Home-Use Device to Monitor Blood Thinner May Issue Inaccurate Results

The U.S. Food and Drug Administration is warning patients and doctors, who use at-home or in-the-office medical devices to monitor levels of the blood thinner, warfarin, that certain test strips used with the devices may provide inaccurate results and should not be relied upon to adjust the drug dosage. Roche Diagnostics issued a voluntary recall of certain test strip lots used with its CoaguChek test meter devices. The recall involves more than 1.1 million packages of CoaguChek XS PT Test Strips that were distributed nationwide from Jan. 12, 2018 to Oct. 29, 2018. The FDA announced this action as a Class I recall, the most serious type of recall, which means the use of these devices may cause serious injuries or death.
 
The FDA is warning patients and health care professionals that they should not rely on these test meter devices to monitor warfarin levels if they’re using test strips affected by the recall. Instead, they should have blood drawn from a vein and have their levels measured by a laboratory test or use an alternative meter device.
 
“These strips are widely used and we are working diligently to warn healthcare providers and the public about the dangers associated with this recall. Using faulty strips can lead to serious errors in medication dosage that could cause serious harm or death in some patients,” said Jeffrey Shuren, M.D., director of the FDA’s Center for Devices and Radiological Health. “We are also working with the company on the swift removal of the recalled strips and to ensure the new corrected strips are distributed to patients and health care providers as quickly as possible.”
 
Millions of Americans take the blood thinner warfarin (also known by the brand names Coumadin and Jantoven) to prevent and treat blood clots. The drug may be prescribed for patients with certain types of irregular heartbeats, blood clots in the legs or lungs, or certain medical device implants such as artificial heart valves. Achieving the correct warfarin dosage is crucial, and patients need regular monitoring to test how long it takes their blood to clot. The response is measured by a blood test to check the International Normalized Ratio, or INR. This test can be performed by an accredited laboratory on blood drawn from a vein or with a fingerstick blood draw using an INR test meter at home or in a doctor’s office.
 
The FDA’s warning concerning the CoaguChek XS PT Test Strips is based on medical device reports submitted by Roche Diagnostics to the agency indicating that the test strips may provide results that are higher than the actual INR. As a result of incorrect INR results, some patients may be prescribed an insufficient warfarin dose or instructed to interrupt warfarin use, which may increase the risk for dangerous blood clots. Approximately 90 medical device reports and two serious patient injuries involving strokes were reported to the FDA.
 
Incorrect INR results are of particular concern for individuals at an increased risk of blood clots including those with mechanical heart valves, atrial fibrillation (irregular heartbeat) who are at a high risk of stroke, or those who had a recent blood clot. It is important to note that problems with the CoaguChek XS PT test strips are not likely to be evident to the patient.
 
Roche Diagnostics attributes the cause of the problem to a recent re-calibration of the test strips to a different international standard that occurred earlier this year. They plan to provide new batches of re-calibrated test strips, based on the previous international standard, to their customers by the end of November; the FDA reviewed validation data submitted by the company for these recalibrated strips. The test strips are used with the CoaguChek XS plus, CoaguChek XS Pro, CoaguChek XS professional, CoaguChek XS PST, and CoaguChek Vantus test meter devices.
 
Patients who are using CoaguChek meters should contact their healthcare provider to get information about alternative test methods and to address questions regarding their individual testing schedule. Patients should also contact their patient self-testing service providers to find out when they will be getting their corrected test strips. Health care providers and patients may contact Roche Diagnostics to learn more details about the recall.
 
All healthcare providers, patients, and caregivers are strongly encouraged to voluntarily report INR test meter problems directly to the FDA through MedWatch, the FDA’s voluntary reporting program. Problems should be reported whenever one suspects that there may be an issue with an INR test meter such as a malfunction or incorrect result, or that the meter caused or contributed to a serious injury or death.
 
The FDA is committed to continuing to communicate publicly on this issue and will provide updates related to this recall when available.