Evaluation of the Modified SAMe-TT2R2 Score to Predict Good Anticoagulation Control with Warfarin Among non-valvular Atrial Fibrillation Patients

Background: The SAMe-TT2 R2 Score was developed to identify vitamin K antagonists control outliers before non-valvular atrial fibrillation (AF) patients start treatment. SAMe-TT2 R2 Score was derived and validated using a primarily white Caucasian population to predict TTR. Given that non-Caucasian race already confers 2 points in this score, the SAMe-TT2 R2 score requires validation and/or re-calibration despite race of population. Method: We conducted a cohort retrospective study that included all non-valvular atrial fibrillation patients who were on warfarin therapy from January to December 2019. Then we calculated the modified SAMe-TT2 R2 and SAMe-TT2 R2 for all study populations and we correlated the result with patients' TTR. The TTR was calculated through the Rosendaal's method. Results: We had 662 patient using warfarin therapy, among those 662, 60.9% were under cardiology and using it for cardiac indication, and only 18.1% diagnosed to have non-valvular AF. Modified SAMe-TT2 R2 score has good relation to original SAMe-TT2 R2 score as showed 75.71% (95% CI. 63.99 to 85.17%), 100% (95% CI. 92.89 to 100%) and 15% (95% CI. 3.21 to 77.95%); accuracy, sensitivity and specificity in relation to SAMe-TT2 R2 respectively. In addition to that in this small cohort we found that there is universal relationship between SAMe-TT2 R2 score, Modified SAMe-TT2 R2 score and TTR; TTR >=65% associate with low score (<2) of both SAMe-TT2 R2 , Modified SAMe-TT2 R2 score. Conclusion: The use of Modified SAMe-TT2 R2 score allows clinicians to make an informed decision on whether to start vitamin K antagonist or other non-vitamin K antagonist oral anticoagulant despite the race of the patients.