Comparison of Reporting and Transparency in Published Protocols and Publications in Umbrella Reviews: Scoping Review

Background: Inconsistencies between a protocol and its umbrella review (UR) may mislead readers about the importance of findings or lead to false-positive results. Furthermore, not documenting and explaining inconsistencies in the UR could reduce its transparency. To our knowledge, no study has examined the methodological consistency of the protocols with their URs and assessed the transparency of the URs when generating evidence. Objective: This study aimed to investigate the inconsistency of protocols with their URs in the methodology and assess the transparency of the URs. Methods: We searched medical-related electronic databases from their inception to January 1, 2022. We investigated inconsistencies between protocols and their publications and transparencies in the search strategy, inclusion criteria, methods of screening and data extraction, quality assessment, and statistical analysis. Results: We included 31 protocols and 35 publications. For the search strategy, 39 inconsistencies between the protocols and their publications were found in 26 of the 35 (74%) URs, and 16 of these inconsistencies were indicated and explained. There were 84 inconsistencies between the protocols and their URs regarding the inclusion criteria in 31 of the 35 (89%) URs, and 29 of the inconsistencies were indicated and explained. Deviations from their protocols were found in 12 of the 32 (38%) URs reporting the methods of screening, 14 of the 30 (47%) URs reporting the methods of data extraction, and 11 of the 32 (34%) URs reporting the methods for quality assessment. Of the 35 URs, 6 (17%) were inconsistent with their protocols in terms of the tools for quality assessment; one-half (3/6, 50%) of them indicated and explained the deviations. As for the statistical analysis, 31 of the 35 (89%) URs generated 61 inconsistencies between the publications and their protocols, and 16 inconsistencies were indicated and explained. Conclusions: There was a high prevalence of inconsistencies between protocols and publications of URs, and more than one-half of the inconsistencies were not indicated and explained in the publications. Therefore, how to promote the transparency of URs will be a major part of future work.