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A roadmap to using randomization in clinical trials
Vance W Berger1, Louis Joseph Bour2, Kerstine Carter3
1National Institutes of Health, Bethesda, MD, USA.
BMC Medical Research Methodology
|August 17, 2021
Summary
Choosing the right restricted randomization procedure is crucial for clinical trial validity. This paper offers a guide to selecting and applying these methods, ensuring robust statistical inference and reliable trial results.
Area of Science:
- Clinical Trials
- Biostatistics
- Medical Research Methodology
Background:
- Randomization is fundamental for clinical trials comparing treatments, mitigating bias and ensuring group similarity.
- Restricted randomization procedures offer various probabilistic structures and statistical properties for subject allocation.
- Selecting the appropriate procedure is vital for the integrity of clinical trial data.
Purpose of the Study:
- To provide a systematic roadmap for choosing and applying restricted randomization procedures in clinical trials.
- To explore the statistical properties and performance of different restricted randomization methods.
- To guide practical implementation of randomization in clinical research.
Main Methods:
- Surveyed available restricted randomization procedures for 1:1 allocation in parallel group trials.
- Evaluated statistical properties including balance/randomness, Type I error rate, and power.
- Conducted simulations comparing procedures under various scenarios, including violated model assumptions, and provided real-life examples.
Main Results:
- Restricted randomization procedures differ in induced balance/randomness and robustness to violated assumptions (e.g., time trends, misspecification, bias).
- Some procedures demonstrate greater robustness, and covariate-adjusted analysis may be necessary for result validity.
- Special attention is needed for randomization in small sample size clinical trials.
Conclusions:
- The selection of randomization design, data analytic techniques, and analysis strategy are critical for clinical trial validity.
- Randomization-based tests offer robust and valid alternatives to likelihood-based tests.
- Clinical investigators should more frequently consider randomization-based tests for their trials.
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