Process evaluation of complex interventions: Medical Research Council guidance

TLDR

Complex interventions, such as those targeting smoking and obesity, require process evaluation to understand implementation and contextual factors, because randomized trials alone cannot explain how interventions work or can be replicated. The updated MRC guidance aims to provide a framework for conducting and reporting process evaluation studies within complex intervention trials. The guidance was developed through a 2010 MRC‑funded workshop that brought researchers together to identify the need for and design a process evaluation framework. The workshop concluded that researchers, funders, and reviewers would benefit from clear guidance on process evaluation.

Abstract

Process evaluation is an essential part of designing and testing complex interventions.New MRC guidance provides a framework for conducting and reporting process evaluation studiesAttempts to tackle problems such as smoking and obesity increasingly use complex interventions.These are commonly defined as interventions that comprise multiple interacting components, although additional dimensions of complexity include the difficulty of their implementation and the number of organisational levels they target. 1Randomised controlled trials are regarded as the gold standard for establishing the effectiveness of interventions, when randomisation is feasible.However, effect sizes do not provide policy makers with information on how an intervention might be replicated in their specific context, or whether trial outcomes will be reproduced.Earlier MRC guidance for evaluating complex interventions focused on randomised trials, making no mention of process evaluation. 2 Updated guidance recognised the value of process evaluation within trials, stating that it "can be used to assess fidelity and quality of implementation, clarify causal mechanisms and identify contextual factors associated with variation in outcomes." 3However, it did not provide guidance for carrying out process evaluation. Developing guidance for process evaluationIn 2010, a workshop funded by the MRC Population Health Science Research Network discussed the need for guidance on process evaluation. 4There was consensus that researchers, funders, and reviewers would benefit from guidance.A group of researchers with