Effectiveness of the 'Healthy School and Drugs' prevention programme on adolescents' substance use: a randomized clustered trial

Aim: To evaluate the effectiveness of the Healthy School and Drugs programme on alcohol, tobacco and marijuana use among Dutch early adolescents.
Design: Randomized clustered trial with two intervention conditions (i.e. e-learning and integral).
Setting: General population of 11-15-year-old adolescents in the Netherlands.
Participants: A total of 3784 students of 23 Dutch secondary schools.
Measurements: Structured digital questionnaires were administered pre-intervention and at 32 months follow-up. The primary outcome measures were new incidences of alcohol (life-time and 1-month prevalence), tobacco (life-time and 1-month prevalence) and marijuana use (life-time prevalence).
Findings: Main effect analyses showed no programme effects on incidences of alcohol consumption (life-time prevalence: e-learning condition: B = 0.102, P = 0.549; integral condition: B = −0.157, P = 0.351; 1-month prevalence: e-learning condition: B = 0.191, P = 0.288; integral condition: B = −0.140, P = 0.445), tobacco consumption (life-time prevalence: e-learning condition: B = 0.164, P = 0.444; integral condition: B = 0.160, P = 0.119; 1-month prevalence: e-learning condition: B = 0.088, P = 0.746; integral condition: B = 0.261, P = 0.093), or marijuana consumption (life-time prevalence: e-learning condition: B = 0.070, P = 0.732; integral condition: B = 0.186, P = 0.214).
Conclusion: The non-significant impact of the Healthy School and Drugs programme (a Dutch school-based prevention programme for early adolescents) on incidences of alcohol, tobacco and marijuana use indicates that the programme is either ineffective or implemented inadequately.