JSM 2011 Online Program

The views expressed here are those of the individual authors and not necessarily those of the JSM sponsors, their officers, or their staff.

Abstract Details

Activity Number: 89
Type: Contributed
Date/Time: Sunday, July 31, 2011 : 4:00 PM to 5:50 PM
Sponsor: Biopharmaceutical Section
Abstract - #302307
Title: Sample Size Calculation for Proportional Hazards Cure Model
Author(s): Songfeng Wang*+ and Jiajia Zhang and Wenbin Lu
Companies: University of South Carolina and University of South Carolina and North Carolina State University
Address: Department of Epidemiology and Biostatistics, Columbia, SC, 29208,
Keywords: Clinical trial ; Proportional hazards cure model ; Power ; Sample Size ; Weighted log-rank test
Abstract:

In clinical trials with time-to-event endpoints, it is not uncommon to see a significant proportion of patients being cured (or long-term survivors). The popularly used sample size formula derived under the proportional hazards (PH) model may not be proper to design a survival trial with a cure fraction. To account for a cure fraction, the PH cure model is widely used, where a PH model is used for survival times of uncured subjects and a logistic distribution is used for the probability of patients being cured. In this paper, we develop a sample size formula based on the PH cure model by investigating the asymptotic distributions of the standard weighted log-rank statistics under the null and local alternative hypotheses. The derived sample size formula under the PH cure model is more flexible since it can be used to test the differences in the short-term survival and/or cure fraction. Furthermore, the impacts of accrual methods and lengths of accrual and follow-up periods on sample size calculation are investigated using simulations under different scenarios. The results show that ignoring the cure rate can lead to either an underpowered or overpowered study.


The address information is for the authors that have a + after their name.
Authors who are presenting talks have a * after their name.

Back to the full JSM 2011 program




2011 JSM Online Program Home

For information, contact jsm@amstat.org or phone (888) 231-3473.

If you have questions about the Continuing Education program, please contact the Education Department.