Wednesday April 1, 2009
LOW DOSE VITAMIN K: DOES IT DECREASES RISK OF BLEEDING

Recent article published in Annals of Internal Medicine by Crowther helps to sort this practice. Low-dose oral vitamin K decreases the international normalized ratio (INR) but its effects on bleeding events are uncertain.

OBJECTIVE: To see whether low-dose oral vitamin K reduces bleeding events over 90 days in patients with warfarin-associated coagulopathy.

DESIGN: Multicenter, randomized, placebo-controlled trial with 14 anticoagulant therapy clinics in Canada, the United States, and Italy.

Method: Nonbleeding patients with INR values of 4.5 to 10.0 either received oral vitamin K, 1.25 mg (355 patients randomly assigned; 347 analyzed), or matching placebo (369 patients randomly assigned; 365 analyzed). Bleeding events (primary outcome), thromboembolism, and death (secondary outcomes) were measured.

Results: 56 patients (15.8%) in the vitamin K group and 60 patients (16.3%) in the placebo group had at least 1 bleeding complication. Major bleeding events occurred in 9 patients (2.5%) in the vitamin K group and 4 patients (1.1%) in the placebo group (absolute difference, 1.5 percentage points [CI, -0.8 to 3.7 percentage points]). Thromboembolism occurred in 4 patients (1.1%) in the vitamin K group and 3 patients (0.8%) in the placebo group (absolute difference, 0.3 percentage point [CI, -1.4 to 2.0 percentage points]). The day after treatment, the INR had decreased by a mean of 1.4 in the placebo group and 2.8 in the vitamin K group.

Limitation: Patients who were actively bleeding were not included, and warfarin dosing after enrollment was not mandated or followed.

CONCLUSION: Low-dose oral vitamin K did not reduce bleeding in warfarin recipients with INRs of 4.5 to 10.0.



Reference: click to get abstract

Crowther MA, Ageno W, Garcia D, Wang L et al. Oral vitamin K versus placebo to correct excessive anticoagulation in patients receiving warfarin: a randomized trial. Ann Intern Med. 2009; 150(5):293-300