Administration and Leadership, Coronavirus, Exclusives

Assessing Real-World EMS Operations During a Pandemic Using Retrospective Patient Acuity and Mortality Data

The photo shows the inside of an ambulance.
The inside of an ambulance at Cherry Point (NC) Fire and Emergency Services. (U.S. Marine Corps photo by Sgt. Micha Pierce)

Despite being in existence since the 1970s, prehospital medicine, more commonly referred to as “emergency medical services” (EMS), is rather nascent with a dearth of available data. Consequently, there are still many unknown considerations when developing, deploying and staffing EMS services. Prior to the COVID-19 pandemic of 2020, the role of EMS during pandemic emergencies was unknown given that the EMS system had never been deployed for a pandemic response in the United States.


We examine the utilization of EMS services for pandemic response within a large urban corridor located in the Midwestern geography of the United States and the level of patient acuity that was treated and transported during a pandemic. We found evidence suggesting that EMS may have transported the more severe cases of COVID-19 within the sample population and therefore is an important role in pandemic response.


While there has never been a study in which the EMS systems in the United States have been examined in order to answer the research questions proposed, there is insight into how EMS practitioners are trained to prepare for deployment of prehospital/EMS resources during a pandemic. Initial prehospital medical texts stress that during a pandemic, EMS plays a critical role in transporting higher volumes of patients and act as a source of disease surveillance.1

Additionally, as the U.S. government began to develop effective strategies to combat COVID-19, publications from local, state and federal government suggested that EMS would encounter an increased  number of patients in addition to seeing patients present with higher acuity.2 Consequently, the EMS system was preparing for more patients who would require critical field interventions, such as advanced airway management.

Finally, EMS strategic planning for pandemic responses have included tiered responses in which basic life support (BLS) transport units can be utilized more often than advanced life support (ALS) units in preparation for an overload of pandemic related illnesses that required ALS interventions in the field.3

Research Questions

  1. What is the significance of municipal 911 EMS services during a pandemic in the United States in regards to the transportation and field treatment of patients?
  2.  How many patients were transported by EMS as compared to private means (control)?
  3. What was the difference in intensive care unit (ICU) admit rate and mortality rate for EMS patients compared to those who arrived by private means?

By comparing outcomes for those patients who arrived via EMS versus those who arrived by private means, this research hopes to showcase the significance of municipal EMS services during a pandemic within the United States. Our goal was to provide an insight for public safety leaders to reference when planning, mitigating, and deploying EMS services during a pandemic. Additionally, we hope that by comparing EMS to private means for transport, EMS providers will have a greater understanding of the expected patient acuity that will be imposed on front line first responders in future pandemic outbreaks in the United States.



  • The term EMS is defined as any municipally operated ambulance service that provides field treatments and transport decisions for patients who access the healthcare system via a public safety access point (PSAP).
  • The term “car,” refers to any patient that arrived at the ED via personally owned vehicle (POV).
  • The term “walk-in,” refers to any patient that arrived to an ED by a personal means other than a POV.
  • The term “public transportation” refers to any patient that arrived to an ED via a commonly accessible mode of public transportation to include bussing, rail, taxi or trolley/tram.
  • The term “private means” includes all arrivals by “car,” “walk-in,” and “public transportation” and will be aggregated into one term for the duration of this paper.

All other modes of arrival, including private ambulance, aeromedical transport, or mobile critical care unit, were removed. These date points were removed because those patients had already arrived at one emergency department (ED) and were subsequently transferred to another healthcare facility. 


This was a retrospective study examining statistical data obtained at the point of arrival for patients presenting to 18 ED’s via EMS and private means. The ED’s were located across a Combined Statistical Area (CSA) of 3.6 million people. The number of EMS agencies listed within this CSA and transported patients to the hospital system includes 164 unique municipal jurisdictions.

The time frame of the study was determined from the date in which the governor of the state declared the pandemic as a state of emergency. This date was March 9, 2020. The duration of the study was the first 100 full days of the pandemic emergency with an end date defined as June 17, 2020. 

A “COVID19 positive” patient was defined as any patient that had a RT-PCR positive test within 48 hours of their arrival to an ED.  A modeling of the studies design is depicted below in Figure 1.

Figure 1: Descriptive Characteristics of Covid19 Positive Patients and Means of Arrival to Emergency Departments


During the 100 days of the study120,867 patients were delivered to system ED’s. Private means were a combined 80.7% of those patients (n = 97, 517) while EMS delivered nearly one-fifth of the patient volume at 19.3% (n = 23,350).

Only 19.6% of patients who arrived via private means were subsequently tested upon arrival (n =19,151) but patients who arrived via EMS were twice as likely to be tested for COVID19 at 36.9% (n = 8629). Despite this, the percentage of patients that tested positive was relatively the same regardless of their arrival mode at 5.6% (1,089) for private means and 5.4% (469) for EMS.

Despite having similar positive test percentages between the two groups, patients arriving by private means had an ICU admit rate of 4.9% (54 ICU admits out of 1,089 positive tests) while those who arrived by EMS had an ICU admit rate of 23.6% (111 ICU admits out of 469 positive tests).

Patients who entered the hospital system via private means and were subsequently admitted to an ICU had a mortality of 16.6% (9 expired out of 54 ICU admits). Patients who entered the hospital system via EMS and were subsequently admitted to an ICU had a mortality of 40.5% (45 expired out of 111 ICU admits). This stratification is shown in Figure 2 below.

Figure 2: Descriptive Characteristics of Covid19 Positive Patients ICU admissions and Mortality defined by Means of Arrival

A chi-square test of independence was performed to examine the relation between patient mode of arrival and mortality. The relation between these variables was significant, X2 (1, N = 1558) = 75.3305, p = .00001). Patients transported by EMS had a higher mortality rate after being admitted to an ICU.


As noted earlier, EMS has never been deployed during a nationwide pandemic response within the United States. Theories as to the role of EMS have been speculative over the last few four decades without real world observations until COVID-19. Our study found that EMS plays a very critical role in transporting the very sickest of patients. 

By tracing COVID19 positive patients from their means of arrival to disposition, we are able to highlight the significance of EMS in pandemic. By isolating municipal 911 EMS delivered patients and examining their ICU admit rate and mortality rate compared to patients who arrived by the defined private means, we further defined and justified the community value of publicly operated 911 EMS systems in a given community. Based on patient mortality as an indicator of COVID-19 acuity, it appears that publicly funded 911 EMS systems provide treatment and transport to the sickest of patients. Those patients have a mortality rate nearly five times that of the patients who are able to self-transport via private modes to the hospital.

Similarly, this original research of EMS and pandemic response showcases the additional value that EMS brings to the community during such public health and pandemic crises. It illustrates that public funding of EMS at all levels of the government is a financially responsible investment of public tax dollars. At the local level, arguments for additional staffing, and certainly to maintain current staffing models, can be made based upon the important role that municipal EMS systems play in the pandemic strategic framework.

This study can assist in justification of additional state and federal grant dollars being allocated and awarded to local municipal EMS systems in order to prepare, mitigate and respond to future pandemics. Pandemic response, from the standpoint of the U.S. Department of Homeland Security, has been and continues to be a major concern for policy makers and purse-holders.4 Regardless if future pandemics are naturally occurring or manmade pathogens, EMS is a significant community asset in the care and treatment of the very sickest of the nation’s citizens.


During the first 100 days of the COVID-19 pandemic, marked by the initial and rapid spread of the disease, public 911 EMS systems treated and transported patient populations representing the most sick and critical in communities across the United States. Using mortality data, our research suggests that EMS has a significant role in future pandemic response. Additionally, policy makers and agency administrators/chiefs can justify and should advocate for additional staffing and funding in order to mitigate future outbreaks in order to best utilize the important role EMS plays in significant pandemic threats.


  1. Bledsoe, B. E., & Porter, R. S. (2016). Paramedic Care: Principles & Practice, Vols. 1-5 (5th Edition) (5th ed.). Pearson.
  2. Federal Healthcare Resilience Task Force EMS/Prehospital Team. (2020, April 16). COVID-19: Considerations, Strategies, and Resources for Emergency Medical Services Crisis Standards of Care. National Highway Transportation Safety Administration Office of EMS.
  3. Los Angeles County Emergency Medical Services Agency. (2009, December). Recommended Actions for EMS Providers To Prepare For and Respond to Pandemic Influenza. Lacounty.Gov.
  4. Chertoff, Michael; Secretary, Department of Homeland Security. (2006)