A Simple Mantel-Haenszel Type Test for Noninferiority

Randomized clinical trials designed to establish noninferiority of an experimental therapy as compared to a standard (active-control) therapy as measured by binomial proportions are being widely used. Randomization is often stratified by prognostic factors. We propose a Mantel-Haenszel (MH) type test to demonstrate noninferiority in terms of the differences in success proportions and when the noninferiority margin is not necessarily uniform in all strata. It is assumed that the efficacy of the active control is documented in at least one earlier placebo-controlled trial. Derivation of the new test originates from Wittes and Wallenstein, who have discussed asymptotic unconditional power and sample size for the MH test. We provide an easy to calculate formula for sample size. We call the new test as W-square test. It may be an alternative to the one proposed by Yanagawa et al. Yanagawa's Neriproct suppository data are analyzed using the W-square test. A SAS code that calculates the p-value is provided.