Obesity-related cardiovascular deaths tripled in the last two decades, new study finds

Heart disease is killing fewer Americans overall, however, cardiovascular deaths where obesity was listed as a key contributing factor have tripled between 1999 and 2020, according to a new study published Wednesday in the Journal of the American Heart Association. And, Black women had the highest mortality rate out of all the population groups studied.

“I think this data is really important in that it shows us a problem,” said Mamas Mamas, professor of cardiology at Keele University in the U.K., and primary investigator of the study. “And it shows that it disproportionately affects one underserved, underprivileged group. I think you need that information and then to plan, OK, what do we do? How do we address this through policy?”

Obesity affects about 42% of the U.S. population, nearly a 10% increase from the preceding decade, according to the Centers for Disease Control and Prevention. Excess weight gain is driven by a complex, interconnected web of genetic, physiologic and environmental factors. Some of the key drivers include where individuals live, their access to health care and nutritious food, as well as safe places for physical activity. Obesity disproportionately affects people in underrepresented racial and ethnic groups, putting them at a higher risk for cardiovascular disease.

Still, obesity does not directly cause cardiovascular disease — it contributes to risk factors like type 2 diabetes, hypertension, and dyslipidemia. Previous research has also shown that obesity prevention strategies, whether at the individual level or population level, have not been successful in the long term, which adds urgency to addressing this public health issue.

“This is now an opportunity for us to understand more about the determinants of these different trends that they’ve highlighted, which is really the goal of analytic epidemiology,” said Ashley Felix, a cancer epidemiologist at Ohio State University who was not a part of the study.

In the new study, researchers analyzed data on cardiovascular disease deaths in which obesity was listed as a contributing factor. Under cardiovascular deaths, they included medical codes found on death certificates for ischemic heart disease, heart failure, hypertension, cerebrovascular disease, and other forms of heart disease. They also looked at race and gender and compared individuals living in urban versus rural settings to understand how different population groups were affected.

Researchers relied on data collected on 281,135 deaths between 1999 and 2020 from the Multiple Cause of Death database, which includes mortality and population counts from all U.S. counties — 43.6% were women; 78.1% were white; 19.8% were Black; 1.1% were Asian or Pacific Islander; and 1% were American Indian or Alaska Native.

Across the racial groups, the most common cause of death was ischemic heart disease followed by hypertensive disease. Overall, obesity-related cardiovascular death rates tripled from 2.2 per 100,000 people to 6.6 per 100,000 during the study period, according to the researchers. They also found that mortality, adjusted for age, was highest among Black individuals (11.6 per 100,000 people in 2020), followed by American Indian adults or Alaska Native adults (6.7 per 100,000).

Black women had the highest rates of obesity-related heart disease deaths than all others. The opposite was true for other racial groups: Men experienced more obesity-related cardiovascular deaths.

The study authors cited previous research to speculate that the mortality among Black women was higher because they experience more psychosocial stressors due to microaggressions even while receiving care, which could contribute to higher rates of cardiovascular disease. “If I was a Black woman with a cardiovascular condition, whether it be in the U.K., U.S., wherever, I wouldn’t get as good care, so I think that perhaps is part of it,” Mamas said. This could include the impact of being more likely to be labeled an “angry Black woman” while other patients would be seen as passionate advocates of their own health.

“I think it’s fine to make that hypothesis,” said Felix, “but it’s not borne out in the data that they’re showing.” She added, however, that since it is a descriptive epidemiological study, it is meant to generate hypotheses that lead to future studies.

“There’s something about being Black that presents more pressure,” said Queen Henry-Okafor, an assistant professor at the Vanderbilt School of Nursing who was not involved in the study. “And then being a Black woman presents a whole different dynamic, which I think is not really talked about.”

Among Black adults, those living in urban areas had higher rates of obesity-related cardiovascular deaths compared to those living in rural areas, whereas rural living was associated with higher mortality rates for people in all other racial groups.

According to the researchers Black individuals living in urban communities may be impacted more by socioeconomic deprivation — which includes level of education, housing, income, and access to healthful food — and health inequalities than Black people living in rural areas. Black people also did not benefit from increased access to health care that appears to benefit other racial groups who live in urban areas.

“It could be just a surrogate for having access to highly processed food that might be easier to access in a city as opposed to a rural environment,” said Noel Bairey Merz, medical director of the Barbra Streisand Women’s Heart Center in Los Angeles.

Merz cautioned that study findings tell a limited story because it relied primarily on death certificates, on which doctors do not have to list obesity as a secondary cause of death. “We don’t have the body weight, we don’t have the body mass index, and there’s good data about sex differences in obesity,” said Merz, who was not involved with the study.

“So, we are winning the war,” Merz said about overall cardiovascular deaths decreasing across all groups. “And why is that? Because we treat hypertension, because we treat dyslipidemia, because we have better diabetes drugs now. So I’m a little worried this is not maybe the right message we should be talking about.”

Merz added that because the dataset is not detailed, it also limits how these data could be used for future interventions. “They didn’t adjust for diabetes, they didn’t adjust for cholesterol. Why? Because they didn’t have those types of SIC codes. It’s not a detailed dataset. I’m sure they would have if they could have, but they couldn’t.”

Researchers acknowledged that deaths from cardiovascular disease in general are going down for all populations, while emphasizing that Black people have not seen that same level of decrease compared to other groups. Broadly, the researchers said data was limited and there could have been coding and data entry errors, which could affect the results. However, the results still underscore the need to address obesity more effectively in individuals and communities.

“So why are we seeing a threefold increase [in mortality] in obese patients?” Mamas, the study’s principal investigator, asked. “Overall cardiovascular deaths have decreased, but this and other papers have shown that they’ve decreased at different levels, according to the background of the patient.”

From an epidemiological point of view, Felix believes that the data is a good first step in looking at trends because few are looking at these relationships.

“It’s why we need descriptive epidemiology, we need to actually document these relationships,” said Felix. “And we might suspect the views of the patterns that are occurring, but this kind of use of population level data is important to just state what is happening currently.”

“This study shows us what’s happening. It doesn’t tell us why it’s happening and that’s the really important part. It’s showing us there’s a problem, it affects particular groups, but it doesn’t tell us why. I think you have to define if there’s a problem and who it’s affecting. And then you can start to think about why and how to address the problem.”