Effectiveness of training family physicians to deliver a brief intervention to address excessive substance use among young patients: a cluster randomized controlled trial.

Background: Brief interventions delivered by family physicians to address excessive alcohol use among adult patients are effective. We conducted a study to determine whether such an intervention would be similarly effective in reducing binge drinking and excessive cannabis use among young people. Methods: We conducted a cluster randomized controlled trial involving 33 family physicians in Switzerland. Physicians in the intervention group received training in delivering a brief intervention to young people during the consultation in addition to usual care. Physicians in the control group delivered usual care only. Consecutive patients aged 15-24 years were recruited from each practice and, before the consultation, completed a confidential questionnaire about their general health and substance use. Patients were followed up at 3, 6 and 12 months after the consultation. The primary outcome measure was self-reported excessive substance use ( 1 episode of binge drinking, or 1 joint of cannabis per week, or both) in the past 30 days. Results: Of the 33 participating physicians, 17 were randomly allocated to the intervention group and 16 to the control group. Of the 594 participating patients, 279 (47.0%) identified themselves as binge drinkers or excessive cannabis users, or both, at baseline. Excessive substance use did not differ significantly between patients whose physicians were in the intervention group and those whose physicians were in the control group at any of the follow-up points (odds ratio [OR] and 95% confidence interval [CI] at 3 months: 0.9 [0.6-1.4]; at 6 mo: 1.0 [0.6-1.6]; and at 12 mo: 1.1 [0.7-1.8]). The differences between groups were also nonsignificant after we re stricted the analysis to patients who reported excessive substance use at baseline (OR 1.6, 95% CI 0.9-2.8, at 3 mo; OR 1.7, 95% CI 0.9-3.2, at 6 mo; and OR 1.9, 95% CI 0.9-4.0, at 12 mo). Interpretation: Training family physicians to use a brief intervention to address excessive substance use among young people was not effective in reducing binge drinking and excessive cannabis use in this patient population. Trial registration: Australian New Zealand Clinical Trials Registry, no. ACTRN12608000432314.