The value of social practice theory for implementation science: learning from a theory-based mixed methods process evaluation of a randomised controlled trial

BACKGROUND: Although there is trial evidence that complex interventions are effective for the self-management of heart failure, little evidence supports their effectiveness in routine practice. We used Social Practice Theory to guide a Type 1 Hybrid Trial: a mixed methods process evaluation of a complex intervention for heart failure. The objective of this paper is to explore the value of Social Practice Theory for implementation science. METHODS: Social Practice Theory informed a mixed methods process evaluation of a multi-centre randomised controlled trial of a 12 week home-based intervention to optimise self-care support for people with heart failure and their caregivers - Rehabilitation EnAblement in Chronic Heart Failure (REACH-HF). Interviews were conducted with 19 people with heart failure and 17 caregivers at 4 months and 12 months after recruitment into the trial. Cases were constructed at the level of the individual, couple, facilitator and centre; and included multi-modal process and outcome data. Evaluative coding and subsequent within- and cross-case analyses enabled the development of a typology of relationships linking fidelity of intervention delivery and tailoring of content to individual needs and concerns. Social Practice Theory was used to interrogate the relationships between elements of the intervention and their implementation. RESULTS: Of 216 trial participants, 107 were randomised to the intervention (REACH-HF plus usual care). The intervention was most effective when fidelity was high and delivery was tailored to the individual's needs, but less effective when both tailoring and fidelity were low. Theory-based analysis enabled us to model complex relationships between intervention elements (competencies, materials and meanings) and social context. The findings illustrate how intervention fidelity and tailoring are contextual and how the effectiveness of the REACH-HF intervention depended on both optimal alignment and implementation of these elements. CONCLUSION: The study demonstrates the utility of theory-based analysis which integrates data from multiple sources to highlight contexts and circumstances in which interventions work best. Social Practice Theory provides a framework for guiding and analysing the processes by which a complex intervention is evaluated in a clinical trial, and has the potential to guide context-specific implementation strategies for clinical practice. TRIAL REGISTRATION: ISRCTN, IISRCTN86234930 . Registered 13th November 2014.