Emergency department use as a component of total ambulatory care: a population perspective

Abstract

Objectives: (a) To describe the overall proportion of ambulatory care provided in emergency departments for a complete urban population, (b) to describe the variation across small geographic areas in the overall proportion of ambulatory care provided in emergency departments and (c) to identify attributes of small-area populations that are related to the provision of high proportions of total ambulatory care in emergency departments.

Design: Cross-sectional ecologic study combining 4 sources of secondary data on health service utilization and socioeconomic status.

Setting: Winnipeg.

Participants: A total of 657,871 residents of metropolitan Winnipeg in the period April 1991 to March 1992, grouped into 112 neighbourhoods.

Main outcome measure: A proportion calculated, for each neighbourhood population, from the estimated count of emergency department visits divided by the population's use of total ambulatory care for a sample of 55 days in the study period.

Results: The overall proportion of ambulatory care provided in emergency departments was 4.9% (range 2.6% to 10.8%), representing 35.5 emergency department visits per 100 person-years. Neighbourhoods with a higher proportion of total ambulatory care provided in emergency departments were characterized by lower mean household income, a higher proportion of emergency department visits for mental illness and a higher proportion of residents with treaty Indian status. Measures of need for medical care for were not consistently associated with the proportion of ambulatory care received in emergency departments.

Conclusions: In a health care system with an adequate supply of primary care physicians and universal insurance, this study has documented significant variation across small geographic areas in the proportion of total ambulatory care received in emergency departments. In the absence of strong evidence that this variation was associated with underlying need, the results suggest that attention be paid to the accessibility of conventional primary care.