The second problem GIFT will tackle is the long-standing debate concerning appropriate target levels of clotting ability in the blood, a quantity known as the International Normalized Ratio (INR). INR refers to blood clotting speed: the higher the number, the longer blood takes to clot. A higher INR increases the chances that a patient will start bleeding, but also decreases the chances that a patient will develop a clot.

The American Academy of Orthopedic Surgeons currently recommends an INR of less than 2.0. However, the American College of Chest Physicians has set forth a recommended target INR of 2.0 to 3.0. Until now, no study has attempted to compare these two guidelines of warfarin treatment to determine which strikes the best balance between bleeding and clot risk.

All participants in GIFT will receive warfarin treatment. For half of the patients, warfarin dose will be decided based on clinical formulas that account for age, body size, medications and smoking status. The other half will receive a warfarin estimate based on these factors plus genetics. Each group will also be split, with one half trying to reach a target INR of less than 2.0 and the other half striving for an INR of 2.5. The researchers anticipate that after the initial two weeks of treatment, patients will have reached an appropriate level of warfarin with little adjustment needed thereafter.

"The first aim is a test of the paradigm of personalized medicine," Gage says. "We have been working in the field for eight years. Now, it's exciting to go see that results of these efforts will be used to care for thousands of patients."

Source: Washington University School of Medicine