Article, Emergency Medicine

A comparison of acuity levels between 3 freestanding and a tertiary care ED

a b s t r a c t

Introduction: Freestanding emergency departments (FEDs) have grown in popularity. They often provide Emergent care in areas distant from other EDs. Investigations and research to characterize the operation and dynamics of FEDs are needed.

This study characterizes the severity of illness seen at FEDs and compares it with a hospital-based urban tertiary care ED using the Emergency Severity Index , a quantification of patient acuity.

Methods: Patient ESI levels were analyzed retrospectively over1 year for a single hospital system with1 main urban hospital-based ED and 3 FEDs. Data analysis was completed using analysis of variance with and without time as a factor. Results: The average ESI level at the main ED (3.04) was lower than the FEDs, respectively (3.42, 3.22, and 3.38) (P b .001). Patient ESI levels were significantly different between FEDs (P b .001).

Conclusion: The main ED demonstrated lower ESI levels and thus higher acuity than the 3 affiliated FEDs. There were significantly different Acuity levels between the main ED and 3 FEDs as well as between individual FEDs.

(C) 2015


In recent years, there has been a large increase in the number of freestanding emergency departments (FEDs), with more than 200 active nationwide in 2010 and growth of more than 20% in 1 year [1]. With FEDs becoming more popular, additional research is necessary to determine how useful they are to the community and how sustainable they are for the health system.

One subject of interest is the acuity of cases treated at FEDs. The Emergency Severity Index is a commonly used classification system for ED triage acuity [2]. The ESI takes into account both the pa- tient and resources needed to treat them. Ranging from 1 to 5, with 1 re- quiring the most resources, ESI levels are usually determined by a triage nurse who uses an algorithm to assign a level (Fig. 1).

Many believe that FEDs do not treat higher acuity cases. In the past, FEDs treated mostly minor illness and injury, leaving high-acuity cases to hospital-based EDs [3]. No prior studies have looked at ESI levels at FEDs. This study collected and analyzed data on the distribution of ESI scores at FEDs vs those at a main hospital-based urban tertiary care ED.


This study retrospectively analyzed ESI levels of patients presenting to the 3 FEDs and the main ED of 1 health care system. The internal review board approved this study.

* Corresponding author. Akron General Medical Center, 1 Akron General Ave, Akron, OH 44307.

E-mail address: [email protected] (E.L. Simon).

The main ED is an adult-only tertiary care level I trauma center, cer- tified stroke center, and accredited chest pain center with residency teaching programs. The ED has 33 beds plus 5 minor treatment rooms. The annual ED volume is 55000 patients. The hospital serves a metro- politan area with an estimated population of 700000 [1]. The health care system includes 3 FEDs located 9.6 miles north (FED 1), 11.4 miles west (FED 2), and 11.8 miles south (FED 3) of the main campus. All 4 EDs treat patients who arrive by either private vehicle or by ambu- lance. Each FED has full resuscitation capabilities. Emergency medical services (EMS) within the study region have been instructed to take all trauma team activation, ST-elevation myocardial infarctions, and strokes to the main ED. All other EMS transports can be directed toward the FEDs at the discretion of the patient, family, or EMS protocol.

Data collection was done with the ED’s electronic Tracking system (LOGICARE version The data included the ESI levels of all pa- tients from the 4 EDs who presented from August 2012 to July 2013. A baseline data set was also collected for the main ED from June 2006 to May 2007, before the 3 FEDs opened. The data were analyzed using R (version 3.0.2).

Analysis of variance and Tukey test were performed on the ESI data from the main ED and each FED to determine if the mean of each popu- lation was differed significantly. A P b .05 was considered to be statisti- cally significant.


A total of 54560 patients at the main ED were included, with 54318 having a recorded ESI. Freestanding emergency departments 1, 2, and 3

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had volumes of 19748 patients, 15921 patients, and 12630 patients. Emergency severity index scores were recorded in 19656, 15828, and 12617 cases, respectively. The ESI levels for the main ED and each FED based on the month can be viewed in Fig. 2. Emergency severity index distributions for each facility are portrayed in Fig. 3.

When we analyzed the data without considering time, ESI levels were significantly different between the main ED and each FED. The av- erage ESI level at the main ED was lower, indicating higher acuity, when compared with the FEDs individually (P b .001). Patient ESI levels were also significantly different between FEDs (P b .001). Emergency severity index levels for each facility with 95% confidence intervals can be found in the Table.

When we analyzed the data considering time as a factor and com- pared the main ED with each FED individually, we found that there was a statistically significant difference between ESI levels each month, September to July (P b .001) and August (P b .02) with the main ED being the lowest, indicating highest acuity. The only exception to this was for FED 2 during the months of September (P = .471) and October (P = .844).


Fig. 1. Algorithm used for determinig ESI levels.

The average ESI level of the main ED was lower than that of each FED, indicating that, on average, cases seen at the main ED have higher acuity than those that are seen at the FEDs. This may partly be because EMS is instructed to take many ESI 1 cases (ST-elevation myocardial in- farction, trauma, and stroke) directly to the main ED. The effect of this is seen in the large distribution of ESI 1 cases at the main ED compared with the ESI 1 cases at each FED (1.77% vs 0.21%, 0.15%, and 0.12%). Emergency medical services decision may also contribute to the large amount of ESI 2 cases at the main ED (24.76% vs 3.57%, 10.90%, and 8.14%); however, those can be taken to FED.

Fig. 2. Emergency severity index levels for each facility by month.

E.L. Simon et al. / American Journal of Emergency Medicine 33 (2015) 539541 541







0.21 ESI 2









44.59 ESI 3


Main ED ESI Distribution

FED 1 ESI Distribution


0.37 0.15













45.11 ESI 3


FED 2 ESI Distribution

FED 3 ESI Distribution

Fig. 3. Depicts ESI levels at the main ED and FED 1, 2, and 3, respectively.


Average ESI level with 95% confidence interval

Facility Average ESI level with 95% CI

Main ED 3.04 (3.04-3.05)

FED 1 3.42 (3.40-3.43)

FED 2 3.22 (3.20-3.23)

FED 3 3.38 (3.36-3.39)

Abbreviation: CI, confidence interval.

The ESI difference between FEDs may be attributed to differences in demographics in the associated locations. The area around FED 2 has many nursing homes that use the facility, which may contribute to the higher number of ESI 2 and 3 cases compared with the other FEDs (Fig. 3).

Besides the difference in ESI 1 and 2 cases between the main ED and each FED, the number of ESI 5 cases was much more common at the main ED than at the FEDs (3.98% vs 0.46%, 0.37%, and 0.43%). The main ED is in a city that has an estimated median income of $31392 per year, which is substantially lower than the US national average annual income of $44321. The large number of low acuity cases may reflect this demographic, limited access to other providers, and a calculated convenience to the working poor, especially those working

more than 1 job. In contrast, FEDs 1, 2, and 3 are in municipalities that have median annual incomes of $64299, $115089, and $61900 [4,5]. The main ED patient population was composed of 22.7% self-pay, whereas the populations at FEDs 1, 2, and 3 had self-pay proportions of 14.4%, 11.8%, and 12.7%, respectively.


The main hospital-based ED demonstrated lower ESI levels and thus higher acuity than the 3 affiliated FEDs. There were significantly different acuity levels between the main ED and3 FEDs as well as between individual FEDs. The main ED had more ESI 1 and ESI 5 cases than any of the 3 FEDs.


  1. Simon EL, Griffin PL, Jouriles NJ. The impact of two freestanding emergency depart- ments on a tertiary care center. J Emerg Med 2012;43(6):1127-31.
  2. Gilboy N, Tanabe P, Travers D, Rosenau AM. Emergency Severity Index : a triage tool for emergency department care, version 4. Implementation handbook2012 ed. . Rockville, MD: Agency for Healthcare Research and Quality; 2011[AHRQ Publication No. 12-0014].
  3. Kinney TJ, Gerson L. Utilization of a freestanding emergency center by patients with and without private physicians. Ann Emerg Med 1983;12(12):762-4.
  4. United States of America, United States Census Bureau. State & County QuickFacts (In-

    ternet); 2014[Accessed 2014 June 23].

    United States of America, Social Security Administration. National average wage index

    (Internet); 2012[Accessed 2014 June 23].

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