Pharmacoeconomic model of enoxaparin versus heparin for prevention of deep vein thrombosis after total hip replacement

The costs of heparin and enoxaparin to prevent deep vein thrombosis (DVT) after total hip replacement in the U.S. treatment environment were compared. A decision model was used in a pharmacoeconomic comparison of subcutaneous enoxaparin and subcutaneous heparin, each given for seven days, for the prophylaxis of DVT. In the model, three outcome pathways could follow prophylaxis: proximal DVT, distal DVT, and no DVT (but with a possible false-positive clinical diagnosis of DVT). Probabilities of thromboembolic events and major bleeding were derived from three randomized clinical trials. Account was also taken of the effects of pulmonary embolism (PE). Pharmacoeconomic studies and expert opinion were relied on for the model's principal resource-use categories and costs for DVT prophylaxis, clinical diagnosis of DVT and PE, and DVT and PE treatment. The outcome of choice for the model was the number of DVT events avoided. Regardless of the trial data used, the total mean cost of enoxaparin prophylaxis ($3336 to $3380) exceeded the cost of heparin prophylaxis ($3292 to $3330). However, enoxaparin was more cost-effective in avoiding DVT than heparin, irrespective of the trial on which the analysis was modeled. A sensitivity analysis involving length of hospital stay and length of prophylactic therapy showed the model to be robust and gave the advantage in all instances to enoxaparin in cost per DVT avoided. A model of enoxaparin versus heparin DVT prophylaxis after total hip replacement showed that enoxaparin was more costly than heparin in overall expected treatment costs but more cost-effective in the avoidance of DVT.