Variables which achieved statistical significance in the multivariable linear regression model and thereby were maintained were: INR, A allele of the 1639G>A polymorphism in VKORC1, CYP2C9*2 and CYP2C9*3 alleles, prior warfarin dose, age, BSA, stroke, diabetes, race, target INR and use of amiodarone or fluvastatin. Here, CYP2C9 is linked to diabetes mellitus.