The Medicare claims database can be a useful resource in monitoring serious cardiac adverse effects of QT-prolonging drugs, which are generally difficult to predict and quantify.

Based on data from 1.2 million Medicare beneficiaries and over 5 million patient-years of follow-up, we detected an increased risk of some commonly prescribed drugs including levofloxacin, citalopram, and escitalopram for ventricular arrhythmia and sudden death.