The INRatio and INRatio2 caused quite a stir when they were recalled in 2014 for providing erroneous readings, but it appears the trouble with the devices is far from over. The devices are used to measure and monitor certain levels in the blood for patients who take the anticoagulant Warfarin.

The INRatio and INRatio2 measure the prothrombin time (PT), or time it takes the blood to clot. The PT level in a patient’s blood can be used to identify any bleeding problems and can also determine whether or not anticoagulants like Warfarin are working.

These blood-monitoring devices were used in a pivotal clinical trial called ROCKET AF that compared Warfarin to a new type of anticoagulant, Xarelto. The success of the trial led to Xarelto’s approval by the FDA in 2011.

In the five short years since its release onto the market, Xarelto has come under increasing fire from doctors and patients. Unlike Warfarin, Xarelto has no antidote, meaning there is no way to consistently reverse the effects of Xarelto in the event of an uncontrollable bleeding event. This has led to more than 5,300 lawsuits against the manufacturers alleging it failed to warn patients of the risks associated with Xarelto.

In 2014, the INRatio’s manufacturer voluntarily recalled its devices after receiving hundreds of reports the devices were providing inaccurate readings. It is estimated the devices provided incorrect readings as much as 30% of the time. For plaintiffs in the Xarelto litigation, news the blood-monitoring device used in Xarelto’s clinical trials was recalled led them to believe the data collected in the trial had been compromised.

Xarelto plaintiffs aren’t the only ones who are upset over the INRatio device. INRatio’s manufacturer, Alere, has been working on a way to fix the devices’ inaccurate readings for more than two years. The company finally submitted its proposed fix in the form of a software enhancement to the FDA last December. But the FDA doesn’t believe Alere’s software enhancement will do the trick, and has advised the company to institute another recall of its devices.

Alere took the FDA’s advice and instituted a second voluntary recall of the INRatio and INRatio2 earlier this week. This could have major consequences for all pending Xarelto litigation.