Warfarin Dosing Made Easy

A new study in NEJM shows that genetic information does, in fact, improve dosing estimates of warfarin. The authors used data from 4,043 patients to determine the best parameters for their prediction algorithm, which is available as an online calculator. They tested their results on a validation set of 1,009 subjects and found that information on two variants, CYP2C9 and VKORC1, "significantly increased the accuracy of dose predictions, with the improvements being seen mainly in patients at the extremes (i.e. those who required higher or lower doses of the drug than the population average)," Daniel MacArthur says. According to a press release, the NIH is going to make use of these findings and that launching the largest prospective, multi-center, randomized clinical trial in the US to test whether using genetic information to prescribe the initial warfarin dose will improve patient outcomes. The trial will enroll 1,200 participants and is scheduled to begin next month.