The Centers for Medicare and Medicaid Services (CMS), a division of the US Department of Health & Human Services, will not provide reimbursement for genetic tests that help doctors determine optimal dosing for the blood-thinning drug warfarin (brand name Coumadin®). Citing the lack of evidence of a direct correlation between the tests and improvement in patients’ health, CMS has stated that it will not pay for these tests under the Medicare program. More than one million Medicare beneficiaries take warfarin each year.
Warfarin response tests screen for a patient’s sensitivity to the blood thinner by identifying variants in a pair of genes that are believed to affect the drug’s delivery--CYP2C9 and VKORC1. CYP2C9 helps the body metabolize, or break down warfarin, and VKORC1 helps regulate the ability of warfarin to prevent blood clots. Prior studies have shown that 1/3 of patients metabolize warfarin differently, depending on their genetic makeup. Compared to other patients, they experience an increased bleeding risk and need lower doses of the drug. In current therapy for thrombosis, dosage and administration of warfarin is customized for each patient.
Before these tests were available, doctors employed a trial-and-error approach to treatment, based on a patient’s age, weight and other factors. The patient’s blood had to be tested every few days early on to determine if it was clotting and adjust the dosage if needed. The risk for serious bleeding is typically highest during the first few days of treatment. If given too large a dose of warfarin, patients are at risk for internal bleeding. When given too low a dose, patients are at risk for developing blood clots. Thousands of patients are admitted to hospitals yearly due to complications from warfarin dosing.
The CMS argues that the genetic tests do not show evidence of decreasing the risk of blood clots or hemorrhage. Further, tests results are sometimes received after the initial dose is calculated and periodic blood tests are still required to see how well the blood is clotting. CMS said that benefits to patients “seem to us premature, even though they are intuitively appealing.” It cites other factors that can determine the body’s ability to metabolize warfarin, including: diet, liver function, interactions from other drugs and ethnicity. The agency did, however, say it will cover the cost of the tests as part of a clinical trial to collect more data. The tests range in cost from $50-$500, Nanosphere, Osmetech and ParagonDx are some of the companies that sell warfarin genetic tests to hospitals and laboratories.
Responses to the decision have varied. Edward Abrahams, executive director of the Personalized Medicine Coalition and a proponent of the tests, said that costly clinical trials required by Medicare might be unreasonable for diagnostic tests. On the other hand, Kathy Hudson, director of the Genetics and Public Policy Center at Johns Hopkins University, agreed with the CMS decision. “We should pay for what works,” she said.
The proposed decision, which appears on the CMS Web site, was open for public comment until June 3, 2009.
Read more about the issue and CMS’s decision.
Source: The New York Times, May 5, 2009