Racial differences in post-neonatal mortality in Chicago: what risk factors explain the black infant's disadvantage?

OBJECTIVES: To investigate the extent to which the place of residence affects the black to white differential in post-neonatal (28-365 days) mortality, we performed a univariate analysis and multivariate logistic regression of the 1982-1983 Illinois vital records. Chicago Police violent crime information and 1980 US Census income data.
METHODS: Four environmental predictors of post-neonatal death were examined: a median family income of < $10,000 per year, a poverty prevalence of > 50%, violent crime rates of > 11/1000 and limited community access to primary medical care based on physician supply ratios.
RESULTS: The post-neonatal mortality rate of black (n = 50,765) infants was three times that of white (n = 50,690) infants: 10/1000 versus 3/1000, respectively. Thirty-six percent of the white infants had none of the environmental risk factors, whereas only 13% of the black infants had none of the risk factors. For black infants, the presence of any one factor was associated with a slightly increased risk of post-neonatal mortality (9/1000 as compared to 7/1000 with no risk factors), whereas the presence of two or more risk factors was associated with a higher risk (11/1000). When the number of these environmental risk factors were taken into account, the OR for black infants declined from 3.0 (95% CI 2.5-3.6) to 1.7 (95% CI 1.5-1.9). When the differences in maternal age, education, marital status and infant birth weight were also taken into account the odds ratio of post-neonatal death for blacks was 1.5 (95% CI 1.3-1.7).
CONCLUSIONS: We conclude that a substantial proportion of the black to white difference in post-neonatal mortality is associated with specific environmental conditions.