Comprehensive care processes for substance use disorders in adult mental health services: A systematic review

Assessment and care of substance use disorder within mental health services are essential due to the high prevalence and harms associated with comorbidity. Substance use disorder assessment and care are routinely recommended in clinical guidelines; however, processes are not agreed. This systematic review of routine clinical practice in relation to substance use disorders in adult mental health service aims to identify routine assessment and diagnosis processes, the proportion of patients and service episodes in which they occur and their outputs.

We searched MEDLINE, PsycINFO, Embase and relevant Cochrane databases for articles until July 2024 reporting on substance use assessment, diagnosis or treatment in adults receiving routine mental health service and locating additional articles by snowballing. Variables including setting, study method, period, cohort, substances, clinical assessment type, diagnosis and care pathways were compared.

In 137 heterogeneous studies reporting routine practice within a wide variety of adult mental health service from 29 nations, 44 (32%) expected or reported on substance use assessment in domains of pattern or impact. However, 23 studies (17%) reported structured approaches to substance use disorder assessment, while 67 (49%) reported a diagnostic structure, including classification system. Diagnostic prevalence varied markedly. Treatment was reported in 16 studies (12%) and no substance use disorder outcomes were reported.

This systematic review shows marked variation in routine practice in mental health service across a range of substance use disorder assessment and diagnosis processes. To better identify substance use disorder, enhance its care and reduce associated morbidity, adult mental health service may benefit from standardising expectations and systematically monitoring the performance of substance use assessment and diagnosis.