Cost‐Effectiveness of Enoxaparin versus Low‐Dose Heparin for Prophylaxis Against Venous Thrombosis after Major Trauma

We attempted to determine health and economic outcomes from the perspective of an integrated health system of administering enoxaparin 30 mg twice/day versus heparin 5000 U twice/day for prophylaxis against venous thrombosis after major trauma. A decision-analytic model was developed from best literature evidence, institutional data, and expert opinion. We assumed that 40% of proximal deep vein thromboses (DVTs) and 5% of distal DVTs are diagnosed and confirmed with initial or repeat duplex scanning; 50% of undiagnosed proximal DVTs result in pulmonary embolism; 2% and 1% of undiagnosed proximal DVTs will lead to readmission for DVT and pulmonary embolism, respectively, and pulmonary embolism-related mortality rates range from 8-30%. Length of hospital stay data and 1996 institutional drug use and acquisition cost data were used to estimate the cost of enoxaparin and heparin therapy. Diagnosis and treatment costs for DVT and pulmonary embolism were derived from institutional charge data using cost: charge ratios. A second analysis of patients with lower extremity fractures was completed. One-way and multiway sensitivity analyses were performed. For 1000 mixed trauma patients receiving enoxaparin versus heparin, our model showed that 62. 2 (95% CI -113 to -12) DVTs or pulmonary emboli would be avoided, resulting in 67. 6 (8 to 130) life-years saved at a net cost increase of 104, 764 (-329, 300 to 159, 600). Enoxaparin versus heparin resulted in a cost of 1684 (-3600 to 9800) for each DVT or pulmonary embolus avoided and a discounted cost/life-year saved of 2303 (-8100 to 19, 000). For 1000 patients with lower extremity fractures, enoxaparin versus heparin resulted in a cost of 751 (-4200 to 3300) for each DVT or pulmonary embolus avoided and a discounted cost/life-year saved of 1017 (-10, 200 to 6300). Although enoxaparin increases overall health care costs, it is associated with a cost/additional life-year saved of only 2300, which is generally lower than the commonly used hurdle rate of 30, 000/life-year saved. The cost-effectiveness ratio is more favorable in patients with lower extremity fractures than in the general mixed trauma population.