7 Despite these dangers, warfarin has dominated the field of outpatient thromboprophylaxis for over half a century and remains resistant to challenge by numerous contenders, such as vena cava filters, 8 combined antiplatelet therapy, 9 and low molecular weight heparin. Outside a clinical trial setting, the incidence may double. Even within the strictures of a clinical trial, the risk of major bleeding while on warfarin ranges from 0.5 to 4.2 per 100 patients per year.

6 It is also true, however, that warfarin can be an exceptionally difficult medication to manage, with its narrow therapeutic index, myriad drug interactions, and susceptibility to changes in diet. It has been established for some time that warfarin use can bring about significant reductions in mortality for patients with atrial fibrillation 5 or venous thromboembolism. As the incidence of both atrial fibrillation and venous thromboembolism increases exponentially among the elderly, the number of anticoagulated patients will continue to increase. To a lesser extent, the growing prevalence of warfarin use is the result of a trend towards a longer duration of therapy for venous thromboembolic disease. 4 Much of this increase can be attributed to a series of trials conducted in the 1990s that demonstrated the value of warfarin in preventing cardioembolic disease in patients with atrial fibrillation. 3 In countries, such as Sweden and the United Kingdom, where such data have been published, it is estimated that 1% of the entire population is now taking warfarin. Per capita use of warfarin in the United States quadrupled during the years 1988 to 2000, 2 and it tripled in Canada during the later interval of 1996 to 2006. 1 This topic is of interest to our readers and to much of the medical community patients taking vitamin K antagonists (warfarin, for the most part) are all around us. on the management of patients taking vitamin K antagonists who require urgent surgical procedures. In this issue of the Journal is a review by Grobler et al.

Antidote warfarin overdose