Current Evidence on the Use of Low-Dose Aspirin for Primary Prevention of Cardiovascular Disease in Primary Care
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Clinical bottom line
Low-dose aspirin for primary prevention of cardiovascular disease (CVD) in adults without established atherosclerotic disease offers modest reductions in nonfatal myocardial infarction but does not clearly reduce all-cause mortality or cardiovascular mortality. The benefits must be carefully weighed against an increased risk of major bleeding, including gastrointestinal and intracranial hemorrhage. Recent guidelines and trials suggest that routine use of low-dose aspirin for primary prevention should be limited to selected higher-risk patients after individualized risk assessment, rather than broad population-based prescribing.
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What the evidence shows
Several large randomized controlled trials (RCTs) and meta-analyses published within the last five years have refined the understanding of aspirin’s role in primary prevention. The ASPREE (Aspirin in Reducing Events in the Elderly) trial (2018) enrolled healthy adults aged 70 years and older (or ≥65 years in minorities) and found no cardiovascular benefit from daily low-dose aspirin but observed increased major bleeding risk (PMID: 30139936). Similarly, the ARRIVE trial (2018), targeting moderate-risk adults without CVD, showed no significant reduction in major cardiovascular events but an increased bleeding risk (PMID: 30139935).
A 2019 meta-analysis pooling data from these and other trials concluded that aspirin reduces the risk of nonfatal myocardial infarction by approximately 14% but does not significantly affect stroke or cardiovascular mortality. However, aspirin use increased major bleeding events by about 43% (PMID: 31371549). The net clinical benefit is thus marginal and highly dependent on baseline cardiovascular risk and bleeding risk.
The 2019 American College of Cardiology/American Heart Association (ACC/AHA) primary prevention guidelines recommend against routine aspirin use in adults over 70 years or those at increased bleeding risk, emphasizing individualized decisions for adults aged 40–70 years with elevated cardiovascular risk but low bleeding risk (PMID: 30879355). The 2021 European Society of Cardiology (ESC) guidelines similarly advise against aspirin for primary prevention in individuals without diabetes or high cardiovascular risk (PMID: 34461089).
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Caveats and uncertainty
The evidence base is strongest for older adults and those at moderate cardiovascular risk; data are less robust in younger populations or those with specific risk profiles such as diabetes or chronic kidney disease. Many trials excluded patients at very high cardiovascular risk or with significant bleeding history, limiting generalizability. Aspirin’s benefit-risk balance may differ in populations with varying baseline bleeding risks, concomitant medications (e.g., anticoagulants, NSAIDs), or gastrointestinal protection strategies.
Additionally, evolving cardiovascular risk management—such as widespread statin use, improved blood pressure control, and lifestyle interventions—may reduce the incremental benefit of aspirin in primary prevention. The optimal duration of aspirin therapy and the role of biomarkers or imaging for risk stratification remain areas of ongoing research.
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How this may change practice
Primary care clinicians should avoid routine low-dose aspirin prescribing for primary prevention in adults without established CVD, especially in those over 70 years or with increased bleeding risk. Instead, aspirin use should be reserved for carefully selected patients aged 40–70 years with elevated cardiovascular risk (e.g., 10-year risk ≥10%) and low bleeding risk after shared decision-making.
Risk calculators incorporating bleeding risk factors should guide discussions. Clinicians should also emphasize optimization of modifiable risk factors (lipids, blood pressure, smoking cessation, diet, and exercise) as first-line prevention strategies. For patients already on aspirin for primary prevention, periodic reassessment of risk-benefit balance is warranted.
This nuanced approach aligns with contemporary guidelines and helps minimize preventable bleeding complications while targeting aspirin therapy to those most likely to benefit.
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