Socioeconomic Trends in Regional Inequality in MI and Stroke Care Utilization in Korea, 2009–2024

Background

Regional inequality in healthcare utilization may change differently across socioeconomic groups, but longitudinal evidence comparing disease-specific patterns remains limited. This study examined whether temporal trends in regional inequality in healthcare utilization for myocardial infarction (MI) and stroke differed by socioeconomic status (SES) in Korea.

Methods

Using Korean National Health Insurance Service (NHIS) data from 2009 to 2024, annual healthcare utilization rates were calculated for MI and stroke across 252 municipal-level districts (“si-gun-gu”). SES was classified into Medical Aid (MA) beneficiaries and five NHIS premium quintiles (Q1–Q5), with MA as the reference group. For each SES group and year, regional inequality was measured using quintile difference, decile difference, quintile ratio, decile ratio, coefficient of variation, and Theil index. Linear regression models were fitted for each disease-specific inequality measure, including centered year, SES, and Year×SES interaction terms, to test whether temporal slopes for Q1–Q5 differed from that of MA.

Results

For MI, no significant Year×SES interaction was found for any inequality measure, indicating statistically parallel temporal trends across SES groups. For stroke, a significant Year×SES interaction was observed for decile difference (p = 0.016), and quintile difference showed borderline significance (p = 0.055). Regional inequality in stroke healthcare utilization increased more steeply in the MA group than in higher-income groups, particularly Q4 and Q5. No significant interaction was found for quintile ratio, decile ratio, coefficient of variation, or Theil index.

Conclusions

Temporal trends in regional inequality differed by SES for stroke, but not for MI. The steeper increase among MA beneficiaries suggests an increasing overlap between regional and socioeconomic disadvantage in stroke care, warranting targeted equity-oriented policy responses.

Key messages

• Temporal trends in regional inequality in healthcare utilization were largely similar across socioeconomic groups for MI, but differed for stroke.

• Among stroke patients, regional inequality increased more steeply in Medical Aid beneficiaries, suggesting compounded geographic and socioeconomic disadvantage.