Incorporating Alternative Care Site Characteristics Into Estimates of Substitutable ED Visits

Background: Several recent efforts to improve health care value have focused on reducing emergency department (ED) visits that potentially could be treated in alternative care sites (ie, primary care offices, retail clinics, and urgent care centers). Estimates of the number of these visits may depend on assumptions regarding the operating hours and functional capabilities of alternative care sites. However, methods to account for the variability in these characteristics have not been developed. Objective: To develop methods to incorporate the variability in alternative care site characteristics into estimates of ED visit "substitutability." Research Design, Subjects, and Measures: Our approach uses the range of hours and capabilities among alternative care sites to estimate lower and upper bounds of ED visit substitutability. We constructed "basic" and "extended" criteria that captured the plausible degree of variation in each site's hours and capabilities. To illustrate our approach, we analyzed data from 22,697 ED visits by adults in the 2011 National Hospital Ambulatory Medical Care Survey, defining a visit as substitutable if it was treat-and-release and met both the operating hours and functional capabilities criteria. Results: Use of the combined basic hours/basic capabilities criteria and extended hours/extended capabilities generated lower and upper bounds of estimates. Our criteria classified 5.5%-27.1%, 7.6%-20.4%, and 10.6%-46.0% of visits as substitutable in primary care offices, retail clinics, and urgent care centers, respectively. Conclusions: Alternative care sites vary widely in operating hours and functional capabilities. Methods such as ours may help incorporate this variability into estimates of ED visit substitutability.