A survey of oral vitamin K use by anticoagulation clinics

Despite published reports of its safety and efficacy, oral vitamin K (phytonadione) may not be widely used for patients with warfarin-associated coagulopathy. We tested the hypothesis that recommendations for phytonadione use from the American College of Chest Physicians (ACCP) Fifth Consensus Conference on Antithrombotic Therapy are not routinely incorporated into the clinical practice of many anticoagulation clinics.

Surveys were mailed to 100 separate clinics in the southwestern region of the United States that are members of the Anticoagulation Forum, an association of anticoagulation clinic personnel and medical directors in the United States and Canada. Respondents were presented with 4 scenarios involving asymptomatic patients taking warfarin whose international normalized ratio is supratherapeutic. In each scenario, the respondents were told the patient's international normalized ratio and whether the patient was at "high" risk for bleeding.

Of 53 respondents, 13 (25%) indicated that their clinics never use oral phytonadione. Eighteen (34%) indicated that their clinics use subcutaneous phytonadione, despite the absence of a recommendation for this in the ACCP guidelines published in 1998. For each scenario, we made a judgment as to whether the respondent's management was consistent with guidelines found in the ACCP Fifth Consensus Conference on Antithrombotic Therapy. Overall, only 17 respondents (32%) provided all 4 answers consistent with the ACCP recommendations.

For patients with supratherapeutic international normalized ratio values, our survey suggests that a substantial number of anticoagulation clinics underutilize oral phytonadione.