The INRatio Monitor is a handheld device that is used by patients on warfarin, a blood-thinning drug that prevents blood clots.
Patients must frequently check blood-clotting times so they can adjust the dose. Accuracy is extremely important. Patients could have a stroke if they take too little warfarin, or bleed to death if they take too much.
Problems with inaccurately low readings have been known for over a decade. In 2005 and 2006, the FDA issued warnings to the device’s manufacturer for failing to act on complaints about erroneous results.
Yet it was not until December 2014 that Alere issued a Class I recall for INRatio Test Strips, reporting three deaths and nearly 19,000 complaints since 2013. The entire system — including INRatio and INRatio2 Monitors — were recalled in July 2016.
Adding to the controversy, INRatio Monitors were used in a major clinical trial comparing warfarin to the new blood-thinner Xarelto. Critics say false readings may have skewed results against warfarin.
Earlier this year, FDA investigators concluded that the faulty devices had a “minimal” impact. The Xarelto trial was led by Dr. Robert M. Califf, now head of the FDA.