Is Clopidogrel Plus Aspirin More Cost-Effective for Patients
Combined aspirin and clopidogrel treatment offers greater clinical benefit to patients with acute coronary syndromes (ACS) than aspirin alone, but the financial implications of combined therapy have not been fully explored. This treatment might be more economically feasible if offered to high-risk patients only.
To evaluate cost-effectiveness of adding clopidogrel to aspirin therapy in high-risk patients with ACS, and assess the optimum therapy duration.
Schleinitz and Heidenreich analyzed data from the randomized Clopidogrel in Unstable Angina to Prevent Recurrent Events (CURE) trial, which enrolled patients with non-Q-wave myocardial infarction (MI) or unstable angina and electrocardiographic changes. Patients received 325 mg aspirin daily, with or without 75 mg clopidogrel daily, for 1 year. Exclusion criteria included revascularization during the preceding 3 months, prolonged ST-segment elevation, oral anticoagulation or glycoprotein IIb/IIIa inhibition 3 days previously, and risk of heart failure or hemorrhage. A markov model was constructed on the basis of fatal or nonfatal occurrence of stroke, MI and revascularization, intracerebral or gastrointestinal bleeding, clopidogrel-related thrombocytopenic purpura and age-related death.
The outcomes were life expectancy, measured in quality-adjusted life years (QALYs), lifetime cost of treatment and the cost-effectiveness ratio of aspirin plus clopidogrel versus aspirin alone.
The model included data from 12,562 patients. Analysis of the 64-year-old base-case patient showed that life expectancy and treatment costs in patients treated with clopidogrel plus aspirin were 9.61 QALYs and US$129,300, after the initial event, compared with 9.51 QALYs and $127,700, respectively, for aspirin monotherapy. When compared with aspirin alone, the incremental cost-effectiveness ratio of combined therapy was $15,400 more per QALY. The life expectancy, effectiveness and cost-effectiveness of combined treatment were dependent on the risk of bleeding associated with clopidogrel; the cost of a QALY grew from $13,400 to $18,800 with an increase in bleeding risk of 13% to 67%. The cost-effectiveness advantage of combined therapy versus aspirin alone was simulated over a range of cost-effectiveness thresholds. When the threshold was $0—which assumed that combined therapy was cost-saving compared with aspirin monotherapy—combined therapy was optimal in only 0.3% of the simulated situations; by contrast, at a threshold of $50,000 per QALY—a figure frequently used as the maximum that society will pay for 1 QALY—it was preferable in 97.2%. For the first month of therapy, the addition of clopidogrel was associated with an increase in survival of 0.04 QALYs at a cost of $54. For up to 1 year, each month of clopidogrel increased survival by 0.005 QALYs at a cost of $140 per month. The cost-effectiveness of clopidogrel plus aspirin began to decline after 1 year.
The addition of clopidogrel to aspirin for 1 year increases life expectancy by 4 weeks in high-risk patients with ACS compared with aspirin alone, and lies within acceptable cost-effectiveness limits.
Combined aspirin and clopidogrel treatment offers greater clinical benefit to patients with acute coronary syndromes (ACS) than aspirin alone, but the financial implications of combined therapy have not been fully explored. This treatment might be more economically feasible if offered to high-risk patients only.
To evaluate cost-effectiveness of adding clopidogrel to aspirin therapy in high-risk patients with ACS, and assess the optimum therapy duration.
Schleinitz and Heidenreich analyzed data from the randomized Clopidogrel in Unstable Angina to Prevent Recurrent Events (CURE) trial, which enrolled patients with non-Q-wave myocardial infarction (MI) or unstable angina and electrocardiographic changes. Patients received 325 mg aspirin daily, with or without 75 mg clopidogrel daily, for 1 year. Exclusion criteria included revascularization during the preceding 3 months, prolonged ST-segment elevation, oral anticoagulation or glycoprotein IIb/IIIa inhibition 3 days previously, and risk of heart failure or hemorrhage. A markov model was constructed on the basis of fatal or nonfatal occurrence of stroke, MI and revascularization, intracerebral or gastrointestinal bleeding, clopidogrel-related thrombocytopenic purpura and age-related death.
The outcomes were life expectancy, measured in quality-adjusted life years (QALYs), lifetime cost of treatment and the cost-effectiveness ratio of aspirin plus clopidogrel versus aspirin alone.
The model included data from 12,562 patients. Analysis of the 64-year-old base-case patient showed that life expectancy and treatment costs in patients treated with clopidogrel plus aspirin were 9.61 QALYs and US$129,300, after the initial event, compared with 9.51 QALYs and $127,700, respectively, for aspirin monotherapy. When compared with aspirin alone, the incremental cost-effectiveness ratio of combined therapy was $15,400 more per QALY. The life expectancy, effectiveness and cost-effectiveness of combined treatment were dependent on the risk of bleeding associated with clopidogrel; the cost of a QALY grew from $13,400 to $18,800 with an increase in bleeding risk of 13% to 67%. The cost-effectiveness advantage of combined therapy versus aspirin alone was simulated over a range of cost-effectiveness thresholds. When the threshold was $0—which assumed that combined therapy was cost-saving compared with aspirin monotherapy—combined therapy was optimal in only 0.3% of the simulated situations; by contrast, at a threshold of $50,000 per QALY—a figure frequently used as the maximum that society will pay for 1 QALY—it was preferable in 97.2%. For the first month of therapy, the addition of clopidogrel was associated with an increase in survival of 0.04 QALYs at a cost of $54. For up to 1 year, each month of clopidogrel increased survival by 0.005 QALYs at a cost of $140 per month. The cost-effectiveness of clopidogrel plus aspirin began to decline after 1 year.
The addition of clopidogrel to aspirin for 1 year increases life expectancy by 4 weeks in high-risk patients with ACS compared with aspirin alone, and lies within acceptable cost-effectiveness limits.