Development of A Rural-Urban Classification System for Public Health Research that Accommodates Structural Differences Between States

Rural environments in the United States present challenges to wellness, but there is a lack of tools to categorize rurality at the subcounty level. The most common tool, the FDA's 2010 RUCA codes, uses data that are over a decade old and cannot accommodate regional differences in rurality. The purpose of this study was to develop a census-tract classification system of rurality and demonstrate its use in describing HIV outcomes. We transformed census-tract measures (population density, natural resource workforce, walkability index, household type, and air quality) into local scales of rurality using factor analysis. We surveyed public health practitioners to determine cut-points and compared the resulting categorization to RUCA codes. We described the incidence of HIV in WA by rural category. Our classification system categorized 25% of census tracts as rural, 19% as periurban and 56% as urban. Our survey yielded cut-offs that were more conservative in categorizing areas urban than RUCA codes. The rate of HIV diagnosis was substantially higher in urban areas. Our rural-urban classification system offers an alternative to RUCA codes that is more responsive to regional differences.