Originally published by 2 Minute Medicine^® (view original article). Reused on AccessMedicine with permission.

1. Preventative aspirin was used uniformly by persons with diabetes across age groups, while in persons without diabetes it was used less in young seniors (60-69 and 70-79) and equally in those 80+, potentially outside of clinical recommendations.

2. Based on the results of this study and current guidelines, a large proportion of elderly patients may be taking preventative aspirin inappropriately.

Evidence Rating Level: 4 (Below average)

Study Rundown:

The benefit of using aspirin to prevent cardiovascular events in patients with known disease has been well established. This study sought to identify the benefit of using aspirin to prevent cardiovascular disease in patients without existing cardiovascular disease (CVD) (aka “primary prevention”). Aspirin is a drug that increases the risk of bleeding events, but its ability to decrease vascular events in persons without cardiovascular disease is debated. Previously, aspirin was used for primary prevention in people with diabetes with a major CVD risk factor for 10 years, but updated guidelines suggest case-by-case consideration in older adults due to the potential harms. This cross-sectional study investigated the prevalence of aspirin use for primary prevention by age, sex, and CVD risk category in US nationally representative patients from the National Health and Nutrition Examination Survey (NHANES) 2011 and 2018, aged 60 years or older, with and without diabetes (n=7103). 61.7% of diabetics used aspirin, with a uniform distribution of ages, more men than women, and more participants with a CVD history than not. 42.2% of non-diabetics used aspirin, particularly those over 80, men, those with high CVD risk factors, or those with CVD history. Diabetics were twice as likely to take aspirin for primary prevention. This study calculated that 9.9 million US adults 70 years or older are taking aspirin outside of current clinical guidelines for primary prevention. A strength of the study was the size of the database used, encompassing a nationally representative sample. One limitation is that the database did not feature information on aspirin dose or frequency of use, so aspirin use was treated as a binary variable. Some misclassification may have occurred due to the self-reported nature of the data and the assumption that diabetic patients included all participants taking diabetic medications (ignoring pre-diabetic patients take glucose lowering agents); misclassification would have led to more conservative estimates of the true difference. Similarly, aspirin is used for cancer prevention, which could not be distinguished and would have led to misclassification causing a more conservative estimate.

Click to read the study in JAMA Network Open

Click to read an accompanying editorial in JAMA Network Open

Relevant Reading: Association of Aspirin Use for Primary Prevention With Cardiovascular Events and Bleeding Events: A Systematic Review and Meta-analysis

In-Depth [cross-sectional study]:

This study used the NHANES results pooled from 2011 and 2018 (n=39156) by the National Center for Health Statistics to identify senior (60 years or older) participants (n=7299) excluding those data missing diabetic status (n=4), cardiovascular disease status (n=184), and aspirin use (n=8). Patients were assumed diabetic if they received a physician diagnosis or used glucose-lowering medications. Participants (n=7103) were 69.6±0.1 years old; 45.2% were men, and 75.8% white. 23.0% of participants were labelled in this study as having diabetes (95%CI, 21.6%-24.3%). 46.7% of overall participants used aspirin: 61.7% of participants with diabetes used aspirin, and 42.2% of participants without diabetes. Extrapolating from these results to the US population in 2018, 9.9 million US adults that were 70 years or older used aspirin for primary prevention (over half of older US adults); this is despite that fact that the American Diabetes Association recommends against aspirin in older adults. These results suggest that aspirin may be overprescribed in this patient group. Diabetes was associated with 2-fold higher odds of aspirin use when adjusted for age, race, sex, education, CVD risk, and BMI (1.98, 95%CI, 1.47-2.67). Participants without diabetes or CVD who used aspirin were older (70.2±0.3 vs 68.4±0.2); thus, older participants without diabetes had increased odds of using aspirin, after being corrected for race, sex, education, and BMI (70-79 years: 1.50; 95%CI, 1.23-1.83; 80+ years: 1.59; 95%CI, 1.24-2.04). Aspirin use was greater in people with diabetes than those without it in younger seniors (60-69 years: 62.2±2.4 vs 36.0±1.8%; 70-79 years: 61.9%±2.4% vs 48.5±1.6%), but not beyond 80. Aspirin use was greater in seniors with diabetes than those without who did not have CVD, who had 0 CVD risk factors (43.0±12.0% vs 19.9±3.3%, p=0.02) or 1 or more CVD risk factors (57.8±2.0% vs 39.3±1.2%, p<0.001). Aspirin use did not differ in seniors with or without diabetes with a history of CVD. In participants with diabetes with or without CVD, aspirin use did not differ by high or low CVD risk (1.69; 95%CI, 0.65-4.39). Participants without diabetes, after adjusting for covariates, had a higher likelihood of aspirin use if they had a high risk for CVD (2.46; 95%CI, 1.63-3.71) or history of CVD (8.27; 95%CI, 5.54-12.34). In participants with diabetes, the odds of aspirin use were greater in those with a history of CVD compared to low-risk CVD (3.00; 95%CI, 1.18-7.59) when adjusted for all other variables.

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