Low dose vitamin K to improve therapeutic quality control of oral anticoagulant treatment: a randomized double-blind placebo controlled trial.

Background:

It has been shown that oral anticoagulant control is less stable at a low dietary intake of vitamin K.

We hypothesize that a low dose vitamin K supplement results in a more stable anticoagulation in patients using vitamin K antagonists.

The primary objective of this study:

is to test this hypothesis clinically.




Methods:

The study is a double blind, randomized, placebo controlled trial in patients who use phenprocoumon and have an indication for long-term oral anticoagulant treatment.

Two hundred patients will be randomized to receive adjusted-dose phenprocoumon and a daily vitamin K supplement of 100 micrograms or to receive adjusted-dose phenprocoumon and placebo for 24 weeks.

The primary endpoint is the percentage of time the INR is within the therapeutic range.

1. Oral anticoagulant control is less stable at a low average intake of vitamin K;

2. As a consequence, a low dose vitamin K supplement results in a more stable anticoagulant effect in patients using vitamin K antagonists (VKA);

3. Dietary intake of vitamin K is associated with sensitivity to VKA and stability of anticoagulant treatment;

4. Polymorphisms of the VKORC1 gene are associated with sensitivity to VKA and stability of anticoagulant treatment.

N/A

1. Treatment group: 100 microgram vitamin K for 24 weeks;

2. Placebo group: placebo for 24 weeks.