The Effectiveness of Universal, Selective and Combined Prevention for Alcohol Use: Results from a Cluster Randomised Controlled Trial

Background: Alcohol use and associated harms are among the leading causes of burden of disease among young people, highlighting the need for effective prevention. The Climate and Preventure (CAP) study was the first trial of a comprehensive approach to alcohol use prevention which combined a universal intervention (delivered to an entire school year group) with a personality-targeted selective intervention (delivered to high-risk students only).

Method: A cluster randomized controlled trial was conducted between 2012-2015 with 2190 students (mean age: 13.3yrs) from 26 Australian high schools. Participants were randomized to receive one of four conditions; universal prevention for all students (Climate); selective prevention for high-risk students (Preventure); combined universal and selective prevention (Climate and Preventure; CAP); or health education as usual (Control). All students were followed up for 3 years post-baseline and a longer-term follow is currently underway. This longer-term follow-up will extend over a critical risk-period as students transition from school to early adulthood, spanning 7 years post baseline and assessing drinking, drug use, and other risk behaviours.

Results: Analyses up to 3-years post baseline demonstrate the effectiveness of universal, selective and combined approaches in preventing harmful alcohol use among both low- and high-risk adolescents, as well as reducing mental health symptoms in the high-risk students. Compared to control group, effect sizes for the universal, selective and combined interventions ranged from d = -0.21 to d = -0.56 (p<0.05), and Number Needed to Treat (NNT) values ranged from 6 to 12. These compare extremely favourably to other alcohol prevention programs. These results will be presented along with the study protocol of the long-term follow-up.

Conclusion: Results support the effectiveness of universal, selective and combined approaches to alcohol prevention up to 3 years post baseline. As very little is currently known about the effectiveness of school-based prevention programs beyond age 17, the longer-term follow-up of the CAP study which is underway will addresses a crucial knowledge gap. We hope the findings will indicate which prevention approaches are most sustainable long-term, vital information to inform policy nationally and internationally, as economic modelling suggests substantial societal benefit can be gained from even modest reductions in alcohol use.