Genetics to Help Determine Dose of Blood Thinners After Joint Surgery

Warfarin, commonly prescribed to prevent blood clots in patients undergoing joint replacement surgery, is associated with a range of adverse effects that include major bleeding and requires careful, individualized dosing to achieve the best possible treatment outcomes. A new study finds that incorporating a patient's genetic makeup into the dosing decision can refine the dosing decision and significantly reduce the risk of complications. Results from the 5-year national GIFT study (Genetics Informatics Trial of Warfarin to Prevent Deep Venous Thrombosis) conclude that patients who received genetically determined warfarin dose had a 27 percent reduction in complications compared to patients who received a standard dose. These improvements included a 75% reduction in major bleeding, 15% fewer incidents of blood clots, and 30% reduced incidence of excessive international normalized ratios, a lab test used to assess warfarin's effect. The findings were reported in the September 26 issue of the Journal of the American Medical Association.

Since 2007 the FDA has included language in warfarin packaging that encourages use of genetic guidance in dosage determination, if available. Of the present study, Scott Woller, MD, co-director of the Thrombosis Program at Intermountain Medical Center and principal investigator for Intermountain Healthcare said "In 2017, what I think GIFT shows us is that when we give warfarin based on an individual's genes, we can reduce their risk for adverse outcomes compared to using a standardized approach. What's uncertain now is how that observation can be pragmatically adopted clinically to provide cost-effective care." He noted that individual genotyping has been challenging from the perspective of cost effectiveness but that "The day may come when patients go to the doctor, have their blood pressure taken, and then a cheek swab is used to genotype their whole genome."

Read a news story about the study findings.

The journal abstract may be read here.