The once “obvious” benefits of aspirin therapy for primary prevention of cardiovascular disease have recently been called into question, with newer data suggesting that the risk of bleeding outweighs cardiovascular benefits for many patients. However, more than 90 percent of participants in the three most recent aspirin trials (ASPREE, ASPIRE, ARRIVE) identified as non-Hispanic white, so more information is needed about the risks and benefits of aspirin in diverse populations.

The Southern Community Cohort Study (SCCS) is a prospective cohort of over 80,000 adults (about 70 percent black) in the Southeastern United States in a low-income, underinsured population. This study analyzed survey data from 65,000 non-Hispanic black or white SCCS participants aged 40-79 years (median 52 years) without indications for aspirin for secondary prevention of cardiovascular disease. Investigators defined low-dose aspirin use as 81-162 mg at least two days per week for at least one month at the time of enrollment. Aspirin use was self-reported, and details about frequency of aspirin use or whether participants were taking aspirin due to a doctor’s advice were not reported. Participants were stratified by a modified Framingham risk score that substituted body mass index for lipid levels into low (< 6 percent), intermediate (6-9.9 percent), or high (≥ 10 percent) ten-year cardiovascular risk. Systolic blood pressure was known for 17 percent of participants and the researchers used reported prior diagnoses of hypertension to impute blood pressure values for the risk scores.

Black participants were less likely to take aspirin than white participants in all three risk categories (low 6.1 percent vs.10.2 percent, intermediate 9.8 percent vs.15.5 percent, high 17.8 percent vs. 26.8 percent, p <0.001 for all categories). When adjusted for covariates, black participants were less likely to take aspirin than their white counterparts (adjusted odds ratio 0.79, 95% CI 0.75-0.82). Participants with diabetes, concomitant NSAID use, health insurance, higher educational attainment, and higher household income were more likely to take aspirin. Fatal ischemic heart disease, as identified by national vital status data after mean 11 years follow-up, occurred at a higher rate among white participants than in black participants (incidence rate ratio 1.21, 95% CI 1.07-1.36). Low-dose aspirin was not associated with a lower rate of ischemic cardiac death among black (adjusted hazard ratio 1.18, 95% CI 0.98-1.4) or white (adjusted hazard ratio 0.86, 95% CI 0.68-1.1) participants. Adverse event data were not reported.

Several issues limit our ability to draw firm conclusions about true aspirin use and its related benefit. The authors failed to delineate frequency of aspirin use and taking it two days a week vs. seven makes a difference. Further, we don’t know if aspirin was recommended by a medical provider, so we can’t draw conclusions about adherence. It would also be helpful to know if combining an imputed blood pressure with substitution of BMI for lipid values results in a valid Framingham risk category. The authors do not provide information about Hispanic participants because of an insufficient sample size, so the study does not look at impact “across race and ethnicity.” On the other hand, this study offers information about a disproportionately under-studied population: non-Hispanic blacks had a lower rate of aspirin use compared with whites, and in this real-life cohort, aspirin use was not associated with a reduction in ischemic cardiac death.

For more information, see the topic Aspirin for Primary Prevention of Cardiovascular Disease in DynaMed.

EBM Focus articles provide concise summaries of clinical trials most likely to inform clinical practice curated by the DynaMed editorial team.