Is neighbourhood obesogenicity associated with body mass index in women? Application of an obesogenicity index in socioeconomically disadvantaged neighbourhoods.

An aggregate index is potentially useful to represent neighbourhood obesogenicity. We created a conceptually-based obesogenicity index and examined its association with body mass index (BMI) among 3786 women (age 18-45y) in socio-economically disadvantaged neighbourhoods in Victoria, Australia. The index included 3 items from each of 3 domains: food resources (supermarkets, green grocers, fast food restaurants), recreational activity resources (gyms, pools, park space), and walkability (4+ leg intersections, neighbourhood walking environment, neighbourhood safety), with a possible range from 0 to 18 reflecting 0-2 for each of the 9 items. Using generalised estimating equations, neighbourhood obesogenicity was not associated with BMI in the overall sample. However, stratified analyses revealed generally positive associations with BMI in urban areas and inverse associations in rural areas (interaction p=0.02). These analyses are a first step towards combining neighbourhood characteristics into an aggregate obesogenicity index that is transparent enough to be adopted elsewhere and to allow examination of the relevance of its specific components in different settings.