The geographical accessibility of hospitals to the aged: a geographic information systems analysis within Illinois

This article uses geographic information systems and their related tools to empirically measure and display the geographic accessibility of the aged population to hospital facilities within Illinois.

Geographic accessibility of Illinois' aged population is measured from each of the state's 10,796 census block groups to the state's 214 hospital facilities. Block group demographic compositions and centroids are obtained from 1990 census files. Hospital coordinates are obtained by the authors.

Of five alternative measures of accessibility considered, empirical estimates are obtained for two: choice set and minimum distance. Access to both general hospitals and the subset having specialized geriatric facilities is measured with special attention to differences in accessibility between the aged within metropolitan statistical areas (MSAs) and those outside MSAs. Cumulative accessibility distributions and their summary statistics provide a basis of comparison among subgroups. DATA COLLECTION AND EXTRACTION: Geographic information systems (GIS) and their related tools are used as a means of efficiently capturing, organizing, storing, and retrieving the required data. Hospitals and census block groups are geocoded to specific locations in the database, and aspatial attributes are assigned to the hospitals and block groups. The GIS database is queried to produce shaded isarithm and point distribution maps that show the location of hospitals relative to surrounding aged populations.

The vast majority of Illinois' aged population is within close proximity to hospital facilities. Eighty percent (1,147,504 persons) of the aged in Illinois are within 4.8 miles (7.7 km) of a hospital and 11.6 miles (18.7 km) of two hospitals. However, geographic accessibility differences between the aged living in MSAs and those living outside MSAs to hospitals offering geriatric services are substantial; but there is no evidence that the aged's geographical accessibility to hospitals is less favorable than that of the general population. Detailed accessibility measures permitted by geographic information system technology call into question the continued use of crude empirical accessibility measures.