Prescribing warfarin appropriately to meet patient safety goals.

The anticoagulant warfarin is increasingly used in a variety of disorders associated with risk of thromboembolism. The drug is undoubtedly effective but is linked to numerous nutrient, disease, and drug interactions; safe use of warfarin therefore necessitates close patient monitoring, using the international normalized ratio. The predominant adverse effect is bleeding, and individuals respond to warfarin in different ways. Both high and subtherapeutic international normalized ratios warrant attention, whereas a high international normalized ratio, with or without bleeding, mandates prompt patient evaluation. The 2008 National Patient Safety Goals require medical institutions to develop processes to ensure the safe use and monitoring of anticoagulant use. Last August, the US Food and Drug Administration revised the prescribing information for warfarin to include genetic testing before initiating therapy, although this is still not covered by most health plans.