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Sequential urn designs with elimination for comparing K > or =3 treatments
D Stephen Coad1, Anastasia Ivanova
1Department of Mathematics, University of Sussex, Falmer, Brighton BN1 9RF, U.K. d.s.coad@sussex.ac.uk
Statistics in Medicine
|April 2, 2005
Summary
This study introduces a sequential procedure for comparing multiple treatments using adaptive randomization and early stopping rules. The "drop-the-loser" method proved most effective for treatment selection and efficiency.
Area of Science:
- Biostatistics
- Clinical Trial Design
- Medical Research Methodology
Background:
- Comparing multiple treatments (K >= 3) with binary outcomes requires efficient adaptive designs.
- Sequential procedures can optimize patient allocation and treatment selection during trials.
- Existing methods may not fully leverage adaptive randomization for early elimination of ineffective treatments.
Purpose of the Study:
- To propose and evaluate a fully sequential procedure for comparing K >= 3 treatments with binary responses.
- To incorporate adaptive urn designs and stopping rules for efficient treatment elimination.
- To assess the performance of the proposed procedure, including treatment failures and allocation, and its application in dose-finding studies.
Main Methods:
- A fully sequential procedure employing adaptive urn designs for patient randomization.
- Incorporation of stopping rules to eliminate less promising treatments during the trial.
- Simulation studies to evaluate the performance of various adaptive urn designs.
- Application and comparison in a lung cancer study and dose-finding scenarios.
Main Results:
- The 'drop-the-loser' rule demonstrated superior effectiveness compared to equal allocation and other designs.
- The sequential elimination procedure efficiently allocates patients and reduces treatment failures.
- The method is practical for real-world applications, as shown in a lung cancer study.
- Performance comparison with a recent method in dose-finding studies indicates its viability.
Conclusions:
- The proposed sequential procedure with adaptive urn designs and the 'drop-the-loser' rule is effective for comparing multiple treatments.
- This approach enhances efficiency in clinical trials by enabling early elimination of inferior treatments.
- The methodology offers practical benefits and potential for extensions in dose-finding and other adaptive trial designs.