Historical ‘redlining’ practices associated with worse cardiometabolic disease
Historical housing discriminatory practices are associated with modern-day cardiometabolic disease and risk factors years after such practices were outlawed, according to an analysis of census-level data.
In a cross-sectional study, researchers found that “redlining” practices that graded neighborhoods according to perceived investment risk was associated with rates of CAD, chronic kidney disease, increased risk for comorbidities and a lack of access to appropriate medical care that persist today.
“Residential segregation policies that were started approximately a century ago continue to be associated with current-day health outcomes, including cardiometabolic disease,” Sadeer Al-Kindi, MD, cardiologist at University Hospitals Harrington Heart & Vascular Institute and assistant professor of medicine at Case Western Reserve University in Cleveland, told Healio. “This may be related to intergenerational health inequity, urban designs, including roadways, environmental toxicities, access to health care and other factors.”
Historically disadvantaged areas and disease
Al-Kindi and colleagues assessed the mean prevalence of 2019 cardiometabolic outcomes and risk factors at the census tract-level according to digitized maps based on Home Owners’ Loan Corporation (HOLC) grading. The system of government security maps developed in the 1930s assigned neighborhoods one of four color-coded “grades” based on potential lending risk: A (“best,” or green); B (“still desirable,” or blue); C (“definitely declining,” or yellow); and D (“hazardous,” or red). The D-rated neighborhoods were deemed “redlined” neighborhoods.
“Although these housing practices were outlawed in the 1960s, subtle discriminatory practices have continued to perpetuate and shape current social (eg, widening disparities in socioeconomic status and residential segregation) and built environmental structures over the past century, widening health inequities,” the researchers wrote.
Researchers used HOLC-graded data and calculated the percentage of intersection between each graded neighborhood boundaries and the 2020 U.S. Census tract boundaries, excluding census tracts with less than 20% total area of intersection. The researchers used the graded intersections to generate a scale using their corresponding HOLC numeric scores, with 1 through 4 corresponding with A through D. Additionally, researchers used the CDC PLACES database to calculate potential confounders, including prevalence estimates of census tract-level health indicators, as well as the Environmental Protection Agency’s environmental justice tool to assess census tract-level exposure of particulate matter and diesel particulate matter.
Outcome variables included markers of health care access (cholesterol screening in the past 5 years, routine health care checkup in the past year, and lack of health insurance in adults aged 18 to 64 years), cardiometabolic risk factors (diabetes, current smoking, obesity, hypertension and high cholesterol) and cardiometabolic outcomes (prevalence of CAD, stroke and chronic kidney disease).
Researchers linked the graded census tracts to the prevalence of cardiometabolic indicators, followed by calculating the average of each indicator across census tracts in each HOLC grade.
The findings were published in the Journal of the American College of Cardiology.
There were 11,178 HOLC-graded census tracts included comprising 38,537,798 people. A-graded areas covered 7.1% of census tracts, B-graded areas covered 19.4% of census tracts, C-graded areas covered 42% of census tracts and D-graded areas covered 31.5% of census tracts. Across the four HOLC grades, the percentage of Black individuals increased (13.2%, 21.7%, 23.3%, and 32.2%, respectively), as did the percentage of Hispanic individuals (8.5%, 17.1%, 25.9%, and 28.8%, respectively).
Health outcomes by neighborhood
Researchers found that neighborhoods with better HOLC grades had higher rates of cholesterol screening (P < .001) and routine health visits (P < .001) compared with neighborhoods with worse HOLC grades, whereas the prevalence of people without insurance aged 18 to 64 years nearly doubled from A through D-graded areas, from 10.5% to 21.4% (P < .001).
Across graded areas, researchers also observed an overall increase in stepwise increments in the prevalence of diabetes (9.2% to 13.5%; P < .001), obesity (28.5% to 35.3%; P < .001), hypertension (30% to 33.8%; P < .001) and smoking (13.1% to 20.6%; P < .001). Researchers also observed increases across HOLC grades A through D in the prevalence of CAD (5.3% to 6.2%), stroke (2.9% to 4.2%), and chronic kidney disease (2.7% to 3.6%; P < .001 for all comparisons). However, there was a decrease across HOLC grades A through D in the prevalence of high cholesterol (31.3% to 29.2%; P < .001).
In a fully adjusted model, there was a positive association between historically redlined census tracts and prevalence of CAD (beta = 0.02; P = .063), stroke (beta = 0.03; P < .001), and chronic kidney disease (beta = 0.04; P < .001).
“We found neighborhoods with so-called better HOLC grades had higher cholesterol screening and routine health visits when compared to neighborhoods with worse HOLC grades, and the prevalence of adults 18 to 64 years old without health insurance nearly doubled from A- through D-graded areas” Issam Motairek, MD, a clinical research associate at University Hospitals Harrington Heart & Vascular Institute in Cleveland, said in the release. “In each stepwise increase across the HOLC grading spectrum, from A to D, we also observed an overall increase in rates of diabetes, obesity, hypertension and smoking.”
Disparities in exposures
The researchers noted that the association between redlining and health outcomes is multifactorial; however, disparities in environmental exposures and in socioeconomic attributes may help explain the poor health outcomes in redlined neighborhoods.
“Addressing social and environmental determinants for patients with or at risk for cardiometabolic health who reside in redlined neighborhoods is crucial to counteract health disparities and improve overall population health outcomes,” Al-Kindi told Healio. “Additionally, initiation of novel community-based preventive and health care delivery models may be helpful to improve health outcomes in redlined neighborhoods. Further, investigating neighborhood effects on incident cardiovascular health, beyond traditional risk factors, may improve utilization of personalized preventive interventions in high-risk individuals.”
The researchers wrote that future studies should examine microlevel neighborhood characteristics, which make redlined neighborhoods more susceptible to disease.
For more information:
Sadeer Al-Kindi, MD, can be reached at sadeer.al-kindi@uhhospitals.org; Twitter: @sadeer_alkindi.
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