Sample size determination for win statistics in cluster-randomized trials

Fuente: arXiv
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Autori principali: Fang, Xi, Cao, Zhiqiang, Li, Fan
Natura: Preprint
Pubblicazione: 2025
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author Fang, Xi
Cao, Zhiqiang
Li, Fan
author_facet Fang, Xi
Cao, Zhiqiang
Li, Fan
contents Composite endpoints are increasingly used in clinical trials to capture treatment effects across multiple or hierarchically ordered outcomes. Although inference procedures based on win statistics, such as the win ratio, win odds, and net benefit, have gained traction in individually randomized trials, their methodological development for cluster-randomized trials remains limited. In particular, there is no formal framework for power and sample size determination when using win statistics with composite time-to-event outcomes. We develop a unified framework for power and sample size calculation for win statistics under cluster randomization. Analytical variance expressions are derived for a broad class of win statistics, yielding closed-form variance expressions and power procedures that avoid computationally intensive simulations. The variance expressions explicitly characterize the roles of the rank intracluster correlation coefficient, cluster size, tie probability, and outcome prioritization for study planning purposes. Importantly, our variances nest existing formulas for univariate outcomes as special cases while extending them to complex, hierarchically ordered composite endpoints. Simulation studies confirm accurate finite-sample performance, and we supply a case study to illustrate the use of our method to re-design a real-world cluster-randomized trial.
format Preprint
id arxiv_https___arxiv_org_abs_2510_22709
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Sample size determination for win statistics in cluster-randomized trials
Fang, Xi
Cao, Zhiqiang
Li, Fan
Methodology
Composite endpoints are increasingly used in clinical trials to capture treatment effects across multiple or hierarchically ordered outcomes. Although inference procedures based on win statistics, such as the win ratio, win odds, and net benefit, have gained traction in individually randomized trials, their methodological development for cluster-randomized trials remains limited. In particular, there is no formal framework for power and sample size determination when using win statistics with composite time-to-event outcomes. We develop a unified framework for power and sample size calculation for win statistics under cluster randomization. Analytical variance expressions are derived for a broad class of win statistics, yielding closed-form variance expressions and power procedures that avoid computationally intensive simulations. The variance expressions explicitly characterize the roles of the rank intracluster correlation coefficient, cluster size, tie probability, and outcome prioritization for study planning purposes. Importantly, our variances nest existing formulas for univariate outcomes as special cases while extending them to complex, hierarchically ordered composite endpoints. Simulation studies confirm accurate finite-sample performance, and we supply a case study to illustrate the use of our method to re-design a real-world cluster-randomized trial.
title Sample size determination for win statistics in cluster-randomized trials
topic Methodology
url https://arxiv.org/abs/2510.22709