Income-Related Mortality Inequalities and Its Social Factors among Middle-Aged and Older Adults at the District Level in Aging Seoul: An Ecological Study Using Administrative Big Data

This study investigated income-related health inequality at sub-national level, focusing on mortality inequality among middle-aged and older adults (MOAs). Specifically, we examined income-related mortality inequality and its social factors among MOAs across 25 districts in Seoul using administrative big data from the National Health Insurance Service (NHIS). We obtained access to the NHIS’s full-population micro-data on both incomes and demographic variables for the entire residents of Seoul. Slope Index of Inequality (SII) and Relative Index of Inequality (RII) were calculated. The effects of social attributes of districts on SIIs and RIIs were examined through ordinary least squares and spatial regressions. There were clear income-related mortality gradients. Cross-district variance of mortality rates was greater among the lowest income group. SIIs were smaller in wealthier districts. Weak spatial correlation was found in SIIs among men. Lower RIIs were linked to lower Gini coefficients of income for both genders. SIIs (men) were associated with higher proportions of special occupational pensioners and working population. Lower SIIs and RIIs (women) were associated with higher proportions of female household heads. The results suggest that increasing economic activities, targeting households with female heads, reforming public pensions, and reducing income inequality among MOAs can be good policy directions.

Occupational inequalities in mortality in South Korea using nationally representative mortality follow-up data from the late 2000s and after

Many Korean and international studies have found higher mortality and poorer health conditions among manual workers than among non-manual workers. However, a recent study using unlinked data argued that since the economic crisis in Korea in the late 2000s, the mortality estimates of male Korean non-manual workers have been higher than those of manual workers. Our work using individually linked data from the late 2000s and after aimed to examine mortality inequality by occupational class. We analyzed Korea National Health and Nutrition Examination Survey data that were individually linked to cause-of-death data. Cox regression analysis was used to identify the hazard ratios for mortality by occupational class. Of 11,766 men aged between 35 and 64, 397 died between 2007 and 2018: 142 died from cancer, 68 from cardiovascular diseases, 88 from external causes, and 99 from other causes. After controlling for age, the mortality estimates for manual workers were 1.85 times higher than those for upper non-manual workers (P < 0.05). We observed no evidence of reversed mortality inequality among occupational classes in Korea since the 2000s; this previously reported finding might have been due to numerator-denominator bias arising from the use of unlinked data.

The Stratification Index for Comparing Between-Group Differences in Mortality: Evidence from Finnish Income Groups

The study of the mortality differences between groups has traditionally focused on metrics such as life expectancy and standardized mortality rates, which give insights into how group characteristics are linked with average levels of mortality. Additional insights can be gained by examining differences in lifespan distributions between groups. Here, we propose a new summary measure of mortality inequality by comparing group-specific lifespan distributions. Our proposed index, mortality stratification, measures the degree of overlap in the lifespan distributions. It helps to capture important between-group differences that conventional life-expectancy comparisons miss. In order to test its utility, we apply the stratification index to Finnish income quintile groups over the period from 1996 to 2017. We find that both stratification and life-expectancy differences between income groups increased substantially from 1996 to 2008; subsequently, the life-expectancy difference declined, whereas stratification stagnated for men and increased for women. By comparing results between different summary measures, we conclude that the stratification index can behave in different ways empirically and thus uncover a unique domain of inequalities in mortality.