Exploring the components of an efficacious computer brief intervention for reducing marijuana use among adults in the emergency department

Objective: To examine the efficacious components of a computer-delivered brief intervention (CBI) for reducing marijuana use among adults presenting to a low-income urban emergency department (ED), which a prior report found to decrease marijuana use at a 6-month follow-up. Method: Participants were 237 ED patients reporting recent drug use (46% male; 54% African-American; mean age, 30.7) who were randomized to receive a CBI consisting of an interactive program guided by a virtual health counselor. The primary outcome was past 30-day marijuana use at 6-month follow-up assessed using the Timeline Follow-Back (TLFB). Intervention components related to change in marijuana use at 6 month follow-up examined in the current study included participant responses to items within five CBI domains that were rooted in motivational interviewing: goals for change, strengths, evoking-change (concerns about use and benefits of change), challenges, and tools for change. Results: The evoking-change domain was related to significant reductions in marijuana use at 6 months (B = −2.91, SE = 1.10, p <.01). Within this domain, items focused on concerns about family and friends were related to reductions in marijuana use of up to 5.5 fewer days of marijuana use in the past month (B = −5.49, SE = 1.63, p <.01). Conclusions: An ED-based brief intervention, delivered by computer, was effective in reducing marijuana use. Intervention components focused on perceived concerns about use and benefits of change in relation to family and friends were critical domains within a CBI associated with reductions in marijuana use at 6-month follow-up.