Background Case studies involve up-close, in-depth, and detailed examination of a subject (the case) and related contextual conditions. They can capture lay perspectives and provide a ‘thick’ description of not just public health programme outcomes but implementation processes and context. Whilst being valued by practitioners, case study evidence is often poorly regarded by policy makers as anecdotal. This is especially true for ‘practice-based’ case studies that involve lay people in their production. There is potential to develop robust methods to synthesise practice-based case study evidence across multiple cases. This paper reports on a project to develop and pilot an approach to synthesising practice-based case study data concerning community wellbeing.

Methods We conducted a rapid review to scope and select appropriate methods for collecting and synthesising practice-based case studies. This involved existing collections of practice-based case studies (websites and reports), backward and forward citation searching of key methodological texts, and hand searching six key academic journals. One identified method was piloted on a sample of practice-based case studies about community infrastructure for community wellbeing.

Results Eighteen publically available case study collections were reviewed and the most common information fields mapped. None of the online collections undertook further synthesis of the case studies presented. A review of forty methodological texts found that: i) practice-based case studies are commonly descriptive and often used to celebrate successes, raising questions about the depth of information that is likely to be available in a synthesis; ii) a range of methods for synthesising research-based case studies exists, with matrices/frameworks commonly used to manage complexity, but we identified no specific methods for synthesising practice-based case study evidence; iii) traditional notions of validity and reliability are not appropriate measures of quality and alternative criteria of ‘convincingness’, ‘authenticity’, and ‘plausibility’ may be more useful; iv) and data collection templates can help standardise information and enhance quality of practice-based case studies and their synthesis.

Conclusion The synthesis method developed was piloted on a sample of practice-based case studies about community wellbeing. Results showed the value of synthesising practice-based case studies to produce rich data on context and processes of community projects, and information about health inequalities, but less data on outcomes. The method offers a means of supporting the production and effective utilisation of practice-based case studies in order to facilitate greater inclusion of experiential evidence from community practice into evidence-based public health.