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Sample size calculators for planning stepped-wedge cluster randomized trials: a review and comparison
Yongdong Ouyang1,2, Fan Li3,4, John S Preisser5
1Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, ON, Canada.
International Journal of Epidemiology
|June 9, 2022
Summary
Researchers need help choosing stepped-wedge cluster randomized trial (SWCRT) software. This review classifies 18 calculators, highlighting their features and limitations to guide selection for power and sample size calculations.
Area of Science:
- * Biostatistics and Clinical Trial Design
- * Health Services Research Methodology
Background:
- * Stepped-wedge cluster randomized trials (SW-CRTs) are increasingly popular but have complex design variations.
- * Existing power and sample size calculation software for SW-CRTs vary in features and applicability.
- * No comprehensive resource currently guides researchers in selecting appropriate SW-CRT calculators.
Approach:
- * Reviewed and classified 18 SW-CRT power and sample size calculators across major platforms (R, SAS, Stata, Excel, PASS, nQuery).
- * Summarized calculator features, including design types, outcome measures, correlation structures, treatment effects, and handling of incomplete designs, cluster-size variation, and secular trends.
- * Detailed discussion of four key calculators, identifying strengths and limitations, with practical examples.
Key Points:
- * Calculator choice significantly impacts power and sample size calculations for SW-CRTs.
- * Different calculators accommodate varying design complexities and analytical approaches.
- * An R Shiny app is provided to assist researchers in selecting suitable calculators.
Conclusions:
- * A systematic review and classification of SW-CRT calculators are essential for accurate trial planning.
- * Researchers should carefully consider calculator features against their specific SW-CRT design needs.
- * The developed resource and accompanying app facilitate informed decision-making for SW-CRT sample size and power calculations.
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