NORMATIVE MODELS AND HEALTH-CARE PLANNING - NETWORK-BASED SIMULATIONSWITHIN A GEOGRAPHIC INFORMATION-SYSTEM ENVIRONMENT

Objectives. Network analysis to integrate patient, transportation, and hospital characteristics for healthcare planning in order to assess t he role of geographic information systems (GIS). A normative model of base-level responses of patient flows to hospitals, based on estimated travel times, was developed for this purpose. Data Sources/Study Sett ing. A GIS database developed to include patient discharge data, locat ions of hospitals, US TIGER/Line files of the transportation network, enhanced address-range data, and U.S. Census variables. The study area included a 16-county region centered on the city of Charlotte and Mec klenburg County, North Carolina, and contained 25 hospitals serving ne arly 2 million people over a geographic area of nearly 9,000 square mi les. Study Design. Normative models as a tool for healthcare planning were derived through a spatial Network analysis and a distance optimiz ation model that was implemented within a GIS. Scenarios were develope d and tested that involved patient discharge data geocoded to the five -digit zip code, hospital locations geocoded to their individual addre sses, and a transportation network of varying road types and correspon ding estimated travel speeds to examine both patient discharge levels and a doubling of discharge levels associated with total discharges an d DRG 391 (Normal Newborns). The network analysis used location/alloca tion modeling to optimize for travel time and integrated measures of s upply, demand, and impedance. Data Collection/Extraction Methods. Pati ent discharge data from the North Carolina Medical Database Commission , address-ranges from the North Carolina Institute for Transportation Research and Education, and U.S. Census TIGER/Line files were entered into the ARC/INFO GIS software system for analysis. A relational datab ase structure was used to organize the information and to link spatial features to their attributes. Principal Findings. Advances in healthc are planning can be achieved by examining baseline responses of patien t flows to distance optimization simulations and healthcare scenarios conducted within a spatial context that uses a normative model to inte grate characteristics of population, patients, hospitals, and transpor tation networks. Model runs for the defined scenarios indicated that a doubling of the 1991 patient discharge levels resulted in an areal co nstriction of the service areas to those zip codes immediately adjacen t to the hospitals, thereby leaving substantial areas unassigned to ho spitals during the allocation process, but that doubling the demand fo r obstetrics care (DRG 391) resulted in little change in the pattern o f accessibility to care as indicated by the size, orientation, and pat tern of the service areas. Conclusions. The GIS-Network system support ed ''what if'' simulations, portrayed service areas within a spatial c ontest, integrated disparate data in the execution of the location/all ocation model, and used estimated travel time along a transportation n etwork instead of Euclidean distance for calculating accessibility. Th e results of the simulations suggest that the GIS-Network system is an effective approach for exploring a variety of healthcare scenarios wh ere changes in the supply, demand, and impedance variables can be exam ined within a spatial context and where variations in system trajector ies can be simulated and observed.