Cluster randomised controlled trial of an online intervention to prevent ecstasy and new psychoactive substance use among adolescents: final results and implications for implementation

Abstract

ObjectivesTo evaluate the effectiveness of the onlineClimate Schools: Ecstasy and Emerging Drugs moduleover 2 years, and examine the impact of intervention dose on outcomes.DesignCluster randomised controlled trial.SettingSecondary schools in Australia.Participants1126 students (aged 14.9 years) from 11 schools.InterventionFive schools were randomly allocated to the four-lesson internet-basedClimate Schools: Ecstasy and Emerging Drugsmodule. This universal intervention uses cartoon storylines to deliver harm-minimisation information about ecstasy and new psychoactive substances (NPS). It was delivered during health education classes over 4 weeks. Six schools were randomised to the control group (health education as usual). Participants were not blinded to intervention allocation.Outcomes measuresStudents completed self-report surveys at baseline, post-test, 6, 12 and 24 months post-baseline. Intentions to use ecstasy and NPS (including synthetic cannabis and synthetic stimulants), knowledge about ecstasy and NPS and lifetime use of ecstasy and NPS were assessed. This paper reports the results at 24 months post-baseline.AnalysisMixed effects regressions were conducted to analyse intervention effects from baseline to 24 months. Post hoc analyses using Inverse Probability of Treatment Weighting compared controls with students who: i) completed all four lessons (‘full dose’) and ii) partially completed the intervention (≤three lessons, ‘incomplete dose’).ResultsPrimary analyses found that controls were significantly more likely to intend on using synthetic cannabis compared with intervention group students (OR=3.56, p=0.01). Results from the weighted analyses indicated that controls reported significantly lower knowledge about ecstasy (p=0.001) and NPS (p=0.04) compared with the full-dose group. No significant differences were observed between the incomplete dose and control groups.ConclusionsThe online intervention was effective in modifying students’ intentions to use synthetic cannabis up to 24 months; however, this study highlights the importance of delivering prevention programmes in full to maximise student outcomes.Trial registration numberACTRN12613000708752.