Income-Based Inequalities in Health System Performance in the US and South Korea.
Sungchul Park1, Karen Eggleston2,3, Young Kyung Do1,4
1Department of Health Policy and Management, College of Medicine, Seoul National University, Seoul, South Korea.
JAMA Health Forum
|March 20, 2026
Summary
This study found that income disparities impact health system performance in both the US and South Korea, with greater inequalities observed in the US. Policy interventions are crucial to address these income-based health differences, especially in the United States.
Area of Science:
- Health Services Research
- Health Economics
- Social Determinants of Health
Background:
- Income is a significant social determinant of health.
- Cross-national comparisons of health system performance can highlight disparities.
- The US and South Korea, OECD members with high poverty rates, offer distinct health system contexts for comparison.
Purpose of the Study:
- To compare overall health system performance between the US and South Korea.
- To analyze income-related inequalities in health system performance across the two nations.
Main Methods:
- A repeated cross-sectional study design was employed, utilizing nationally representative adult samples from the US and South Korea.
- Data were sourced from the Medical Expenditure Panel Survey (MEPS), National Health and Nutrition Examination Survey (NHANES), Korean Health Panel Study (KHPS), and Korean National Health and Nutrition Examination Survey (KNHANES) between 2009 and 2019.
- Annual household income, categorized into country-specific deciles, served as the primary exposure. Thirty health system performance indicators across six domains (spending, utilization, access, health status, behavioral risks, clinical outcomes) were analyzed using regression models to estimate income-related inequalities.
Main Results:
- US adults exhibited higher mean total healthcare spending than South Korean adults across all income deciles, despite similar self-reported health status.
- A one-decile increase in income was associated with a greater decrease in total healthcare spending in the US (-$142) compared to South Korea (-$33).
- Larger income-related disparities were observed in the US for self-reported good health (2.4 pp vs. 1.5 pp) and preventive service utilization (e.g., dental checkups: 4.0 pp vs. 0.6 pp).
Conclusions:
- Income is associated with health system performance disparities in both the US and South Korea.
- The US demonstrates more pronounced income-related inequalities in health system performance compared to South Korea.
- Targeted structural and systemic policy interventions are necessary to mitigate income-based health inequalities, particularly within the US health system.
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