Since FDA approval in 1954, warfarin has been recognized as an effective but also potentially dangerous medication. Despite decades of clinical trial data supporting the benefits of warfarin, bleeding risk combined with the challenges of maintaining international normalized ratios (INRs) in the therapeutic range are important considerations and limitations to the use of warfarin. Consequently, new anticoagulants (novel oral anticoagulants [NOACs]) have been developed that require no monitoring and have minimal interactions with foods and other drugs. Although these new agents are cost-effective from a societal perspective, they may be more costly to an institution or individual and that may explain, in part, why warfarin remains the most widely used anticoagulant in the world.1 Although the NOACs seem to be at least comparable with warfarin for reducing stroke risk and as safe if not safer than warfarin in terms of bleeding risk, the pivotal trials of these agents compared NOACs with warfarin among patients who achieved time in therapeutic ranges (TTR) of only 55% to 68%.2 Thus the question remains regarding the clinical outcomes for patients who have well-managed warfarin therapy.
Passman R. Time in Therapeutic Range in Warfarin-Treated PatientsIs Very Good Good Enough?. JAMA. 2016;316(8):872-873. doi:10.1001/jama.2016.10402