Equivalence and noninferiority study designs

Such a step is not required from a statistical point of view, as a result of the role of a properly executed randomization process, but it can be comforting if it supports the clinical relevance of the effect after adjustment for the baseline covariate. If there are specific explanatory factors that are suspected of having an effect on the outcome of interest at the start of a study, it is advisable to incorporate them into the overall study design (for example, through stratified randomization). A brief discussion of this topic has been published by Roberts and Torgerson (1999). The EMEA CPMP has also published a guidance document on baseline covariates (EMEA CPMP 2003). 

The goal of equivalence trials is to demonstrate that a new (test) drug (T) and an active comparator drug (C) are equivalent or have a similar effect. This means that, in the best-case scenario, the test treatment is trivially better than the reference treatment and, in the worst, it is tolerably worse. 

1 Why the hypothesis-testing strategies are different in these designs 

Given that the research questions in these trials are different from those used in superiority trials, the formats of the null and alternate hypotheses are also different. The research question associated with an equivalence trial is Does the test drug demonstrate equivalent efficacy compared with the comparator drug The null hypothesis, 

Chapter 1 2 Additional statistical considerations in clinical trials 

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