Abstract
Venous thromboembolism, a disease now recognized in most cases to have a genetic basis,1 is the discharge diagnosis of more than a quarter-million patients in U.S. hospitals annually.2 Heparin has been the standard initial therapy for this condition since the 1940s. For many years, evidence of the efficacy of heparin in these patients was based on experimental studies in animals and uncontrolled clinical experience. Not until 1992 did a randomized, double-blind trial demonstrate that patients with deep-vein thrombosis do indeed require initial treatment with full-dose heparin.3 Admission to the hospital has been deemed necessary for patients with deep-vein thrombosis in . . .