The value of the ‘SAME-TT2R2’ score in predicting good anticoagulation control in an Asian population

Abstract

Introduction: Studies in predominantly white population have found that the SAMe-TT2R2 score predicts the time in therapeutic range (TTR) in patients with atrial fibrillation (AF) on warfarin. Nevertheless, defining ‘non-Caucasians’ as high-risk renders its use in the other populations limited. In this study we assessed and recalibrated the SAMe-TT2R2 score in an Asian population. Method: Consecutive patients with non-valvular AF diagnosed in our institution between 1997 and 2011 and were on warfarin were stratified according to the SAMeTT2R2 score, and TTR was calculated using the Rosendaal method. The predictive power of the SAMeTT2R2 score for TTR >70% was assessed. Results: Among the 1,428 patients (76.2±8.7 years, 47.5% male) included in this study, TTR decreased with increasing SAMe-TT2R2 score (p=0.016, figure 1). The corresponding sensitivity, specificity, positive and negative predictive values to predict TTR >70% were 85.7%, 17.8%, 10.1% and 92%, respectively. At a mean follow-up of 4.7±3.6 years, 338 (23.7%) patients developed an ischemic stroke with an annual incidence of 4.96%/year, and 63 (4.4%) patients had an intracranial hemorrahge with an annual incidence of 0.9%/year. Patients who had SAMe-TT2R2 ≤2 had the lowest annual risk of ischemic stroke (p<0.001), and showed a trend towards the lowest risk of intracranial hemorrhage. Conclusion: The SAMe-TT2R2 score correlates with with TTR in Chinese patients, with a score >2 demonstrating high sensitivity and negative predictive value for good anticoagulation control. Chinese patients who have SAMe-TT2R2 >2 should be considered for non-vitamin K antagonist anticoagulation to maximise therapeutic benefit.