Prediction of unstable anticoagulation with acenocoumarol versus warfarin in atrial fibrillation

Background: The SAMe-TT2R2 (sex female, age, medical history, treatment, tobacco use, race) score was developed in patients with atrial fibrillation (AF) on warfarin. The present study aimed to 1) compare the anticoagulation quality and management of AF patients treated with warfarin with those on acenocoumarol and 2) optimize the SAMe-TT2R2 score to detect AF patients at high risk of unstable anticoagulation with acenocoumarol and warfarin. Methods: In a single-center retrospective study, 320 patients with AF, including 15 (5%) after valve replacement, aged 40-82 (median 70) years, including 203 (63%) receiving acenocoumarol and 117 (37%) treated with warfarin, were studied. The SAMe-TT2R2 score was modified based on the candidate factors retrieved from univariate regression and assessed using the receiver operating curves (ROC). Results: A median SAMe-TT2R2 score was 2 (1-3). Proportions of patients with >= 2 points and 0-1 points in the SAMe-TT2R2 score who had the time in therapeutic range (TTR) <= 70% were similar (61 [67%] vs. 63 [56%], p = 0.11). A modified score, involving medical history (myocardial infarction [MI] and chronic obstructive pulmonary disease [COPD], 1 point), statin treatment (1 point) and tobacco use (2 points) had a higher area under the curve (AUC) in patients on acenocoumarol compared to SAMe-TT2R2 (0.66; 95% confidence interval 0.58-0.73 vs. 0.56; 0.48-0.64, p = 0.042); >= 1 point indicated TTR > 70% with a sensitivity and specificity of 61% and 63%, respectively. Conclusions: The SAMe-TT2R2 score is less effective in predicting unstable anticoagulation with acenocoumarol versus warfarin. Adding statin use and highlighting COPD and previous MI increases a predictive value of this score for acenocoumarol.