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What is a process evaluation when used alongside a randomised controlled trial?
  1. Carol Bugge
  1. School of Health and Life Sciences, Glasgow Caledonian University, Glasgow, UK
  1. Correspondence to Professor Carol Bugge, School of Health and Life Sciences, Glasgow Caledonian University, Glasgow, UK; Carol.Bugge{at}

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Nursing research often tests complex interventions. For example, the intervention may be delivered by different nurses, with varying levels of seniority and expertise and in diverse geographical locations. The efficacy (can it work) or effectiveness (does it work in the real world) of complex interventions is often evaluated within randomised controlled trials (RCTs). The most recent UK Medical Research Council (MRC) guidance1 on developing and evaluating complex interventions has shifted the emphasis from a focus of solely understanding whether or not an intervention achieves its intended outcomes to additional considerations such as why and how an intervention may, or may not, have an effect. The complex nature of the intervention, and the context within which it is delivered, means that there are multiple other processes that may influence whether or not the intervention is effective in real-world clinical practice.2 Process evaluations are recommended to support understanding of these features that are beyond effectiveness.1–3 This paper will explore the use of process evaluation studies connected to RCTs.

What is meant by process evaluation?

Process evaluations studies may run alongside, or after, an RCT.2 3 A helpful definition is ‘a study which aims to understand the functioning of an intervention, by examining implementation, mechanisms of impact and contextual factors’.4 There are many examples of process evaluation in the literature, however, the studies are not always labelled as a process evaluation which may make them more difficult to identify.3 5 6

What areas of process are studied?

The processes that are of interest in any given study will vary depending on the phase of the research. For example, is the research developmental, evaluative or is its main focus implementation. The processes may be related to the trial itself (such as recruitment), the intervention …

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  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Provenance and peer review Commissioned; internally peer reviewed.