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Abstract Details

Activity Number: 245
Type: Contributed
Date/Time: Monday, July 30, 2012 : 2:00 PM to 3:50 PM
Sponsor: Biopharmaceutical Section
Abstract - #305597
Title: A Simple Approach in Determining Sample Size and Power for Assessing Noninferiority of a Test Treatment When There Is a Placebo
Author(s): Jerry Weaver*+
Companies: Novartis
Address: One Health Plaza, East Hanover, NJ, 07936,
Keywords: non-inferiority fraction ; generalized variance ; sample size formula ; optimal sample size allocation
Abstract:

For trials in which assessing non-inferiority of a test treatment is an objective, it is sometimes preferred to define an appropriate contrast among the means such that a pre-specified fraction of the effect between the active comparator and placebo is preserved. Alternatively, one can write a more transparent contrast of the means by utilizing a pre-specified fraction that discounts this effect. A generalized variance that takes into consideration the correlation structure among the treatment mean estimators is derived within the context of a linear model. Utilizing this generalized variance leads to a sample size formula in which the experimenter can sufficiently power the study for assessing non-inferiority. Moreover, for parallel group studies the experimenter can optimize the overall total sample size through efficient allocation among the three treatment groups. Interestingly, the optimal sample size allocation in many common situations involving parallel group trials is not an equal sample size allocation among the treatment groups.


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