Longitudinal assessment of urban form and weight gain in African-American women.

BACKGROUND: Numerous cross-sectional studies have found higher levels of obesity among residents of auto-oriented, sprawling areas compared to residents of more urban areas. PURPOSE: The association between neighborhood urban form and 6-year weight change was prospectively analyzed in the Black Women's Health Study, a cohort study of U.S. black women who enrolled in 1995 and are followed biennially with mailed questionnaires. METHODS: The analysis included 17,968 women who lived in New York City, Chicago, or Los Angeles and were followed from 1995 to 2001. Factor analysis was used to combine variables describing the urban form of participants' residential neighborhoods into an "urbanicity" score. Mixed linear regression models were used to calculate least-squares means for weight change across quintiles of the urbanicity score. Incidence rate ratios (IRRs) and 95% CIs for incident obesity in relation to the urbanicity score among women who were not obese at baseline were derived from Cox regression models. All results were adjusted for age, region, lifestyle factors, and neighborhood SES. Analyses were conducted in 2008-2010. RESULTS: In multivariate analysis, mean weight gain for women in the highest quintile of urbanicity score (most urban) was 0.79 kg less than for those in the lowest quintile, with a significant trend (p=0.003). The IRR for incident obesity in the highest quintile relative to the lowest was 0.83 (95% CI=0.71, 0.97), with a significant trend (p=0.042). CONCLUSIONS: Policies that encourage dense, urban residential development may have a positive role to play in addressing obesity in black women