Background:

Income inequality can negatively affect population health by increasing social stress and conflict, and reducing trust, public goods and healthcare access. However there is limited evidence from low and middle-income countries (LMICs) with high levels of inequality. This study investigates the association between income inequality, morbimortality and risk factors of non-communicable diseases (NCDs) in 26 Brazilian states from 2002 to 2017.
Methods:

Data was acquired for men and women from the Global Health Data Exchange, the Brazilian Institute of Geography and Statistics, and the Brazilian Ministry of Health, totalling 416 state-year observations. Disability-adjusted life years (DALYs) and risk factors of NCDs were the dependent variables. Gini Index was the main independent variable. Multivariate linear panel regressions were performed, controlling for state and time fixed effects, gross domestic product per capita, population ageing, poverty and access to healthcare.
Findings:

A 1% increase in the Gini Index was associated with increases in alcohol abuse (of 923•4 DALYs per 100,000 people, 95%CI 217•6 to 1629•0) and diabetes mellitus morbidity (of 893•3 DALYs per 100,000 people, 95%CI 127•7 to 1659•0), and decreases in morbidity from attention disorder (of -4•0 DALYs per 100,000 people, 95%CI -7•4 to -0•5) and autism spectrum (of -2•4 DALYs per 100,000 people, 95%CI -4•3 to -0•5). These associations were greater for men, further supported by associations with alcohol use as a risk factor.
Interpretation:

This study provides evidence from a highly unequal LMIC, Brazil, of negative associations between income inequality and NCDs, and the importance of addressing wider social determinants of health.