Background: A key aspect of any intervention to improve obesity is to better understand the environment in which decisions are being made related to health behaviors, including the food environment.
Methods: Our aim was to examine the extent to which proximity to six types of food establishments is associated with BMI z-score and explore potential effect modification of this relationship. We used geographical information software to determine proximity from 49,770 pediatric patients' residences to six types of food establishments. BMI z-score obtained from the electronic health record was the primary outcome.
Results: In multivariable analyses, living in closest proximity to large (β, -0.09 units; 95% confidence interval [CI], -0.13, -0.05) and small supermarkets (-0.08 units; 95% CI, -0.11, -0.04) was associated with lower BMI z-score; living in closest proximity to fast food (0.09 units; 95% CI, 0.03, 0.15) and full-service restaurants (0.07 units; 95% CI, 0.01, 0.14) was associated with a higher BMI z-score versus those living farthest away. Neighborhood median income was an effect modifier of the relationships of convenience stores and full-service restaurants with BMI z-score. In both cases, closest proximity to these establishments had more of an adverse effect on BMI z-score in lower-income neighborhoods.
Conclusions: Living closer to supermarkets and farther from fast food and full-service restaurants was associated with lower BMI z-score. Neighborhood median income was an effect modifier; convenience stores and full-service restaurants had a stronger adverse effect on BMI z-score in lower-income neighborhoods.