EDITOR—I was surprised by Sackett's contribution in the cluster of letters about clinical equipoise.1 He attacks the word equipoise, on the ground that it is not used as commonly as the alternative word, uncertainty. Uncertainty, unlike equipoise, covers a range of situations, not just clinical trials. It is the meaning behind the word that is important.

Equipoise has been clearly defined within the paradigm of expected utility theory.2 “Patient equipoise” applies when the expected utilities of comparator treatments are equivalent. This provides …