Integrating genotypes in the SAMe-TT2R2 score for the prediction of anticoagulation control in Chinese patients with atrial fibrillation on warfarin.

ABSTRACT

INTRODUCTION: The SAMe-TT2R2 score has been proposed to predict whether patients with atrial fibrillation (AF) would be well anti-coagulated with warfarin or not. However, it might over-estimate the number of patients under suboptimal warfarin treatment in non-Caucasians. This study was designed to modify the SAMe-TT2R2 score with genotypes and validate it in Chinese AF patients treated with warfarin. MATERIAL AND METHODS: Consented Chinese-Han patients (n=510) with AF under the treatment of warfarin for at least 3months were randomly divided into a derivation (n=310) and a validation cohort (n=200). For each patient, CYP2C9*3 and VKORC1 -1639 A/G genotyping was performed, and the time in therapeutic range (TTR) was calculated over this period. RESULTS: The modified SAMe-TT2R2 score was established by adding "warfarin genotype bins" to replace "the non-white race" variable. In the validation cohort, the discrimination performance of the modified score for good anticoagulation control (TTR≥70%) was significantly improved (c- index increased from 0.60 to 0.67). Significantly increased risks of major bleedings (HR 4.91; 95% CI 1.03-23.37; adjusted p=0.04) and all bleedings (HR 1.93; 95% CI 1.14-3.25; adjusted p=0.01) were found in patients with modified scores ≥2, as compared with patients with modified scores of 0-1. CONCLUSIONS: The modified SAMe-TT2R2 score could improve the ability for the identification of good anticoagulation control, and the prediction of major bleeding events in Chinese patients with AF treated by warfarin.