The impact of a freestanding ED on a regional emergency medical services system.

OBJECTIVE: The objective of the study is to examine the effect of the opening of a freestanding emergency department (FED) on the surrounding emergency medical services (EMS) system through an examination of EMS system metrics such as ambulance call volume, ambulance response times, and turnaround times.

METHODS: This study is based on data from the county's computer-aided dispatch center, the FED, and the Maryland Health Services Cost Review Commission. The analysis involved a pre/post design, with a 6-month washout period. The preintervention period was April to October 2010, and the postintervention period was April to October 2011. Data were analyzed using standard t tests.

RESULTS: The average daily number of EMS-related calls received in the computer-aided dispatch center was lower after the FED opened (16.3 [95% confidence interval {CI}, 15.7-16.9] vs 15.8 [95% CI, 14.9-16.9]). One-fourth of all patients were transported by ambulance to the FED after it opened. Use of the FED and adjacent hospitals increased by 8647 visits (15.8%) during the study period. Turnaround time for the county's ALS units decreased from 26.8 (95% CI, 26.2-27.5) to 25.1 (95% CI, 24.3-25.8) minutes. The ambulance out-of-service interval decreased from 87.3 (95% CI, 86.0-88.5) to 81.1 (95% CI, 79.7-82.4) minutes. Based on change in out-of-service this study had a small effect size (Cohen's d = 0.33).

CONCLUSIONS: The opening of an FED was associated with a modest improvement in time-specific EMS system metrics: a decrease in ambulance turnaround time and shorter out-of-service intervals.