Through a realist lens: Looking for theories to explain successful residential treatment for substance use disorder.

Background: Fifteen years ago, Professor Moos suggested we should focus on understanding the relevance of common treatment processes to successful outcomes from addiction interventions rather than empirically testing treatments. He posited that treatment success could be explained by reference to theories of behaviour change. Notwithstanding that approach, researchers still rely on systematic reviews to answer ‘what works’, with varied success. Recently there have been calls for different research methods to be used to understand the complexity of treatment programmes. We used a novel literature review method within addiction research to identify theories that would explain outcomes from residential treatment for substance use disorder (SUD).

Methods: We conducted a realist review to unpick the mechanisms within complex treatment programmes. The review sought to explain outcome patterns using a model of generative causation identifying the circumstances in which mechanisms of change are activated, or not. The primary mode of analysis was retroductive – the process of inference used to explicate hidden mechanisms.

Results: We developed six programme theories to articulate the mechanisms of change described within the original studies. From these, we postulated three overarching theories that best explained successful and unsuccessful outcomes from residential treatment for SUD – the need to belong, meaning in life and self-determination theory.

Conclusion: A realist review offers addiction researchers a useful lens through which to understand the complexity of treatment programmes and to identify causal mechanisms. Realist reviews are more relevant than systematic reviews that extract data from studies which have removed complexity from the studied interventions. They build on the findings of idiographic constructivist studies by developing theory that supports transferability of findings. However, findings would be strengthened by the existence of primary studies that used realist research approaches.