F10 and Stroke: The Rivaroxaban Once Daily Oral Direct Factor Xa Inhibition Compared with Vitamin K Antagonism for Prevention of Stroke and Embolism Trial in Atrial Fibrillation (ROCKET AF) study 16 was a double-blind, double-dummy trial comparing rivaroxaban 20 mg once daily (15 mg once daily in patients with a creatinine clearance between 30 and 49 ml/min) to dose-adjusted warfarin.