Table 2. Summary of realist review methodology
Step 1Initial programme theory (IPT) developmentAn IPT is a first attempt to develop an understanding of the research question. To develop the IPT for this review, two scoping searches were run of the literature to identify: (a) existing theoretical perspectives; and (b) common intervention designs in relation to test-ordering practice. Full details of the search strategies are provided in supplementary Table S2. The IPT was further developed via the input of the stakeholder group and is presented in full in supplementary Figure S1.
Step 2Searching for evidenceThe main search for evidence was undertaken with the aim of assembling a body of relevant data that could be used to develop and refine the programme theory. A broad range of sources were searched (n = 15) to ensure that literature across multiple disciplines was considered. Full details of the main search strategy are provided in supplementary Table S3.Additional documents were identified via supplementary search methods such as citation tracking (snowballing) and via personal contacts and networks.69,70Further searches were undertaken later to identify relevant substantive theory to act as a theoretical lens through which to understand the review’s overall findings.71 The search strategies employed are provided in supplementary Table S4.
Step 3Selection and appraisalDocument selection was based on an assessment of relevance (whether or not documents contained data that could be used to develop theoretical explanations [‘programme theory’]) and rigour (whether data were considered credible in relation to their role in contributing to the theory).26,72Included documents provided data on important contexts, mechanisms, and outcomes related to clinician decision making in relation to laboratory test ordering in primary care settings, or provided data related to analogous settings or decisions, or relevant theoretical perspectives. More details on data selection processes are provided in supplementary Table S1.
Step 4Data extraction and organisationIncluded documents were read closely and coded in NVivo (version 12 Pro) to organise the data and identify important concepts that could inform the realist analysis. The characteristics of included documents (n = 145) are provided in supplementary Table S5.
Step 5Analysis and synthesisAnalysis and synthesis of included data involved the iterative development of realist ‘context–mechanism–outcome configurations’ (CMOCs).These are theoretical causal explanations describing how important contexts trigger the mechanisms that generate observed outcomes. Members of the stakeholder group provided feedback on the relevance and resonance of the developing theories. CMOC development and refinement continued until the reviewers agreed theoretical saturation was reached.A ‘final programme theory’ (FPT) was developed after consideration of the full set of CMOCs and drawing on theoretical literature.Full details of the CMOCs developed and illustrative data excerpts are provided in supplementary Tables S6–S8.