Published in:
01-02-2008
Effect of low-dose vitamin K supplementation in patients on warfarin with fluctuating international normalized ratios
Authors:
B. Sipe, L. Heyerly, K. Thornton, R. Jones, D. Kaminskas
Published in:
Journal of Thrombosis and Thrombolysis
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Issue 1/2008
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Excerpt
Background A small previous study has suggested that a small regular dietary vitamin K intake improved international normalized ratio (INR) control in warfarin patients. As a follow-up to this finding we designed a study assessing impact of a low dose vitamin K supplementation (LVK) on INR control in patients with fluctuating INRs (goal range 2–3). Design Patients were enrolled who had fluctuating INRs not related to disease, diet or other medications. Vitamin K 100 mcg daily was added to the normal warfarin dose. INRs were assessed for 6 months pre and post-LVK in a crossover design and compared for percent INRs in range, days required between prothrombin times and variance of INRs. Statistical tests included Mann–Whitney test for comparison of 2 groups and F-test for comparison of variances. Results Preliminary results for 18 patients (age 67.7 ± 9.3) demonstrate actual in range improvement of 64.7% vs. 50.2%, P = 0.001 (77.5% vs. 64.7%, Rosendaal equation). Days between clinic visits for INR testing increased from 11.8 days to 14.5 days, P < 0.0001 and variances of INRs pre and post-LVK were highly significant, P = 0.00000225. Conclusion Preliminary results of this ongoing study suggest that LVK may stabilize fluctuating INRs in difficult to control warfarin patients to improve efficacy and safety of this important therapy. …