Comparison of a Single End Point to Determine Optimal Initial Warfarin Dosing (5 mg Versus 10 mg) for Venous Thromboembolism

There remains considerable controversy regarding optimal initial warfarin dosing in patients with acute venous thromboembolism. Therefore, an open-label, randomized trial comparing 2 warfarin initiation nomograms (5 vs 10 mg) was conducted in patients with acute venous thromboembolism. All participants received fondaparinux for ≥5 days as a "bridge" to warfarin. The primary end point was defined as the number of days necessary to achieve 2 consecutive international normalized ratio laboratory test values >1.9. A total of 50 patients were enrolled and randomly assigned to each of the treatment arms. The median time to 2 consecutive international normalized ratios was 5 days in the 2 groups. There was no statistical difference in achieving the primary end point using either the 5- or the 10-mg nomogram (p = 0.69). These results should provide clinicians with increased warfarin dosing options in patients presenting with acute venous thromboembolism.