Education, income inequality, and mortality: a multiple regression analysis.

OBJECTIVE To test whether the relation between income inequality and mortality found in US states is because of different levels of formal education. DESIGN Cross sectional, multiple regression analysis. SETTING All US states and the District of Columbia (n=51). DATA SOURCES US census statistics and vital statistics for the years 1989 and 1990. MAIN OUTCOME MEASURE Multiple regression analysis with age adjusted mortality from all causes as the dependent variable and 3 independent variables-the Gini coefficient, per capita income, and percentage of people aged >/=18 years without a high school diploma. RESULTS The income inequality effect disappeared when percentage of people without a high school diploma was added to the regression models. The fit of the regression significantly improved when education was added to the model. CONCLUSIONS Lack of high school education accounts for the income inequality effect and is a powerful predictor of mortality variation among US states.