Achieving Integrated Treatment: A realist synthesis of service models and systems for co-existing serious mental health and substance use conditions

Approximately 30-50% of people with serious mental illness have co-existing drug/alcohol problems (COSMHAD), associated with adverse health/social care outcomes. UK guidelines advocate both co-occurring needs being met within mental health services but uncertainty remains about how to operationalise this to improve outcomes. Various unevaluated service configurations exist in the UK. A realist synthesis was undertaken to identify, test and refine programme theories (PTs) explaining how context shapes the mechanisms through which UK service models for COSMHAD work, for whom, and in what circumstances. Structured and iterative realist searches of 7 databases identified 5,099 records. A two-stage screening process identified 132 papers. Three broad contextual factors shaped COMSHAD services across 11 PTs: committed leadership; clear expectations regarding COSMAHD from mental health and substance use workforces; and clear care coordination processes. These contextual factors led to increased staff empathy, confidence, legitimisation and multidisciplinary ethos which improved care coordination, and increased people with COSMHAD’s motivations to work towards their goals. Our synthesis highlights that integrating COSMHAD care is complex and both individual and cultural behavioural shifts in leadership, workforce and service delivery is essential to ensure people with COSMHAD receive compassionate, trauma informed care that meets their needs.