Previous research suggests that the excess mortality associated with antipsychotics is greatest early in treatment, with the relative risk trending toward no mortality effect of drug as the duration of antipsychotic use increases (2). The Lopez et al. study assessed medications every 6 months, without tracking interim changes. Periodic assessments such as this create challenges when interpreting results that are related to adverse events for which the greatest excess risk occurs early in treatment. This is a particularly important issue in a dementia sample, where death is not a rare occurrence. That is, if someone both started an antipsychotic and died during the time between two assessments, there would be no record that the individual received an antipsychotic before they died, and only those who survived the early treatment period would be recorded as receiving an antipsychotic. Thus, data are lost from individuals who may be particularly vulnerable to the adverse event of interest, in this case death. This is termed “depletion of susceptibles” and may lead to bias in effect estimates, as those who survive treatment through an initial high-risk period are often less susceptible to an adverse effect. This is one reason that new-user designs are generally preferred in pharmacoepidemiology studies of adverse drug effects (3).