Does local income and wealth inequality affect mortality? A register-based fixed effects study of 58 million...

Aim: The Income Inequality Hypothesis asserts that income inequality causes negative health burdens within wealthy nations. We aimed to test the hypothesis in Norway, examining the relationship between both income and wealth inequality, net of individual economic resources, and individual all-cause mortality. To this day, little is known about the association between wealth inequality and mortality. In Norway, wealth is far more unequally distributed than income and can be a more prevalent indicator of long-term financial security. Methods: We estimated discrete-time event history models from Norwegian register data, covering all Norwegian-born men and women aged 25-84 years during the period 1993-2013. We include fixed effects at the municipal level, adjusting for time-invariant characteristics in the local area. Our data contain approximately 58.5 million person-year observations after sample restrictions. Results: Overall, increased income and wealth inequality (measured using Gini coefficients of individuals' pensionable income and net worth) is not associated with higher mortality risk in Norway. With a one percentage point increase in income inequality, odds ratio (OR) for mortality was estimated at 0.998 (95% confidence interval (CI) 0.996-1.001) for men and 1.002 (95% CI 0.999-1.006) for women. Corresponding OR from increased wealth inequality was 0.998 (95% CI 0.997-1.000) for men and 0.999 (95% CI 0.998-1.001) for women.