Aspirin use for primary prevention in older adults

Aspirin use for cardiovascular disease (CVD) prevention is common among adults 60 years and older.1 Although some use aspirin for secondary prevention, many older adults use daily aspirin for primary prevention despite guidelines recommending limiting such use.2, 3 Widely-cited research published in 2018 suggest the risk–benefit balance of aspirin use in CVD prevention in older adults is outweighed by bleeding and other side effects.4 In the context of new data and guidelines, this study describes the prevalence and trends in aspirin use from 2015 to 2020 among adults ages 60–79 living in five Upper Midwestern states. Three cross-sectional telephone surveys of non-institutionalized resident adults ages 60–79 from June–December 2015, June–December 2017, and October–March 2019–20 were conducted among adults living in Iowa, Minnesota, North Dakota, South Dakota, and Wisconsin. Addresses with zip codes and associated landline telephone numbers were used to generate random samples within states proportional to population size. Sampled households were sent a letter describing the study. One respondent per household was selected. The overall participation was 48% after accounting for refusals, address errors, and disconnected telephones. Trained interviewers administered a 10-min telephone survey that included questions about aspirin use, history of cardiovascular disease (CVD), cardiovascular risk factors, media exposure, doctor discussions about aspirin, health behaviors and demographic characteristics. In a previously published study, using the same telephone survey, self-reported aspirin use was evaluated with blood levels of thromboxane B2.5 Sensitivity and specificity were over 90%. Data are presented as n (%) for categorical variables and mean (SD) for continuous variables. Categorical data were compared using chi-square tests. Analyses were performed in Stata version 16.1 (StataCorp. 2019. Stata Statistical Software: Release 16. College Station, TX: StataCorp LLC). The University of Minnesota Institutional Review Board approved this study and participants provided verbal consent. The surveys included 7921 individuals ages 60–79, of which 4194 were women and 3727 were men. Participants without a history of CVD or bleeding met the definition for primary prevention and included 3533 women and 2709 men. Demographic characteristics were similar to census data for these states. Aspirin use for primary prevention was stable for the first two survey years (46% in both 2015 and 2017) but fell to 37% in the last survey (2019–2020), (Figure 1). The use for secondary prevention was flat at over 70% for all three surveys (Figure 1). Self-report of discontinuing aspirin rose from 17% to 26% from 2015 to 2019–20. Reasons for stopping aspirin use in 2019–20 are shown in Table 1. The leading reasons were doctor advice and/or “heard negative news”. The number of negative messages heard in the media was greatest in the 2019–20 survey (Table 1). Reports on the use of aspirin for “coronary thrombosis” are over seven decades old but it was not until early clinical trials that aspirin became widely used for prevention of myocardial infarction and stroke. In the United States, the U.S. Preventive Services Task Force (USPSTF) released guidelines for the use of aspirin for primary prevention in 2002, 2009 and 2016.5 In 2002, there was no upper age limit. In 2009, the USPSTF added an upper age limit of 79. The 2016 USPSTF provided Class C advice for those 60–69 years and cited insufficient evidence for those 70 and older.2 In 2018, three large clinical trials of aspirin initiation (ASCEND, ASPREE, ARRIVE) produced mixed results with the ASPREE trial of healthy older adults finding increased bleeding and other complications.4, 6, 7 Following the release of these studies, substantial media and professional discussion of inappropriate aspirin use ensued. The USPSTF 2022 report recommended against aspirin initiation for those 60 years and older.3 Similar recommendations against use of aspirin for primary prevention were published in American Heart Association guidelines and the updated Beers criteria.8, 9 The current survey finds aspirin use for primary prevention continues to be common among those over age 60 with the highest use in those 70–79 years. It also finds that aspirin use significantly declined between 2017 and 2019–20 among this older age group (46%–37%, p < 0.001). Continued use of aspirin in those 60 years and above, despite national guidelines, probably stems from a number of factors. These include self-prescription without a clinician's advice and the availability of aspirin, without prescription, at a low price. Aspirin is also heavily advertised for secondary CVD prevention and the distinction between primary and secondary prevention is not always apparent. Finally, some suggest that continuation of aspirin use is not the same as the initiation of aspirin.10 Observational data from the national Swedish Registry finds that those who were taking aspirin and discontinue use have a 30% increase in CVD events beginning almost immediately and continuing for several years.11 The issue of discontinuation has not been well studied. In the context of new guidelines, what can the practicing clinician do? This study provides some insights. Many older adults still take a daily aspirin. Those who do use aspirin are frequently self-prescribing and/or not at high risk.12 Those who quit, do so based on consultation with a clinician or media reports. There is an opportunity during routine clinical visits to explore the appropriateness of aspirin use and make recommendations. Russell V. Luepker: Concept and design, acquisition of subjects and/or data, analysis and interpretation of data, and preparation of manuscript. Jeremy R. Van't Hof: Acquisition of subjects and/or data, analysis and interpretation of data, and preparation of manuscript. Milton Eder: Concept and design, analysis and interpretation of data, and preparation of manuscript. John R. Finnegan: Concept and design, and preparation of manuscript. Niki Oldenburg: Acquisition of data. Sue Duval: Concept and design, acquisition of subjects and/or data, analysis and interpretation of data, and preparation of manuscript. This work was supported by the National Institutes of Health (R01HL126041), and the Lillehei Heart Institute of the University of Minnesota. The authors declare that there is no conflict of interest. Not involved.