Do racial inequities in infant mortality correspond to variations in societal conditions? A study of state-level income inequality in the U.S., 1992-2007.

BACKGROUND: Prior studies have examined the association between income inequality and overall infant mortality rates (IMR). We examine effects of income inequality on racial inequities in IMR over the period 1992-2007 in the U.S.

METHODS: Race-specific state IMR data were obtained from 1992 to 2007, from which absolute and relative IMR inequities were calculated. Fixed and random effects models, adjusted for state-level median income, percent poverty, percent high school graduates, and unemployment rate, were used to determine contemporaneous and lagged state-level associations between income inequality and racial IMR inequities.

RESULTS: Racial IMR inequities varied significantly across the U.S. Contemporaneous income inequality was negatively associated with white IMR only. Two-year lagged income inequality was negatively associated with black IMR and had the most pronounced effect on racial inequities in IMR.

DISCUSSION: Future studies should consider lagged effects of income inequality on IMR and other health outcomes, and should examine other potential societal conditions that may account for state-level variations in racial IMR inequities.