Variation in Warfarin Dose Adjustment Practice is Responsible for Differences in the Quality of Anticoagulation Control between Centers and Countries: An Analysis of Patients Receiving Warfarin in the RE-LY Trial

Circ.ahajournals.org: October 1, 2012

The outcome of atrial fibrillation (AF) patients on warfarin partially depends on maintaining adequate time in therapeutic INR range (TTR). Large differences in TTR have been reported between centers and countries. The association between warfarin dosing practice, TTR, and clinical outcomes was evaluated in RE-LY trial patients receiving warfarin.

Methods and Results—RE-LY provided an algorithm for warfarin dosing, recommending no change for in-range, and 10-15% weekly dose changes for out-of-range INR values. We determined whether dose adjustments were consistent with algorithm recommendations, but could not verify whether providers used the algorithm. Using multi-level regression models to adjust for patient, center, and country characteristics, we assessed whether algorithm-consistent warfarin dosing could predict patient TTR and the composite outcome of stroke, systemic embolism or major hemorrhage.  Read more