Introduction
QTE, depressive disorder, MDD, depression, disability
Major depressive disorder (MDD) is a leading cause of global distress and disability.This debate also depends on how antidepressant efficacy is distributed in populations and in individuals, which is less commonly studied. Both population-level distributions and individual-level distributions matter, and the conceptual differences between them are subtle but important as explained in the eAppendix in Stone et alWe model the distribution of antidepressant response using a quantile treatment effect (QTE) framework.Rank similarity is appropriate when the features that affect a participant’s rank within one treatment arm exert a similar effect in both arms. This is clinically plausible in the depression context because many of the same factors are highly clinically significant in determining the course of a patient’s depression in either arm of a trial. For instance, patients with worsening social circumstances tend to have worse depression responses compared with their same-arm peers in the trial whether assigned to drug or placebo. Similarly, patients whose depression before the trial had been long-standing tend to have worse depression responses compared with their same-arm peers whether assigned to drug or placebo. Rank similarity would be violated if factors that affect antidepressant responsiveness were more important for determining relative rank within an arm than features that affect the course of depression regardless of treatment assignment. A recent review stated that such factors have not been conclusively identified,