A multi-country economic evaluation of low-dose aspirin in the primary prevention of cardiovascular disease

Background: Low-dose aspirin (acetylsalicylic acid) is standard care in patients with a history of cardiovascular disease (CVD). The use of low-dose aspirin in primary prevention is not yet fully established, although meta-analyses and US and European guidelines support its use in people at increased risk of CVD. The primary objective of this study was to assess the economic consequences of the use of low-dose aspirin in the primary prevention of CVD in four European countries (UK, Germany, Spain and Italy). Methods: Based on results (benefits and harms) reported in meta-analyses, a state-transition model was developed to predict the cost effectiveness of low-dose aspirin in the primary prevention of CVD. The model consists of five health states: no history of CVD, history of stroke, history of myocardial infarction (MI), history of stroke and MI, and death. A 10-year time horizon and 1-year cycles were used. Secondary prevention data were derived from the aspirin arm of the CAPRIE (Clopidogrel versus Aspirin in Patients at Risk of Ischaemic Events) study. Direct costs from the public healthcare payer's perspective were used (EURO, 2003 values). Effects were expressed in life-years (LY) and QALYs gained. Quality weights were obtained from published data. Country-specific discounting was applied on effects and costs (3.5% for the UK, 5% for Germany and 3% for Spain and Italy). Univariate sensitivity analysis and Monte Carlo simulation were performed to assess uncertainty in the results. Results: For patients with an annual risk of coronary heart disease (CHD) of 1.5%, the model resulted in 10-year savings with low-dose aspirin of on average EURO201 (95% CI 81, 331),EURO281 (95% CI 141, 422), EURO797 (95% CI 301, 1331) and EURO427 (95% CI 122, 731) per patient in the UK, Germany, Spain and Italy, respectively. Average total cost was almost 3- to 4-fold higher in Spain and Italy than in the UK and Germany. Savings (non-significant) start in the first year of treatment in all countries. Sensitivity analyses on cost of complications, utility, discounting, stroke rate and gastrointestinal bleeding rate showed the robustness of the results. From an annual risk of CHD of 0.236% for the UK, 0.324% for Germany, 0.244% for Spain and 0.560% for Italy, low-dose aspirin was cost saving compared with placebo. Monte Carlo analysis showed aspirin dominance in about 97% of cases for the three studied annual risks of CHD (0.6%, 1.0% and 1.5%) in the UK, Germany and Spain. In Italy, aspirin dominance in > 95% of cases was seen at annual risks of 1% and 1.5%. Conclusions: Administering low-dose aspirin to patients with an annual risk of CHD of >= 1% appears to be significantly cost saving from the healthcare payer's perspective in all countries analysed. Sensitivity analyses (CHD risk and bleedings) suggested the results were robust.