Individual and Population Benefits of Daily Aspirin Therapy: A Proposal for Personalizing National Guidelines

Study Questions:

What is the net benefit from taking daily aspirin, and what are the individual and public health implications of a more individualized decision-making approach?

Methods:

The authors used data from the National Health and Nutrition Examination Survey (2001-2006) representing all US persons ages 30-85 years with no history of myocardial infarction, and applied a Markov model based on randomized evidence and published literature to estimate lifetime effects of aspirin treatment in quality-adjusted life years (QALYs). Validated prediction indices were used to estimate the risk of each of four primary outcomes in the absence of aspirin therapy: myocardial infarction, ischemic stroke, gastrointestinal bleeding, and intracerebral hemorrhage. Disutility included complications of aspirin and simple distaste for aspirin.

Results:

Treatment benefit varied greatly by an individual’s cardiovascular disease (CVD) risk. Almost all adults have fewer major clinical events on aspirin, but for most, events prevented would be so rare that even a very small distaste for aspirin use would make treatment inappropriate. With minimal dislike of aspirin use (disutility, 0.005 QALY per year), only those with a 10-year cardiac event risk >6.1% would have a net benefit. A disutility of 0.01 QALY moves this benefit cut point to 10.6%. Multiple factors altered the absolute benefit of aspirin, but the strong relationship between CVD risk and magnitude of benefit was robust. For individuals with a 10-year CVD risk of 10.6%, a net gain in 1 QALY required treatment of 20 people for 5 years, whereas for individuals with a 10-year risk between 6.1% and 10.6%, 43 people would need to be treated to achieve this same net QALY gain.

Conclusions:

The benefits of aspirin therapy depend substantially on an individual’s risk of CVD and adverse treatment effects. Understanding who benefits from aspirin use and how much can help clinicians and patients to develop a more patient-centered approach to preventive therapy.

Perspective:

The novel contribution of the analysis is the findings that implementation of the aspirin guideline in the US would result in 500,000 QALYs saved in men and 170,000 QALYs saved in women. This is a supportable cost-effective health care strategy (at least in men) if the assumptions are accurate. But considering the failure of aspirin to reduce CV events in diabetes and peripheral vascular disease in recent placebo-controlled trials, the true impact of aspirin for primary prevention in the modern era is still not clear.

Clinical Topics: Prevention, Vascular Medicine, Atherosclerotic Disease (CAD/PAD)

Keywords: Myocardial Infarction, Diabetes Mellitus, Peripheral Vascular Diseases, Primary Prevention


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