Pitfalls in the economic evaluation of thrombolysis in myocardial infarction. The impact of national differences in the cost of thrombolytics and of differences in the efficacy across patient subgroups

BACKGROUND: The economic evaluation of the results of the Global Utilization of Streptokinase and Tissue Plasminogen Activator for Occluded Coronary Artery (GUSTO) trial found that recombinant tissue plasminogen activator is more cost-effective than streptokinase for the treatment of acute myocardial infarction. AIM: We evaluated the impact on a cost effectiveness analysis, of the differences in the cost of thrombolytics among countries and of differences in efficacy across patient subgroups. METHODS: We considered the crude costs of streptokinase and recombinant tissue plasminogen activator in Germany, Italy, the United Kingdom, and the United States of America, and the 30-day mortality found in the GUSTO trial. We calculated the incremental costs for each life saved when streptokinase is substituted by recombinant tissue plasminogen activator. We also calculated the incremental costs for each life saved for two protocols implying a selective use of streptokinase and recombinant tissue plasminogen activator (age-selective protocol: recombinant tissue plasminogen activator in patients < or = 75 years, streptokinase in older patients; site-selective protocol: recombinant tissue plasminogen activator in anterior acute myocardial infarction, streptokinase in non-anterior acute myocardial infarction). RESULTS: The incremental costs for each life saved when streptokinase is substituted by recombinant tissue plasminogen activator in all GUSTO patients vary greatly among countries: the incremental costs for each life saved are 31%, 45%, and 97% higher in Germany, Italy, and the United States of America compared to the United Kingdom. The use of a site-selective protocol implies a halved cost-effectiveness ratio compared to the use of recombinant tissue plasminogen activator in all cases of acute myocardial infarction. CONCLUSIONS: (1) The cost-efficacy of recombinant tissue plasminogen activator vs streptokinase in acute myocardial infarction varies greatly among countries due to differences in the cost of drugs. (2) A selective use of thrombolytics for some sites of infarction is more cost-effective than the exclusive use of recombinant tissue plasminogen activator.