Exploring racial disparity in obesity: A mediation analysis considering geo-coded environmental factors

- Environmental level risk factors for obesity were generated using GIS techniques.
- Racial disparity in obesity was partially explained by environmental and behavior factors.
- MART model accounts for the hierarchical structure, nonlinear relationships, and complex interactions among variables.
- Neighborhood walkability, measured by three correlated factors, is significant in explaining the racial disparity in obesity.

Research shows a consistent racial disparity in obesity between white and black adults in the United States. Accounting for the disparity is a challenge given the variety of the contributing factors, the nature of the association, and the multilevel relationships among the factors. We used the multivariable mediation analysis (MMA) method to explore the racial disparity in obesity considering not only the individual behavior but also geospatially derived environmental risk factors. Results from generalized linear models (GLM) were compared with those from multiple additive regression trees (MART) which allow for hierarchical data structure, and fitting of nonlinear and complex interactive relationships. As results, both individual and geographically defined factors contributed to the racial disparity in obesity. MART performed better than GLM models in that MART explained a larger proportion of the racial disparity in obesity. However, there remained disparities that cannot be explained by factors collected in this study.