Bleeding Complications With Warfarin Use

Abstract

The anticoagulant warfarin sodium (Coumadin; Bristol-Myers Squibb, Princeton, New Jersey) is approved for the prevention and/or treatment of venous thrombosis, pulmonary embolism, and thromboembolic complications associated with atrial fibrillation and/or cardiac valve replacement and to reduce the risk of death, recurrent myocardial infarction, and thromboembolic events after myocardial infarction. It is used to treat patients in hospitals and in long-term care and outpatient settings and has well-recognized bleeding complications as an adverse effect of treatment. In 1997, warfarin and insulins were identified as the drugs most commonly implicated in adverse events in an emergency department at a single institution¹ and in nationally representative emergency department data in 2002² and 2004 through 2005³ in the United States. In a sample of 9 National Electronic Injury Surveillance System (NEISS) hospital emergency departments from July 17, 2002, through September 30, 2002,² warfarin and insulin products together accounted for 16% of all adverse drug events and, in patients 50 years and older, they accounted for 69% of unintentional overdoses and 33% of all adverse drug events. Similarly, from January 2004 through December 2005, in a nationally representative sample of all hospitals in the United States and its territories, warfarin or insulins were implicated in 1 of 7 estimated adverse drug events in emergency departments (14.1%; 95% confidence interval [CI], 9.6%-18.6%) and in more than 25% (95% CI, 17.3%-35.2%) of estimated adverse drug event hospitalizations.³