BACKGROUND:

The study, a subproject within a SCOR in Thrombosis, should help to improve the long-term clinical outcome of patients with proximal deep-vein thrombosis (popliteal, femoral or iliac vein thrombosis) by improving their survival and reducing morbidity from recurrent thromboembolic events, and should help to determine if one or more specific biochemical measures, including antiphospholipid antibodies and activated factor VII, will define a subset of patients at increased risk of recurrent venous thromboembolism.

The study is part of a SCOR in Hemostatic and Thrombotic Diseases, the RFA for which was released by the NHLBI in April 1994.

DESIGN NARRATIVE:

Warfarin Trial

A multicenter, randomized clinical trial was conducted from March 1996 through January 2001 comparing warfarin therapy for three years to warfarin therapy for three months. The study was performed at thirteen participating hospitals in Oklahoma. The 600 hundred patients were recruited, randomized to either warfarin therapy for three years or warfarin therapy for three months and followed for at least three years. The primary outcome measure was total mortality. Secondary outcome measures included vascular death, objectively documented recurrent venous thromboembolism, and bleeding complications (major and minor). Additional specific aims included: determining the prevalence of antiphospholipid antibodies, antithrombomodulin antibodies, and activated protein C resistance in consecutive patients with proximal-vein thrombosis; determining if these measures, and/or the level of activated factor VII were associated with an increased risk of recurrent venous thromboembolic events, and if so, whether these events were reduced by continuing long term warfarin treatment. These latter specific aims were achieved by performing the laboratory parameters concurrently in patients entered into the clinical trial, and relating these measures to the clinical outcomes on long-term follow-up.