Evaluation of SAMe-TT₂R₂ risk score for predicting the quality of anticoagulation control in a real-world cohort of patients with non-valvular atrial fibrillation on vitamin-K antagonists

Clinicians need to get better at identifying patients who would have poor quality of anticoagulation control with vitamin-K antagonists (VKAs). We assessed the predictive ability of SAMe-TT₂R₂ score, recently conceived for the prior purpose, and examined its relationship with major bleeding, thromboembolic (TE) complications, and death.

Retrospectively, 911 consecutive patients with non-valvular atrial fibrillation (NVAF) started on VKAs within 8 months were studied. The percentage of international normalized ratios in therapeutic range (PINRR) at different levels was used as a metric of anticoagulation quality. We also tested the SAMe-TT₂R₂ predictability for major bleeding, TE complications, and death throughout 10 ± 3 months. The PINRR decreased from 62% at zero point to 53% at ≥4 points of SAMe-TT₂R₂. 82.1% of patients who achieved PINRR ≥ 70% had 0 or 1 point of SAMe-TT₂R₂. SAMe-TT₂R₂ performed significantly better at PINRR 70% than at 65 and 60% (c-statistic = 0.60 vs. c-statistic = 0.56). The calibration of SAMe-TT₂R₂ was excellent (Hosmer–Lemeshow test P-values ≥ 0.6). SAMe-TT₂R₂ showed significant association with the composite outcome of major bleeding, TE complications, and death [n = 98; hazard ratio (HR) = 1.32; 95% confidence interval (CI) 1.08–1.60]; the c-statistic was 0.57 (95% CI: 0.51–0.62) and P = 0.03. As individual outcomes, SAMe-TT₂R₂ was significantly associated with death (n = 60; HR = 1.3; 95% CI: 1.03–1.69), but not with either major bleeding (n = 30; HR = 1.2; 95% CI: 0.85–1.76) or TE complications (n = 15; HR = 1.01; 95% CI: 0.58–1.77).

Among NVAF patients, SAMe-TT₂R₂ could represent a useful clinical tool to identify patients who would have poor quality of anticoagulation control with VKAs. SAMe-TT₂R₂ successfully predicts the composite outcome of major bleeding, TE complications, and death.