Mark A. Crowther, MD, MSc; David Garcia, MD
Potential Financial Conflicts of Interest:Consultancies: M.A. Crowther (Anton Pharmaceuticals).
Crowther MA, Garcia D. Vitamin K to Correct Overanticoagulation. Ann Intern Med. 2009;151:435. doi: 10.7326/0003-4819-151-6-200909150-00021
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Published: Ann Intern Med. 2009;151(6):435.
Our study found that low-dose oral vitamin K does not reduce bleeding in asymptomatic patients who present with INR values between 4.5 and 10.0. Thus, one should not recommend vitamin K to patients similar to those we enrolled if the intent is to reduce bleeding.
The INR decreased more rapidly in patients who received vitamin K, consistent with the pattern we have observed in previous studies. This INR decrease confirms that the formulation used in our study was effective (1). Similarly, we decided only after extensive discussion that we would not mandate how warfarin was given after study drug administration. We agree with Drs. Swaim and Macik that patients whose INR decreased quickly (whether they received vitamin K or placebo) probably had less-dramatic reductions of warfarin dose. Such warfarin dose adjustment is not only appropriate but also reflects routine clinical practice. Thus, our study represents the best estimate of the efficacy (or lack thereof) of vitamin K in the “real world.”
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