[Noninferiority trials: several simple principles].
Noninferiority trials make it possible to show that the efficacy of a new treatment is not worse than that of the reference treatment, but not to conclude that efficacy is strictly equivalent. Even though a noninferiority trial is conclusive, there remains the possibility that the new treatment is inferior to the reference treatment (within the margin of the noninferiority margin set a priori, that is, before the results were known). A treatment shown not to be inferior does not represent therapeutic progress unless it has other advantages, in terms, for example, of tolerance or ease of use. Setting the noninferiority margin is a clinical and not a statistical problem. It requires determining the greatest acceptable loss of efficacy relative to the reference treatment. This loss of efficacy set by the noninferiority margin cannot exceed the efficacy of the reference treatment, since that could amount to loss of the entire treatment benefit.
Vicaut
Eric
E
Unité de Recherche Clinique, Hôpital Fernand Widal, Paris. eric.vicaut@lrb.ap-hop-paris.fr
Cucherat
Michel
M
D002986:Clinical Trials as Topic / Q000706:statistics & numerical data*; D006801:Humans; D016896:Treatment Outcome