Income inequality, residential poverty clustering and infant mortality: a study in Rio de Janeiro, Brazil.

In this paper, we propose an approach to investigate the hypothesis that the residential concentration of poverty affects health status more deeply than when poverty is randomly scattered in a given geographical area. To characterize the geographic pattern of poverty in the city of Rio de Janeiro, Brazil, an index that measures the heterogeneity of poverty concentration among sub-areas was proposed. We used census data and defined poverty by means of the household head monthly income. The 153 neighborhoods that compose the city were used as the geographic units, and the census tracts as the sub-areas. The proposed index measures differences of poverty concentration across census tracts within a neighborhood. The effects of geographic poverty clustering on infant mortality related variables (early neonatal mortality rate; post-neonatal mortality rate; proportion of adolescent mothers; and fertility rate among adolescents) were estimated by partial correlation coefficients, controlling for the neighborhood poverty rate. Our study revealed that intra-city variations of the post-neonatal mortality rate are associated with geographic patterns of poverty, and that pregnancy in adolescence is strongly and contextually correlated with intra-neighborhood poverty clustering, even after adjustment for the poverty rate. The evidence of relevant health differences associated with the spatial concentration of poverty supports the hypothesis that properties of the environment of residence contextually influence health. Our findings suggest that prevention of some infant mortality related problems has to be focused directly on features of communities, considering their physical, cultural and psychosocial characteristics, being of particular concern the health of communities segregated from the society at large by extreme poverty.