomized controlled trial of school-based prevention of tobacco, alcohol and drug use: The EU-Dap design and study population

Background The empirical evidence of effectiveness of many school-based programs against substance abuse is rather weak. The EU-Dap study is a multicenter cluster randomized community trial (CRCT) designed to evaluate such a program. This paper presents study design and baseline characteristics of the study population. Methods 170 schools from 9 centers from seven countries (Austria, Belgium, Germany, Greece, Italy, Spain, Sweden), stratified according to average social status in the catchment area, were randomized to either three variants of the active intervention (basic curriculum, basic with peer involvement, and basic with parent involvement) or to a control group. The program under evaluation is based on a comprehensive social influence approach, and was delivered during the scholar year 2004–2005 to a population of 12- to 14-year-old students attending junior high school. An anonymous questionnaire administered before and after the intervention was used to track behavioral and attitudinal changes. Results All in all, we included in the study 143 schools and 7079 students, of which 3547 in the intervention groups and 3532 in the control group. At baseline, 34.9% of students had smoked cigarettes, 24.7% had been drunk, and 8.9% had used cannabis at least once in life. Discussion EU-Dap is the first European multicenter randomized study to evaluate the effectiveness of a school program targeting tobacco, alcohol and drug use. The baseline assessment showed high prevalence and wide geographical variations of substance use.