Potential bypassing of nearest emergency department by EMS transports

Objective Guidelines recommend emergency medical services (EMS) patients to be transported to the nearest appropriate emergency department (ED). Our objective was to estimate the prevalence of EMS transport to an ED other than the nearest ED ("potential bypassing"). Data sources Illinois Prehospital Patient Care Report Data of EMS transports (July 2019 to December 2019). Data collection/extraction methods We identified all EMS ground transports with an advanced life-support (ALS) paramedic to an ED for patients aged 21 years and older. Using street address of incident location, we performed geocoding and driving route analyses and obtained estimated driving distance and time to the destination ED and alternative EDs. Main outcome and measures Our main outcomes were dichotomous indicators of potential bypassing of the nearest ED based on distance and time. As secondary outcomes we examined potential bypassing indicators based on excess driving distance and time. Study design We used Poisson regression models to obtain adjusted relative rates of potential bypassing indicators by acuity level, primary impression, patient demographics and geographic characteristics. Principal findings Our study cohort of 361,051 EMS transports consisted of 5.8% critical, 37.2% emergent and 57.0% low acuity cases transported to 222 EDs. The observed rate of potential bypassing was approximately 34% of cases for each acuity level. Treating the cardiovascular primary impression code group as the reference case, we found small to no differences in potential bypassing rates across other primary impression code groups of all acuity levels, with the exception of critical acuity trauma cases for which potential bypassing rate was 64% higher (incidence rate ratio = 1.64, 95% confidence interval, 1.54-1.74). Compared to zip codes with one ED within a 5-mile vicinity, potential bypassing was higher in areas with no ED or multiple EDs within a 5-mile vicinity. Conclusion Approximately one-third of EMS transports potentially bypassed the nearest ED. EMS transport destination may be motivated by factors other than proximity.