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INRatio Device to Leave U.S. Market, Company Says

Cheryl Thompson

Cheryl A. Thompson

The company marketing the INRatio Monitor System has announced the intention to withdraw the now-questionable point-of-care device from the U.S. market.

Alere Inc. stated on Monday that it is working with FDA to determine when to discontinue the INRatio and INRatio2 PT/INR Monitor System, which determine the International Normalized Ratio (INR) in samples of capillary whole blood.

The company in December 2014 had issued an "urgent correction" notice stating that the two devices, under certain circumstances, could display an INR that is lower than that obtained through a laboratory method. This problem could arise with blood samples from patients with any anemia accompanied by a hematocrit of <30%, any condition associated with elevated fibrinogen levels, or any bleeding or unusual bruising, the company said.

FDA categorized the correction, affecting devices manufactured from April 2008 through December 2014, as a Class I recall.

Information in the correction turned out also to be applicable to the PT/INR Monitor System used in the international study known as ROCKET AF, according to an investigation by the European Medicines Agency.

The study compared a fixed dosage of rivaroxaban with INR-monitored warfarin therapy for the prevention of stroke and systemic embolism in patients with atrial fibrillation.

On July 6, the New England Journal of Medicine published the letter "Point-of-Care Warfarin Monitoring in the ROCKET AF Trial," by J. Robert Powell, and a response written on behalf of the ROCKET AF executive committee, steering committee, and investigators.

Powell, who is associated with the Eshelman School of Pharmacy at the University of North Carolina, Chapel Hill, questioned how the data from the study should be interpreted, given the problem with the device that aided in the selection of warfarin dosages.

The response acknowledged limitations in the follow-up attempt to validate the device-determined INRs.

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