Survivor function estimators under group sequential monitoring based on the logrank statistic.
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.
Fred Hutchinson Cancer Research Center, 1100 Fairview Ave. N. MP1002, PO Box 19024, Seattle, WA 98109-1024, USA. mgorfine@whi.org
Malka
M
Gorfine
D000319:Adrenergic beta-Antagonists / Q000627:therapeutic use; D015982:Bias; D002986:Clinical Trials as Topic / Q000706:statistics & numerical data; D003198:Computer Simulation; D006801:Humans; D009203:Myocardial Infarction / Q000188:drug therapy / Q000401:mortality / Q000517:prevention & control; D016016:Proportional Hazards Models; D016019:Survival Analysis; D013995:Time
D000319:Adrenergic beta-Antagonists