Long-term, Low-intensity Warfarin (Coumadin) Therapy Highly Effective Method of Preventing Recurrent Venous

Long-Term, Low-Intensity Warfarin Therapy for the Prevention of Recurrent Venous Thromboembolism The National Institute of Health recently discontinued what was to be a 5-year trial on the use of long-term, low-dose warfarin (Coumadin) therapy for the prevention of Recurrent Ve n o u s Thromboembolism (VTE). The "PREVENT" trial was stopped almost two years early, according to a recent report in the April 10th issue of the New England Journal of Medicine (see abstract below) because such strong benefits were observed that the study's independent Data and Safety Monitoring Board concluded that it was unnecessary to continue. "This is an important finding for the estimated half million Americans who each year experience either deep vein thrombosis (DVT) or pulmonary embolism. These results suggest that low-dose warfarin is a safe and effective way to pre - vent future episodes of these potentially serious blood clotting problems."- Claude Lenfant, M.D., NHLBI Director. The randomized, double-blind PREVENT trial was designed to enroll 750 patients, aged 30 years and older, with documented idiopathic DVT or pulmonary embolism within the previous two years who had at least three uninterrupted months of treatment with full-dose warfarin. The trial began in 1998 and was scheduled for completion in 2005, but instead was discontinued in December of 2002. When the study was terminated early, 508 patients at 52 clinical sites in the U.S., Canada, and Switzerland had been enrolled and followed for two years on average, with some patients followed for up to four years. According to per -protocol and as-treated analyses, the reduction in the risk of recurrent venous thromboembolism was between 76 and 81 percent . Recurrent DVT or pulmonary embolism occurred in 37 of 253 patients assigned to placebo (7.2 per 100 person-years) and in 14 of 255 patients assigned to low-dose warfarin with target interna- tional normalized ratio of 1.5 - 2.0 (2.6 per 100 person-years; risk reduction, 64%; hazard ratio, 0.36; 95% confidence interval, 0.19 - 0.67; P < .001). The current standard of care for idiopathic DVT and pulmonary embolism is five to 10 days of intravenous or subcutaneous heparin followed by three to six months of full-dose warfarin. Often treatment is discontinued because of bleeding risk with long-term use of full-dose warfarin, leading to recurrent thrombo- sis in 6% to 9% of patients annually. "The PREVENT results strongly suggest that long-term use of low-intensity warfarin should be considered a new standard of care for the management of venous thrombosis after stopping full- dose warfarin therapy," Dr. Ridker.