Emergency department reliance: a discriminatory measure of frequent emergency department users.

OBJECTIVE: High emergency department (ED) use has previously been defined as a person's having a large number of ED visits, implying that all frequent users are the same. ED reliance (EDR), the percentage of all health care visits that occur in the ED, considers ED use in relation to primary care use and, thus, may discriminate among high-ED-user populations. Our objective was to determine whether EDR, as a complementary use measure, could differentiate frequent users secondary to increased need for care from those with access issues.
METHODS: We conducted an analysis of prospectively collected data from the Medical Expenditure Panel Survey from 2000-2001 and 2001-2002. Frequent ED users were defined as having >or=2 ED visits, and EDR was dichotomized as high (>0.33) or low (<or=0.33). Odds of being a frequent user or having high EDR were analyzed by using logistic regression.
RESULTS: A total of 8823 children were included. Within frequent-ED-use populations, young children and children with special health care needs were less likely (odds ratio: 0.55 and 0.72, respectively) to have high EDR, whereas those with lower education, low income, and public insurance and those of black race were more likely to have high EDR.
CONCLUSIONS: EDR is a readily available measure in large administrative databases that discriminates among frequent-user populations, differentiating increased need for ED services from lack of access to quality primary care.