Defining neighborhood boundaries for urban health research in developing countries: a case study of Accra, Ghana

The neighborhood has been used as a sampling unit for exploring variations in health outcomes. In a variety of studies census tracts or ZIP codes have been used as proxies for neighborhoods because the boundaries are pre-defined units for which other data are readily available. However these spatial units can be arbitrary and do not account for social-cultural behaviors and identities that are significant to residents. In this study for the city of Accra, Ghana, our goal was to create a neighborhood map that represented the boundaries generally agreed upon by the residents of the city using the smallest available census unit, the enumeration area (EA), as the base unit. This neighborhood map was then used as the basis for mapping spatial variations in health within the city. The first step in demarcating the boundaries was to identify features that limit a person's movement including the major roads, drainage features, and railroad tracks that people use to partially define their neighborhood boundaries. Once an initial set of boundaries were established, they were iteratively modified by walking the neighborhoods, talking to residents, public officials, and others. The resulting neighborhood map consolidated 1723 EAs into 108 neighborhoods covering the entire Accra metropolitan area. Results indicated that the team achieved 71% accuracy in mapping neighborhoods when the neighborhood keyed to the survey EA was compared with the response given by the interviewees in the 2008–2009 Women's Health Survey of Accra when asked which neighborhood they lived in.