An Aspirin a Day? New Study Assesses Rate of Inappropriate Aspirin Use for Primary Prevention of CVD

By: Svetlana Akbasheva, Staff Writer

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Aspirin 81 mg, or “baby” aspirin, has become almost ubiquitously known as being “heart-healthy” and for playing a role in preventing heart attacks and strokes. With cardiovascular disease reigning as the number one cause of death worldwide, more than 50 million adults in the United States currently take daily low-dose aspirin therapy for cardiovascular protection.^1,2 However, aspirin is not for everyone, and its antiplatelet properties can do more harm than good in certain patients.

According to the American Heart Association and American Stroke Association guidelines, low-dose aspirin is appropriate in two general groups of patients.^2,3 The first group describes patients who have already suffered a cardiovascular event and require secondary prevention against future occurrences. The second group encompasses patients with no history of cardiovascular events but who would be candidates for primary preventative therapy, i.e. those with a ten-year cardiovascular disease (CVD) risk score of greater than or equal to six percent. Therefore, in patients without a cardiac history whose ten-year CVD risk score is less than 6%, the bleeding complications associated with low-dose aspirin are thought to outweigh its cardioprotective effects.^2,3

A recent study was conducted to estimate the rate of inappropriate low-dose aspirin use for primary prevention of CVD in the United States.² A cohort of patients on aspirin therapy between January 2008 and June 2013 was identified using the American College of Cardiology’s Practice Innovation and Clinical Excellence (PINNACLE) registry, in which 119 medical practices are enrolled nationwide. As the main aim of the study was to identify inappropriate use of aspirin for primary prevention, patients on aspirin for secondary prevention were excluded. Another exclusion criterion was patients who were on any other anticoagulant or antiplatelet medications. Within the primary prevention cohort, the ten-year CVD risk score was calculated for each patient using the Framingham general CVD risk assessment tool. This instrument assesses the risk of future cardiovascular events using variables that include age, sex, cigarette smoking, hypertension, diabetes, and cholesterol levels. The study authors classified subjects with a ten-year CVD risk score of less than six percent as receiving inappropriate aspirin therapy.²

The results of the study showed that 11.6% of patients on aspirin for primary prevention of cardiovascular disease had a ten-year CVD risk score of less than six percent and thus were not appropriate candidates for aspirin therapy.² Inappropriate aspirin use varied widely among different medical practices and was more prevalent in younger patients. The study retained similar results after doing three separate analyses that excluded women over 65, diabetic patients, and patients on statin therapy, respectively, as these three groups thought to be possible sources of confounding.²

It is important to note that this study had several limitations; study authors did not have access to aspirin doses, many subjects were excluded due to inadequate information, and the study did not assess adverse effects (e.g., bleeding) in patients with a calculated ten-year CVD score of less than six percent.² However, even with the limited information available, the outcome that about 10% of patients may be inappropriately receiving aspirin for primary prevention of cardiovascular events appears significant. In addition, the over the counter availability of aspirin makes it even more likely that many patients are taking this medication without consulting their doctor.

The bleeding risk with low-dose aspirin therapy is not insignificant and should not be overlooked. In fact, it is due to this risk that the FDA recently rejected Bayer’s request to allow for the marketing of aspirin for primary prevention of CVD.⁴ Just because a medication is available over-the-counter does not mean that it is safe and appropriate for everyone; all patients should be evaluated by their doctor or pharmacist before the decision to begin aspirin therapy is made.

SOURCES:

1. Cardiovascular diseases (CVDs). Available at: http://www.who.int/mediacentre/factsheets/fs317/en/. Updated 01/2015. Accessed 02/20/2015.
2. Hira RS, Kennedy K, Nambi V, et al. Frequency and practice-level variation in inappropriate aspirin use for the primary prevention of cardiovascular disease: insights from the national cardiovascular disease registry’s practice innovation and clinical excellence registry. J Am Coll Cardiol. 2015;65(2):111-21.
3. Goldstein LB, Bushnell CD, Adams RJ, et al. AHA/ASA guideline: guidelines for the primary prevention of stroke. Stroke. 2011;42:517-84.
4. Use of aspirin for primary prevention of heart attack and stroke. Fda.gov. Available at: http://www.fda.gov/drugs/resourcesforyou/consumers/ucm390574.htm. Updated 05/02/2014. Accessed 02/20/2015.

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