Person:

Sequist, Thomas

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. Citation: Duncan DT, Sharifi M, Melly SJ, Marshall R, Sequist TD, Rifas-Shiman SL, Taveras EM. 2014. Characteristics of walkable built environments and BMI z-scores in children: evidence from a large electronic health record database. Environ Health Perspect 122:1359–1365; http://dx.doi.org/10.1289/ehp.1307704

Objective

New approaches for obesity prevention and management can be gleaned from 'positive outliers', i.e., individuals who have succeeded in changing health behaviors and reducing their body mass index (BMI) in the context of adverse built and social environments. We explored perspectives and strategies of parents of positive outlier children living in high risk neighborhoods.

Methods

We collected up to five years of height/weight data from the electronic health records of 22,443 Massachusetts children, ages 6-12 years, seen for well-child care. We identified children with any history of BMI ≥95th percentile (n=4007) and generated a BMI z-score slope for each child using a linear mixed effects model. We recruited parents for focus groups from the sub-sample of children with negative slopes who also lived in zip codes where >15% of children were obese. We analyzed focus group transcripts using an immersion/crystallization approach.

Results

We reached thematic saturation after 5 focus groups with 41 parents. Commonly cited outcomes that mattered most to parents and motivated change were child inactivity, above-average clothing sizes, exercise intolerance, and negative peer interactions; few reported BMI as a motivator. Convergent strategies among positive outlier families were family-level changes, parent modeling, consistency, household rules/limits, and creativity in overcoming resistance. Parents voiced preferences for obesity interventions that include tailored education and support that extend outside clinical settings and are delivered by both health care professionals and successful peers.

Conclusions

Successful strategies learned from positive outlier families can be generalized and tested to accelerate progress in reducing childhood obesity.