Health Disparities
Association between Shifting Contributions to District-Level Life Expectancy Variation and National Life Expectancy Gains in South Korea, 1999-2022: A Partial Least Squares Analysis Using Repeated Cross-Sectional Data Ikhan Kim* Ikhan Kim Kim Kosin University
Background: Improving overall population health while reducing regional health disparities is a key policy goal in South Korea. However, little is known about how age- and cause-specific contributions to regional life expectancy variation have changed over time or how these changes relate to national life expectancy gains. This study examined trends in district-level life expectancy variation in South Korea from 1999 to 2022, identified age- and cause-specific contributions, and quantified their associations with national life expectancy gains.
Methods: We analyzed sex-, 5-year age group–, district-, and cause-specific population and death data for South Korea from 1999 to 2022. Life expectancy at birth was calculated by sex, year, and district using conventional life table methods. District-level variation was summarized using the mean difference from the national mean. Age- and cause-specific contributions were estimated using a stepwise replacement algorithm, and partial least squares regression was used to assess associations with changes in national life expectancy.
Results: National life expectancy increased from 71.9 to 80.1 years among men and from 79.4 to 86.0 years among women between 1999 and 2022. Over the same period, district-level life expectancy variation declined from 2.35 to 1.27 years among men and from 1.10 to 0.93 years among women. Contributions to regional variation shifted progressively toward older age groups. In addition to neoplasms, cardiovascular diseases, respiratory diseases, and external causes, contributions from neurological and infectious diseases also increased over time. Notably, higher contributions of infectious disease mortality at older ages were associated with smaller national gains in life expectancy.
Conclusions: District-level life expectancy variation followed a convergence pattern among men but a stagnation pattern among women. Reductions in mortality disparities at younger ages were accompanied by a shift in contributions toward older ages. Further decreases in regional life expectancy disparities may require, beyond existing efforts, additional strategies to address geographic inequalities in mortality from infectious and neurological diseases among older populations.