Evaluation of 16 Genotype-Guided Warfarin Dosing Algorithms in 310 Korean Patients Receiving Warfarin Treatment: Poor Prediction Performance in VKORC1 1173C Carriers

Abstract Purpose The purpose of this study was to evaluate the performance of 16 previously published warfarin dosing algorithms in Korean patients. Methods The 16 algorithms were selected through a literature search and evaluated using a cohort of 310 Korean patients with atrial fibrillation or cerebral infarction who were receiving warfarin therapy. Findings A large interindividual variation (up to 11-fold) in warfarin dose was observed (median, 25 mg/wk; range, 7–77 mg/wk). Estimated dose and actual maintenance dose correlated well overall ( r range, 0.52–0.73). Mean absolute error (MAE) of the 16 algorithms ranged from –1.2 to –20.1 mg/wk. The percentage of patients whose estimated dose fell within 20% of the actual dose ranged from 1.0% to 49%. All algorithms showed poor accuracy with increased MAE in a higher dose range. Performance of the dosing algorithms was worse in patients with VKORC1 1173TC or CC than in total ( r range, 0.38–0.61 vs 0.52–0.73; MAE range, –2.6 to –28.0 mg/wk vs –1.2 to –20.1 mg/wk). Implications The algorithms had comparable prediction abilities but showed limited accuracy depending on ethnicity, warfarin dose, and VKORC1 genotype. Further studies are needed to develop genotype-guided warfarin dosing algorithms with greater accuracy in the Korean population.