Warfarin substantially decreases stroke risk among patients with atrial fibrillation yet has a narrow therapeutic window (international normalized ratio [INR] values of 2.0-3.0) and is associated with multiple drug and food interactions.1 Non–vitamin K oral anticoagulants do not require drug monitoring and have similar or improved safety and efficacy relative to warfarin but are more costly.2 Whether patients previously stable on warfarin should be switched to non–vitamin K oral anticoagulants remains controversial but may be informed by determining whether patients receiving warfarin who have stable INR values remain stable over time.
Pokorney SD, Simon DN, Thomas L, Gersh BJ, Hylek EM, Piccini JP, Peterson ED. Stability of International Normalized Ratios in Patients Taking Long-term Warfarin Therapy. JAMA. 2016;316(6):661-663. doi:10.1001/jama.2016.9356