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 2018—ASCEND (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 (2–4). 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*
| Guideline | Recommendations |
|---|---|
| 2012 ACCP guidelines | Suggested for adults aged ≥50 y without symptomatic CVD (grade 2B) |
| 2015 AHA/ADA scientific statement | Reasonable in adults with 10-y CVD risk ≥10% and without increased risk for bleeding (ACC/AHA class IIa, LOE B; ADA grade C) |
| Reasonable in adults with DM at intermediate risk (10-y CVD risk of 5%−10%) (ACC/AHA class IIb, LOE C; ADA grade E) | |
| 2016 ADA guidelines | Consider in those with type 1 or 2 DM who are at increased CVD risk (10-y risk >10%) and are not at increased bleeding risk (grade C) |
| Not recommended for adults with DM at low ASCVD risk (10-y risk <5%) (grade C) | |
| Clinical judgment required in patients with DM aged <50 y with other risk factors (e.g., 10-y risk of 5%−10%) (grade E) | |
| 2016 USPSTF recommendation statement | Initiate in adults aged 50–59 y with 10-y CVD risk ≥10% (grade B) |
| Individual judgment required in adults aged 60–69 y with 10-y CVD risk ≥10% (grade C) | |
| No recommendation in adults aged <50 y (grade I) | |
| No recommendation in adults aged ≥70 y (grade I) | |
| 2019 AHA/ACC guidelines | May be considered in adults aged 40–70 y who are at higher ASCVD risk but not at increased bleeding risk (COR IIb, LOE A) |
| Should not be used on a routine basis in adults aged >70 y (COR III, LOE B-R) | |
| Should not be used in adults of any age who are at increased risk for bleeding (COR III, LOE C-LD) |
ACC = American College of Cardiology; ACCP = American College of Chest Physicians; ADA = American Diabetes Association; AHA = American Heart Association; ASCVD = atherosclerotic cardiovascular disease; COR = class of recommendation; CVD = cardiovascular disease; DM = diabetes mellitus; LOE = level of evidence; USPSTF = U.S. Preventive Services Task Force.
From reference 1.
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, myocar-dial infarction, or stroke. We conducted multivariable logistic regression to identify demographic and clinical factors associated with aspirin use.
Our sample included 14 328 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 = 14 328)*
| Characteristic | Adults, unweighted n | Aspirin Use†, % | Estimated U.S. Population Using Aspirin (Millions)† | AOR for Aspirin Use (95% CI)‡ |
|---|---|---|---|---|
| Age | ||||
| 40–49 y | 3552 | 7.0 | 2.57 | 1.00 (reference) |
| 50–59 y | 3873 | 18.4 | 6.73 | 2.51 (2.11–3.00) |
| 60–69 y | 3708 | 34.7 | 10.15 | 5.54 (4.58–6.70) |
| 70–79 y | 2136 | 44.6 | 6.50 | 7.67 (6.32–9.31) |
| ≥80 y | 1047 | 46.2 | 3.05 | 9.68 (7.61–12.31) |
| Sex | ||||
| Female | 8136 | 21.8 | 14.54 | 1.00 (reference) |
| Male | 6180 | 25.5 | 14.47 | 1.32 (1.18–1.48) |
| Race | ||||
| White | 10 346 | 25.1 | 20.80 | 1.00 (reference) |
| Black | 1471 | 23.7 | 3.20 | 0.97 (0.82–1.16) |
| Hispanic | 1508 | 19.7 | 3.35 | 0.96 (0.78–1.17) |
| Asian | 666 | 15.1 | 1.15 | 0.63 (0.46–0.88) |
| Other | 300 | 21.2 | 0.50 | 0.74 (0.51–1.06) |
| Body mass index | ||||
| <18.5 kg/m2 | 192 | 10.8 | 0.16 | 0.40 (0.24–0.68) |
| 18.5–24.9 kg/m2 | 4120 | 24.3 | 6.73 | 1.00 (reference) |
| 25.0–29.9 kg/m2 | 4993 | 24.5 | 10.79 | 1.22 (1.07–1.39) |
| 30.0–34.9 kg/m2 | 2690 | 26.9 | 6.39 | 1.30 (1.12–1.51) |
| 35.0–35.9 kg/m2 | 1086 | 26.3 | 2.48 | 1.16 (0.93–1.43) |
| ≥40 kg/m2 | 1235 | 23.7 | 2.58 | 1.21 (0.98–1.49) |
| History of peptic ulcer disease | ||||
| No | 13 297 | 23.1 | 26.76 | 1.00 (reference) |
| Yes | 1008 | 28.3 | 2.24 | 0.91 (0.75–1.11) |
| Hypertension | ||||
| No | 8486 | 15.5 | 11.94 | 1.00 (reference) |
| Yes | 5812 | 36.5 | 17.04 | 1.74 (1.56–1.94) |
| Hyperlipidemia | ||||
| No | 8933 | 17.2 | 13.54 | 1.00 (reference) |
| Yes | 5324 | 34.5 | 15.38 | 1.63 (1.47–1.81) |
| Diabetes | ||||
| No | 12 629 | 20.6 | 22.54 | 1.00 (reference) |
| Yes | 1680 | 46.5 | 6.45 | 2.07 (1.77–2.42) |
| Smoking status | ||||
| Never | 8260 | 21.2 | 15.83 | 1.00 (reference) |
| Current | 2058 | 22.4 | 3.63 | 1.28 (1.09–1.52) |
| Former | 3935 | 29.3 | 9.47 | 1.13 (1.01–1.27) |
AOR = adjusted odds ratio; CVD = cardiovascular disease.
Analyses used sample weights and were conducted using survey proc commands (including PROC SURVEYLOGISTIC) in SAS, version 9.4 (SAS Institute), to account for the complex National Health Interview Survey sampling design and nonresponse and to generate U.S. population estimates.
Weighted percentage of sample with each characteristic and associated population estimate taking aspirin for primary prevention.
Model adjusted for each characteristic in the table and for physician visit in the past year. Because of missing covariates, 13 995 adults were included in the adjusted model.
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 wide-spread 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.
Acknowledgment:
The authors thank Aaron Fleishman, MPH, for checking the statistical programs and outputs and the participants of NHIS for their important contributions.
Grant Support: Dr. Juraschek is supported by grant K23HL135273 from the National Heart, Lung, and Blood Institute of the National Institutes of Health.
Footnotes
The institutional review board at Beth Israel Deaconess Medical Center deemed this study not to be human subjects research.
Publisher's Disclaimer: Disclosures: Disclosures can be viewed at www.acponline.org/authors/icmje/ConflictOfInterestForms.do?msNum=M19-0953.
Contributor Information
Colin W. O’Brien, Harvard Medical School, Boston, Massachusetts.
Stephen P. Juraschek, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts.
Christina C. Wee, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts.
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