Exploratory analysis of spatial data in nutritional epidemiogy: identifying food stores distribution patterns in the urban area

Introduction: There is growing interest in the environmental effects on nutritional status. The aim of this study was the assess food stores distribution patterns though the application of Exploratory Analysis of Spatial Data... [ view full abstract ]

Introduction: There is growing interest in the environmental effects on nutritional status. The aim of this study was the assess food stores distribution patterns though the application of Exploratory Analysis of Spatial Data (ESDA).
Methods: Food availability in all stores located at 258 census tracts in the urban area of the city of Santos, Brazil was assessed using a validated instrument (n=672). A Healthy Eating Score (HES) was calculated to each store according to the degree of industrial processing and the nutrient content of available food items. Geographic coordinates of the stores were assessed using GPS receivers and the points were aggregated in census tracts in order to explore the spatial patterns of data. Spatial autocorrelation was examined. Moran's I local and global values were used to identify spatial cluster of census tracts according to HES and food environment variables. Moran Maps and Lisa Cluster Maps were plotted to identify and characterize hotspot clusters of nutritional scores.
Results: Local and global significant Moran's I statistics could be observed in the store distribution aggregated by census tracts: HES (I=0.155, p=0.01), convenience stores (I=0.240, p=0.04), supermarket and medium stores (I= 0.030, p=0.01), greengroceries (I=0.040, p=0.01) and candy stores (I= 0.151, p=0,01). Bars (drinks and snacks) ( I= 0,238 p=0,01) and Bars with meals (I= 0,4472 p=0,01). Conclusion: The results suggest different patterns of distribution of food stores that may affect food availability. ESDA may be a useful tool for the identification of spatial distribution patterns of the food environment that may have effect on nutritional status and health.