Perspective:

The authors tested an important clinical question and found that INR variability is an independent predictor of adverse events in anticoagulation of AF patients beyond the traditional measure of TTR. Although this analysis was limited to Veterans Administration patients (primarily men) who are managed in anticoagulation clinics, the results are not surprising to anyone who regularly cares for warfarin patients, and likely can be extended to patients treated outside of formal anticoagulation clinics as well. However, both the TTR and the INR variability measures are not available before a patient initiates therapy and therefore are not helpful when deciding between warfarin and a newer target-specific oral anticoagulant (e.g., dabigatran, rivaroxaban, or apixaban). Nonetheless, both of these measures can be useful for large anticoagulation clinics that are implementing quality improvement initiatives to improve the anticoagulation care provided as a means of targeting the most ‘at-risk’ patients.