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Blinded and unblinded internal pilot study designs for clinical trials with count data
Simon Schneider1, Heinz Schmidli, Tim Friede
1Department of Medical Statistics, University Medical Center Göttingen, Germany. simon.schneider@med.uni-goettingen.de
Biometrical Journal. Biometrische Zeitschrift
|May 25, 2013
Summary
Blinded sample size reestimation procedures for count data trials maintain power. While unblinded methods show slight bias, blinded procedures offer more stable sample size variation, crucial for planning clinical trials.
Area of Science:
- Biostatistics
- Clinical Trial Design
Background:
- Internal pilot studies are common for addressing sample size uncertainties.
- Blinded sample size reestimation for count data is a recent development.
- Regulatory authorities favor blinded procedures, but bias concerns exist if treatment effects are misspecified.
Purpose of the Study:
- Compare blinded and unblinded sample size reestimation procedures.
- Evaluate bias, error rates, and sample size distribution.
- Investigate performance under uncertainty in treatment effect estimation.
Main Methods:
- Comparative analysis of blinded and unblinded procedures.
- Assessment of statistical properties including power and significance levels.
- Extension of methods to overdispersed counts using quasi-likelihood.
Main Results:
- Both procedures maintain desired power.
- Unblinded procedures are slightly liberal; blinded procedures maintain nominal significance levels.
- Blinded estimators can be biased for control event rates with treatment effect uncertainty, unlike unblinded estimators.
Conclusions:
- Blinded procedures offer smaller sample size variation, beneficial in practice.
- Differences in mean sample sizes are small compared to deviations from the true required size.
- Methods are applicable to overdispersed count data and illustrated with multiple sclerosis trials.
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