Introduction
The CAPRIE trial demonstrated that clopidogrel hydrogen sulfate, compared with aspirin, is superior over a 2-year period in the secondary prevention of fatal and non-fatal ischaemic vascular events, in patients with a recent myocardial infarction (MI), ischaemic stroke (IS) or diagnosis of peripheral arterial disease (PAD) [RRR = 8.7%;p = 0.043]. Benefits are more evident in the CAPRIE high risk atherothrombotic sub-populations, whose life expectancy is significantly reduced, with previous history of one of the following clinical conditions: prior cardiac surgery, IS or MI, hypercholesterolemia and/or diabetes, polyvascular disease.
Objective
This economic analysis aimed at estimating, in the perspective of the Italian NHS, the cost-effectiveness of clopidogrel hydrogen sulfate versus aspirin as a secondary prevention therapy in patients at high risk of cardiovascular disease, following an ischemic event as MI, IS, or diagnosis of peripheral artery disease.
Methods
This economic analysis is based on a 2-year Markov model (four 6-month cycles), which compares clopidogrel hydrogen sulfate and aspirin by providing incremental cost-effectiveness ratios (ICER) in the management of patients with recent MI, IS and diagnosis of PAD and related high risk subgroups — with prior CABG, prior MI or IS, with diabetes and/or hypercholesterolemia and polyvascular disorders, in the perspective of the Italian NHS. The model assumes that 1,000 CAPRIE-like patients enter the cycles. Effectiveness data were derived from the CAPRIE trial, survival data were based on the Saskatchewan Health database; Italian healthcare resource consumption data came from an ad hoc survey conducted on 240 specialists and 160 general practitioners with a final validation from clinical experts. Direct costs include hospitalizations, visits, instrumental and laboratory tests, cardiovascular procedures, concomitant medications and medical management of adverse events. Outpatient resources were valued by national ambulatory tariffs; inpatient resources according to the national DRG tariffs; medications were valued as daily cost. Costs were expressed in Euros 2008; clinical benefits and costs were discounted at 3%. Cost-effectiveness was expressed as the cost per Life Year Gained (LYG).
Results
In Italy the 2-year management weighted cost is respectively €17,046 for MI, €11,351 for IS and €4,299 for PAD diagnosis. In the base case analysis, ICER of clopidogrel hydrogen sulfate versus aspirin was €12,200/LYG; in populations at higher risk of recurrence of cardiovascular events, clopidogrel hydrogen sulfate produced a higher number of LYGs at lower incremental costs compared with the base case: in particular, €830/LYG in patients with prior cardiac surgery, €5,910/LYG in patients with history of IS/MI, €5,470/LYG in patients with hypercholesterolemia and/or diabetes, €5,400/LYG in polyvascular disease patients. Irrespective of the sub-population, the model was sensitive to variations in life expectancy and discounting, while frequency of adverse events and cardiovascular events carried only a marginal effect.
Conclusions
In Italy a 2-year treatment with clopidogrel hydrogen sulfate as an alternative to ASA, is a highly cost-effective strategy in secondary prevention of ischaemic fatal and non-fatal events for those high-risk atherothrombotic patients that, within the atherothrombotic population, have a poorer life expectancy. In particular clopidogrel hydrogen sulfate is highly cost-effective especially in patients with previous cardiac surgery.