Cost-Effectiveness Analysis of Enoxaparin versus Unfractionated Heparin for Acute Coronary Syndromes: A Canadian Hospital Perspective

Objective: To determine the cost effectiveness of enoxaparin therapy versus unfractionated heparin (UFH) therapy for patients with unstable coronary artery disease from the perspective of a Canadian hospital. Design: A predictive decision analysis model using published clinical and economic evaluations and costs of medical care in Canada. Patients: A hypothetical cohort of patients presenting to hospital with unstable angina or non-Q-wave myocardial infarction as defined by the Efficacy and Safety of Subcutaneous Enoxaparin in Non-Q-Wave Coronary Events (ESSENCE) trial. Interventions: Two antithrombotic treatment strategies were compared: (i) enoxaparin 1 mg/kg subcutaneously every 12 hours, and (ii) UFH intravenous bolus and constant infusion adjusted to maintain a therapeutic activated partial thromboplastin time. Both treatment strategies included 100 to 325mg of oral aspirin daily. Enoxaparin or UFH was continued for a minimum of 48 hours to a maximum of 8 days. Cumulative outcomes were considered up to 30 days after initial presentation to hospital. Results: At 30 days, 19.8% of patients who received enoxaparin compared with 23.3% of patients who received UFH reached one of the primary composite events. There was no difference in major bleeding between the 2 treatment groups (6.5% enoxaparin vs 6.8% UFH). The average total direct medical cost per patient was $Can848 with the enoxaparin strategy versus $Can892 with the UFH strategy (1999 values). Therapy with enoxaparin was, therefore, considered to be the dominant strategy. Univariate sensitivity analysis indicated that the decision model was not robust to changes in the 30-day composite end-point, probability of recurrent angina, or base costs for treatment of recurrent angina or enoxaparin therapy. Conclusion: Enoxaparin is the dominant antithrombotic pharmacotherapeutic strategy for patients with unstable coronary artery disease.