Randomized Trials of Dabigatran and Warfarin Underestimate Bleeding Risk

Randomized clinical trials have shown that direct oral anticoagulants such as dabigatran decrease mortality in patients with atrial fibrillation (NEJM JW Oncol Hematol Dec 2014, and J Thromb Haemost 2014; 12:1419) and are at least as safe as warfarin (Ann Intern Med 2012; 157:796). The trial data have been used to construct scoring systems to predict thrombosis risk (CHADS₂/CHA₂DS₂VASc) and bleeding risk (HAS-BLED) in patients being considered for anticoagulant therapy.

To determine if the risks predicted by trial data are similar to those actually observed in clinical practice, investigators calculated baseline risk for thrombosis and bleeding among 21,934 patients in a commercial healthcare claims database who were prescribed dabigatran (3…