Distance and the decision to visit an emergency department

Two items which are of importance in planning the provision of health care facilities are the process by which patients select hospital emergency departments and information concerning the catchment areas of these facilities. This study is based on an analysis of emergency department use at Humber Memorial Hospital in Metropolitan Toronto. An evaluation of the patient's decision process indicates that, in comparison with a medical assessment, patients tend to overestimate the seriousness of their complaint. Also, in spite of the fact that a relatively large number of patients possess a family physician, the actual or perceived unavailability of the physician is an important factor in the use of hospital emergency facilities. It is further determined that patients with trivial or non-urgent complaints generally reside within close proximity of the hospital. This evidence indicates that the emergency facilities at Humber Memorial act primarily as an "off-hours" physician surrogate. A triage system is suggested as a possible solution to the problem. With respect to distance from the hospital, the results from this study coincide with conventional geographical theory which suggests that spatial interaction declines with distance, usually in a negative exponential fashion. An analysis of the spatial distribution of patients, using the point of minimum aggregate travel as a reference; shows that the hospital is relatively central to those patients who use it. The area defined by physicians with admitting privileges, however, overlaps considerably with the corresponding areas of neighboring hospitals and only includes about half of the patients in the sample. A need for increased consultation between the hospitals is suggested. Finally, two techniques for establishing a catchment area are evaluated. An area derived from the concept of Thiesson polygons contains those points which are closer to Humber Memorial than any other hospital. However, for planning purposes, it is unlikely that residents would be able to memorize such boundaries and use them in the decision process. A less rigid catchment area for nodal facility such as a hospital is defined by the standard distance circle which is based on the probability of potential patient interaction with the hospital's emergency department.