Concurrent Disorders and Treatment Outcomes: A Meta-Analysis.

Objectives: This rapid review and meta-analysis explores two hypotheses. First, people with a concurrent mental health and substance use disorder (SUD) respond less favorably to currently utilized treatment interventions, than do those with a single disorder. Second, the potential for certain already vulnerable groups including women, members of racialized minority groups and those who live in or near poverty may be even further disadvantaged.

Methods: A multimethod sampling frame of 35 previous systematic reviews and or meta-analyses (2000-2024) augmented with peer-reviewed and grey research literature databases (2020-2024), resulted in the selection of 13 primary studies.

Results: The pooled, sample-weighted risk ratio of 1.71 (95% confidence interval 1.38, 2.13) seemed to strongly suggest that those with concurrent disorders are largely disadvantaged in treatment compared to those with a single disorder.

Conclusions: The results of this review confirmed people with a concurrent disorder are twice as likely to experience such undesirable outcomes as relapse and related poor outcomes including emergency department visits, rehospitalization and death. However, no evidence was found enabling exploration of potential moderations of overall treatment effects by gender, race or income.