A cost-effectiveness model of thrombolytic therapy for acute myocardial infarction

OBJECTIVE: To assess the short- and long-term costs and clinical and quality of life outcomes with the use of streptokinase (SK) vs tissue plasminogen activator (tPA) for acute myocardial infarction (MI). DESIGN: A decision analysis model. PATIENTS: Patients with acute MI who were candidates for thrombolytic therapy and who presented within six hours of symptom onset. MEASUREMENTS: 30-day and one-year mortality, impacts of disabling and nondisabling stroke, reinfarction, hemorrhage, hypotension, anaphylazis, and long-term medical costs. RESULTS: Using 30-day mortality data from the Global Utilization of Streptokinase and Tissue Plasminogen Activator for Occluded Coronary Arteries (GUSTO) trial, the baseline analysis yielded an incremental cost—effectiveness for tPA of $30,300 per additional quality-adjusted life year (QALY) gained, compared with SK. Using one-year mortality data from the GUSTO trial, the analysis yielded an incremental cost—effectiveness for tPA of $27,400 per additional QALY, compared with SK. The incremental cost—effectiveness of tPA over SK was sensitive to the difference in mortality seen with the two agents, exceeding $100,000 per QALY, for a relative survival advantage of approximately one-third that seen in the GUSTO trial. The incremental cost per QALY of tPA remained under $60,000 if the survival benefit was half that seen in the GUSTO trial. The cost—effectiveness of tPA declined with a shorter projected life expectancy following MI and for inferior (vs anterior) wall infarction. The analysis was modestly sensitive to the costs of the thrombolytic agents. CONCLUSIONS: In spite of its higher cost relative to SK, tPA is a cost-effective therapy for MI under a wide range of assumptions regarding clinical outcomes and costs. Presented in part at the Congress of the European Society of Cardiology, August 29–September 2, 1993, Nice, France. Supported by a research grant from Kabi Pharmacia. Dr. Kalish is the recipient of a Merck/American Federation for Aging Research Fellowship in Clinical Geriatric Pharmacology. Dr. Gurwitz is the recipient of a Clinical Investigator Award (K08 AG00510) from the National Institute on Aging, Bethesda, Maryland.