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Confidence Intervals for Adaptive Trial Designs II: Case Study and Practical Guidance
David S Robertson1, Thomas Burnett2, Babak Choodari-Oskooei3
1MRC Biostatistics Unit, University of Cambridge, Cambridge, UK.
Statistics in Medicine
|August 9, 2025
Summary
Confidence intervals (CIs) in adaptive clinical trials can be unreliable. This study evaluates CIs for two-stage group sequential designs, offering guidelines for choosing and reporting them post-trial.
Area of Science:
- Biostatistics
- Clinical Trial Design
- Pharmaceutical Statistics
Background:
- Conventional confidence intervals (CIs) exhibit undercoverage and inconsistency in adaptive clinical trials.
- Regulatory guidance emphasizes caution in interpreting CIs from adaptive trials.
- A clear preference among existing CI methods for adaptive designs is lacking.
Purpose of the Study:
- To explore and evaluate confidence intervals (CIs) for adaptive clinical trials.
- To present an extended case study of CIs for a two-stage group sequential design.
- To provide guidelines for selecting and reporting CIs in adaptive trial settings.
Main Methods:
- Methodological review of CI construction approaches for adaptive designs (Part I).
- Extended case study of a two-stage group sequential trial.
- Comprehensive simulation study of proposed CIs for the case study setting.
Main Results:
- Confidence intervals (CIs) demonstrate notably different properties in adaptive trials.
- The study facilitates an expanded understanding of effective CI procedures post-adaptive trial.
- Simulation results highlight performance variations among different CI methods.
Conclusions:
- Researchers need clear guidance on choosing and reporting CIs for adaptive trials.
- The choice of CI significantly impacts interpretation of treatment effects.
- Proposed guidelines aim to improve the reliability and consistency of CI usage in adaptive designs.
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