Social Factors Influence Racial Disparities in Cardiovascular Disease Mortality

New research suggests Black Americans experience a more than 2-fold higher risk of dying from cardiovascular disease (CVD) than their White counterparts, despite substantial reductions in nationwide CVD-related mortality.¹

The analysis of more than 50,000 adults revealed these racial disparities may be attributed to social factors, including unemployment and low income, rather than known metabolic risk factors, including hypertension and obesity.

“For so many years we have focused on smoking, diet, physical activity, obesity, hypertension, diabetes, and high cholesterol – and we know those are important for the prevention of cardiovascular disease – but it surprised me that the Black-White difference in cardiovascular disease mortality is mainly due to social factors,” said Jiang He, MD, PhD, lead author, and the Joseph S. Copes Chair in Epidemiology at the School of Public Health and Tropical Medicine at Tulane University.²

Mortality from CVD is continually higher in Black patients than in other racial and ethnic groups in the United States. He and colleagues set out to understand the degree to which social, behavioral, and metabolic risk factors are associated with CVD mortality, as well as the extent to which racial differences in CVD mortality continue to persist after accounting for these factors.¹

For the prospective cohort study, investigators searched the National Health and Nutrition Examination Survey (NHANES) 1999 to 2018, collecting health data from 50,808 adults aged ≥20 years. CVD-related deaths were determined from linkage to the National Death Index with follow-up through 2019.

The investigative team examined the association between metabolic risk factors (obesity, diabetes, hypertension, and high cholesterol), lifestyle risk factors (smoking, unhealthy diet, lack of exercise, and lack of or too much sleep), and social risk factors (unemployment, low family income, food insecurity, low education, no regular access to healthcare, no private health insurance, not owning a home, and not married nor living with a partner) with cardiovascular mortality.

Over an average of 9 years of follow-up, 2589 CVD deaths were confirmed. The age- and sex-standardized rates of CVD mortality were:

• 484.7 deaths per 100,000 person-years in Black participants
• 384.5 deaths per 100,000 person-years in White participants
• 292.4 deaths per 100,000 person-years in Hispanic participants
• 255.1 deaths per 100,000 person-years in other race groups

After multiple Cox regression analysis adjusted for all measured risk factors, investigators found multiple social (unemployment, low family income, food insecurity, lack of home ownership, and unpartnered status), behavioral (current smoking, lack of leisure-time physical activity, and sleep 8 hours/day), and metabolic (obesity, hypertension, and diabetes) risk factors were associated with a significantly higher risk for CVD death.

The analysis showed Black adults had a 54% higher cardiovascular disease mortality rate compared to White adults (hazard ratio [HR], 1.54; 95% CI, 1.34 to 1.77). After adjustment for metabolic and behavioral risk factors, the risk was attenuated to 34% (HR, 1.34; 95% CI, 1.16 – 1.55) and 31% (HR, 1.31; 95% CI, 1.15 – 1.50), respectively.

However, once an adjustment was made for social risk factors, the racial difference in CVD mortality disappeared, according to investigators.

“When we adjusted for lifestyle and clinical risk factors, the Black-White disparity in cardiovascular disease mortality was diminished but still persisted,” He said.² “However, after adjusting for social risk factors, this racial difference totally disappeared.”

Despite this, the team was unable to establish causal contributions of social, behavioral, and metabolic risk factors to racial and ethnic disparities in CVD mortality. He emphasized the importance of a good income and access to healthcare, as well as social support from a family or community, as factors that can influence CVD risk.

“It is essential to develop novel community-based interventions for reducing cardiovascular disease risk in Black populations,” He said.²

References

1. He J, Bundy JD, Geng S, et al. Social, Behavioral, and Metabolic Risk Factors and Racial Disparities in Cardiovascular Disease Mortality in U.S. Adults : An Observational Study [published online ahead of print, 2023 Aug 15]. Ann Intern Med. 2023;10.7326/M23-0507. doi:10.7326/M23-0507
2. Tulane (2023) Why are black adults at greater risk of death from heart disease? study blames social factors, EurekAlert! Available at: https://www.eurekalert.org/news-releases/998429 (Accessed: 15 August 2023).