Background: On July 12, 2010, Boston Medical Center (BMC), the busiest emergency department (ED) in Massachusetts, with more than 100,000 adult patient visits per year, consolidated its two fully functional EDs into one. In preparation for this consolidation, BMC implemented systems changes to mitigate potential negative effects on both BMC and emergency medical services (EMS) providers, including Boston Emergency Medical Services (Boston EMS), the provider of 9-1-1 EMS to the City of Boston.
Objective: To examine the impact of the closure of an ED on an urban EMS system in a setting where ambulance diversion is not allowed.
Methods: We performed a before-and-after study that examined the effects of an ED closure on BMC and Boston EMS. We examined ED and Boston EMS volumes and ambulance turnaround intervals from June 1, 2010, to July 11, 2010 (preclosure) as compared with July 12, 2010, to August 26, 2010 (postclosure). Mean ED and Boston EMS volumes and Boston EMS turnaround intervals were calculated in four-hour shifts. We used multivariate analysis to analyze electronic medical systems data from BMC and Boston EMS and linear regression. We used autoregressive integrated moving average (ARIMA) models to determine the effect of the ED closure on turnaround intervals, ED volumes, and transport volumes. All analyses were adjusted for shift, ED volume, day of the week, and citywide EMS transport volumes.
Results: After ED closure, there was a statistically significant increase of 0.89 minutes (p = 0.02) in the mean EMS turnaround intervals. Additionally, the total ED volume decreased by 3.67 visits per shift (p < 0.001). The ratio of patients transported by Boston EMS to BMC remained unchanged (p = 0.11) for two weeks before and two weeks after the closure.
Conclusions: The closure of one ED resulted in a statistically significant increase in turnaround intervals and a significant decrease in ED volume independent of EMS volumes. In the absence of ambulance diversion, ratios of EMS turnaround intervals and EMS volumes according to hospital destination can be used as alternatives to ambulance diversion times to examine the effects of system-level changes such as closure of an ED on an urban EMS system.