Abstract
AIMS: This meta-analysis reviewed 15 clinical trials (18 study sites/arms), examining the efficacy of an integrated cognitive-behavioral intervention (CBI) delivered to individuals with an alcohol or other drug use disorder and a co-occurring mental health disorder (AOD/MHD). Outcomes were alcohol or other drug use and mental health symptoms at post-treatment through follow-up. METHODS: The inverse-variance weighted effect size was calculated for each study and pooled under random effects assumptions. RESULTS: Integrated CBI showed a small effect size for AOD (g = 0.188, P = 0.061; I2 = 86%, τ2 = 0.126, k = 18) and MHD (g = 0.169, P = 0.024; I2 = 58%, τ2 = 0.052, k = 18) outcomes, although only MHD outcomes were statistically significant. Analysis by subgroup suggested that effect magnitude varied by type of contrast condition (integrated CBI + usual care vs. usual care only; integrated CBI vs. a single-disorder intervention), follow-up time point (post-treatment vs. 3-6 months) and primary AOD/MHD diagnosis, although these sub-groups often contained significant residual heterogeneity. In a series of mixed effects, meta-regression models, demographic factors were non-significant predictors of between-study heterogeneity. For AOD outcomes, greater effects were observed in higher quality studies, but study quality was not related to effect size variability for MHD outcomes. CONCLUSIONS: The current meta-analysis shows a small and variable effect for integrated CBI with the most promising effect sizes observed for integrated CBI compared with a single disorder intervention (typically an AOD-only intervention) for follow-up outcomes, and for interventions targeting alcohol use and/or post-traumatic stress disorder. Given the clinical and methodological variability within the sample, results should be considered a preliminary, but important step forward in our understanding of treatment for co-occurring AOD/MHD.