Pragmatic randomized controlled trial of a web-based intervention for alcohol use among Brazilian college students: Motivation as a moderating effect

Abstract

Background: Web-based personalized normative feedback (PNF) interventions are less effective than their laboratory versions. Participant motivation may account for this reduced effect, but there is only a limited amount of research into the influence of motivation on PNF effectiveness. We evaluated the effectiveness of a web-based PNF in reducing alcohol use and consequences among college students with different motivation levels.

Methods: Pragmatic randomized controlled trial among Brazilian college drinkers aged 18-30 years (N = 4460). Participants were randomized to a Control or PNF group and followed-up after one (T1), three (T2) and six (T3) months. Outcomes were: AUDIT score (primary outcome), the number of consequences, and the typical number of drinks. Motivation for receiving the intervention was assessed with a visual analog scale (range: 0-10). Generalized mixed models assessed intervention effects via two paradigms: observed cases and attrition models.

Results: PNF reduced the number of typical drinks at T1 (OR = 0.71, p = 0.002), T2 (OR = 0.60, p < 0.001) and T3 (OR = 0.68, p = 0.016), compared to the control. Motivated students (score ≥3) receiving PNF also reduced the number of typical drinks at T1 (OR = 0.60, p < 0.001), T2 (OR = 0.55, p < 0.001) and T3 (OR = 0.56, p = 0.001), compared to the control. However, the attrition models were more robust at T1 and T2. In contrast, low-motivated students receiving the PNF increased AUDIT score at T3 (b = 1.49, p < 0.001).

Conclusions: The intervention reduced alcohol use, and motivation for receiving the intervention moderated the intervention effects. Motivated students reduced their typical alcohol use, whereas low-motivated students increased their AUDIT score.

Keywords: Alcohol; College student; Internet; Motivation; Personalized normative feedback; Pragmatic trial.