Most Cochrane systematic reviews and protocols did not adhere to the Cochrane’s risk of bias 2.0 tool

Abstract

OBJECTIVE: The aim of this study was to identify the frequency of Cochrane systematic reviews and Cochrane systematic reviews protocols using (or planning to use) the risk of bias 2.0 tool to assess the risk of bias of the included randomized clinical trials. STUDY DESIGN: This is a meta-research study. METHODS: We included Cochrane systematic reviews or Cochrane systematic reviews protocols that planned to include randomized clinical trials. We assessed the Cochrane Database of Systematic Reviews and screened for issues published after the launch of risk of bias 2.0 tool (2019-2022). Two independent investigators performed the study selection and data extraction. RESULTS: We analyzed 440 Cochrane systematic reviews and 536 Cochrane systematic reviews protocols. Overall, 4.8% of the Cochrane systematic reviews and 28.5% of the Cochrane systematic reviews protocols used or planned to use risk of bias 2.0 tool. Although low, adherence is increasing over time. In 2019, 0% of Cochrane systematic reviews used risk of bias 2.0 tool, compared to 24.1% in 2022. In Cochrane systematic reviews protocols, adherence increased from 6.9% in 2019 to 41.5% in 2022. A total of 274 (62.1%) Cochrane systematic reviews had their protocols published before 2018; only one used risk of bias 2.0 tool and reported the change of versions in the “Differences between protocol and revision” section. CONCLUSION: The Cochrane's risk of bias 2.0 tool has low adherence among Cochrane protocols and systematic reviews. Further efforts are necessary to facilitate the implementation of this new tool.