Incidence rate of infective endocarditis by socioeconomic position: a Danish nationwide cohort study (2000-2022)

People with lower socioeconomic positions have a higher risk of cardiac and infectious diseases than those with higher socioeconomic positions. However, how the increasing incidence of infective endocarditis among different socioeconomic groups has played out remains unclear. We therefore aimed to investigate nationwide temporal trends in infective endocarditis incidence rate by socioeconomic position in Denmark.

Using nationwide Danish registries, we investigated infective endocarditis incidence rate (2000-2022). As socioeconomic position indicator, we used affluence level (accounting for household-level income and wealth), dividing the population into low, medium, and high affluence. Average annual percentage changes were computed to evaluate temporal trends. Slope index and relative index of inequality were calculated to obtain inequality gradients.

Per 100,000 person-years, the incidence rate increased from 8.7 in 2000 to 21.2 in 2022 among low; from 7.4 to 14.3 among medium; and from 6.2 to 13.1 among high affluence people. The average annual percentage change was 4.3% among low, 3.5% among medium, and 3.7% among high affluence people. The slope index of inequality increased from 3.8 additional cases per 100,000 person years (95% CI: 0.4-7.3) in 2000 to 12.3 (95% CI: 7.4-17.1) in 2022. The relative index of inequality increased from 1.68 (95% CI: 0.90-2.44) to 2.13 (95% CI: 1.49-2.78).

The infective endocarditis incidence rates increased in all affluence levels, with highest rates consistently found in the lowest affluence group, indicating that people with lower socioeconomic positions faced a disproportionately higher risk of infective endocarditis. These findings highlight the need to consider socioeconomic factors when addressing modifiable determinants that may curb the rise in infective endocarditis incidence.

Independent Research Fund Denmark (grant no. 3101-00102B) and Center for Population Medicine, Department of Clinical Epidemiology, Aarhus University.