Prospective Study of the Outcomes of Ambulatory Patients With Excessive Warfarin Anticoagulation

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Abstract
OPTIMAL management of outpatients who are receiving warfarin sodium and who have asymptomatic elevations in international normalized ratios (INRs) remains uncertain. Published recommendations from the American College of Chest Physicians Consensus Conference1 are variably adhered to in practice2,3 and likely reflect clinicians' concerns about the net benefit of phytonadione (vitamin K1) therapy, the lack of prospective data on conservative management, and the practical barriers to timely administration of phytonadione in an outpatient setting. Although the relative risk of hemorrhage with elevated INRs is well documented,4-8 the absolute short-term risk of hemorrhage resulting from isolated elevations in INRs in individual patients has not been prospectively studied. In addition, there is little information on the rate of spontaneous INR decay after temporary discontinuation of warfarin therapy. Such information would help guide rational management of elevated INRs in the outpatient setting.