Income inequality and cause-specific mortality in Taiwan: A multilevel analysis

OBJECTIVES: Income inequality has been associated with worse population health in various studies. However, few studies were used multilevel approach to test the effect of income inequality on cause-specific mortality. Thus, we used multilevel analysis to examine the association between income inequality and cause-specific mortality for both genders in Taiwan. METHODS: Data on age-standardized mortality in 2005-2009 were obtained from the Department of Health. Data on the Gini coefficient and median disposable income came from the family income and expenditure survey in 2000. Additionally, township-level educational attainment data were obtained from the Ministry of the Interior, Taiwan. Using a multilevel framework of 349 townships nested within 22 cities/counties, we examined associations of city/county-level income inequality with township-level mortality before and after adjustment for income and educational level. RESULTS: Multilevel models showed that the Gini coefficient at were positive associated with all-cause mortality, as well as cancer, heart disease, pneumonia, and injury mortality. After controlling for city/county-level income and township-level education level, we found that a 0.01 rise in the Gini coefficient increases 12.9 all-cause deaths per 100,000 population (P<0.05), as well as pneumonia (1.01 per 100,000, P<0.05) and injury mortality (2.55 per 100,000, P<0.01). For gender-stratified analysis, the relationship between Income inequality and mortality were greater among male than female in all the causes of death, except for diabetes mellitus. CONCLUSIONS: These findings show new evidence for the contextual effects of income inequality on different cause-specific mortality in Taiwan, suggesting that we may use it to explore the mechanisms linking income inequality to population health.