A Novel Fixed-Dose Activated Prothrombin Complex Concentrate Regimen for Warfarin-Associated Hemorrhages: A Retrospective Cohort Comparison of Two Regimens.

The optimal fixed-dose strategy for managing warfarin-associated hemorrhages remains unknown and few studies have evaluated the use of Factor VIII Inhibitor Bypass Activity (FEIBA). This retrospective cohort study's primary efficacy outcome was the percentage of patients who achieved a post-FEIBA INR ≤ 1.5 following receipt of the old and new dosing regimens. In the old group patients received 500 or 1000 units for an INR < 5 or ≥5, respectively. In the new group patients received 1000, 1500, or 2000 units for an INR < 5, 5-9.9, or ≥10, respectively. Eighteen patients were included in each group. The median (IQR) pre-FEIBA INR in the old and new groups was 6.1 (3.1-12.9) and 5.3 (3.4-13.0), respectively [difference: -0.8 (95 CI%, -7.2 to 6.5)]. The median (IQR) post-FEIBA INR in the old and new groups was 1.6 (1.4-2.1) and 1.4 (1.2-1.5), respectively [difference: -0.2 (95% CI: -0.6 to 0.0)]. A post-FEIBA INR ≤ 1.5 was achieved in 14 (78%) patients in the new group and 9 (50%) patients in the old group (relative risk: 1.56; 95% CI, 0.91 to 2.7; p = 0.16). The post-FEIBA INR values in the patients who did not achieve a post-FEIBA INR ≤ 1.5 in the new group were 1.6, 1.6, 1.8, and 2.4. Among patients with a baseline INR ≥ 10, significantly more patients in the new group achieved a post-FEIBA INR ≤ 1.5 compared to the old group (86% vs. 17%, respectively). These findings suggest that the new FEIBA dosing regimen may improve INR reversal compared with the previous regimen, particularly among patients with a baseline INR ≥ 10, but larger studies are needed to confirm this observation.