PURPOSE: Data regarding the use of oral Vitamin K for management of excessively elevated INR (International Normalized Ratio) in patients with no signs and symptoms of bleeding is limited; there is no definitive conclusion as to when oral vitamin K is clinically appropriate. To assess the current written protocol in a pharmacist managed anticoagulation clinic, data on patients given oral vitamin K for excessively elevated INR was reviewed.
METHODS: The anticoagulation clinic database was queried to find patients with an excessively elevated INR who received oral Vitamin K according to protocol between August 2004 and November 2009. Patients with significant bleeding were referred for medical management and not managed by this protocol. A retrospective review of patient records was performed.
RESULTS: Eighty-one incidents of administration of oral vitamin K to reverse an INR > 6 were reviewed. In half of these incidents, the INR was > 9. There were 30 subtherapeutic INRs, 34 therapeutic INRs, and 17 supratherapeutic INRs upon follow-up 48 - 72 hours after initial elevated INR. Of those supratherapeutic, 9 incidents had INRs 4 at 2 days; of those subtherapeutic, 11 patients had INRs < 1.8 at 2 days. Patients with lower weekly warfarin dosages tended to be supratherapeutic at first follow-up INR. This trended towards significant with a p-value of 0.0648 from ANOVA.
CONCLUSION: Overall, the protocol functioned well. Individuals with lower weekly warfarin dosages are more sensitive to anticoagulation and took longer to return to their goal therapeutic ranges. These more sensitive patients might benefit from vitamin K.
CLINICAL IMPLICATIONS: Management of excessively elevated INRs is a common anticoagulation clinic issue. Better defining when it is appropriate to administer oral vitamin K might improve outcomes.
DISCLOSURE: Ronald Sing, No Financial Disclosure Information; No Product/Research Disclosure Information