CONCLUSION
Methodological and reporting quality of COS studies remains subject to
variation. This is most frequent in the involvement of patients as
research partners, outcome selection and the Delphi process. There is a
clear need for further methodological research within COS development
studies to determine the impact of qualitative research, the feasibility
and acceptability of global COS, and attrition bias upon the degree on
consensus. Clarification on these issues will help to promote the
research integrity of COS development studies. The importance of
implementation of COS also requires attention, including the impact and
on-going relevance of the final number of core outcomes on uptake in
clinical practice. Clarification on these areas will allow future core
outcome set developers to actively engage with published methodological
and reporting criteria and enhance the quality and ultimate success of
their studies.