4.2 Reporting standards of included COSs
For the COS-STAR checklist, only 34.1% of studies can identify in the
title that the paper reports the development of a COS. The compliance
rates of 8 criteria belonging to ”introduction” and ”discussion”
sections were greater than 85%, and the compliance rates of 9 criteria
in the methods section ranged from 27.3% - 68.2%. The influence of
methodology on the quality of COSs was considered significant. More than
a third of the studies did not fully report protocol/registry entry,
information sources, and funding sources, which may reduce the
transparency of the COS developed. Moreover, only a few studies
published their protocol on peer-reviewed journals, and most registered
with limited information. We could not find any registration information
or published protocol for more than 40% of COSs. Given that no study
met the item 11 criterion (describe any changes from the protocol),
further consideration is needed whether COS not deviating from the
protocol should report this item. This would improve the applicability
and suitability of this criterion. The characteristics of the people
involved were not presented in 61.4% of studies. All outcomes
considered at the start of the consensus process and descriptions of any
other outcomes introduced/dropped during the consensus process were
absent in more than half of the studies. The recommended outcomes in
43.2% of COSs were unclear or ambiguous, which may limit their use.
Only twenty-four (54.5%) COSs met all two other information criteria
(sources of funding and conficts of Interest). Total COS-STAR compliance
criteria of OG COSs was significantly positively correlated with prior
protocol, indicating that COS developed with prior protocol may improve
the reporting quality of COS reporting. Therefore, further studies
should consider improving the transparency and robustness of the
reporting standard through publishing a previous protocol based on Core
Outcome Set-STAndardised Protocol Items (COS-STAP)
statement.3