Abstract
In this paper we investigate a group sequential analysis of censored survival data with staggered entry, in which the trial is monitored using the logrank test while comparisons of treatment and control Kaplan-Meier curves at various time points are performed at the end of the trial. We concentrate on two-sample tests under local alternatives. We describe the relationship of the asymptotic bias of Kaplan-Meier curves between the two groups. We show that even if the asymptotic bias of the Kaplan-Meier curve is negligible relative to the true survival, this is not the case for the difference between the curves of the two arms of the trial. A corrected estimator for the difference between the survival curves is presented and by simulations we show that the corrected estimator reduced the bias dramatically and has a smaller variance. The methods of estimation are applied to the Beta-Blocker Heart Attack Trial (1982), a well-known group sequential trial.
Original language | English |
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Pages (from-to) | 175-193 |
Number of pages | 19 |
Journal | Lifetime Data Analysis |
Volume | 9 |
Issue number | 2 |
DOIs | |
State | Published - Jun 2003 |
Keywords
- Group sequential test
- Kaplan-Meier curve
- Local alternatives
- Logrank test
- Secondary parameter