Longer-Term Efficacy of a Digital Life-Skills Training for Substance Use Prevention

Abstract

The main objective of this study was to test the longer-term and differential efficacy of a mobile phone‒based life-skills training program designed to prevent substance use among adolescents. A 2-arm, parallel-group, cluster RCT with assessments at baseline and follow-up after 6 and 18 months was conducted. The efficacy of the intervention was compared with that of an assessment-only control condition. A total of 1,473 students with a mean age of 15.4 years were recruited in 2019/2020 within 89 Swiss secondary and upper secondary school classes. The automated intervention program included online feedback and individually tailored text messages provided over 22 weeks. The contents were based on social cognitive theory and addressed self-management, social, and substance use resistance skills. Primary outcomes included 30-day prevalence rates for problem drinking and tobacco use. The 18-month follow-up assessments were completed by 1,232 study (83.6%) participants. Those in the intervention group reported lower tobacco-smoking prevalence than the controls (OR=0.67; 95% CI=0.47, 0.96), but no significant difference in problem drinking (OR=0.84; 95% CI=0.61, 1.17) was observed. Among secondary outcomes, the intervention was effective at reducing cannabis-smoking prevalence (OR=0.55; 95% CI=0.39, 0.76) and cannabis use days (Cohen's d= -0.19; 95% CI= -0.29, -0.09), whereas no effects were observed for quantity of alcohol use, quantity of cigarettes smoked, well-being, or social skills. No significant moderators of the primary outcomes were observed. An automated mobile phone‒based life-skills training program produced longer-term effectiveness in preventing tobacco smoking and cannabis use, whereas no effects were observed for problem drinking. These results suggest that digitally delivered life-skills training programs are similarly effective and are an easy-to-implement alternative to training conducted within a school curriculum. This study is registered at ISRCTN41347061 (registration date: 21/07/2018).