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Assessing the potential for outcome reporting bias in a review: a tutorial.
Kerry Dwan1, Carrol Gamble, Ruwanthi Kolamunnage-Dona
1Centre for Medical Statistics and Health Evaluation, University of Liverpool, UK. kerry.dwan@liverpool.ac.uk
Trials
|May 14, 2010
Summary
This study demonstrates how to detect outcome reporting bias (ORB) in systematic reviews. While ORB was suspected in some trials for a magnesium and asthma review, the main conclusions remained robust.
Area of Science:
- Medical Research Methodology
- Clinical Trial Analysis
- Systematic Review Evaluation
Background:
- Outcome reporting bias (ORB) distorts meta-analysis results by selectively publishing variables based on outcomes.
- This bias can significantly impact pooled treatment effect estimates in medical research.
- Assessing ORB is crucial for the integrity of systematic reviews and meta-analyses.
Purpose of the Study:
- To demonstrate a method for assessing systematic reviews and trial reports for outcome reporting bias (ORB).
- To apply this assessment method using an example review on magnesium for asthma treatment.
- To evaluate the impact of potential ORB on the conclusions of the example systematic review.
Main Methods:
- Systematic review assessment for ORB by checking exclusion criteria and outcome reporting in eligible studies.
- Utilized the ORBIT (Outcome Reporting Bias In Trials) project system for classifying studies regarding ORB suspicion.
- Contacted trial authors for missing outcome data and performed sensitivity analysis to test conclusion robustness.
Main Results:
- Two studies were excluded from the magnesium review for not reporting key outcomes.
- Six included studies failed to report hospital admission, and two did not report pulmonary function.
- High suspicion of ORB was noted in four studies, but sensitivity analysis confirmed that review conclusions were not overturned.
Conclusions:
- The paper provides a practical demonstration of assessing systematic reviews for outcome reporting bias using a magnesium and asthma example.
- Systematic reviews should not exclude studies based on unreported outcomes and must consider potential ORB in all included studies.
- Ensuring complete outcome reporting is vital for accurate systematic review findings and reliable meta-analyses.
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