Commentary

In the US, more than 1 million people each year receive anticoagulation treatment to treat or prevent various thromboembolic complications. Of those receiving such treatment, the INR values will be >3.9 approximately 8% to 9% of the time.¹ The risk for substantial bleeding increases progressively with every 1 point increment of INR above 4.0.² For patients with serious bleeding, transfusion with fresh frozen plasma or prothrombin concentrate is the appropriate intervention. In asymptomatic patients, reduction of the INR can be achieved passively by withholding treatment or actively by giving vitamin K. Is active treatment more safe and effective than passive withholding? A recent review of the literature identified the need for large, well designed, randomised controlled trials to answer this question.³

A previous prospective cohort study by Crowther et al suggested that 1 mg of oral vitamin K was safe and effective in reversing anticoagulation for most patients within 16 hours of treatment.⁴ The current study by Crowther et al provides additional insight into optimal treatment. Oral vitamin K in asymptomatic patients without an overt bleeding risk produces a clinically important increase in the proportion of target range INR values. For unclear reasons, the intervention group had fewer bleeding episodes during the 3 month follow up period. Active oral treatment appears to be safe and effective, but it is also unclear whether additional benefit and equivalent safety exist using intravenous or subcutaneous vitamin K administration.