Presentation (CTI)

OBJECTIVES: Substance use among adolescents generates significant long-term health and societal costs. Unplugged is a school-based prevention programme targeting psychoactive substance use in middle-school students and has been evaluated across Europe. In France, Santé publique France, as the programme’s evaluation coordinator, aimed to estimate its return on investment.
METHODS: A cost-benefit model from a societal perspective was developed, inspired by the Washington State Institute for Public Policy (WSIPP). It followed a cohort of French adolescents over their lifetime and covered tobacco, alcohol, and cannabis. Avoided costs included nicotine replacement therapy, cardiovascular diseases, cancers, fatal road accidents, end-of-life care, and years of life lost. A discount rate of 2.5% was applied for the first 30 years, then 1.5% thereafter. Scenario analyses explored alternative perspectives, assumptions on intervention effect duration and decay, inclusion of additional morbidity (alcohol-related cirrhosis, cannabis-related psychotic disorders), disability costs from road accidents, and the impact of cannabis-related school dropout, valued through lifetime income differences by education level.
RESULTS: In the base case, the cost-benefit ratio reached €148.74 per euro invested, corresponding to over €1.9 billion in avoided costs versus €28 million in programme costs. Benefits were mainly driven by alcohol-related outcomes. Restricting the analysis to a healthcare payer perspective reduced the ratio to €5.96 per euro. Assuming a shorter intervention effect (15 vs 24 months) lowered it to €59.51. Alternative decay functions (Weibull, exponential) produced ratios of €141.95 and €60.53, highlighting sensitivity to these assumptions.
CONCLUSIONS: Unplugged appears highly cost-beneficial. Even under conservative assumptions, returns substantially exceed implementation costs, and including additional morbidity and societal outcomes is likely to strengthen this conclusion.