Income variability and incident cardiovascular disease in diabetes: a population-based cohort study

Area of Science:

• Cardiology
• Public Health
• Health Economics

Background:

• Longitudinal income changes are key to understanding cardiovascular health disparities.
• Limited research exists on the cardiovascular disease (CVD) risk associated with income dynamics in individuals with type 2 diabetes (T2D).

Purpose of the Study:

• To investigate the association between income variability, income decline, sustained low income, and the risk of incident cardiovascular disease (CVD) in adults with type 2 diabetes (T2D).

Main Methods:

• Utilized a large, nationally representative sample (1,528,108 adults aged 30-64 with T2D) from the Korean National Health Insurance Service database (2009-2012, mean follow-up 7.3 years).
• Assessed annual income using monthly health insurance premiums over a 5-year period to calculate income variability (intraindividual standard deviation of percent change).
• Analyzed incident fatal and nonfatal CVD events using insurance claims, calculating Hazard Ratios (HRs) adjusted for confounders.

Main Results:

• Higher income variability was significantly associated with increased CVD risk (HR highest vs. lowest quartile 1.25).
• Experiencing an income decline, especially to the lowest level, elevated CVD risk, irrespective of initial income status.
• Sustained low income over 5 years increased CVD risk (HR 1.38), while sustained high income decreased it (HR 0.71).

Conclusions:

• Income variability, income declines, and sustained low income are linked to higher cardiovascular disease (CVD) risk in individuals with type 2 diabetes (T2D).
• Further research is needed to elucidate the mechanisms through which income dynamics influence CVD risk in this vulnerable population.