Modelling the long term cost effectiveness of clopidogrel for the secondary prevention of occlusive vascular events in the UK

OBJECTIVE: To assess the long term cost effectiveness of clopidogrel monotherapy compared with acetylsalicylic acid (aspirin; ASA) monotherapy in patients at risk of secondary occlusive vascular events (OVEs) in the UK. DESIGN: Cost utility analysis based on clinical data from CAPRIE (a multicentre randomised controlled trial, involving 19185 patients); long-term effects were extrapolated beyond the trial period using a Markov model populated with data from UK observational studies. Health economic evaluation carried out from the perspective of the UK National Health Service. PARTICIPANTS: A representative cohort of 1000 UK patients aged 60 years (approximate mean age of the CAPRIE population), with the qualifying diagnoses of myocardial infarction, ischaemic stroke and peripheral arterial disease, who are at risk of secondary OVEs (non-fatal myocardial infarction, non-fatal stroke or vascular death). INTERVENTIONS: Patients were assumed to receive treatment with either clopidogrel (75 mg/day) for 2 years followed by ASA (325 mg/day, average) for their remaining lifetime, or ASA alone (325 mg/day, average) for life. MAIN OUTCOME MEASURES: Incremental cost per life year gained and incremental cost per quality-adjusted life year (QALY) gained. RESULTS: In the base case, the incremental cost effectiveness of clopidogrel versus ASA in this population is estimated at 18888 pounds per life year gained and 21 489 pounds per QALY gained. Multiple deterministic and probabilistic sensitivity analyses suggest the model is robust to variations in a wide range of input parameters. CONCLUSION: Two years of treatment with clopidogrel can be considered a cost effective intervention in patients at risk of secondary OVEs in the UK.