Prevalence of Aspirin Use for Primary Prevention of Cardiovascular Disease in the United States: Results from the 2017 National Health Interview Survey.

Background: Physicians and medical professional societies have widely supported use of aspirin for primary prevention of cardiovascular disease (CVD) in persons who are at increased risk (1) (Table 1). Three randomized controlled trials published in 2018ASCEND (A Study of Cardiovascular Events in Diabetes), ARRIVE (Aspirin to Reduce Risk of Initial Vascular Events), and ASPREE (Aspirin in Reducing Events in the Elderly)sought to evaluate the benefits and risks of aspirin use for primary prevention of CVD in adults with diabetes, average-risk adults, and older adults, respectively (24). Collectively, these studies showed few benefits and consistent bleeding risks. ASCEND studied adults with diabetes and found fewer serious vascular events among those assigned aspirin but also an increase in major bleeding. Similarly, ARRIVE showed no difference in cardiovascular events between aspirin users and nonusers who were at average risk. Finally, ASPREE found increased overall mortality and unchanged cardiovascular mortality in older adults assigned aspirin. In light of these findings, in March 2019, the American Heart Association and American College of Cardiology (AHA/ACC) released updated guidelines, which now recommend against routine aspirin use in persons older than 70 years and those with increased bleeding risk (5). However, the extent to which these populations take aspirin for primary prevention in the United States is unknown. Table 1. Current and Recent Guideline and Consensus Documents on Aspirin Use for the Primary Prevention of CVD* Objective: To characterize aspirin use for primary prevention of CVD among U.S. adults. Methods and Findings: We used data from the Sample Adult component of the 2017 National Health Interview Survey (NHIS), a nationally representative in-person household survey of health and disability among U.S. adults. The final response rate was 53.0% (ftp://ftp.cdc.gov/pub/Health_Statistics/NCHS/Dataset_Documentation/NHIS/2017/srvydesc.pdf). Participants aged 40 years or older were asked the following questions about aspirin use: Has a doctor or other health professional ever told you to take a low-dose aspirin each day to prevent or control heart disease? Are you now following this advice? and On your own, are you now taking a low-dose aspirin each day to prevent or control heart disease? We classified participants who answered yes to either of the 2 latter questions as taking aspirin for CVD prevention. To focus on primary prevention, we excluded participants with a self-reported history of angina, coronary heart disease, myocardial infarction, or stroke. We conducted multivariable logistic regression to identify demographic and clinical factors associated with aspirin use. Our sample included 14328 adults. The mean age was 57.5 years; 54% were women, and 33% were nonwhite. Among adults aged 40 years or older without CVD, 23.4% (approximately 29 million persons) reported taking daily aspirin for prevention of CVD. Of these, 22.8% (6.6 million persons) did so without a physician's recommendation. Nearly half of adults aged 70 years or older without CVD reported aspirin use (Table 2). After adjustment, older age, male sex, and cardiovascular risk factors (hypertension, hyperlipidemia, diabetes, and smoking) were statistically significantly associated with aspirin use. Of note, a history of peptic ulcer disease was not statistically significantly associated with lower aspirin use. Table 2. Aspirin Use Among Adults Aged 40 Years or Older Without CVD, by Demographic and Clinical Characteristics (n = 14328)* Discussion: Nearly 30 million U.S. adults aged 40 years or older use aspirin to prevent CVD, including nearly half of older adults without self-reported CVD and a quarter of adults without CVD but with a history of peptic ulcer disease. Our findings have important implications in light of recent evidence and guidelines recommending against aspirin use for primary prevention of CVD in these 2 subgroups. Although prior AHA/ACC guidelines recommended aspirin only in persons without elevated bleeding risk, the 2019 guidelines now explicitly recommend against aspirin use in those older than 70 years (5). Our findings also suggest that a substantial portion of adults may be taking aspirin without their physician's advice and potentially without their knowledge. Our study had limitations. Aspirin use was based on self-reported data, and the term low-dose was not clearly defined, which may have led to misclassification. In addition, NHIS did not ask adults younger than 40 years about aspirin use, limiting the scope of our study. Finally, we were unable to calculate atherosclerotic CVD risk scores because blood pressure and cholesterol levels were not measured. In summary, aspirin use in the United States is widespread among groups at risk for harm. In light of recent trials and guidelines, our findings show a tremendous need for health care practitioners to inquire about ongoing aspirin use and to counsel patients about the balance of benefits and harms, especially among older adults and those with prior peptic ulcer disease.