Proximity as a factor in the selection of health care providers: emergency room visits compared to obstetric admissions and abortions.

Abstract Physical accessibility has long been identified as a potential barrier to health services in the United States, particularly in rural areas with low provider/population ratios and long travel distances to the nearest and second nearest hospital. In metropolitan areas with multiple providers all at reasonable distances, travel time is less of a barrier; however, it remains an important factor in the selection of a hospital, especially for emergency room visits which require no physician referral or appointment. Use of a hospital for one service strongly increases the likelihood of the use of the same hospital for other unrelated services. This paper first replicates these relationships using ER visits, abortions and obstetrical admissions and. second, elaborates the implications for health planning. A simple gravity model is proposed as an economical and easy to update technique for HSAs. Based on a patient flow matrix from small, census tract size neighborhoods to the existing hospitals, models are formulated to reflect the flow patterns. They help the planners to identify underserved areas, provide hospital administrators with a method to define their service area and make it possible to predict changes in flow patterns should existing facilities expand or restrict their capacities.