False PT/INR Results May Appear for Some Patients

Alere has issued a voluntary correction to users of the Alere INRatio and INRatio 2 PT/INR Monitor system of certain medical conditions that should not be tested with the system (INRatio Monitor INRatio 2 Monitor and INRatio Test Strips).

Certain medical conditions may result in an INR result that is clinically significantly lower than a result using a laboratory method (reference INR). The system should not be used in patients with:

Anemia of any type with hematocrit <30%
Any conditions associated with elevated fibrinogen levels including:

Acute inflammatory conditions (eg, acute viral or bacterial infections such as pneumonia or influenza)
Chronic inflammatory conditions (eg, rheumatoid arthritis, Crohn’s disease, ulcerative colitis, infectious liver diseases such as hepatitis, or inflammatory kidney diseases such as diabetic nephropathy and glomerulonephritis).
Severe infection (eg, sepsis)
Chronically elevated fibrinogen for any reason
Hospitalized or advanced stage cancer or end stage renal disease patients requiring hemodialysis.

Any bleeding or unusual bruising, clinically observed or reported by the patient.

In these cases, patients should have their INR and warfarin therapy monitored by a laboratory INR method. To obtain the most accurate results, healthcare professionals and patient self-testers are also recommended to do the following:

Patients should have periodic verification of their INR using a laboratory INR method.
If a significantly discrepant low result on the INRatio and INRatio 2 monitor system vs. plasma-based laboratory INR method occurs, patient should immediately be transitioned to an alternative method for monitoring their INR and warfarin therapy.
Significant discrepancy in INR results may delay decision to reverse a supratherapeutic INR level following the established guidelines for monitoring warfarin therapy.

Take caution when the incorrect INR result is within the therapeutic range but the actual value is supratherapeutic, (eg, when the actual INR value is 6 or greater).

Patients should be tested to confirm that their hematocrit falls within the 30–55% range.

The device concerns have been reported to the Food and Drug Administration, and Alere is investigating into these events.

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