Why we should be prioritizing the average treatment effect on the treated over other estimands when evaluating drug and device safety.

Abstract

When a drug or medical device is suspected of having a safety problem, observational studies are often utilized with an active comparator cohort design and covariate balancing using the propensity score. Each covariate balancing method is an estimator for a particular estimand, with each estimand characterizing the target population of interest differently as it relates to the treatment effect. In this article, I argue that characterizing the average treatment effect in the treated population (A