LAUSR

The requirement that literature searches that identify studies for inclusion in systematic reviews should be systematic, explicit and reproducible extends, at least by implication, to other types of literature review. However, realist reviews commonly require literature searches which challenge systematic reporting; searches are iterative and involve multiple search strategies and approaches. Notwithstanding these challenges, reporting of the "realist search" can be structured to be transparent and to facilitate identification of innovative retrieval practices. Our six-component search framework, consolidates and extends the structure advanced by Pawson, one of the originators of realist review: formulating the question, conducting the background search, searching for programme theory, searching for empirical studies, searching to refine programme theory and identify relevant mid-range theory, and documenting and reporting the search process. This study reviews reports of search methods in 34 realist reviews published within the calendar year of 2016. Data from all eligible reviews were extracted against the search framework. Realist search reports poorly differentiate between the different search components. Review teams often conduct a single "big bang" multi-purpose search to fulfil multiple functions within the review. However, it is acknowledged that realist searches are likely to be iterative and responsive to emergent data. Overall the search for empirical studies appears most comprehensive in conduct and reporting detail. In contrast, searches to identify and refine programme theory are poorly conducted, if at all, and poorly reported. Use of this framework offers greater transparency in conduct and reporting while preserving flexibility and methodological innovation.