A just-in-time adaptive personalized mobile app intervention produces limited short-term reductions in heavy episodic drinking frequency in college students: A randomized control trial during the COVID-19 pandemic.

Background: High-risk drinking among college students is common, and alcohol expectancies and experienced consequences are proximal predictors of use. This study tested short- and long-term efficacy of a personalized just-in-time adaptive intervention with daily messages about alcohol use, alcohol expectancies, and consequences delivered via mobile app.

Methods: Participants were 408 students enrolled at a 2- or 4-year college (75% 4-year; 64% female) who completed twice-daily assessments for 21 days and follow-up surveys at 1-, 6-, and 12-months. Data collection spanned January 2020 through April 2022. Participants were randomized to either an intervention condition receiving daily intervention messages and other related alcohol and expectancy-focused content via the app or an assessment-only control condition. Both conditions were administered daily surveys through the app.

Results: Poisson multilevel models were conducted to examine intervention effects on alcohol outcomes (i.e., drinks per week, heavy episodic drinking frequency, peak estimated blood alcohol concentration, and alcohol-related consequences, as well as positive and negative alcohol expectancies) at each follow-up assessment. On average, participants in both conditions reported decreased alcohol use outcomes, consequences, and expectancies at 1-, 6-, and 12-month follow-up compared to baseline. A single statistically significant difference between participants in the intervention and control conditions was observed at 1-month follow-up. Specifically, participants in the intervention condition reported a 17% greater decrease in heavy episodic drinking frequency than participants in the control condition, on average.

Conclusions: Findings highlight the complexities of developing, implementing, and testing adaptive interventions, particularly within the context of the COVID-19 pandemic.