The Clinical Interpretation of Noninferiority Trials.

Noninferiority trials are designed to demonstrate that a new treatment is not unacceptably worse than a standard treatment, considering an allowable difference termed the noninferiority margin. We highlight that selection of noninferiority margins at the time of study design can be biased toward wider margins that favor noninferiority claims. We discuss a clinically oriented approach to interpretation of results with a focus on confidence intervals and recommend that readers base their judgments regarding noninferiority on margins reflecting patient values and preferences rather than those set by investigators. We provide examples from trials in inflammatory bowel diseases.