Influence of warfarin dose-associated genotypes on the risk of hemorrhagic complications in Chinese patients on warfarin

This study was designed to evaluate the effect of the warfarin dose-associated genotypes, CYP2C9*3 (rs1057910), VKORC1 −1639 G/A (rs9923231), and CYP4F2 1347 C/T (rs2108622), on hemorrhagic complications in Han Chinese patients. Consecutively recruited patients requiring more than 1 year of warfarin treatment were followed from the initiation of warfarin anticoagulation for at least 3 months. CYP2C9*3 , VKORC1 −1639 G/A, and CYP4F2 1347 C/T were genotyped by sequencing. The association between genotypes and warfarin hemorrhagic complications was evaluated using Cox proportional hazard regression, adjusted for demographic and clinical factors. Of 312 eligible patients obtaining stable warfarin anticoagulation in 3 months, 11 major and 69 minor hemorrhages occurred over 147 person-years. The CYP2C9*3 genotype conferred an increased risk of all [hazard ratio (HR) 3.07, 95 % confidence interval (CI) 1.57–6.01] and minor hemorrhage (HR 3.28, 95 % CI 1.62–6.65), but not major hemorrhage (HR 0.44, 95 % CI 0.04–4.72). CYP2C9*3 also conferred an increased risk of over-anticoagulation with international normalization ratio (INR) ≥4 (HR 2.92, 95 % CI 1.08–7.85). VKORC1 −1639 G/A, and CYP4F2 rs2108622 did not confer significant increase in risk for hemorrhage or over-anticoagulation. Kaplan–Meier curves showed that time to all hemorrhagic events was significantly shorter for patients with CYP2C9*3 genotype than non-carriers ( P = 0.001), but not for patients with VKORC1 −1639 G/A or CYP4F2 rs2108622 genotype ( P = 0.3 and 0.2). CYP2C9*3 may be the main genetic factor in hemorrhagic complications in Chinese patients under warfarin anticoagulation.