Aspirin use, in general, should be restricted to people with a prior history of cardiovascular disease (CVD) [BIHS, 2017].
Aspirin may be considered beneficial for primary prevention if an individual’s future risk of stroke or heart attack is higher than average.
An accurate quantitative assessment of CVD risk is essential before prescribing aspirin for individuals in the primary prevention of CVD, where the evidence for benefit versus harm is very limited.
Antiplatelet therapy is not recommended in people who do not have CVD, due to the increased risk of major bleeding [ESC, 2016].
In a systematic review of six trials (n = 95,000), which compared the long-term use of aspirin vs control in people without overt CV or cerebrovascular disease, a risk reduction from 0.57% per year to 0.51% per year of serious vascular events was found, and major gastrointestinal (GI) and extracranial bleeds increased by 0.03% per year. The risk of vascular mortality was not changed by treatment with aspirin.
In a Japanese study (n = 14,464), people aged 60–85 years with hypertension, dyslipidaemia or diabetes mellitus were randomized to treatment with 100 mg aspirin or placebo. The 5-year cumulative primary outcome event rate (death from CV causes) was not significantly different between the groups, but treatment with aspirin significantly increased the risk of extracranial haemorrhage requiring transfusion or hospitalization (P = 0.004).
However, in a position paper, an ESC working group suggested that aspirin should be considered in the primary prevention of CVD in people at a high risk of major cardiovascular events — more than 2 per 100 subject-years, provided there is no clear evidence of increased risk of bleeding (GI bleeding or peptic ulcer disease, no concurrent use of other medications that increase bleeding risk) [Halvorsen, 2014].
In the absence of such conditions, people with a 10-year risk of major CV of more than 20% should be given low-dose aspirin, and people with a risk 10–20% should be considered potentially eligible