Environmental risk factors for asthma emergency care: A multilevel approach for ecological study (New York)

This cross-sectional, retrospective ecological study describes a model for evaluating environmental risk factors to explain neighborhood differences in adult use of New York City's Harlem Hospital Asthma Emergency Department (Asthma ED) services. A multilevel or "nested" design incorporates methods for hypothesis testing using geographic information systems (GIS) to help map existing data from Harlem Hospital Center, city agencies, and other sources; as a tool to screen for clusterings of residences associated with increased visits to the Asthma ED; to facilitate the definition of environmental variables, and for creating new spatial districts to be used as units of analysis.; Spatial data analysis accomplished with the aid of GIS and point pattern analysis revealed clusterings of addresses for Asthma Emergency Department visitors. Multilevel modeling offered the means whereby variables measured on the building and/or neighborhood levels of analysis could be analyzed for their direct effects on the health outcome (asthma visits) while accounting for the influence of other variables and partitioning the variance between variables to manage multicollinearity, or correlations between explanatory variables. Buildings and segments were classified according to whether they ran in a northsouth or east-west direction to facilitate analysis.; Results of modeling show both building and neighborhood level effects of environmental variables on increased Asthma Emergency Department (ED) visits. Variables found to have a direct effect on Asthma ED visits included building violations, pollution sources, segment density, and corner location of a building with models differing by geographic direction of streets and level of analysis. The study points to the importance of examining the influence of environmental factors at different spatial scales for a deeper understanding of ecological conditions which may lead to asthma exacerbation and increased Emergency Department use. Specific policy implications are proposed to improve the health outcomes of inner-city residents with asthma.