Impact of health insurance expansion on patients' financial burden and family well-being in South Korea

South Korea achieved universal health coverage through a mandatory national health insurance system, but has historically lacked comprehensive benefits coverage, leading to a high proportion of out-of-pocket spending. In 2013, the government expanded benefits coverage for high-cost disease groups, including cancer, cardiac diseases, cerebrovascular diseases, and rare diseases. While prior studies show that this health insurance expansion reduced out-of-pocket spending at the individual level, its broader implications for family well-being remain unclear. To assess the effects of the 2013 health insurance expansion on patients’ financial burden and family well-being, we conducted difference-in-differences analyses with entropy balancing using longitudinal data from the 2010–2017 Korea Health Panel Survey. Our analysis confirms that the benefits coverage expansion reduced patients’ out-of-pocket spending by 30 %, though, effects on overall family well-being were insignificant. However, our subgroup analyses suggest that family members with higher educational attainment experienced improvements in mental health when a household member was affected by the policy. Our finding indicates that while health insurance expansion provides direct financial benefits across the entire study population, its indirect effects on family well-being vary by educational level. This highlights the critical role of education in maximizing the broader benefits of health insurance expansion.