Highlights
- •Redundant trials exist despite previous findings of the same clinical question.
- •Existing high certainty evidence may not be considered when planning new trials.
- •Redundant trials should be avoided because of their ethical implications.
Abstract
Objective
To identify clinical trials registered later than 2015, that study the effect of an
intervention on a primary outcome whose “Certainty of Evidence” (CoE) has already
been rated “high” in a Cochrane SR.
Study Design and Setting
We searched the Cochrane Library for all SRs from 2015. We analyzed SRs of interventions
and excluded withdrawn reviews or those with no Summary of Findings (SoF) table. We
retrieved the GRADE CoE ratings of each SR's primary outcomes in the SoF tables and
identified those rated “high.” We searched the World Health Organization International
Clinical Trials Registry Platform and ClinicalTrials to identify records of clinical
studies that tackled those outcomes and were registered after the date of publication
of the respective 2015 SR.
Results
We selected 602 SRs. Eighty-one contained a “high” CoE rating on at least one primary
outcome, totaling 152 primary outcomes rated “high.” We found 39 clinical trials registered
for primary outcomes with evidence already rated as “high” in a 2015 Cochrane SR.
Conclusion
This study shows the existence of clinical trials registered to study primary outcomes
whose CoE has already been rated “high” in a Cochrane SR.
Keywords
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Article info
Publication history
Published online: February 05, 2021
Accepted:
January 21,
2021
Footnotes
Declarations of interest: None.
Identification
Copyright
© 2021 Elsevier Inc. All rights reserved.
