Results of an economic model to assess the cost-effectiveness of enoxaparin, a low-molecular-weight heparin, versus warfarin for the prophylaxis of deep vein thrombosis and associated long-term complications in total hip replacement surgery in the United States

Background: Premature death due to pulmonary embolism is a short-term complication of deep vein thrombosis (DVT). The long-term clinical course after DVT can be further complicated by excess mortality, recurrent venous thromboembolism (VTE), and the post thrombotic syndrome (PTS), which may produce sizable long-term economic burdens. Objective: The goal of this study was to determine the cost-effectiveness of the low-molecular-weight heparin (LMWH) enoxaparin versus warfarin for the universal prophylaxis of DVT and associated long-term complications in US patients undergoing total hip replacement surgery (THRS). Methods: A model was constructed to assess the long-term cost-effectiveness of the 2 treatments. Patients undergoing THRS were exposed to a short-term risk of developing a DVT. Patients surviving a DVT were exposed to increased risk of long-term complications of DVT, including PTS, recurrent VTE, and increased mortality. Published literature, augmented by expert opinion, served as input for the model's resource use and costs for DVT prophylaxis, clinical diagnosis, and treatment of DVT, VTE, and PTS. Results: When the analysis included only the short-term consequences of DVT, therapy with enoxaparin resulted in a net cost of $133 per patient and a net increase of 0.04 quality-adjusted life-years (QALYs) per patient. Thromboprophylaxis with enoxaparin versus warfarin resulted in $3733 per QALY saved. In contrast, when the long-term consequences of DVT were included, enoxaparin resulted in net lifetime savings of $89 per patient and net QALY benefits of 0.16 per patient. Conclusions: To the best of our knowledge, this is the first US economic analysis comparing DVT prophylaxis with the LMWH enoxaparin versus warfarin that included the long-term complications of DVT. Our model suggests that use of enoxaparin in patients undergoing THRS reduces the economic burden associated with these long-term complications. Key words: postphlebitic syndrome, cost-benefit analysis, economic model, heparin, low-molecular-weight, warfarin.