Temporal changes of access to primary health care in Illinois (1990-2000) and policy implications.

This paper examines temporal changes of access to primary health care in Illinois between 1990 and 2000 in a Geographic Information System (GIS) environment. Census data at the census tract level in 1990 and 2000 were used to define the population (demand) distribution and related socioeconomic attributes, and the Physician Masterfile of American Medical Association in corresponding years was used to define the physician (supply) distribution at the zip code level. A two-step floating catchment method was employed to measure the spatial access, considering locations of physicians and population and travel times between them. Various socioeconomic and demographic variables were consolidated into three factors (i.e., socioeconomic disadvantages, sociocultural barriers, and high healthcare needs) for measuring the nonspatial access. Spatial and nonspatial factors were finally integrated together to assess the primary care physician shortage areas. The study shows that spatial accessibility to primary care physician for the majority of the state improved from 1990 to 2000. Areas with worsened spatial accessibility were primarily concentrated in rural areas and some limited pockets in urban areas. The worst among these worsened areas appeared to be associated with populations with high scores of socioeconomically disadvantages, sociocultural barriers, and healthcare needs. Improving the accessibility of those socioeconomically disadvantaged population groups is critical for the success of future policies.