Control of INR Test Results Are Key to Patient Safety

By: Alere Staff
Publication Date: Mon, 03/19/2012

Warfarin is prescribed for eligible patients at risk for developing dangerous blood clots. The most common side effect of warfarin is bleeding, and the risk of bleeding is closely related to warfarin dose.1

A study conducted by researchers at the University of Cincinnati Academic Health Center, and published in the medical journal Neurology, highlights the importance of careful warfarin management. The study included 251 patients who had experienced a bleeding event in the brain. Only 20% of the patients were taking warfarin. Investigators analyzed these 51 patients to determine whether International Normalized Ratio (INR) levels affected the severity of the bleeding event, measured by blood volume.2

The year-long study found that warfarin patients who were well managed and who maintained INR values in target range are not at higher risk for a bleeding event in the brain than those not taking warfarin. Warfarin users were not more likely to have IVH (intravascular hemorrhage) than other patients (not taking warfarin). However, the authors did find that larger blood loss was more common in warfarin patients with INR test results greater than 3.0.2

Patients should work with their healthcare team to improve control of warfarin therapy. Better warfarin management can be achieved with ongoing patient education to enhance understanding of the potential for dietary and/or medication interactions, as well as with more frequent INR testing.

  1. Bristol-Myers Squibb Company. Medication Guide for Warfarin Tablets and Warfarin for Injection (Package Insert). Princeton, NJ: Bristol-Myers Squibb Company. 2009.
  2. Flaherty, M.L., et al. Warfarin use leads to larger intracerebral hematomas. Neurology. 2008. 71, 1084-1089.