MACE Rates Fell Across Income Groups, But Gaps Persisted

Incidence of major adverse cardiovascular events (MACE) declined across every income group in Denmark from 1988 to 2023, but people in the lowest income quartile consistently had higher rates than those in the highest, according to a study published in JAMA Network Open.¹

The nationwide open cohort study used Danish national registries to follow all residents aged 30 years or older, totaling 5,932,672 individuals over the study period. The exposure was equivalized disposable household income, which weights income by household size, and each person was classified into an income quartile every year. MACE was defined as the first hospital admission for acute myocardial infarction, unstable angina, stroke, or heart failure.

MACE Rates Fell 37% to 44% in Highest and Lowest Earners

Age-standardized MACE incidence declined across all 4 income quartiles for both sexes. Among males in the lowest quartile, the rate dropped from 191.1 to 119.6 per 10,000 person-years, while in the highest quartile it fell from 153.5 to 85.9 per 10,000 person-years. Among females, rates fell from 116.0 to 70.4 per 10,000 person-years in the lowest quartile and from 89.5 to 53.1 per 10,000 person-years in the highest.

Rates generally declined for each individual MACE component and held when income was adjusted for inflation. For the combined end point of MACE or all-cause mortality, the rate among males fell from 433.8 to 331.8 per 10,000 person-years in the lowest quartile and from 309.0 to 177.0 per 10,000 person-years in the highest. Among females, it declined from 276.5 to 203.9 in the lowest quartile and from 191.9 to 119.0 in the highest.

Income Gap Showed No Meaningful Change Over 35 Years

With the highest quartile as the reference, incidence rate ratios for MACE were generally highest in the lowest quartile throughout the study. The only exception was among males in 1993, when the second quartile was higher. The relative index of inequality, which summarizes the gap across the full income range, ranged from 1.3 (95% CI, 1.2-1.5) to 1.9 (95% CI, 1.7-2.1), with no meaningful change over time for either sex. A likelihood ratio test was significant, but the authors attributed this to the large sample size picking up small, irrelevant shifts.

In 2023, 27.5% of people in the lowest quartile had hospital-recorded cardiovascular disease vs 13.5% in the highest, and diabetes prevalence was 5.6% vs 1.6%. This held even as the median age of the lowest quartile fell from 68.0 years in 1988 to 61.8 years in 2023, while median age rose in every other quartile.

Females had lower MACE incidence than males despite being overrepresented in the lowest income quartile in 1988, suggesting that income alone does not explain sex differences in cardiovascular risk, the authors wrote.

A 2020 analysis of US National Health and Nutrition Examination Survey data from 1999 to 2016 found a less even pattern, though it measured self-reported prevalence rather than hospital-recorded incidence. Declines in cardiovascular disease prevalence occurred primarily among the highest-resources group, while prevalence among the rest of the population fell more slowly, stayed flat, or rose, depending on the condition.² The Danish investigators noted it remains undetermined whether their findings apply to countries with greater income inequality or less access to care for lower socioeconomic groups.¹

The MACE definition excluded cardiovascular death because of uncertainty in cause-of-death classification. Denmark's 1994 switch from the International Classification of Diseases, 8th Revision (ICD-8) to ICD-10 diagnosis coding may also affect comparability, although the authors used a validated code mapping to limit this. The findings should not be interpreted causally, as registry data cannot establish whether low income preceded comorbidity or resulted from it.

“Together, these findings indicate that while advances in improvements in cardiovascular health have benefited the entire population of Denmark, socioeconomic inequality in cardiovascular outcomes has not been eliminated,” wrote the researchers of the study.

References

1. Denholt CS, Wood-Kurland HK, Sørensen KK, et al. Socioeconomic inequality and major adverse cardiovascular events. JAMA Netw Open. 2026;9(10):e2639072. doi:10.1001/jamanetworkopen.2026.39072
2. Abdalla SM, Yu S, Galea S. Trends in cardiovascular disease prevalence by income level in the United States. JAMA Netw Open. 2020;3(9):e2018150. doi:10.1001/jamanetworkopen.2020.18150