In this cohort study of Danish residents aged 30 years or older from 1988 to 2023, the incidence of MACE declined across all socioeconomic groups, although individuals with lower income generally experienced higher incidence rates throughout the study period.
Key Findings
Results
Age-standardized incidence rates of MACE decreased across all income groups from 1988 to 2023 but remained highest in the lowest income quartile throughout the entire study period.
The study covered 5,932,672 individuals aged 30 years or older registered in the Danish Civil Registration System from 1988 to 2023.
The annual study population increased from 3.06 million in 1988 to 3.85 million in 2023.
MACE was defined as the first hospital admission for acute myocardial infarction, unstable angina, stroke, or heart failure.
Age-standardized incidence rates were calculated annually, stratified by income quartile and sex.
Results
For males in the lowest income quartile, age-standardized MACE incidence rates declined from 191.1 to 119.6 per 10,000 person-years between 1988 and 2023.
In 1988, the rate in the lowest income quartile for males was 191.1 (95% CI, 186.3–196.0) per 10,000 person-years.
By 2023, this rate had fallen to 119.6 (95% CI, 116.0–123.2) per 10,000 person-years.
In the highest income quartile for males, rates declined from 153.5 (95% CI, 142.9–164.0) to 85.9 (95% CI, 81.2–90.6) per 10,000 person-years over the same period.
The absolute gap between lowest and highest income quartile males was approximately 37.6 per 10,000 person-years in 1988 and approximately 33.7 per 10,000 person-years in 2023.
Results
For females in the lowest income quartile, age-standardized MACE incidence rates declined from 116.0 to 70.4 per 10,000 person-years between 1988 and 2023.
In 1988, the rate in the lowest income quartile for females was 116.0 (95% CI, 113.0–118.9) per 10,000 person-years.
By 2023, this rate had fallen to 70.4 (95% CI, 68.1–72.6) per 10,000 person-years.
In the highest income quartile for females, rates declined from 89.5 (95% CI, 81.9–97.2) to 53.1 (95% CI, 49.0–57.1) per 10,000 person-years.
The absolute gap between lowest and highest income quartile females was approximately 26.5 per 10,000 person-years in 1988 and approximately 17.3 per 10,000 person-years in 2023.
Results
The study population aged over the 35-year observation period, with median age increasing from 50.8 to 55.8 years.
Median age in 1988 was 50.8 years (IQR, 40.2–65.6 years).
Median age in 2023 was 55.8 years (IQR, 43.3–68.8 years).
The sex composition shifted from a majority female population in 1988 (52.1%) to a majority male population in 2023 (51.1%).
This is relevant context because age-standardized rates were used to account for the aging population when making temporal comparisons.
Methods
The study used equivalized disposable household income as the measure of socioeconomic status, drawing on data from Danish national registries over a 35-year period.
This was a nationwide, population-based open cohort study using Danish national registry data.
Included all residents of Denmark aged 30 years or older who were alive in each year between January 1, 1988, and January 1, 2023, with available income observations in the current or preceding 5 years.
Individuals were followed up to December 31 of each year, to death, or to emigration.
Income was categorized into quartiles; the exposure measure was equivalized disposable household income.
Data were analyzed from August 2025 to July 2026.
What This Means
This research examined whether income-based inequality in serious heart and cardiovascular events changed over more than three decades in Denmark. Using data on nearly 6 million people from 1988 to 2023, researchers tracked rates of major adverse cardiovascular events (MACE) — which include heart attacks, unstable angina, stroke, and heart failure — across four income groups. They found that rates of these serious events fell substantially for both men and women across all income levels over the 35-year period.
Despite the overall improvement, people with lower incomes consistently had higher rates of MACE than those with higher incomes throughout the entire study period. For example, in 2023, men in the lowest income group still experienced about 120 cardiovascular events per 10,000 person-years, compared to about 86 per 10,000 for men in the highest income group. Women showed similar patterns, with lower-income women experiencing higher rates than higher-income women at every point in time.
This research suggests that while Denmark — a country with universal healthcare and relatively strong social safety nets — has seen broad cardiovascular health improvements over recent decades, the gap between lower- and higher-income groups has persisted. This indicates that broader reductions in cardiovascular disease have reached all income groups, but socioeconomic inequalities in cardiovascular health have not been eliminated, pointing to the continued importance of addressing the social and economic factors that influence heart health.