LAUSR

Cannabis misuse and opioid use disorder (OUD) are highly comorbid but under-treated and associated with poorer outcomes. This paper reports a double-blind, parallel-group randomized controlled trial to determine the efficacy of single-session, clinician-delivered screening and brief intervention (SBI) for reducing cannabis risk. The primary outcome was the cannabis-specific Alcohol, Smoking, and Substance Involvement Screening Test (ASSIST) scores, measured at three-month post-intervention. The secondary objectives were to determine the efficacy of SBI in reducing the frequency of cannabis use, in risk transition from moderate to low risk, and in prescription and non-prescription opioid use. One hundred forty-three participants were randomly allocated to receive either SBI (n = 72) or control (n = 71) interventions. We performed Per-protocol (PP) (n = 125) and Intention-to-treat (ITT) analysis (n = 143). We adjusted our analysis for age, sex, and baseline ASSIST score. The ITT showed that the SBI group had a significant reduction (F = 39.46, p < .001, Effect size 0.22) in the mean ASSIST at follow-up. PP analyses too revealed a similar positive effect of SBI (F = 53.1; p < .001, Effect size 0.31). At follow-up, the SBI group had a higher number of days of cannabis abstinence. Care providers and policymakers may consider SBI for cannabis use in individuals on medications for OUD.