Evaluation of an interactive mobile phone-based brief intervention to reduce driving under the influence of cannabis among emerging adults: A randomized controlled trial.

Background and Aims: Driving under the influence of cannabis (DUIC) is a national public health concern in the United States. The present study examined the efficacy of a mobile phone-based brief intervention aimed at reducing driving under the influence of cannabis among emerging adult cannabis users in the context of a randomized 3-group randomized clinical trial. Design: Participants in this RCT were randomly assigned to one of three conditions: a) a substance impaired-driving personalized feedback plus MI-style interactive text messaging intervention (PF + MIT), b) a substance impaired-driving personalized feedback only intervention (PF), and c) a substance information control condition (IC). Setting: Participants were recruited from a university in the Southeastern United States and within a 60-mile radius of campus. All interventions were delivered remotely via mobile phone. Participants: 149 emerging adults who endorsed driving under the influence of cannabis at least three times in the past three months were enrolled in the RCT. Intervention and comparator: Participants in the PF + MIT condition (n = 45) received personalized feedback on substance-impaired driving plus a series of interactive, motivational interviewing-style text messages delivered by a trained graduate student over a single session. Participants in the PF condition (n = 50) received personalized feedback only. The control group (IC; n = 54) received standard, non-personalized substance use information. Measurements: The primary outcome was the number of times driving under the influence of cannabis (DUIC) in the past 3 months, which was self-reported via mobile web survey during follow-up assessments at 3- and 6-months post-intervention. The secondary outcome was the number of times driving after simultaneous alcohol and cannabis use (DUIAC) in the past 3 months. Analyses followed an intention-to-treat (ITT) approach.