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 health problems (SMI) have a co-existing alcohol/drug condition. Services for people with co-existing SMI and substance use (COSMHAD) are complex systems with outcomes affected by the type and severity of the mental health or alcohol/drug condition and the interplay between the two. This realist synthesis aimed to explain how context shapes the mechanisms through which service models for COSMHAD work, for whom and in what circumstances. The realist synthesis began with identification of 11 initial programme theories (IPTs) through a stakeholder workshop and policy analysis. Structured searches of 7 databases and iterative realist searches identified 5,099 articles. After two-stage screening, 132 articles were selected. Papers were mapped to the 11 IPTs, and Context, Mechanism and Outcome dyads and triads extracted, tested and refined.

Three broad contextual factors shaped COMSHAD services across the 11 programme theories (PTs): committed leadership, clear expectations regarding COSMAHD from the mental health and substance use workforce and clear coordination processes to integrate care. Within this context, workforce policy, coordinated care pathways and immersive workforce development (mechanism – resources) were shown to lead to increased staff empathy, confidence, legitimisation and multidisciplinary ethos (mechanism – responses) resulting in improved coordination and consistency of COSMHAD care and increased motivation from individuals with COSMHAD to work towards their goals (Outcomes).

The 11 PTs highlight the complexities of integrating care for COSMHAD within the UK service context. The 11 PTs provide insights into the context and mechanisms through which service models work, for whom and in what circumstances. At a meso (policy) level, the findings highlight the importance of committed leadership, workforce development and retention and clear care coordination. At a micro (practice) level, it demonstrates the importance of communication, coordination and collaboration between mental health and substance use providers to improve integration of COSMHAD services.