MedWire News: The British Committee for Standards in Haematology has published updated guidelines on oral anticoagulation with warfarin.
The guidelines replace those published in 2006 and should provide healthcare professionals with clear guidance on the indications for and management of patients on warfarin, say the authors.
To make the current recommendations, the writing group, led by David Keeling (Oxford Radcliffe Hospitals, UK), reviewed data from clinical trials and meta-analyses published in the last 5 years. They covered areas such as the indications for warfarin and the recommended target international normalized ratio (INR), duration of anticoagulation, management of bleeding, and anticoagulant monitoring and dose adjustment.
In most cases, the authors recommend an INR target of 2.5. This should be increased to 3.5 for patients who experience recurrent venous thromboembolism while anticoagulated and within the therapeutic range.
Anticoagulant therapy should last for at least 3 months in patients with deep vein thrombosis (DVT) or pulmonary embolism (PE), but this can be reduced to 6 weeks in cases of calf vein DVT, notes the team.
Longer treatment (6 months initially) with therapeutic-dose low molecular weight heparin (LMWH) rather than warfarin is recommended for patients with cancer, while long-term anticoagulant therapy is not recommended in patients with VTE provoked by surgery or by non-surgical transient triggers (eg, pregnancy).
In addition, patients with unprovoked proximal DVT or PE should be considered for long-term anticoagulation only once physicians have taken into account individual patient factors that may help predict risk for recurrence and bleeding.
The group advises that all hospitals managing patients on warfarin should stock a licensed four-factor prothrombin complex concentrate which should be used for rapid anticoagulation reversal in the event of major bleeding. In cases of minor bleeding, anticoagulation should be reversed with vitamin K 1-3 mg intravenously, they say.
A review of anticoagulant monitoring and dose adjustment indicated that computer-assisted dosing is superior to manual dosing for patients on warfarin.
In addition, the team found that self-testing and self-management of warfarin is associated with improved anticoagulant control but may not be suitable for all patients. For individuals with an unstable INR, supplementing the diet with 100-150 µg vitamin K may improve anticoagulant control, Keeling and co-authors note.
The guidelines are published in the British Journal of Haematology.
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