Individual and situational factors that influence the efficacy of personalized feedback substance use interventions for mandated college students

Abstract

Little is known about individual and situational factors that moderate the efficacy of personalized feedback interventions (PFIs). Mandated college students (N = 348) were randomly assigned either to a PFI delivered in the context of a brief motivational interview (BMI; n = 180) or to a written PFI only (WF) condition and were followed up at 4 months and 15 months postintervention. The authors empirically identified heterogeneous subgroups utilizing mixture modeling analysis based on heavy episodic drinking and alcohol-related problems. The 4 identified groups were dichotomized into an improved group (53.4%) and a nonimproved group (46.6%). Logistic regression results indicated that the BMI was no more efficacious than the WF across all mandated students. However, mandated students who experienced a serious incident requiring medical or police attention and those with higher levels of alcohol-related problems at baseline benefited more from the BMI than from the WF. It may be an efficacious and cost-effective approach to provide a written PFI for low-risk mandated students and an enhanced PFI with a BMI for those students who experience a serious incident or have higher baseline alcohol-related problems.

Figure 1

A flowchart of recruitment, participation, and follow-up rates.

Figure 2

Analyzed mixture models using latent change variables. Solid lines indicate directly estimated parameters and dotted lines indicate either fixed parameters (i.e., factor loadings) or a mixture part of the analyzed model (i.e., class to latent variables). Social desirability was constrained to be equal in mean, variance, and its paths across classes. Level = Outcome levels at 15 months post intervention, IC = Initial change from baseline to 4 months post intervention, SC = Subsequent change from 4 months to 15 months post intervention. Figure 3 shows the results for each alcohol use measure. T1 = baseline, T2 = 4 months post intervention, T3 = 15 months post intervention.

Figure 3

Estimated mean growth trajectories of heavy episodic drinking (HED; Figure 3a) and alcohol-related problems (AP; Figure 3b) for the four-class models specified as shown in Figure 2. In all subsequent analysis, classes 1 through 3 were combined into a single non-improved group, and class 4 was classified as an improved group. pp = the average posterior probability for the most likely class.

Figure 4

The interaction of PFI condition with incident seriousness. The BMI is more efficacious than the WF for mandated students who were referred after a serious incident. BMI = Brief Motivational Interview Intervention; WF = Written Feedback Only Intervention.

Figure 5

The interaction of PFI condition with baseline level of alcohol-related problems (AP). The BMI is more efficacious than the WF for mandated students with higher levels of AP at baseline. BMI = Brief Motivational Interview Intervention; WF = Written Feedback Only Intervention.