Recommendations for future core outcome set developers and wider stakeholders
  1. Core outcome set developers should integrate methodological research into their studies to help determine the impact of qualitative methods upon final core outcome set development
  2. The feasibility and of global acceptability of core outcome sets needs further exploration to develop guidance for researchers which inform stakeholder selection and expectations regarding geographical representation.
  3. When discussing the Delphi survey, attrition should be clearly reported for individual stakeholder groups, the reasons for participant withdrawal described, and the impact of attrition bias upon the degree of consensus considered
  4. Where core outcome sets include a large number of outcomes or when outcome domains are included, further refinement is required to ensure they can be implemented within future research.
  5. Core outcome set developers should commit to supporting the implementation of their core outcome sets, including engaging with research funding organizations, individual researchers, and systematically examining prospective registry records, protocols, and published research.