Cost-effectiveness of enoxaparin vs low-dose warfarin in the prevention of deep-vein thrombosis after total hip replacement surgery.

BACKGROUND Enoxaparin sodium, a low-molecular-weight heparin, was recently approved for use in the United States to prevent deep-vein thrombosis after total hip replacement surgery. Its cost-effectiveness relative to prophylaxis with low-dose warfarin sodium is unknown. METHODS A decision-analytic model was developed to compare two strategies of prophylaxis for deep-vein thrombosis with a strategy of not using prophylaxis in a hypothetical cohort of 10,000 patients undergoing total hip replacement surgery. For each of these strategies, we estimated the expected number of cases of confirmed deep-vein thrombosis or pulmonary embolism, the expected number of thromboembolic deaths, and the expected costs of venous thromboembolic care, including prophylaxis, diagnosis, and treatment. Data were drawn primarily from the published literature. RESULTS Compared with no prophylaxis, the use of low-dose warfarin would be expected to reduce the number of cases of confirmed deep-vein thrombosis from about 1000 (per 10,000 patients) to 420 and the number of thromboembolic deaths from about 250 to 110. Expected costs of care related to deep-vein thrombosis also would be reduced from approximately $530 to $330 per patient. Prophylaxis with enoxaparin would be expected to reduce further the number of cases of confirmed deep-vein thrombosis and the number of thromboembolic deaths (to 250 and 70, respectively) but increase costs of care by approximately $50 per patient. The cost-effectiveness of enoxaparin (relative to low-dose warfarin) is estimated to be approximately $12,000 per death averted. CONCLUSION Although enoxaparin is more costly than low-dose warfarin, its cost-effectiveness in total hip replacement compares favorably with that of other generally accepted medical interventions.