A systematic review and meta-analysis of the prevalence of alcohol and other drug use and problematic use among people accessing mental health treatment in Australia

Objective: Substance use and use disorders are elevated among people accessing mental health treatment, but the nature and patterns of use are unknown. The current study aimed to identify the prevalence of alcohol and other drug (AOD) use and problematic AOD use (i.e. hazardous, harmful, risky, misuse, abuse, dependence, disorder) in Australian mental health settings and conduct a meta-analysis of studies where sufficient data were available.Method: A systematic review of all papers published up to July 2023 identified 59 eligible studies reporting the prevalence of substance use, problematic use, and use disorders among people accessing mental health treatment in Australia. Overall, 55 studies provided sufficient data for a meta-analysis for past year use and problematic use of any AOD overall, alcohol, cannabis, tobacco, stimulants/amphetamines, and opioids.Results: Pooled prevalence estimates of past year use and problematic use among clients of mental health treatment settings varied (5%-58% and 7%-53%, respectively). Past year use and past year problematic use of tobacco were particularly prevalent (58% and 53%, respectively), as was cannabis (38% and 37%, respectively). Several key factors, including the type of mental health disorder, may explain some variation in prevalence estimates.Conclusion: The presence of co-occurring and problematic AOD use should be expected among a considerable proportion of clients of mental health treatment settings, and are a significant concern that services must be prepared to address. As such, screening and assessment of AOD use and use disorders should be part of routine clinical care, and clinicians should be familiar with evidence-based management and treatment strategies, including those that address tobacco.