Measures of spatial accessibility to health care in a GIS environment: synthesis and a case study in the Chicago region

This article synthesizes two GIS-based accessibility measures into one framework, and applies the methods to examining spatial accessibility to primary health care in the Chicago ten-county region. The floating catchment area (FCA) method defines the service area of physicians by a threshold travel time while accounting for the availability of physicians by their surrounded demands. The gravity-based method considers a nearby physician more accessible than a remote one and discounts a physician's availability by a gravity-based potential. The former is a special case of the latter. Based on the 2000 Census and primary care physician data, this research assesses the variation of spatial accessibility to primary care in the Chicago region, and analyzes the sensitivity of results by experimenting with ranges of threshold travel times in the FCA method and travel friction coefficients in the gravity model. The methods may be used to help the US Department of Health and Human Services and state health departments improve designation of Health Professional Shortage Areas.