Objective: This meta-analysis examined 53 controlled trials of cognitive-behavioral treatment (CBT) for adults diagnosed with alcohol- or illicit-drug-use disorders. The aims were to provide an overall picture of CBT treatment efficacy and to identify client or treatment factors predictive of CBT effect magnitude.
Method: The inverse variance weighted effect size (Hedges' g) was calculated for each study and pooled using fixed and random effects methods. Potential study-level moderators were assessed in subgroup analyses by primary drug, type of CBT, and type of comparison condition. In addition, seven client and treatment variables were examined in meta-regression analyses.
Results: Across studies, CBT produced a small but statistically significant treatment effect (g = 0.154, p < .005). The pooled effect was somewhat lower at 6-9 months (g = 0.1 15, p < .005) and continued to diminish at 12-month follow-up (g = 0.096, p < .05). The effect of CBT was largest in marijuana studies (g = 0.513, p < .005) and in studies with a no-treatment control as the comparison condition (g = 0.796, p < .005). Meta-regression analyses indicated that the percentage of female participants was positively associated and the number of treatment sessions was negatively associated with effect size.
Conclusions: The findings demonstrate the utility of CBT across a large and diverse sample of studies and under rigorous conditions for establishing efficacy. CBT effects were strongest with marijuana users, when CBT was compared with no treatment, and may be larger with women than with men and when delivered in a brief format.