INR monitoring — friend or foe?

Managing warfarin therapy can be challenging. Patients need regular INR monitoring to ensure their dose is in the therapeutic range, and this means extra lab requisitions and phone calls to adjust doses.

The newer oral anticoagulants (NOACs), dabigatran (Pradaxa), rivaroxaban (Xarelto), and apixaban (Eliquis) are given in fixed doses and don’t require INR monitoring. A boon to a busy clinician, right? Not necessarily.

What simple test can you use to assess compliance, ensure that patients are adequately anticoagulated, or monitor bleeding risk in the event of an emergency or urgent surgery? The INR test does all of this for patients on warfarin, but there’s no similar widely available test for patients on NOACs.

Further, CADTH research showed that many patients derive a sense of comfort and confidence from INR tests, enjoying regular contact with their health professionals and viewing these tests as a “safety net.” See the report for full details of the focus groups conducted with patients and health professionals.

What about the costs of INR monitoring? They’re less than you might think. A CADTH review found that direct costs to the health care system are about $240 per patient per year. Warfarin itself costs about $55, for a total of less than $300 per patient per year. Compared with about $1,200 per year for a NOAC, warfarin is still a bargain.

Bottom line

• INR monitoring can be helpful in many situations.
• Patients do not find INR monitoring as inconvenient as we may think.
• NOACs are more expensive than warfarin, even when INR monitoring is factored in.

INR - international normalized ratio.