LAUSR

OBJECTIVES Previous guidance of reporting guidelines recommends incorporating the Delphi method to integrate the opinions of experts for consensus when developing reporting guidelines. The purpose of this study was to clarify whether reporting guidelines typically employ the Delphi method, what factors may be associated with the employment of Delphi, and the reporting quality of Delphi. STUDY DESIGN AND SETTING We included all reporting guidelines (n=244) in the Enhancing the QUAlity and Transparency Of health Research (EQUATOR) Network published after January 1, 2011. We assessed the trends and factors associated with conducting Delphi, and the reporting quality of Delphi against current reporting guidelines. RESULTS Of 244, 62 (25%) used Delphi for consensus building. The proportion of reporting guidelines that used Delphi was less than 10% in 2011 and 2012, and 29% in 2019. Year of publication, number of authors, and multiple and simultaneous publications were associated with the use of Delphi. The reporting quality of the Delphi method was moderate in most reporting guidelines developed with Delphi. CONCLUSIONS The use of Delphi in reporting guidelines is insufficient. Users and reviewers should carefully appraise the consensus building in the guidelines. PROTOCOL AND REGISTRATION We applied a pre-specified protocol to conduct this study (Banno M, Tsujimoto Y, Kataoka Y. Reporting quality of the Delphi technique in reporting guidelines: a protocol for a systematic analysis of the EQUATOR Network Library. BMJ Open. 2019;9:e024942). The study was registered in the University Hospital Medical Information Network Clinical Trials Registry (UMIN-CTR) (Trial registration number: UMIN000032685, URL: https://upload.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000037271).