Nick B Polito1, Eric Kanouse1, Courtney M C Jones2, Molly McCann3, Majed A Refaai4, Nicole M Acquisto5. 1. Department of Pharmacy, University of Rochester Medical Center, Rochester, NewYork. 2. Department of Emergency Medicine, University of Rochester, Rochester, NewYork. 3. Departments of Public Health Services and Emergency Medicine, University of Rochester, Rochester, NewYork. 4. Pathology and Laboratory Medicine, University of Rochester Medical Center, Rochester, NewYork. 5. Department of Pharmacy and Emergency Medicine, University of Rochester Medical Center, Rochester, NewYork.
Abstract
BACKGROUND: Vitamin K is reported to begin reversing warfarin within 6 to 12 hours, but this may occur sooner. We sought to determine the rate of international normalized ratio (INR) reversal following vitamin K and relationships with dose, route, and baseline INR. METHODS: We evaluated adult patients receiving vitamin K monotherapy for warfarin reversal. Post-vitamin K INRs through 48 hours were collected. Relationships between vitamin K dose and route and baseline INR on rate of reversal and complete reversal (INR < 1.5) were evaluated. Assessment was performed graphically using scatter plots with a line of best fit and a counting process model to determine variables associated with achieving complete reversal. RESULTS: A total of 469 post-vitamin K INRs from 235 patients were included. Time to first INR follow-up after vitamin K administration averaged 10.5 ± 4.2 hours. A significant decrease was detected in INR values in comparison to the baseline INR (3.0 ± 1.9 vs. 4.7 ± 2.2; p < 0.01). Rapid and steady INR change began immediately after vitamin K administration (0-4 hr). A high vitamin K dose and intravenous route were associated with rapid INR change and complete reversal (Vitamin K 10 mg [hazard ratio, 2.4; 95% confidence interval, 1.4-4.2] and IV route [hazard ratio, 1.8; 95% confidence interval, 1.3-2.6]); however, overall complete reversal at 24 and 48 hours was low (14.5% and 41.7%, respectively). Higher baseline INR was associated with rapid INR change and lower baseline INR with complete reversal. CONCLUSION: Vitamin K alone starts to reverse warfarin immediately. High vitamin K doses and intravenous route are associated with faster INR reversal. Baseline INR also influences rate of correction and frequency of achieving complete reversal.
BACKGROUND:Vitamin K is reported to begin reversing warfarin within 6 to 12 hours, but this may occur sooner. We sought to determine the rate of international normalized ratio (INR) reversal following vitamin K and relationships with dose, route, and baseline INR. METHODS: We evaluated adult patients receiving vitamin K monotherapy for warfarin reversal. Post-vitamin K INRs through 48 hours were collected. Relationships between vitamin K dose and route and baseline INR on rate of reversal and complete reversal (INR < 1.5) were evaluated. Assessment was performed graphically using scatter plots with a line of best fit and a counting process model to determine variables associated with achieving complete reversal. RESULTS: A total of 469 post-vitamin K INRs from 235 patients were included. Time to first INR follow-up after vitamin K administration averaged 10.5 ± 4.2 hours. A significant decrease was detected in INR values in comparison to the baseline INR (3.0 ± 1.9 vs. 4.7 ± 2.2; p < 0.01). Rapid and steady INR change began immediately after vitamin K administration (0-4 hr). A high vitamin K dose and intravenous route were associated with rapid INR change and complete reversal (Vitamin K 10 mg [hazard ratio, 2.4; 95% confidence interval, 1.4-4.2] and IV route [hazard ratio, 1.8; 95% confidence interval, 1.3-2.6]); however, overall complete reversal at 24 and 48 hours was low (14.5% and 41.7%, respectively). Higher baseline INR was associated with rapid INR change and lower baseline INR with complete reversal. CONCLUSION:Vitamin K alone starts to reverse warfarin immediately. High vitamin K doses and intravenous route are associated with faster INR reversal. Baseline INR also influences rate of correction and frequency of achieving complete reversal.