The Effect of Additional Private Health Insurance on Mortality in the Context of Universal Public Health Insurance

(1) Background: Korea operates its national health insurance (NHI) system as a form of public health insurance, and is commonly regarded as having achieved universal health coverage (UHC). However, many Korean households register for additional private health insurance (PHI) programs. Typically, registration rates for PHI are higher for individuals with a higher socioeconomic status (SES). A difference in mortality between those with and without additional PHI would indicate that there are health inequalities within the Korean NHI system under UHC. Therefore, this study aimed to confirm whether additional PHI affects mortality under the Korean NHI system. (2) Methods: We conducted a longitudinal study using the Korean Longitudinal Study of Aging data from the first to the sixth wave. The analysis included 8743 participants, who were divided into two groups: those who only had NHI and those who had both NHI and PHI. Differences in mortality between the two groups were compared using the Cox proportional hazard regression. (3) Results: The group with both NHI and PHI had lower mortality than the group with only NHI (hazard ratio = 0.53, 95% confidence interval: 0.41, 0.9). (4) Conclusions: The results of this study reveal that there are health disparities according to SES and PHI within the Korean NHI system under UHC. Therefore, relevant government institutions and experts should further improve the NHI system to reduce health disparities.