Characteristics of Walkable Built Environments and BMI z -Scores in Children: Evidence from a Large Electronic Health Record Database

BACKGROUND: Childhood obesity remains a prominent public health problem. Walkable built environments may prevent excess weight gain. OBJECTIVES: We examined the association of walkable built environment characteristics with body mass index (BMI) z-score among a large sample of children and adolescents. METHODS: We used geocoded residential address data from electronic health records of 49,770 children and adolescents 4 to < 19 years of age seen at the 14 pediatric practices of Harvard Vanguard Medical Associates from August 2011 through August 2012. We used eight geographic information system (GIS) variables to characterize walkable built environments. Outcomes were BMI z-score at the most recent visit and BMI z-score change from the earliest available (2008-2011) to the most recent (2011-2012) visit. Multivariable models were adjusted for child age, sex, race/ethnicity, and neighborhood median household income. RESULTS: In multivariable cross-sectional models, living in closer proximity to recreational open space was associated with lower BMI z-score. For example, children who lived in closest proximity (quartile 1) to the nearest recreational open space had a lower BMI z-score (β = -0.06; 95% CI: -0.08, -0.03) compared with those living farthest away (quartile 4; reference). Living in neighborhoods with fewer recreational open spaces and less residential density, traffic density, sidewalk completeness, and intersection density were associated with higher cross-sectional BMI z-score and with an increase in BMI z-score over time. CONCLUSIONS: Overall, built environment characteristics that may increase walkability were associated with lower BMI z-scores in a large sample of children. Modifying existing built environments to make them more walkable may reduce childhood obesity.