Coumadin Senstivity Testing Controversial

Implications: Coumadin is a frequently used and efficacious anticoagulant but patients must be monitored closely in order to avoid bleeding complications.  Genetic variations in coumadin metabolism contribute significantly to variations in bleeding risk and sensitivity to the anticoagulant effects of the drug.  A new FDA approved test allows the genetic differences to be measured.

Analysis: This test opens a can of worms.  If the testing takes 2-10 days to get results, then this will delay the institution of Coumadin in patients and require longer duration use of fractionated and unfractionated heparin thereby increasing costs.  The use of this test does not obviate the requirement that all patients started and continued on Warfarin require close monitoring of the INR.  With this label added, physicians will be more vulnerable to claims of malpractice when bleeding occurs in patients on Warfarin if they fail to perform the testing-although it is not clear that the results of the test would have had any real effect on the bleeding in  given patient.  In sum, while the test is useful it is not yet clear that it alters outcomes or will meaningfully change the incidence of bleeding on Coumadin.