Brief Interventions for Cannabis Use in Healthcare Settings: Systematic Review and Meta-analyses of Randomized Trials

Objectives: The efficacy of brief interventions for cannabis use was assessed in a systematic review and meta-analyses. Methods: Systematic searches in academic databases were conducted, and reference lists of included studies were reviewed. Randomized trials were included that compared brief interventions with minimal control interventions for improving cannabis-specific outcomes among participants recruited from healthcare settings. Mean differences (MDs) based on change-from-baseline measurements were pooled using random-effects meta-analyses, with stratification by short term (<= 3 months) and long term (>3 months). Results: Ten reports from 9 studies were included. Most studies were conducted in the United States, including participants who were adults and were recruited from primary care or emergency departments. There were no significant effects of brief interventions on cannabis-specific Alcohol, Smoking and Substance Involvement Screening Test (ASSIST) scores in the short term (MD -1.27 points; 95% confidence interval [CI] -3.75, 1.21; I-2 84.40%). The null pattern of findings was also observed for number of days of cannabis use in the past 30 days in the short term (MD -0.22 days; 95% CI -2.27, 1.82; I-2 60.30%) and long term (MD -0.28 days; 95% CI -2.42, 1.86; I-2 60.50%). The evidence base for other outcomes not subjected to meta-analyses was limited and mixed. Conclusions: Brief interventions did not result in reductions in cannabis-specific ASSIST scores or number of days of cannabis use, whereas the evidence base for other outcomes was limited and mixed. As such, brief interventions in healthcare settings may not be efficacious for cannabis use.