Aspirin for Primary Prevention: A Delicate Balancing Act

The new review consisted of 11 trials including over 100,000 patients
The new review consisted of 11 trials including over 100,000 patients

For the primary prevention of atherosclerotic cardiovascular disease (ASCVD), the decision to use aspirin should be highly individualized, weighing the benefit-to-risk ratio and patient preferences, a study published in JAMA Internal Medicine concluded. 

Clinical decision making on the appropriate use of aspirin for primary prevention of ASCVD requires an individualized benefit-to-risk assessment, Sami Mora, MD, MHS, from the Brigham and Women's Hospital, Boston, MA, explained. Dr. Mora and coauthor JoAnn E. Manson, MD, DrPH, aimed to review advances in individualized assessment for ASCVD and bleeding risk, and to provide an update on trials that studied the use of aspirin for primary prevention. 

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In April 2016, the U.S. Preventive Services Task Force (USPSTF) released recommendations for the use of aspirin in primary prevention of cardiovascular disease and colorectal cancer. For adults 50 to 59 years of age with a ≥10% 10-year ASCVD risk, without elevated bleeding risk, who have a ≥10 year life expectancy, and who are willing to take aspirin daily, the Task Force recommended the use of low-dose aspirin (B recommendation). For adults 60 to 69 years of age, the decision to initiate aspirin for primary prevention should be an individual one (C recommendation).  

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For this review, Drs Mora and Manson conducted a comprehensive literature search which returned a total of 11 trials involving >118,000 patients regarding clinical decision making for aspirin use in the primary prevention of ASCVD. Clinicians should calculate the 10-year ASCVD risk and evaluate risk factors for gastrointestinal bleed in order to provide "a safer and more personalized approach to appropriate selection of candidates for low-dose aspirin (75–81mg/day) for the primary prevention of ASCVD, with secondary considerations for reducing colorectal cancer risk when taken for longer periods (>10 years)."

The net ASCVD benefit and the risk of bleeding with aspirin therapy both increased as the absolute ASCVD risk increased, but the benefits typically exceeded the risks at higher baseline ASCVD risk (≥10% ASCVD 10-year risk). 

The two cases below illustrate the difficulty of weighing the potential benefits and risks of aspirin use for primary prevention of ASCVD:

Patient 1 was a 57-year-old non-smoking male with diabetes and treated hypertension and no prior GI disorders or bleeding. Based on his history and calculated 10-year ASCVD risk of 12.0%, the 2016 USPSTF guidelines and ADA recommendations advise low-dose aspirin therapy. His net benefit of aspirin therapy would be moderate to substantial for preventing ASCVD and colorectal cancer. With low-dose aspirin, his estimated bleeding risk would increase from 0.12% to 0.19% per year and his 10-year ASCVD risk would decrease from 12.0% to 10.2%. In this case, the ASCVD benefit alone outweighed the GI bleeding risk.

Patient 2 was a 68-year-old non-diabetic non-smoking female with treated hypertension and dyslipidemia with a history of peptic ulcer disease. Although her 10-year ASCVD risk was high at 13.2%, the USPSTF would give a grade C recommendation for aspirin use (individualize therapy); the guidelines would also place her at high risk for GI bleeding based on her age and peptic ulcer disease. If she did not have a peptic ulcer history or her hypertension was well controlled, this patient would be a candidate for low-dose aspirin according to her estimated ASCVD risk and clinical trial evidence suggesting a benefit in reducing MI and stroke in women aged ≥65 years. Her GI bleeding risk without aspirin could be as high as 7.8% over 10 years if her ulcer was complicated by bleeding, and as high as 12% with aspirin. In this case, the patient would be a poor candidate for initiating aspirin therapy.

Using a benefit-to-risk assessment approach for shared decision making along with a companion mobile app could help support evidence-based decision making. The Aspirin-Guide, a mobile device app, is a clinical decision making resource with internal risk calculators to help clinicians assess ASCVD risk and bleeding risk for each patient, including age- and sex-specific guidance based on randomized trial results.  This mobile app and other tools may help both patients and clinicians to work together and personalize treatment decisions while incorporating patient preferences.

For more information visit jama.jamanetwork.com

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