Initiating and Maintaining Patients on Warfarin Anticoagulation: The Importance of Monitoring

Abstract
Background: The VA Stroke Prevention in Nonrheumatic Atrial Fibrillation study was a prospective, randomized, double-blind study comparing low-dose warfarin with placebo in patients with nonrheumatic atrial fibrillation. The trial showed a 79% reduction in stroke rate in warfarin randomized patients without an increase in bleeding complications. We examined the need for frequent prothrombin time monitoring (international normalized ratios [INR] were not measured directly) in patients receiving warfarin.