Understanding racial disparities in low birthweight in Pittsburgh, Pennsylvania: The role of area-level socioeconomic position and individual-level factors

Background: Low birthweight (LBW, <2500g) is a leading cause of infant mortality, and disparities exist between Blacks and Whites. About 11% of Pittsburgh births in 2003 were LBW, and the racial difference was wide: 8.4% of LBW infants were born to Whites, whereas 16.0% were born to Blacks. Studies suggest an association between contextual factors and LBW—lower levels of area-level socioeconomic position (SEP) are associated with increased LBW risk. The dissertation's main research hypotheses are whether 1) area-level SEP predicts LBW, 2) racial difference in LBW is partially explained by area-level SEP, and 3) racial difference is explained after controlling for area-level SEP and individual-level factors.Methods: Using U.S. Census 2000 data, area-level SEP measures were created for Pittsburgh: overall neighborhood disadvantage (ONDijk), material and economic deprivation (MEDij), and concentrated disadvantage (CDij). LBW and other individual-level data from 10,830 birth records were obtained from the 2003-2006 Allegheny County birth registry. Multilevel logistic regression was utilized to examine the association between SEP measures and LBW. Results: ONDijk was a significant predictor of LBW (OR: 1.306, p<0.001), remained significant after controlling for race (OR: 1.10, p<0.03), but was no longer significant after controlling for individual-level disadvantage (OR: 1.05, p=0.27). In addition, 74% of Blacks resided in disadvantaged neighborhoods, compared to 13% of Whites. In the unadjusted race model, Blacks were at increased odds of LBW compared to Whites (OR: 2.119, p<0.001), and the race OR decreased after adjusting for ONDijk (OR: 1.917, p<0.001) and individual-level disadvantage (OR: 1.56, p<0.001). Due to the lack of variability of LBW at the block group level, there was insufficient power to test the association between LBW and CDij and MEDij. Conclusions: Findings suggest that contextual factors are associated with LBW: knowing one's race and neighborhood may help predict one's risk for LBW. Public health significance includes using ONDijk as an indicator of areas with higher levels of LBW risk and targeting these neighborhoods for interventions to improve birth outcomes. In addition, understanding racial differences in neighborhood conditions may help further understand the social determinants that contribute to health disparities in LBW between Blacks and Whites

DEVELOPING COMPOSITE AREA-LEVEL INDICATORS OF SOCIOECONOMIC POSITION FOR PITTSBURGH, PENNSYLVANIA

Objective: To develop a process to construct composite area-level indicators of socioeconomic position (SEP) from existing SEP measures and examine how well they predict the proportion of low birth weight (LBW) infants in Pittsburgh, Pennsylvania. Methodology: Twelve existing measures of SEP were derived from U.S. Census 2000 and constructed at block group (BG) and neighborhood (NB) levels. Geocoded individual-level LBW data were obtained from Allegheny County Birth Registry (2003-2006) and aggregated to BG level for Pittsburgh. The indicator development process included multilevel data exploration (boxplots, variance decomposition, mapping, and examining correlations), exploratory multilevel factor analysis (MFA), and model selection. Multilevel linear regression (MLR) and diagnostic tests were used to examine whether indicators of SEP predicted LBW. Results: MFA identified two BG-level factors: "material and economic deprivation" (MEDij, mean=29.8, variance=184.8), representing percentage of individuals or households not owning a car, renting their residence, in poverty, receiving public assistance, and earning low income; and "concentrated disadvantage" (CDij, mean=15.7, variance=164.4), representing percentage of Blacks, single-headed families, having family members under 18 years old, and receiving public assistance. At NB level, all 12 SEP measures were captured in one factor, "overall neighborhood deprivation" (ONDj, mean=29.3, variance =115.9). MLR identified significant associations between both ONDj and MEDij and LBW: a unit increase in ONDj was associated with 0.003 increase in LBW infants (p<0.001), and a unit increase in MEDij was associated with 0.0018 increase (p<0.01). The association between CDij and LBW was moderated by ONDj (p=0.017): in NBs with high ONDj, LBW increased as CDij increased, while in NBs with low ONDj, LBW decreased as CDij increased. This result suggests that lower levels of ONDj may ameliorate the effects of high CDij at the BG level in Pittsburgh. Conclusion: The study outlines a novel approach to examining area-level associations between SEP and health by utilizing MFA to develop BG and NB composite SEP measures; this approach has not been reported in previous neighborhood research. An important public health implication is that these methods facilitate a closer examination of the mechanisms by which SEP at different area-levels could impact health