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Abstract Details
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Activity Number:
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423
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Type:
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Contributed
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Date/Time:
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Tuesday, August 2, 2011 : 2:00 PM to 3:50 PM
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Sponsor:
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Biopharmaceutical Section
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| Abstract - #302519 |
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Title:
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Evaluation of Power of Different Cox Proportional Hazards Models Incorporating Stratification Factors
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Author(s):
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Shanshan Ding*+ and Moumita Sinha
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Companies:
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Biocon Ltd. and University of Minnesota
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Address:
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313 Ford Hall 224 Church Street S.E. , Minneapolis, MN, 55455,
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Keywords:
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Cox proportional harzards model ;
survival time ;
stratification ;
simulation
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Abstract:
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Cox proportional hazards model is widely used in clinical trials for time to event data. Often mega trials have patients randomized by multiple stratification factors. These stratification factors are incorporated in the statistical analysis by using stratified Cox model. In this paper, we compare the stratified Cox model with the Cox proportional model using the stratification factors as covariates to study how the different models influence the power. Simulated data with and without stratification factors are explored with different event rates and variable number of patients in each subcategory. We conclude that fitting a Cox model with the stratification factors as covariates provides higher power compared to modeling the data with stratified Cox proportional model, especially when data structures are more differentiable among strata. This result is also observed when there are subcategories with low sample size.
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