Developing a flow-based spatial algorithm to delineate hospital service areas

Hospital service areas (HSAs) capture most of local patient-to-hospital travel flows, and have been accepted as the most basic unit for analyzing local hospital utilization and hospitalization patterns. If a given HSA includes multiple hospitals providing care for its residents, it is complicated to assign responsibility for small-area variation in hospital performance or healthcare costs to specific hospitals without established HSA managers. The goal of this study is to produce HSAs with the fewest number of hospitals within an HSA unit. Only a very limited number of studies are related to the HSA delineation. This study reviews the existing approaches to delineate a broader range of service areas besides HSAs. A spatial algorithm named Travel-to-Hospital Algorithm (TTHA) was developed and implemented using the individual hospital discharge records from the Florida State Inpatient Database for 2011. The final output, named the TTHA-derived HSAs, included 14 more eligible divisions in Florida than the HSAs produced by the traditional approach (92 vs. 78), with the degree of self-containment comparable between the two sets of HSAs. The TTHA provides insight into the patterns of hospital visits and holds great value for the delineation of other types of service and catchment areas.