A Comparison of Testing Parameters and the Implementation of a Group Sequential Design for Equivalence Studies Using Paired-sample Analysis.

We address the problem of establishing two-sided equivalence using paired-sample analysis of two treatments or two laboratory tests with a binary endpoint. Through real data examples and monte carlo simulations, we compare three commonly used testing parameters, namely, the difference of response probabilities, the ratio of response probabilities, and the ratio of discordant probabilities based on score test statistics for constructing equivalence hypothesis tests of paired binary data. We provide suggestions on the choice of these three testing parameters and proper equivalence margins in hypothesis formulation of equivalence testing. In addition, we describe the implementation of a group sequential design in the context of equivalence testing with early stopping to reject, as well as to declare equivalence.