Main outcomes of M-bridge: A sequential multiple assignment randomized trial (SMART) for developing an adaptive preventive intervention for college drinking

Abstract

Objective: The goal was to develop a universal and resource-efficient adaptive preventive intervention (API) for incoming first-year students as a bridge to indicated interventions to address alcohol-related risks. The aims were to examine: (a) API versus assessment-only control, (b) the different APIs (i.e., 4 intervention sequences) embedded in the study design, and (c) moderators of intervention effects on binge drinking. Method: A sequential multiple assignment randomized trial (SMART) included two randomizations: timing (summer before vs. first semester) of universal personalized normative feedback and biweekly self-monitoring and, for heavy drinkers, bridging strategy (resource email vs. health coaching invitation). Participants (N = 891, 62.4% female, 76.8% White) were surveyed at the end of first and second semesters. The primary outcome was binge drinking frequency (4+/5+ drinks for females/males); secondary outcomes were alcohol consequences and health services utilization. Results: API (vs. control) was not significantly associated with outcomes. There were no differences between embedded APIs. Among heavy drinkers, the resource email (vs. health coach invitation) led to greater health services utilization. Moderator analyses suggested students intending to pledge into Greek life benefited more from any API (vs. control; 42% smaller increase from precollege in binge drinking frequency). Conclusions: Although overall effects were not significant, students at high risk (i.e., entering fraternities/sororities) did benefit more from the intervention. Furthermore, the resource email was effective for heavier drinkers. A technology-based strategy to deliver targeted resource-light interventions for heavy drinkers may be effective for reducing binge drinking during the transition to college. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Conflict of interest statement

Competing interests

The authors declare no conflicts of interest.

Figures

Figure 1:

Study design

Figure 2:

Model-estimated marginal means over time by group (primary aim, N=891)

Figure 3:

Model-estimated marginal means over time by API (secondary aim, N=591)

Figure 4:. Moderators of effect of randomization to any API on change in binge drinking from baseline to follow-up 1 (tertiary aim, N=891)

Note: The ratio of ratios measures the difference between the API group and assessment-only control in change in binge drinking frequency from baseline to follow-up 1. If the ratio of ratios is 1, there is no difference between the groups. If the ratio of ratios is below 1, the API had the desired effect, i.e., reduced the change in binge drinking frequency relative to control. In this figure, a nonzero slope is evidence of effect modification by the proposed moderator. P-values are for the moderator-by-API-by-follow-up-1 interaction.

Figure 5:. Moderators of main effect of Stage 2 selective bridging strategy on change in binge drinking from baseline to follow-up 1 in heavy drinkers only (tertiary aim, N=158)

Note: The ratio of ratios measures the difference between the coach group and the email group in change in binge drinking frequency from baseline to follow-up 1. If the ratio of ratios is 1, there is no difference between the groups. If the ratio of ratios is below 1, coach is better than email, i.e., the coach group had a smaller change in binge drinking frequency. If the ratio of ratios is above 1, email is better than coach. In this figure, a nonzero slope is evidence of effect modification by the proposed moderator. P-values are for the relevant interaction term.