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 perspe ctive of an integrated health system of administering enoxaparin 30 mg twice/day versus heparin 5000 U twice/day for prophylaxis against ven ous thrombosis after major trauma. A decision-analytic model was devel oped from best literature evidence, institutional data, and expert opi nion. We assumed that 40% of proximal deep vein thromboses (DVTs) and 5% of distal DVTs are diagnosed and confirmed with initial or repeat d uplex scanning; 50% of undiagnosed proximal DVTs result in pulmonary e mbolism; 2% and 1% of undiagnosed proximal DVTs will lead to readmissi on for DVT and pulmonary embolism, respectively, and pulmonary embolis m-related mortality rates range from 8-30%. Length of hospital stay da ta 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 inst itutional charge data using cost:charge ratios. A second analysis of p atients with lower extremity fractures was completed. One-way and mult iway sensitivity analyses were performed. For 1000 mixed trauma patien ts 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 $104,76 4 (-$329,300 to $159,600). Enoxaparin versus heparin resulted in a cos t 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). F or 1000 patients with lower extremity fractures, enoxaparin versus hep arin resulted in a cost of $751 (-$4200 to $3300) for each DVT or pulm onary 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 favorab le in patients with lower extremity fractures than in the general mixe d trauma population.