Oral antiplatelet therapy in secondary prevention of cardiovascular events: an assessment from the payer's perspective

BACKGROUND: A wide variety of oral antiplatelet trials have been carried out, and a large number of cost-effectiveness estimates based on them have been published. OBJECTIVE: To assess the cost effectiveness of oral antiplatelet treatments in the prevention of cardiovascular events. METHODS: A comprehensive literature search was carried out in PubMed and the Cochrane Library and the data reviewed. Cost-effectiveness or cost-utility studies of oral antiplatelets published since 2000 were selected. Cost-effectiveness analyses from the perspective of the UK NHS were then carried out using a Markov model with a 6-month cycle length and a lifetime horizon. Inputs from the CAPRIE, CHARISMA, (PCI)-CURE, CREDO, COMMIT, CLARITY, ESPS 2 and ESPRIT trials were included. All estimates of cost found (per event avoided, per QALY gained or per life-year gained) were included. Results were analysed in light of the National Institute for Health and Clinical Excellence (NICE) guidelines for the use of antiplatelets for the prevention of cardiovascular events and all estimates were updated to pound (year 2006 values) for easy comparison. RESULTS: Of the initial 141 studies found, 21 were included in the initial review. The literature and the Markov model subsequently used suggest that aspirin (acetylsalicylic acid) dominates placebo for the secondary prevention of cardiovascular events, as it is effective, is also less costly and is as well tolerated as placebo. Additionally, in periods or patients with elevated risk, more intensive treatment with clopidogrel (alone or together with aspirin) is cost effective compared with aspirin alone for the secondary prevention of ischaemic events. For secondary stroke prevention, combination therapy with aspirin and dipyridamole has a favourable incremental cost-effectiveness ratio (ICER) when compared with aspirin alone and, based on an indirect comparison, also when compared with clopidogrel. CONCLUSIONS: The cost-effectiveness estimates presented in this article support the NICE guidelines for the use of antiplatelets for the prevention of cardiovascular events. Based on these pharmacoeconomic data alone, aspirin should be prescribed for primary or secondary prevention among patients at high risk of cardiovascular events, dipyridamole for the secondary prevention of stroke (for a maximum of 5 years), and clopidogrel for the treatment of symptomatic cardiovascular disease or acute coronary syndrome (for a maximum of 2 years). The cost effectiveness of antiplatelets hinges on the patient's initial risk, the risk reduction associated with treatment, and the price of the treatment. Evidence suggests that the cost effectiveness of antiplatelets can be optimized by individualising the treatment decision based on patient risk and expected risk reduction.