Inequality in the Face of Death: The Socioeconomic Gradient in Mortality of the Spanish Working-Age Population

The purpose of this paper is to evaluate the association between income and mortality over a three year period for working-age Spaniards. Method Data on 693,994 individuals was taken from a social security sampling using a logit model to estimate the probabilities of death for each income decile and the mortality rate ratios (MRR) in three different models: 1) using only income, controlled by age and sex,2) adding socio-economic and geographic variables and, 3) adding level of education. Results: A gradient appears in the mortality rate over income deciles with a maximum MRR of 3.41 in men and 1.68 in women. The shape of the adjustment is clearly non-linear and levels out as income increases. The gradient attenuates for both sexes when variables are introduced that try to capture the inverse causality (2.4 and 1.3). Controlling by level of education reduces the gradient for men (2.2) and intensifies it for women (1.5). Conclusion: The association of the relationship between income and mortality is verified, as well as its non-linear nature, the greater intensity for men than for women, and its persistence when controlling for variables that try to capture causality.