What works, for whom and under what circumstances? Using realist methodology to evaluate complex interventions in nursing: A scoping review.

Background: The Medical Research Council's (MRC) framework recommends basing every evaluation of a complex intervention on a theory that explains WHY an intervention works instead of focusing exclusively on the identification IF an intervention works. Theory-based evaluation approaches such as realist evaluations are promising in this respect. The aim of this scoping review is to examine current scientific literature with regard to the use of realist methodology in studies that evaluate complex nursing interventions. We also seek to answer the question whether realist evaluation studies of complex nursing interventions are embedded in the Medical Research Council's framework.

Methods: A systematic database search in MEDLINE and CINAHL supplemented with snowballing techniques and a hand search in relevant nursing journals were performed between January and February 2018 and updated in July 2019. Both authors independently screened the title / abstract of studies that were initially identified and appraised the full texts if inclusion criteria were fulfilled. Inclusion criteria were the explicit use of realist methodology and a focus on the development or evaluation of complex nursing interventions. Results were summarized narratively.

Results: A total of 28 articles from 22 studies, published between 2010 and 2019, were included. The majority of the studies included originate in the UK. Realist methodology was used by a variety of nursing disciplines, including midwifery, community / public health, critical care, palliative care, gerontological nursing, psychiatric nursing / mental health, and infection control. Study designs included case studies and realist reviews; two studies were conducted alongside a randomized controlled trial. All studies included used more than one method to develop their results; the majority of methods were qualitative by nature. Thirteen of the studies included aimed to develop a theory about what works, for whom and under what circumstances regarding the investigated complex nursing intervention. One study was clearly embedded in the Medical Research Council's framework.

Conclusion: Realist evaluation broadens the methodologies that have traditionally been used in nursing. Conceptual clarity on its principal tenets is still needed, as well as the methods used to assess them. Nursing scientists should be more critical when using novel methodology and contribute to academic debates about limitations. Embedding realist evaluations into the Medical Research Council's framework is in its infancy in nursing and needs more contributions in order to develop a common academic position within the profession. Tweetable abstract Realist methodology in nursing - review of the use, methods, limitations and embedding into the Medical Research Council's framework.