Title

Two-Stage Optimal Designs Based on Exact Variance for a Single-Arm Trial With Survival Endpoints

Document Type

Article

Publication Date

3-4-2020

Publication Title

Journal of Biopharmaceutical Statistics

First page number:

1

Last page number:

10

Abstract

Sample size calculation based on normal approximations is often associated with the loss of statistical power for a single-arm trial with a time-to-event endpoint. Recently, Wu (2015) derived the exact variance for the one-sample log-rank test under the alternative and showed that a single-arm one-stage study based on exact variance often has power above the nominal level while the type I error rate is controlled. We extend this approach to a single-arm two-stage design by using exact variances of the one-sample log-rank test for the first stage and the two stages combined. The empirical power of the proposed two-stage optimal designs is often not guaranteed under a two-stage design setting, which could be due to the asymptotic bi-variate normal distribution used to estimate the joint distribution of the test statistics. We adjust the nominal power level in the design search to guarantee the simulated power of the identified optimal design being above the nominal level. The sample size and the study time savings of the proposed two-stage designs are substantial as compared to the one-stage design.

Keywords

Cancer trials; Exact variance; One-sample log-rank test; Optimal designs; Two-stage designs

Disciplines

Biostatistics | Clinical Trials

Language

English

UNLV article access

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