According to the U.S. Department for Health and Human Services, as of 2018, African Americans were 30% more likely to die from heart disease than non-Hispanic whites.
Thus, the risk calculator for atherosclerotic cardiovascular disease (ASCVD) used by medical practitioners gives considerable weight to race. But as more researchers recognize race as a social construct that has little direct effect on health, Meredith Duncan, Ph.D., is looking to rewrite that calculator.
“Sometimes people want to think about race as being biologic because there are some pieces of our genetic makeup that code for the color of our skin. But functionally, the way this impacts our health is negligible. Race is a social construct because it’s something that developed through human interaction as a way to categorize people,” says Duncan, assistant professor of Biostatistics and director of Graduate Studies for the University of Kentucky College of Public Health’s Ph.D. Program in Epidemiology and Biostatistics.
Instead, Duncan is seeking to investigate whether stressors resulting from structural racism—the laws, rules, or policies that result in and support harmful treatment of others based on race—better explain why people of color are at greater risk of developing ASCVD events (heart attack, stroke, and cardiovascular death).
What is ASCVD?
ASCVD is a buildup of plaque or thickening due to inflammation on the inside of the walls of an artery. This reduces blood flow and oxygen supply to vital body organs and extremities and can lead to heart attack, stroke, and cardiovascular death.
Elevated levels of cholesterol and triglycerides in the blood, high blood pressure, cigarette smoking, and diabetes are believed to be the main triggers of ASCVD.
According to the National Institutes of Health’s National Heart, Lung, and Blood Institute, disease linked to ASCVD is the leading cause of death in the United States and about half of Americans between ages 45 and 84 have undiagnosed ASCVD.
Research Overview
With a two-year grant from the University of Kentucky Center for Clinical and Translational Science KL2 Career Development Program, Duncan is studying whether social determinants of health (SDOH)—the economic, social, environmental, and psychosocial factors that influence health—paint a more accurate picture of someone’s risk of atherosclerotic cardiovascular disease than race.
Many SDOH, such as poverty rate, education level, access to health care, housing and food security, and safety, are directly affected by structural racism.
“[Structural racism] really impacts the access to services that people have: how close they are to hospitals, what the police presence looks like, and how that police presence interacts with the people living in those areas,” Duncan said. “Because of the history of those types of things, people of color tend to experience greater stress and discrimination, and that increased stress and discrimination can lead to things like heightened blood pressure or greater cholesterol,” Duncan added. “And it's those things that specifically then go on to impact their cardiovascular disease risk. “Structural racism is not something that we can directly measure. But it has legs that kind of go down and influence a lot of things. It influences socioeconomic status and someone's access to health care, and we can directly measure those types of things," said Duncan.
“[Structural racism] really impacts the access to services that people have: how close they are to hospitals, what the police presence looks like, and how that police presence interacts with the people living in those areas,” Duncan said.
“Because of the history of those types of things, people of color tend to experience greater stress and discrimination, and that increased stress and discrimination can lead to things like heightened blood pressure or greater cholesterol,” Duncan added. “And it's those things that specifically then go on to impact their cardiovascular disease risk.
“Structural racism is not something that we can directly measure. But it has legs that kind of go down and influence a lot of things. It influences socioeconomic status and someone's access to health care, and we can directly measure those types of things," said Duncan.
Testing the Hypothesis
To test this hypothesis, Duncan has amassed data from the Framingham Heart Study, Jackson Heart Study, Coronary Artery Risk Development in Adolescents, Multiethnic Study of Atherosclerosis, Hispanic Community Heath Study, and Reasons for Geographic and Racial Differences in Stroke cohorts.
This combined sample contains approximately 40,000 individuals, more than double the number used to develop the commonly used ASCVD risk estimating equations.
“For socioeconomic status I have education, marital status, employment, household income, and the number of people in the household that income supports. In addition, we have whether someone has health insurance, how many hospitals are in a 5-mile radius of where they live, or the minimum distance to hospital from their residence to capture access to care,” she said.
Another tool Duncan uses to gauge SDOH is the Area Deprivation Index, which looks at 17 different dimensions of neighborhood quality and deprivation, including access to educational institutions, health systems, not-for-profit organizations, and government agencies. A measure of racial and ethnic segregation at the census tract level will also be examined.
“I hope and think that by incorporating a lot of these social determinants of health, we're getting perhaps a more overall picture of what someone’s living situation looks like and how that could then impact their cardiovascular disease risk," said Duncan. “If adding these SDOH variables attenuates the effect of race and ethnicity, this paves the way for removing race and ethnicity as risk factors for ASCVD. It’s not the color of a person’s skin or their ethnicity that predisposes a person to ASCVD, it’s the extra stress experienced by people of color that leads to this excess risk, and that’s what I want to explicitly demonstrate.”
“I hope and think that by incorporating a lot of these social determinants of health, we're getting perhaps a more overall picture of what someone’s living situation looks like and how that could then impact their cardiovascular disease risk," said Duncan.
“If adding these SDOH variables attenuates the effect of race and ethnicity, this paves the way for removing race and ethnicity as risk factors for ASCVD. It’s not the color of a person’s skin or their ethnicity that predisposes a person to ASCVD, it’s the extra stress experienced by people of color that leads to this excess risk, and that’s what I want to explicitly demonstrate.”
Public Health Impact: The Risk Assessment Equation
Should her research show that SDOH do provide a better predictor of ASCVD than race, Duncan plans to create an assessment equation
“I would really love if the risk equations that I develop can replace what we are currently doing, because in addition to assuming underlying ASCVD risk differs by race, the current equations do not include anyone of Hispanic ethnicity,” she said. “There are more Hispanic men and women in the country than non-Hispanic Black men and women, so we're missing a huge swath of the population by not including them in our tools." "With the current tool, providers are instructed to use the equations developed in non-Hispanic White individuals when estimating risk for Hispanic participants, but on average, Hispanic men and women have lower rates of ASCVD than their non-Hispanic White counterparts, which can result in overestimation of risk and overtreatment," Duncan adds.
“I would really love if the risk equations that I develop can replace what we are currently doing, because in addition to assuming underlying ASCVD risk differs by race, the current equations do not include anyone of Hispanic ethnicity,” she said. “There are more Hispanic men and women in the country than non-Hispanic Black men and women, so we're missing a huge swath of the population by not including them in our tools."
"With the current tool, providers are instructed to use the equations developed in non-Hispanic White individuals when estimating risk for Hispanic participants, but on average, Hispanic men and women have lower rates of ASCVD than their non-Hispanic White counterparts, which can result in overestimation of risk and overtreatment," Duncan adds.
Duncan also sees a risk assessment equation that looks at SDOH rather than race being beneficial to Kentuckians, especially those in Appalachian regions of Kentucky, who studies have shown have the worst cardiovascular risk profile in the country.
Eastern Kentucky also has a median household income 40% less than the national figure, fewer doctors, and lower education rates.
“The current equations don't predict risk very well in people of lower socioeconomic status, regardless of their race or ethnicity,” Duncan said. “It does not do a great job for people in Appalachia. I am hoping that by adding in these social determinants we are accurately capturing the social deprivation of people in Appalachia. This can help improve risk prediction in that population as well.”
Meredith Duncan is an assistant professor in the University of Kentucky's Department of Biostatistics. Her Ph.D. is in epidemiology, but due to her strong analytic background she considers herself an applied biostatistician. Duncan has worked in cardiovascular research since 2013.
Her personal research focuses on cardiovascular health disparities among people of color and LGBTQ+ individuals. Duncan teaches graduate-level courses aimed at equipping students with skills in scientific writing and survival analysis.
Research reported in this article was supported by the National Center for Advancing Translational Sciences of the National Institutes of Health under Award Number UL1TR001998. The content is solely the responsibility of the author and does not necessarily represent the official views of the National Institutes of Health.
At the UK College of Public Health, our vision is to be the catalyst of positive change for population health. Our mission is to develop health champions, conduct multidisciplinary and applied research, and collaborate with partners to improve health in Kentucky and beyond. Learn more about our people, programs and passion for public health at cph.uky.edu.
