Ensayos clínicos de no inferioridad: qué son y cuándo deben realizarse

Randomized controlled trials (RCTs) are the gold standard design of studies evaluating novel interventions, pharmaceutical and otherwise. The standard RCT design is a 'superiority' study to assess if the tested intervention is better than existing treatments. However, a new intervention that has additional benefits, such as better adverse effect profile, may be useful even if it is not more effective than existing treatments. In such cases, a non-inferiority (NI) design may be preferable. In NI designs, once NI is demonstrated, sequential analysis for superiority may be done, provided it is pre-specified. This article discusses the utility and principles of an NI design. Examples to illustrate the design are taken from published trials of anticoagulation in atrial fibrillation.