Pokorney SD, et al. - Given that patients with atrial fibrillation (AF) taking warfarin sodium commonly experience bleeding and thrombotic events (eg, stroke and systemic embolism), researchers examined if there is an independent association of history of therapeutic warfarin control in these AF patients with subsequent bleeding or thrombotic events. In this multicenter cohort study of 176 primary care, cardiology, and electrophysiology clinics in the United States, data were obtained during 51,830 visits among 10,137 patients with AF. Findings revealed an association of three metrics of prior warfarin control (time in therapeutic range, variation in international normalized ratio (INR) values, and maximum INR) with bleeding risk, but the association was only slightly more so than traditional clinical factors. No measures of INR control were noted to be significantly associated with stroke risk.