Factors predicting poor anticoagulant control on warfarin in a Thai population with non-valvular atrial fibrillation (NVAF): the ACAChE score

Background In many low- to middle-income countries in Asia, patients with NVAF usually received warfarin for thromboembolic prevention due to cost-effectiveness. The SAMe-TT2R2 score has been proposed to predict TTR in NVAF patients. However, the SAMe-TT2R2 score has not been much validated in Asian population. Interestingly, it may overestimate patients who had TTR < 65% due to regarding being Asians as a risk factor. Objectives To determine the factors predicting poor anticoagulant control on warfarin, create new scoring system, and compare with the SAMe-TT2R2 score in a Thai population with NVAF. Methods This is a retrospective study in a tertiary care hospital. We enrolled NVAF patients who received warfarin from January 2014 to December 2018. TTR was calculated based on Rosendaal method. Multiple logistic regression and AUC-ROC curve were used for analysis. Results A total of 864 patients were enrolled with mean age of 73.6 ± 11.58 years. The mean TTR was 48.1 ± 25.2%. Using multivariate regression analysis, the predictive factors for TTR < 65% were antiplatelet use (OR 4.49, p ≤ 0.001), LVEF < 40% (OR 1.92, p = 0.037), chronic kidney disease (GFR < 50 ml/min/1.73 m 2 ) (OR 1.68, p = 0.013), history of CHF (OR 1.7, p = 0.047), and age ≥ 75 years (OR 1.4, p = 0.037). Based on the regression coefficients, we developed the new scoring system called ACAChE score [A, antiplatelet use (4 points); C, chronic kidney disease, GFR < 50 ml/min/1.73 m 2 (2 points); A, age ≥ 75 years (1 point); Ch, history of CHF (2 points); E, LVEF < 40% (2 points)]. ROC curve showed discrimination performance of the ACAChE score and SAMe-TT2R2 score for prediction of TTR < 65% with the C-statistic of 0.62 (95%CI 0.57–0.65) and 0.54 (95%CI 0.50–0.58), respectively. Conclusion In Thai NVAF patients, the ACAChE score (antiplatelet use, chronic kidney disease (GFR < 50 ml/min/1.73 m 2 ), age ≥ 75 years, history of congestive heart failure, and LVEF < 40%) has better prediction for TTR < 65% than SAMe-TT2R2 score. Thus, it expected to guide the selection of oral anticoagulation in Asian patients with NVAF.