FDA labeling of warfarin includes to consider genetic testing when initiating warfarin, although few patients are offered this testing. Over 30 genes contribute to warfarin dosing effects, but 1/3 of the variance is controlled by polymorphisms in 2 genes: cytochrome P450 (CYP2C9) and vitamin K epoxide reductase (VKORC1). In this cost-effective analysis (abstract), the authors determine that testing afib patients for these 2 genes upon initiation of warfarin (with genotype-guided dosing), is only cost-effective if their risk of bleeding is high (HEMORR2HAGES score >1) (abstract), depending on the cost of the testing. Currently the cost of such testing is about $400, so should be considered ONLY in patients at high risk for bleeding.
Dr. Scheurer is a clinical hospitalist and the Medical Director of Quality and Safety at the Medical University of South Carolina in Charleston, South Carolina, and is Assistant Professor of Medicine. She is a graduate of the University of Tennessee College of Medicine, completed her residency at Duke University, and completed her Masters in Clinical Research at the Medical University of South Carolina. She also serves as the Web Editor and Physician Advisor for the Society of Hospital Medicine.