Originating from the bark of the willow tree, aspirin has been used as an analgesic and anti-inflammatory drug dating back to ancient Greek civilizations. Extracted and purified into salicylic acid, it was first officially introduced in the early 1900’s in the drug form we know today (Ittaman, VanWormer & Rezkalla, 2014). In 1971, aspirin’s exact mechanism of action as a nonselective cyclooxygenase (COX) inhibitor was uncovered and was later found to produce antithrombotic effects by preventing platelet aggregation at low doses (75-100 mg/day), also known as a “baby aspirin.”
 
Today, aspirin is an inexpensive nonsteroidal anti-inflammatory drug (NSAID) that is commonly recommended for secondary prevention of serious cardiovascular disease (CVD) events such as myocardial infarction (MI) or ischemic stroke in high-risk individuals. Researchers began investigating aspirin as a primary prevention measure for individuals without a history of CVD and it was studied rigorously in the 1980’s through early 2000’s. Several trials had found a significant decrease in the risk of serious cardiovascular events, including nonfatal MI, stroke, or cardiovascular death. This led many organizations such as the U.S. Preventive Services Task Force (USPSTF) to support low-dose aspirin use in 2016 for the primary prevention of CVD.
 
However, this recommendation has been controversial due to the increased risk for bleeding complications that can occur with aspirin. An analysis of 10 studies showed that aspirin use was associated with a 58% increase in major gastrointestinal bleeding while another analysis of 11 clinical trials showed an increase in intracranial bleeds in the aspirin group compared with the control group (USPSTF, 2021). Last October, the USPSTF issued changes to its recommendations on aspirin stating that the decision to initiate low-dose aspirin for the primary prevention of CVD in adults ages 40 to 59 years who have a 10% or greater 10-year CVD risk should be individualized and discussed with their clinician. They also recommend against initiating low-dose aspirin use for the primary prevention of CVD in adults aged 60 years or older. New evidence from pooled analyses found that low-dose aspirin did not significantly decrease fatal myocardial infarction, fatal stroke, cardiovascular mortality, or all-cause mortality (USPSTF, 2021).
 
The 2019 American College of Cardiology (ACC) and American Heart Association (AHA) guidelines on the primary prevention of cardiovascular disease had already made the following recommendations regarding aspirin use (Arnett et al., 2019):

• Low-dose aspirin (75-100 mg orally daily) might be considered for the primary prevention of atherosclerotic cardiovascular disease (ASCVD) in select adults 40 to 70 years of age who are at higher ASCVD risk without an increased bleeding risk.
• Low-dose aspirin should not be administered on a routine basis for the primary prevention of ASCVD among adults over the age of 70.
• Low-dose aspirin should not be administered for the primary prevention of ASCVD among adults of any age who are at an increased risk of bleeding.

 
Science continues to evolve, and as new evidence emerges it is critical that all health care professionals stay informed. A simple pill with anti-thrombotic effects, while lifesaving for some individuals, could be lethal for others. Careful analysis of your patient’s medical history and bleeding risks such as gastrointestinal bleeding, peptic ulcer disease, thrombocytopenia, coagulopathy, or blood-thinning drugs, should be evaluated prior to beginning aspirin therapy.
 

References
Arnett, D. K., Blumenthal, R. S., Albert, M. A., Buroker, A. B., Goldberger, Z. D., Hahn, E. J., Himmelfarb, C. D., Khera, A., Lloyd-Jones, D., McEvoy, J. W., Michos, E. D., Miedema, M. D., Muñoz, D., Smith, S. C., Jr, Virani, S. S., Williams, K. A., Sr, Yeboah, J., & Ziaeian, B. (2019). 2019 ACC/AHA Guideline on the Primary Prevention of Cardiovascular Disease: A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines. Circulation, 140(11), e596–e646. https://doi.org/10.1161/CIR.0000000000000678
 
Ittaman, S. V., VanWormer, J. J., & Rezkalla, S. H. (2014). The role of aspirin in the prevention of cardiovascular disease. Clinical medicine & research, 12(3-4), 147–154. https://doi.org/10.3121/cmr.2013.1197
 
U.S. Preventive Services Task Force (2021, October 12). Aspirin use to prevent cardiovascular disease: Preventive medication (Draft Recommendation Statement). https://www.uspreventiveservicestaskforce.org/uspstf/draft-recommendation/aspirin-use-to-prevent-cardiovascular-disease-preventive-medication