Improving core outcome set development: qualitative interviews with developers provided pointers to inform guidance

OBJECTIVES: The objective of the study was to explore core outcome set (COS) developers' experiences of their work to inform methodological guidance on COS development and identify areas for future methodological research. STUDY DESIGN AND SETTING: Semistructured, audio-recorded interviews with a purposive sample of 32 COS developers. Analysis of transcribed interviews was informed by the constant comparative method and framework analysis. RESULTS: Developers found COS development to be challenging, particularly in relation to patient participation and accessing funding. Their accounts raised fundamental questions about the status of COS development and whether it is consultation or research. Developers emphasized how the absence of guidance had affected their work and identified areas where guidance or evidence about COS development would be useful including, patient participation, ethics, international development, and implementation. They particularly wanted guidance on systematic reviews, Delphi, and consensus meetings. CONCLUSION: The findings raise important questions about the funding, status, and process of COS development and indicate ways that it could be strengthened. Guidance could help developers to strengthen their work, but over specification could threaten quality in COS development. Guidance should therefore highlight common issues to consider and encourage tailoring of COS development to the context and circumstances of particular COS.