Background
The Clopidogrel for High Atherothro
mbotic Risk and Ische
mic Stabilization, Manage
ment, and Avoidance (CHARISMA) trial found a statistically significant reduction in cardiovascular events when clopidogrel was added to aspirin in a prespecified subgroup of patients with established cardiovascular disease. However, the econo
mic i
mplications of such a strategy for the Canadian health care syste
m are unknown.
Methods
For each patient in the CHARISMA trial with established cardiovascular disease, costs were estimated by multiplying resource utilization by unit costs derived from populations of Canadian patients in 2008 dollars. Changes in life expectancy due to nonfatal events were estimated with parametric regression models based on the Saskatchewan Health database.
Results
For patients with established cardiovascular disease, a strategy of clopidogrel plus aspirin for median duration of 28 months was associated with a 12.5 % relative reduction in cardiovascular death, myocardial infarction, or stroke compared with aspirin alone (6.9 % vs 7.9 % , m>P =m>.048). Mean cost per patient was CAD$1,488 higher for clopidogrel plus aspirin, and life expectancy increased by 0.057 years. The resulting incremental cost-effectiveness ratio for adding clopidogrel was CAD$25,969 per life-year gained or CAD$21,549 per quality-adjusted life-year. These results were sensitive to the cost of clopidogrel but relatively insensitive to plausible variations in discount rate, costs other than clopidogrel, and the prognostic impact of nonfatal events.
Conclusion
Among the subgroup of patients with established cardiovascular disease in the CHARISMA trial, adding clopidogrel to aspirin increases life expectancy at a cost generally considered acceptable in Canada.
