title: Adapting the Index of Relative Rurality (IRR) to Estimate Rurality at the ZIP Code Level: A Rural Classification System in Health Services Research.
abstract: BACKGROUND
  Accurate analysis of health problems facing rural residents depends on how rurality is defined. Health services research relies frequently on the rural urban commuting area (RUCA) codes to estimate rurality at the small area level. We modified the county-level Index of Relative Rurality (IRR) to the ZIP code level (IRRZIP ) to create an alternative small-area-level rural classification system. We then compared how the 2 rural classification systems differ in how rural areas and populations are defined and in methodological analysis.
  
  
  METHODS
  We linked data for veterans (n = 37,466) who attended the VA Pittsburgh Healthcare System to 2000 United States Census and the US Department of Agriculture's Economic Research Service data.
  
  
  RESULTS
  The RUCA and the IRRZIP do not consistently classify the same ZIP code areas and populations as rural. Using the IRRZIP , each 10th increment in increased rurality was associated with a 2.6 increased odds of receiving primary care at a satellite clinic.
  
  
  CONCLUSIONS
  The IRRZIP is a straightforward measure that is easy to use and interpret and may be a relevant alternative rural classification system that can be used in health services research.
authors.affiliation: Primary Care Service Line, VA Pittsburgh Health Care Systems, Pittsburgh, Pennsylvania.|Department of General Internal Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania.
authors.forename: Sanae
authors.initials: S
authors.lastname: Inagami
authors.affiliation: Center for Health Equity Research and Promotion, VA Pittsburgh Health Care Systems, Pittsburgh, Pennsylvania.
authors.forename: Shasha
authors.initials: S
authors.lastname: Gao
authors.affiliation: School of Information Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania.
authors.forename: Hassan
authors.initials: H
authors.lastname: Karimi
authors.forename: Martine M
authors.initials: MM
authors.lastname: Shendge
authors.affiliation: Health Services Policy and Management, Arnold School of Public Health, University of South Carolina, Columbia, South Carolina.|South Carolina Rural Health Research Center, Columbia, South Carolina.
authors.forename: Janice C
authors.initials: JC
authors.lastname: Probst
authors.affiliation: Center for Health Equity Research and Promotion, VA Pittsburgh Health Care Systems, Pittsburgh, Pennsylvania.
authors.forename: Roslyn A
authors.initials: RA
authors.lastname: Stone
mesh_terms: D006302:Health Services Research / Q000379:methods*; D006801:Humans; D015203:Reproducibility of Results; D019035:Rural Health Services / Q000145:classification*; D017062:Small-Area Analysis; D014481:United States; D014728:Veterans
keywords: geography; health services research; index of relative rurality; observational data; rural classification