Outcome reporting bias in Cochrane systematic reviews: a cross-sectional analysis

Ref ID 130
First Author K. Shah
Journal BMJ OPEN
Year Of Publishing 2020
URL https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7076244/pdf/bmjopen-2019-032497.pdf
Keywords • Cochrane
• Multiplicity
• General medical
• Protocols
• Pre-specification
Problem(s) • Undocumented or unjustified deviations to the review protocol
• Multiplicity of outcomes and lack of pre-specification for outcome reporting
Article Type Empirical
Article Subtype Cross-sectional survey/Methodological systematic review
First Author Country Canada
Aim To assess the presence of discrepancies in outcome reporting between protocol and published studies including inclusions of new outcomes, omission of prespecified outcomes, upgrade and downgrade of secondary and primary outcomes, and changes in definitions of prespecified outcomes in a sample of Cochrane reviews published between May 2007 and August 2014.
Level of Investigation Descriptive
Summary of Findings Of the 350 included Cochrane reviews, 150 (43%) review and protocol pairings contained discrepancies in outcome reporting. When reviews were further scrutinised, 23% (35 of 150) of reviews with discrepancies in outcome reporting contained a high risk of outcome reporting bias, with changes being made after knowledge of results from individual trials.
Number of systematic reviews included 350
Number of eligible systematic reviews assessed 3197
Treatment impacted No
Treatment impacted description
Interpretation impacted Not Applicable
Interpretation impacted description