Creative cost-effectiveness analysis of CAPRIE data— dust in our eyes

Abstract

In the June 15, 2004 issue of The American Journal of Medicine, using data from the CAPRIE study, 1CAPRIE Steering CommitteeA randomised, blinded, trial of clopidogrel versus aspirin in patients at risk of ischaemic events (CAPRIE).Lancet. 1996; 348: 1329-1339Abstract Full Text Full Text PDF PubMed Scopus (6065) Google Scholar Schleinitz et al, 2Schleinitz M.D. Weiss P. Owens D.K. Clopidogrel versus aspirin for secondary prophylaxis of vascular events a cost-effectiveness analysis.Am J Med. 2004; 116: 797-806Abstract Full Text Full Text PDF PubMed Scopus (81) Google Scholar claimed that clopidogrel provides an increase in quality-adjusted life expectancy at a reasonable cost in patients who have had an ischemic stroke or who have symptomatic peripheral artery disease.In CAPRIE 1CAPRIE Steering CommitteeA randomised, blinded, trial of clopidogrel versus aspirin in patients at risk of ischaemic events (CAPRIE).Lancet. 1996; 348: 1329-1339Abstract Full Text Full Text PDF PubMed Scopus (6065) Google Scholar clopidogrel instead of aspirin reduced the absolute risk of a new ischemic event (the composite of cardiovascular death, myocardial infarction, or stroke) by a nonsignificant 0.56% per year in patients who had suffered an ischemic stroke. The corresponding absolute risk reduction was 1.15 % in patients with peripheral artery disease (P = 0.003). This means that the number needed to treat after a stroke was around 179 (95% confidence interval [CI]: 80–∞) and the number needed to treat who had peripheral artery disease was approximately 87 (95% CI: 65–300). The cost of clopidogrel is about $2.20 per day in Sweden. Consequently, the yearly expenditure on clopidogrel instead of aspirin to avoid an ischemic event is approximately $142,000 (95% CI: $63,000–∞) after a stroke and $69,000 (95% CI: $52,000–$238,000) in patients with peripheral artery disease.This is evidently not an intelligent way to utilize health care resources. Any real clinical advantages (and side effects) of clopidogrel as a replacement for aspirin must be made clear beyond reasonable doubt before health economic analyses can contribute to our understanding of how to optimize antiplatelet therapy in patients with atherothrombotic disease. The difference between clopidogrel and aspirin was small in CAPRIE, with an absolute risk reduction of only 0.51% for all patients. On the other hand, the costs of clopidogrel are large compared with aspirin. For that reason, let us not have dust blown in our eyes by creative cost-effectiveness analyses. In the June 15, 2004 issue of The American Journal of Medicine, using data from the CAPRIE study, 1CAPRIE Steering CommitteeA randomised, blinded, trial of clopidogrel versus aspirin in patients at risk of ischaemic events (CAPRIE).Lancet. 1996; 348: 1329-1339Abstract Full Text Full Text PDF PubMed Scopus (6065) Google Scholar Schleinitz et al, 2Schleinitz M.D. Weiss P. Owens D.K. Clopidogrel versus aspirin for secondary prophylaxis of vascular events a cost-effectiveness analysis.Am J Med. 2004; 116: 797-806Abstract Full Text Full Text PDF PubMed Scopus (81) Google Scholar claimed that clopidogrel provides an increase in quality-adjusted life expectancy at a reasonable cost in patients who have had an ischemic stroke or who have symptomatic peripheral artery disease. In CAPRIE 1CAPRIE Steering CommitteeA randomised, blinded, trial of clopidogrel versus aspirin in patients at risk of ischaemic events (CAPRIE).Lancet. 1996; 348: 1329-1339Abstract Full Text Full Text PDF PubMed Scopus (6065) Google Scholar clopidogrel instead of aspirin reduced the absolute risk of a new ischemic event (the composite of cardiovascular death, myocardial infarction, or stroke) by a nonsignificant 0.56% per year in patients who had suffered an ischemic stroke. The corresponding absolute risk reduction was 1.15 % in patients with peripheral artery disease (P = 0.003). This means that the number needed to treat after a stroke was around 179 (95% confidence interval [CI]: 80–∞) and the number needed to treat who had peripheral artery disease was approximately 87 (95% CI: 65–300). The cost of clopidogrel is about $2.20 per day in Sweden. Consequently, the yearly expenditure on clopidogrel instead of aspirin to avoid an ischemic event is approximately $142,000 (95% CI: $63,000–∞) after a stroke and $69,000 (95% CI: $52,000–$238,000) in patients with peripheral artery disease. This is evidently not an intelligent way to utilize health care resources. Any real clinical advantages (and side effects) of clopidogrel as a replacement for aspirin must be made clear beyond reasonable doubt before health economic analyses can contribute to our understanding of how to optimize antiplatelet therapy in patients with atherothrombotic disease. The difference between clopidogrel and aspirin was small in CAPRIE, with an absolute risk reduction of only 0.51% for all patients. On the other hand, the costs of clopidogrel are large compared with aspirin. For that reason, let us not have dust blown in our eyes by creative cost-effectiveness analyses.