The use of aspirin is an effective and low-cost option for the prevention of cardiovascular events in patients with established cardiovascular disease (CVD) (a leading cause of global mortality); the role of aspirin in primary prevention of CVD is less clear.

The World Health Organisation recommends that at least 50% of eligible people receive aspirin for CVD prevention by 2025; it is important to understand the current levels of use of aspirin for secondary prevention of CVD.

A study that used nationally representative health surveys assessed the use of aspirin for the secondary prevention of CVD and its association with individual-level characteristics (Journal of the American Medical Association 2023;330(8):715-724).

The cross-sectional study used pooled, individual participant data from nationally representative surveys conducted in 51 countries; eligible surveys were those that:

1) used a nationally representative sampling frame

2) were conducted in 2013 or later,

3) had individual participant data available 

4) asked respondents questions on the use of aspirin for the prevention of CVD.

The sample included non-pregnant individuals who were aged 40 to 69 years. The primary outcome was self-reported use of aspirin for the secondary prevention of CVD (self-reported history of myocardial infarction, stroke or angina).

The surveys were conducted from 2013 to 2020 in 51 countries; 7 in low-income, 23 in lower-middle-income, 14 in upper-middle-income and 7 in high-income countries. The median response rate was 85% (interquartile range [IQR], 70% to 95%); the response rates were lower in high-income countries (median, 57%) than in other income groups.

The overall pooled sample included 124,505 individuals, of whom 10,589 individuals self-reported a history of CVD (weighted 8.2% [95% CI, 7.7% to 8.6%]). The median age of the participants in the overall pooled sample was 52 years (IQR, 45 to 59 years), 50.5% (95% CI, 49.9% to 51.1%) were female and 53.4% (95% CI, 52% to 54.8%) lived in a rural area.

Among the individuals with a history of CVD, aspirin use for secondary prevention in the overall pooled sample was 40.3% (95% CI, 37.6% to 43.0%); estimates were 16.6% (95% CI, 12.4% to 21.9%) in low-income, 24.5% (95% CI, 20.8% to 28.6%) in lower-middle-income, 51.1% (95% CI, 48.2% to 54%) in upper-middle-income and 65% (95% CI, 59.1% to 70.4%) in high-income countries. At the country level, 41% of the variation in aspirin use for secondary prevention was accounted for by per capita income. Greater aspirin use was observed among individuals who were older, were male, had higher levels of education and lived in urban as opposed to rural areas.

Some limitations of the study were that it was not possible to determine if the self-reported aspirin use was appropriate, if the individual was on other pharmacological therapies such as antithrombotics or other antiplatelets that may be a relative contraindication to aspirin use and most surveys did not distinguish between heart disease vs stroke or whether, a stroke was ischaemic or haemorrhagic.

The authors of the study concluded that globally aspirin is underused in secondary prevention, particularly in low-income countries and that national health policies and health systems should do more to promote aspirin therapy for secondary prevention of CVD.

Where this study fits: the findings of the study suggests that there is suboptimal use of aspirin for secondary prevention of CVD in many parts of the world