Study Finds Disparity in CVD Prevalence Trends Between Income Populations

Salma Abdalla, MBBS, MPH

Findings from a new study revealed a great disparity in cardiovascular disease (CVD) prevalence between individuals with the highest income and the rest of the US population. The study reported that the group with the highest resources generally had a lower CVD rate compared to the lower-resources group.

The results further highlight the effects of increasing economic inequality in the US and the resulting disparity in health outcomes.

A team led by Salma M. Abdalla, MBBS, MPH, at the Boston University School of Public Health used representative data from 9 cycles of the National Health and Nutrition Examination Survey (NHANES) as well as 2010 US Census data to estimate the trends in prevalence of CVD between the highest earners and the rest of the population.

Overall, their analysis included 44,986 participants, all of whom were ≥20 years old.

Using the NHANES income to poverty ratio, they determined that 7926 (17.6%) were in the highest-resources group. Of that subpopulation. 50.3% were 40-59 year old, and 51.9% were men.

Among the remainder of the overall population, or those in the lower-resource group, 34.1% were 40-59 years old, and 53.2% we women.

Additionally, the investigators used the 2010 census estimates as well as linear regression to calculate the age-standardized prevalence of CVD. They also applied regression models to control for potential confounders.

Thus, they found that the prevalence of CVD decreased at a higher rate in the highest-resources group during the study period. For example, angina decreased from 3.4% in 1999 to 0.3% in 2016, heart attack from 3.2% to 1.4%, congestive heart failure from 1.2% to 0.5%, and stroke from 1.1% to 1.0%.

Furthermore, the odds of reporting angina (OR, 0.80; 95% CI, 0.73-0.87; P < .001), heart attack (OR, 0.91; 95% CI, 0.86-0.97; P = .003), and congestive heart failure (OR, 0.90; 95% CI, 0.82-0.99; P = .03) decreased among the same population.

The investigators found no significant change in the odds of reporting stroke (OR, 0.97; 95% CI, 0.90- 1.05; P = .43).

For the remainder of the remainder of the population, the prevalence of angina decreased from 3.3% to 2.6% and heart attack from 4.0% to 3.6%.

However, the prevalence of congestive heart failure increased from 2.6% to 2.8%, and stroke from 2.9% to 3.2%.

The odds of reporting angina (OR, 0.95; 95% CI, 0.92-0.99; P < .05) and heart attack (OR, 0.99; 95% CI, 0.97-1.02; P = .06) decreased over time.

There was no statistically significant change in the odds of reporting congestive heart failure (OR, 1.02; 95% CI, 1.00-1.05; P = .08) and stroke (OR, 1.02; 95% CI, 0.99-1.04; P = .21).

Abdalla and team noted that studies have shown that the overall prevalence of congestive heart failure and stroke has been increasing over the years. Furthermore, it is expected that these conditions will continue to become more prevalent in the future.

“Results of this study suggests that these trends in CHF and stroke are responsive to the increase in prevalence among 80% of the NHANES participants, whereas the prevalence among the richest group either remains constant or is decreasing,” they wrote.

After all, they acknowledge, both conditions are associated with high out-of-pocket expenses, which place a greater burden on those in the lower-income population.

“These findings should motivate further research into the dynamics of income inequality and health outcomes as well as the potential mechanisms behind these inequalities, such as increasing health care expenditures, behavioral risk factors, or other structural factors, which can point to potential solutions,” the investigators concluded.

The study, “Trends in Cardiovascular Disease Prevalence by Income Level in the United States,” was published online in JAMA Network Open.