Structured methodology review identified seven (RETREAT) criteria for selecting qualitative evidence synthesis approaches

OBJECTIVE: To compare and contrast different methods of qualitative evidence synthesis (QES) against criteria identified from the literature and to map their attributes to inform selection of the most appropriate QES method to answer research questions addressed by qualitative research. STUDY DESIGN AND SETTING: Electronic databases, citation searching and a study register were used to identify studies reporting QES methods. Attributes compiled from 26 methodological papers (2001-2014) were used as a framework for data extraction. Data were extracted into summary tables by one reviewer and then considered within the author team. RESULTS: We identified seven considerations determining choice of methods from the methodological literature, encapsulated within the mnemonic RETREAT (Review question - Epistemology - Time/Timescale - Resources - Expertise - Audience and purpose - Type of Data). We mapped 15 different published QES methods against these seven criteria. The final framework focuses on stand-alone QES methods but may also hold potential when integrating quantitative and qualitative data. CONCLUSION: These findings offer a contemporary perspective as a conceptual basis for future empirical investigation of the advantages and disadvantages of different methods of QES. It is hoped that this will inform appropriate selection of QES approaches.