A simple method to identify patients on long-term warfarin who may derive the most benefit from new oral anticoagulants

Marc Carrier, Miriam Kimpton, Philip S. Wells, Nicole Langlois, Shemina Kherani, Gregoire Le Gal

Research output: Contribution to journalArticlepeer-review

6 Scopus citations


In many countries, new oral anticoagulants are only covered for patients with suboptimal anticoagulation control on vitamin K antagonists (VKAs). The quality of VKA management is often reported using the time in therapeutic range (TTR). We sought to predict a TTR 65% or less using a surrogate measure [number of changes in VKA dose and number of international normalized ratio (INR) tests] that could be easily determined by primary care physicians. This cross-sectional study included consecutive patients whose VKA therapy was managed in a specialized anticoagulation clinic. Patients were dichotomized according to their TTR in the past 6 months (TTR > or ≥ 65%). The ability of the number of INR tests and VKA dose changes to predict TTR group was assessed using receiver-operating characteristics (ROC) curve analysis. The analyses included 1381 patients with a median age of 63 years. The mean TTR was 81% (interquartile range 70-90) and 17.4% of patients had a TTR 65% or more. Based on the ROC curve, patients were stratified according to whether they had either 3 or more dose changes or 9 or more INR tests within the last 6 months. The sensitivity to identify patients with TTR 65% or less was 87% and the specificity was 63%. The number of dose changes and the number of INR tests might be used as indicators of TTR; they could offer a simple way for clinicians to identify patients who are good candidates for the new oral anticoagulants. However, external validation studies in different clinical settings are needed to confirm these findings.

Original languageEnglish
Pages (from-to)812-815
Number of pages4
JournalBlood Coagulation and Fibrinolysis
Issue number8
StatePublished - 2014
Externally publishedYes


  • Acenocoumarol
  • Venous thrombosis
  • Warfarin


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