Income Associated With Health System Performance Disparities in US, South Korea

A new analysis published in JAMA Health Forum has linked income-related inequalities and health system performance, finding that disparities in health system performance were associated with income in both the US and South Korea.¹ The results indicate that policy changes are needed to address these inequalities across the board.

Disparities in health have been linked to income inequality due to factors such as access to care and the quality of care those with lower incomes may receive.² Income-related gaps in health care exist in both the US and South Korea, where the federal poverty rate is high overall or in older individuals, respectively. These inequalities could present differently in each country due to the method of health care delivery in each country. This study aimed to conduct a systematic comparison of health system performance and the inequalities in health system performance based on income between the US and South Korea.

The cross-sectional analysis was conducted through the use of the Medical Expenditure Panel Survey (MEPS) and the National Health and Nutrition Examination Survey (NHANES) for data from the US, and the Korean Health Panel Study (KHPS) and the Korean NHANES for data from South Korea. Data from adults aged 18 years and older were used and separated into deciles based on annual household income.

The researchers evaluated 6 domains in this analysis, including health care spending, health care utilization, access to care, health status, behavioral risk factors, and clinical outcomes. Health care spending was the total annual spending on inpatient, outpatient, and emergency department services. Receipt of preventive services and service volume were used to define health care utilization. Self-reported good health was measured for health status, and smoking status, obesity, and alcohol consumption were assessed as behavioral risk factors. Having a usual source of care and reporting unmet needs due to cost were considered part of access to care.

There were 224,168 adults from the US and 179,452 from South Korea included in the study. The datasets for the US featured a larger proportion of adults younger than 39 years, whereas South Korea had a larger proportion of adults aged 50 to 69 years. Women made up the majority of each dataset, making up 51.1%, 51.7%, 52.4%, and 56.1% of the populations in the MEPS, NHANES, KHPS, and Korean NHANES samples.

The US had more pronounced inequalities, with the highest income decile in the US having 42 times more income compared with the lowest decile (mean [SD], $251,531 [$79,628] vs $5923 [4758]). The inequality in South Korea was less pronounced, as the highest income decile had 16 times more income compared with the lowest (mean, $117,654 [$61,249] vs $7375 [$2078]).

Adults with a higher income had lower total health care spending compared with adults with lower income in both countries, as those in the US in the lowest income group spent a mean of $7852 compared with $6510 for those with higher income. Patients in South Korea with lower income spent a mean of $1184 compared with $1025 for the higher-income group. As income increased, spending for both inpatient and emergency department visits decreased in both countries. However, outpatient spending increased as income level increased in the US, whereas it decreased in South Korea as income level increased.

Adults with higher income used fewer health care services compared with those with lower income in both countries. Higher access to care was also found in patients with higher income in both countries. Better health was also reported in those with higher income, though both countries had similar self-reported health status. Higher-income adults reported good health in 94.9% of cases compared with 71.1% in those with lower income in the US.

There were some limitations to this study. Not all participants were institutionalized, which could affect comparability. Self-reported data were relied on for health status for all adults included in the dataset. Cross-national comparability was limited due to differences in design and measurement in the countries. All potential confounding factors could not be accounted for. Some components were not accounted for in the measurement of health care spending. Some of the outcomes may not be directly linked to the health care system, and overall economic resources may have been underestimated due to lack of asset information.

Overall health status and clinical outcomes were similar between the US and South Korea, despite the US spending more for health care overall. The lowest- and highest-income adults had pronounced differences in the US in particular. “These findings underscore the persistence of systemic, income-based health inequalities. Effectively addressing health disparities may require coordinated multisectoral policy interventions,” the authors concluded.

References

1. Park S, Eggleston K, Do YK, Cutler DM. Income-based inequalities in health system performance in the US and South Korea. JAMA Health Forum. 2026;7(3):e260136. doi:10.1001/jamahealthforum.2026.0136
2. Khullar D, Chokshi DA. Health, income, & poverty: where we are & what could help. Health Affairs. October 4, 2018. doi:10.1377/hpb20180817.901935