Background: Mid-to-late adolescence is a critical period for initiation of alcohol and drug problems, which can be reduced by targeted brief motivational interventions. Web-based brief interventions have advantages in terms of acceptability and accessibility and have shown significant reductions of substance use among college students. However, the evidence is sparse among adolescents with at-risk use of alcohol and other drugs.
Objective: This study evaluated the effectiveness of a targeted and fully automated Web-based brief motivational intervention with no face-to-face components on substance use among adolescents screened for at-risk substance use in four European countries.
Methods: In an open-access, purely Web-based randomized controlled trial, a convenience sample of adolescents aged 16-18 years from Sweden, Germany, Belgium, and the Czech Republic was recruited using online and offline methods and screened online for at-risk substance use using the CRAFFT (Car, Relax, Alone, Forget, Friends, Trouble) screening instrument. Participants were randomized to a single session brief motivational intervention group or an assessment-only control group but not blinded. Primary outcome was differences in past month drinking measured by a self-reported AUDIT-C-based index score for drinking frequency, quantity, and frequency of binge drinking with measures collected online at baseline and after 3 months. Secondary outcomes were the AUDIT-C-based separate drinking indicators, illegal drug use, and polydrug use. All outcome analyses were conducted with and without Expectation Maximization (EM) imputation of missing follow-up data.
Results: In total, 2673 adolescents were screened and 1449 (54.2%) participants were randomized to the intervention or control group. After 3 months, 211 adolescents (14.5%) provided follow-up data. Compared to the control group, results from linear mixed models revealed significant reductions in self-reported past-month drinking in favor of the intervention group in both the non-imputed (P=.010) and the EM-imputed sample (P=.022). Secondary analyses revealed a significant effect on drinking frequency (P=.037) and frequency of binge drinking (P=.044) in the non-imputation-based analyses and drinking quantity (P=.021) when missing data were imputed. Analyses for illegal drug use and polydrug use revealed no significant differences between the study groups (Ps>.05).
Conclusions: Although the study is limited by a large drop-out, significant between-group effects for alcohol use indicate that targeted brief motivational intervention in a fully automated Web-based format can be effective to reduce drinking and lessen existing substance use service barriers for at-risk drinking European adolescents.
Trial registration: International Standard Randomized Controlled Trial Registry: ISRCTN95538913; http://www.isrctn.com/ISRCTN95538913 (Archived by WebCite at http://www.webcitation.org/6XkuUEwBx).
Keywords: adolescents; brief intervention; motivational interviewing; randomized controlled trial; substance use; web-based intervention.