Effects of brief substance use interventions delivered in general medical settings: a systematic review and meta‐analysis

Abstract Aims To estimate effects of brief substance use interventions delivered in general medical settings. Methods A systematic review and meta‐analysis of randomized trials conducted since 1990 of brief substance use interventions in patients of any age or severity level recruited in general medical settings. Primary outcomes were any measure of substance use or substance‐related consequences (indexed with Hedges’ g and risk ratios). Mixed‐effects meta‐regressions were used to estimate overall effects and predictors of effect variability. Analyses were conducted separately by brief intervention (BI) target substance: alcohol only or drugs. Findings A total of 116 trials (64 439 participants) were identified; 111 (62 263 participants) provided effect size data and were included in the meta‐analysis. Drug‐targeted BIs yielded significant small improvements in multiple drug/mixed substance use (Hedges' g ) = 0.08; 95% CI = 0.002, 0.15), but after adjusting for multiple comparisons, they did not produce significant effects on cannabis use ( = 0.06; 95% CI = 0.001, 0.12), alcohol use ( = 0.08; 95% CI = −0.0003, 0.17), or consequences ( = 0.05; 95% CI = 0.01, 0.10). Drug‐targeted BIs yielded larger improvements in multiple drug/mixed substance use when delivered by a general practitioner ( = 0.19; 95% CI = 0.187, 0.193). Alcohol‐targeted BIs yielded small beneficial effects on alcohol use ( = 0.12; 95% CI 0.08, 0.16), but no evidence of an effect on consequences ( = 0.05; 95% CI = −0.04, 0.13). However, alcohol‐targeted BIs only had beneficial effects on alcohol use when delivered in general medical settings = 0.17; 95% CI = 0.10, 0.24); the findings were inconclusive for those delivered in emergency department/trauma centers ( = 0.05; 95% CI = 0.00, 0.10). Conclusions When delivered in general medical settings, alcohol‐targeted brief interventions may produce small beneficial reductions in drinking (equivalent to a reduction in 1 drinking day per month). There is limited evidence regarding the effects of drug‐targeted brief interventions on drug use.