Geographic variations in heart disease mortality and socioeconomic status (SES) in Davidson County zip codes, Tennessee: Do differences in geographic levels of analysis matter?

Background: There is sufficient research evidence of the inverse relationship between socioeconomic status and health outcomes. The CDC estimates that behavioral, socioeconomic and physical environmental conditions account for about 90% of total mortality in the US, with only 10% attributable to the lack of access. Study after study has confirmed that mortality and morbidity rates increase as socioeconomic status (SES) decreases, some suggesting a “gradient effect” across US communities, a phenomenon whereby each socioeconomic group's health status is better than the group immediately below it. Problem and Significance: These findings are based on data from epidemiological surveillance systems in place at local and state health departments. Population systems epidemiology has shown that micro-level analysis promotes a clearer understanding that socioeconomically deprived neighborhoods have poorer health, on average, than affluent neighborhoods. This discipline argues that the arrangement of environmental elements such as the pattern of neighborhood experiences and exposures influences the trajectories of individual and population health. Using micro-level data to confirm relationships that have been established with macro–level data is, therefore, significant. Objective: To explore whether zip-code level variations in SES in Davidson county can explain zip-code level variations in heart disease mortality in the county and whether the observed inverse relationship at macro-level data can be confirmed with zip-code data. Methods: Using heart disease mortality data from the Metropolitan Public Health Department and SES data from the US 2000 census, the study will construct a Townsend index of socioeconomic deprivation to investigate this relationship.