‘Smoldering Epidemic’ of CVD Risk Factors in Middle-Aged Adults

Cardiovascular risk factors have been on the rise for the past two decades among middle-aged US adults, with roughly one in two now considered obese, but there’s a noticeably different risk profile depending on income, according to a study published this week.

The prevalence of hypertension is increasing among low-income individuals, but middle-aged adults with higher incomes are experiencing an increase in diabetes and obesity, a trend that is not seen in those who earn less money, Michael Liu, MPhil (Harvard Medical School, Boston, MA), and colleagues reported this week in the Annals of Internal Medicine.

There is an increasingly recognized crisis in middle-aged US adults, said senior investigator Rishi Wadhera, MD, MPhil (Beth Israel Deaconess Medical Center, Boston, MA), noting that while past declines in cardiovascular mortality have largely stagnated in the overall population, cardiovascular deaths have crept steadily upwards in middle-aged individuals.

“The trends in mortality are very alarming, specifically among middle-aged adults, and I think this study reinforces why we're seeing those patterns,” Wadhera told TCTMD. “The burden of cardiovascular risk factors is high and rising in this middle-aged population and we know that the earlier you develop cardiovascular risk factors, the higher your lifetime risk of having a catastrophic cardiovascular event like a heart attack or stroke or experiencing cardiovascular death.”

There is also concern that the increase in cardiovascular mortality might be concentrated in adults with lower incomes, a group that struggles with access to care, poor neighborhood resources, and psychosocial and environmental stressors, say researchers. Their study, said Wadhera, was an attempt to tease out possible changes in risk factors in middle-aged adults by income levels to understand the concerning patterns.

‘We Haven’t Made Any Progress’

The study included 20,761 adults ages 40 to 64 years (mean age 51.4; 51.4% women) participating in the National Health and Nutrition Examination Survey between 1999 and March 2020. Low-income adults were identified based on family income relative to the US poverty thresholds, with an income-to-poverty ratio of less than 2 defining low-income status. Over the study period, the percentage of low-income adults remained relatively stable, making up approximately 25% of the cohort.

Adjusted for age, the prevalence of hypertension, diabetes, obesity, and current cigarette use was consistently higher among low-income adults throughout the study. Hypertension prevalence in low-income adults increased from 37.2% in 1999-2000 to 44.7% in 2017-2020, but there was no change in high-income adults. In the low-income group, however, there was no change in the prevalence of diabetes or obesity over time. In contrast, the prevalence of diabetes increased from 7.8% in 1999-2000 to 14.9% in 2017-2020 in high-income individuals. Similarly, the prevalence of obesity increased from 33.0% to 44.0% in high-income adults.

Roughly one-third of low-income adults were current smokers, a rate that did not change much over 20 years, whereas smoking decreased from 18.6% to 11.5% in the high-income group. Hyperlipidemia decreased significantly in both high- and low-income adults.

The burden of cardiovascular risk factors is high and rising in this middle-aged population. Rishi Wadhera

“There are sort of unique patterns happening to low-income and high-income adults,” said Wadhera. “The overall income-based disparities of hypertension, diabetes, obesity, and cigarette use hasn't really narrowed over two decades. We haven't made any progress.”

In terms of treatment, more than 80% of high- and low-income adults with hypertension were treated, with no changes observed over time. Control of hypertension was low across the study period, particularly when it was defined using the 2017 American College of Cardiology/American Heart Association hypertension guidelines that adopted stricter targets. With diabetes, treatment rates didn’t change over time in the low-income adults but increased significantly in the wealthier group. On the other hand, glycemic control in the treated adults improved in the low-income group but was unchanged in the higher-income adults. 

Doubling Down on Screening and Prevention

To TCTMD, Wadhera said they looked into what could explain the differences observed in the study, including factors such as insurance coverage, healthcare access, and food insecurity, but their adjustments did not change their results.

“If you think about it, there are many other factors beyond those that can confer a higher risk of developing a chronic condition,” he said. “We know lower-income communities have poorer built environments, less green space for physical activity, and we know low-income adults are more likely to experience housing instability, economic shocks, and greater barriers to medication affordability. We also know that low-income adults are more likely to live in communities with less access to nutritious food. So, there are a lot of other factors that could explain the differences we observed.”

Instead, the study suggests there are broader social or environmental risk factors that might be contributing to the inequities, he said. In general, though, the prevalence of cardiovascular risk factors regardless of income level reflects broader trends in health behaviors, including an increase in sedentary time, said Wadhera.

“This is a population where I think we really need to double down in terms of targeted campaigns—at the health system, community, and policy levels—that focus on screening, prevention, and treatment of cardiovascular risk factors,” Wadhera told TCTMD. “Everyone pays attention to people who are older when we typically think of cardiovascular disease, but I think what we're witnessing here is a little bit of a smoldering epidemic of cardiovascular risk factors in middle-aged adults, which could ultimately have really severe downstream consequences in terms of cardiovascular disease and health.”