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Neighborhood Walkable Urban Form and C-Reactive Protein
Citation:
King, K. Neighborhood Walkable Urban Form and C-Reactive Protein. Preventive Medicine. Elsevier Online, New York, NY, 57(6):850-854, (2013).
Impact/Purpose:
Contemporary urban environments play a role in the etiology of health and health disparities through a variely of pathways. Considerable research documents neighborhood variation in disease prevalence (Robert, 1999) and how neighborhood conditions may contribute to social disparities in health (Diez Roux, 2012; Williams and Collins, 2001). Identifying and evaluating underlying mechanisms, then, is crucial (Diez Roux and Mair, 2010). Recently, researchers have emphasized the importance of considering a broad range of contextual predictors rather than continuing to focus primarily on socioeconomic conditions (Entwisle, 2007) and correlated health behaviors. Following this research agenda, the goal is to move beyond documenting social disparities by identifying features of communities which are both causal1y linked to health outcomes and which can be changed by policymakers, institutions, and residents — and the built environment may fit the bill (Browning et al., 2011). This paper examines whether residential walkable urban form predicts concentrations of C-reactive protein (CR2), a biomarker of inflammation. The analysis finds that neighborhood variation in CRP by may be greater than that of other conditions commonly studied in neighborhood context. CRP is a plasma protein produced during the nonspecific acute-phase response to inflammation, infection, and tissue damage. CRP levels predict future cardiovascular incidents and disease (Pepys and Hirschfeld, 2003; Sesso et al., 2003) and incident type 2 diabetes (Capuzzi and Freeman, 2007). A meta-analysis of mortality (Emerging Risk Factors Collaboration, 2010) found a one SD increase in log CRP predicted 37% increase in coronary heart disease, 27% for ischemio stroke, and 55% for vascular modality.
Description:
Background: Walkable urban form predicts physical activity and lower body mass index, which lower C-reactive protein (CRP). However, urban form is also related to pollution, noise, social and health behavior, crowding, and other stressors, which may complement or contravene walkability effects. Purpose: This paper assesses within-neighborhood correlation of CRP, and whether three features of walkable urban form (residential density, street connectivity, and land use mix) are associated with CRP levels. Methods: CRP measures (n=610) and sociodemographic data come from the 2001-3 Chicago Community Adult Health Study, linked with objective built environment data. Results: Within-neighborhood correlations of CRP are greater than those of related health measures. A one standard deviation increase in residential density predicts significantly higher log CRP (e.g. B=0.11,p<.01) in Chicago, while a one standard deviation increase in land use mix predicts significantly lower CRP (e.g. B=-0.19, p<0.0 1). Street connectivity is unrelated to CRP in this highly walkable city. Discussion: Results suggest residential density may be a risk factor for inflammation, while greater walkability of mixed land use areas may be protective. It may be that negative aspects of density overcome the inflammatory benefits of walking.