Equivalence and noninferiority testing in anesthesiology research.

摘要

CLINICAL studies frequently test whether one treatment or intervention is superior to another. When a test for superiority is statistically significant, we happily conclude that one method is better than the other, especially if it is in the expected direction! But what can it mean if the test is not significant? Can we conclude that the treatments are "similar" or "equivalent"? Actually, no, because although it could be that no clinically meaningful population difference exists, it is also possible that one does exist-but either the study was underpowered to detect it (sample size was too small) or we just got unlucky (false negative result). So from a nonsignificant test for superiority, we can really conclude only that no population difference was detected, and not equivalence, even if the observed means are very similar!