The Centers for Medicare & Medicaid Services (CMS) has approved a two-year clinical study that will evaluate the impacts of genetic information and changes in adverse event rates in patients administered the anticoagulant warfarin (Coumadin, Bristol-Myers Squibb), in order to provide evidence on how individual patients respond to the drug.

While warfarin dose and administration must be individualized for each patient according to their response to the drug, these responses are currently evaluated on a trial-and-error basis. The approved randomized, multicenter trial will perform pharmacogenetic testing of the CPY2C9 or VKORC1 alleles to calculate warfarin responsiveness in patients.

According to researchers, the VKORC1 and CPY2C9 alleles contribute to an estimated 60 percent of individual patient variations of warfarin responsiveness. The trial will assess adverse events including major bleeding complications of patients administered warfarin and where genetic information was used to individualize dose.

Conducted by Iverson Genetic Diagnostics, the trial will enroll more than 7,000 patients at 50 U.S. sites, and will be covered by CMS under coverage with evidence development. Elizabeth Ofili, MD, of the Morehouse School of Medicine in Atlanta, and colleagues will conduct the study.