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Undisclosed changes in outcomes in randomized controlled trials: an observational study
Robert Ewart1, Harald Lausen, Norman Millian
1Department of Family and Community Medicine, Southern Illinois University School of Medicine, Springfield, Illinois, USA. rewart@siumed.edu
Annals of Family Medicine
|November 11, 2009
Summary
Undisclosed changes to primary and secondary outcomes in randomized controlled trials (RCTs) are common between registration and publication. These undisclosed outcome modifications impact trial result interpretation and reporting transparency.
Area of Science:
- Clinical Trials
- Medical Research Integrity
- Publication Bias
Background:
- Randomized controlled trials (RCTs) are crucial for evidence-based medicine.
- Ensuring transparency in RCT reporting is vital for reliable scientific interpretation.
- Discrepancies between trial registration and publication may affect perceived treatment effects.
Purpose of the Study:
- To determine the frequency of undisclosed changes in primary and secondary outcomes.
- To assess alterations between the initial trial registry entry and the final published report.
- To highlight the implications of these changes on RCT result interpretation.
Main Methods:
- Retrospective, nonrandom, cross-sectional study design.
- Analysis of RCTs published in 5 major medical journals over a 6-month period.
- Comparison of published outcomes against trial registry entries for undisclosed modifications.
Main Results:
- 110 RCTs were included in the analysis.
- A primary outcome was changed without disclosure in 31% of publications.
- A secondary outcome was changed without disclosure in 70% of publications.
Conclusions:
- Significant undisclosed changes occur in RCT outcomes between registration and publication.
- These undisclosed modifications have substantial implications for interpreting trial findings.
- Improved transparency through disclosure of outcome changes is recommended.
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