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Optimal allocation to treatment sequences in individually randomized stepped-wedge designs with attrition
1Department of Methodology and Statistics, Utrecht University, Utrecht, The Netherlands.
Clinical Trials (London, England)
|February 24, 2023
Summary
This study presents optimal individual allocation methods for stepped-wedge trials, crucial for efficient individually randomized trials with participant attrition. The findings guide researchers in planning effective stepped-wedge study designs.
Area of Science:
- Biostatistics
- Clinical Trial Design
- Epidemiology
Background:
- Stepped-wedge designs are common in cluster randomized trials but less explored for individually randomized trials.
- This research focuses on optimal individual allocation within stepped-wedge designs.
Purpose of the Study:
- To derive optimal individual allocation strategies for individually randomized stepped-wedge trials.
- To provide a methodology for efficient trial planning, considering participant attrition.
Main Methods:
- A statistical model accounting for repeated measures within subjects and attrition is presented.
- Matrix algebra is used to determine the relationship between allocation and treatment effect variance.
- Optimal allocation minimizes the variance of the treatment effect estimator.
Main Results:
- Optimal allocation depends significantly on the correlation parameter and attrition rate.
- Uniform allocation is often less efficient than the derived optimal allocation.
- A constrained optimal allocation method is provided for practical feasibility.
Conclusions:
- The methodology aids researchers in efficiently planning individually randomized stepped-wedge trials.
- Accurate prior estimates of attrition and intraclass correlation are necessary for optimal design.
- Clear reporting of these estimates is recommended for future trial planning.
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