Bias due to selective inclusion and reporting of outcomes and analyses in systematic reviews of randomised trials of healthcare interventions

Ref ID 141
First Author M. J. Page
Journal THE COCHRANE LIBRARY
Year Of Publishing 2014
URL https://pubmed.ncbi.nlm.nih.gov/25271098/
Keywords Cochrane
Protocols
Multiplicity
Pre-specification
General medical
Problem(s) Multiplicity of outcomes and lack of pre-specification for outcome reporting
Undocumented or unjustified deviations to the review protocol
Number of systematic reviews included 485
Summary of Findings Based on a meta-analysis of four of the seven included studies (which included 485 Cochrane Reviews), 38% (95% confidence interval (CI) 23% to 54%) of systematic reviews added, omitted, upgraded or downgraded at least one outcome between the protocol and published systematic review. The association between statistical significance and discrepant outcome reporting between protocol and published systematic review was uncertain. The meta-analytic estimate suggested an increased risk of adding or upgrading (i.e. changing a secondary outcome to primary) when the outcome was statistically significant, although the 95%CI included no association and a decreased risk as plausible estimates (RR 1.43, 95% CI 0.71 to 2.85; two studies, n = 552 meta-analyses). Also, the meta-analytic estimate suggested an increased risk of downgrading (i.e. changing a primary outcome to secondary) when the outcome was statistically significant, although the 95% CI included no association and a decreased risk as plausible estimates (RR 1.26, 95% CI 0.60 to 2.62; two studies, n = 484 meta-analyses).
Did the article find that the problem(s) led to qualitative changes in interpretation of the results? Yes
Are the methods of the article described in enough detail to replicate the study? Yes