Abstract
BACKGROUND: Little is known about the mechanisms of change underlying brief interventions and the patient characteristics that may affect them. The present study tested whether the stages of change mediate the effects of a BMI with and without a telephone booster relative to brief advice (i.e., multiple mediation). Further, the present study tested whether the effects of the BMI conditions on the stages of change were contingent on patients' alcohol use severity (i.e., moderated mediation). METHODS: The present study is a secondary analysis using data from injured adult patients at 3 trauma centers who were screened for inclusion in the study and randomly assigned to brief advice (n = 200), BMI (n = 203), or BMI with a telephone booster (n = 193) (Field et al., 2014). Participants completed a baseline assessment and 3-, 6-, and 12-month follow-up assessments that included self-report measures of the stages of change, alcohol use, and alcohol-related problems, as well as other variables of interest. RESULTS: The results demonstrated significant and consistent mediation at p < 0.05 wherein BMI with a telephone booster increased action at 3-month follow-up leading to reduced likelihood of at-risk drinking, less alcohol use, and fewer alcohol problems at both 6- and 12-month follow-up. However, moderated mediation analyses suggested that the effects of the BMI conditions on the stages of change were not contingent on patients' alcohol use severity. CONCLUSIONS: This study contributes to the understanding of stages of change as potential mechanisms of change in BMI. Directions for future research are discussed.