Many ED malpractice claims allege a patient was mistriaged. But what if the plaintiff attorney takes things a step further and claims that the tool used to triage patients was unreliable?

“Plaintiff’s counsel could certainly attempt to attack the use of any triage tool,” says Megan Kures, JD, a senior attorney in the Boston office of Hamel Marcin Dunn Reardon & Shea.

Whether they choose to do so might depend on how strongly the ED provider relied on the tool, or whether the ED provider testifies that he or she used the tool. “Whether or not literature can be used to attack the tool will depend upon evidentiary considerations,” Kures says. “This tactic may be subject to a Daubert-type analysis,” referring to a tool judges use to determine the validity of an expert witness’s scientific testimony.

An unreliable triage tool can form the basis for a claim against the hospital, as can departmental policies and protocols, Kures notes. However, determining acuity still is largely a matter of judgment exercised by ED providers, regardless of what tool is used for triage. Thus, the tool will “likely take a back seat to the provider’s own thought process and practices,” Kures says. “As there are many variabilities that come into play, triage tools are viewed as more of a guideline.”

Most often, malpractice allegations involving ED triage claim that the nurse failed to appreciate the significance of the presenting complaint and symptoms. Further, such claims allege the nurse failed to ensure that the patient was seen in a timely manner, Kures explains. “Plaintiffs’ attorneys may allege that the triage nurse failed to appropriately determine the patient’s acuity and assigned the patient to the wrong track,” Kures says.

Another common allegation: The ED nurses failed to advocate for the patient by seeking appropriate resources to expedite treatment. “We do see cases where an otherwise stable-appearing patient rapidly declines in the waiting area while waiting to be seen,” Kures says.

Typically, both the triage nurse and any emergency physician (EP) who saw the patient or was consulted by the ED nurse are named in such cases. “Whether or not the hospital is named will often depend upon the jurisdiction and any damages caps that may come into play,” Kures adds.

The Emergency Severity Index (ESI) is the leading triage tool in the United States.1 “It has some good qualities, but it is not incredibly reliable,” says Jeremiah Hinson, MD, assistant professor in the department of emergency medicine at Johns Hopkins University School of Medicine. Of 3,024 hospitals surveyed in a 2012 study, 56.9% used the ESI.1

The authors of a recent study assessed the accuracy and variability of triage score assignment by ED nurses using the ESI in three countries, including the United States. Nearly 30% of high-acuity patients were undertriaged. Less than half of all pediatric patients were scored correctly.2

The results of another recent study revealed that initial ESI-determined triage score was classified as inaccurate for 16,426 of 96,071 patient encounters in Brazil, despite rigorous, ongoing training of ESI users.3 Several factors identifiable at time of presentation were linked to undertriage. These included shortness of breath, chest pain, advanced age, bradycardia, tachycardia, hyperthermia, hypoxia, and neurologic complaints.

“High variability is high-risk,” says Hinson, the study’s lead author. “We want to decrease variability. The current tool doesn’t allow for that.”

Some EDs have adopted a “quick flow” model, with level 4 and level 5 patients cared for in a separate area of the department. “If the patient ends up needing a hospital admission, the patient could be cared for by providers with less training, less supervision, and fewer resources available to them,” Hinson offers. This also can lead to mistriage due to cognitive bias. “If you are working in urgent care and caring for a patient who was designated as urgent care by your facility, there’s a bias to assuming the patient does not have serious pathology,” Hinson says. He names these two important implications for EDs that want to reduce liability risks:

  • ED providers need to first recognize there is variability in any triage tool;
  • Systems are needed to reassess patients after the initial triage and reconsider acuity levels.

Some EDs place physicians at triage who order diagnostic studies while patients are waiting for a bed, with acuity levels reassessed based on the findings. A low-acuity patient would be assigned a higher triage level in light of an abnormal chest X-ray, ECG, or change in clinical appearance.

“Triage is performed when we have the smallest amount of data available,” Hinson explains. “As more data become available, we need a way to incorporate those new findings.”

As “the highest-risk place in the ED,” triage requires experienced ED nurses, regardless of what system is used, says Paula Tanabe, PhD, RN, FAEN, FAAN, who helped develop the ESI. Tanabe is one of four members of the ESI Triage Research Group that worked with the Agency for Healthcare Research & Quality to develop training materials for the ESI. “Triage tools provide a framework. But an experienced ED nurse is even more critical than any tool,” says Tanabe, associate dean for research development and data science and professor of nursing and medicine at Duke University.

ED nurses must conduct a good assessment while applying a reliable and valid system. “While ESI is never perfect, all triage systems will rely upon the training and experience of the ED nurse,” Tanabe says.

Alexander M. Rosenau, DO, CPE, FACEP, also a member of the ESI Triage Research Group, says, “I understand and appreciate all practitioners’ hope for perfection in triage. Machine learning and artificial intelligence all offer tantalizing hopes for the future but are in no way here.”

Some electronic medical records incorporate ESI. “But it is the nurse, not the machine, that is the ultimate arbiter,” Rosenau notes. That may change as new techniques, natural language, and physical assessment techniques adequate for a computer or robot to use are invented, trialed, and implemented.

“The robot that can accomplish this is not in existence at this point,” Rosenau says. “Most important is the realization that triage is a system for ‘acuity on presentation’ assessment.” Its purpose is to route patients to the right place within the ED, used by experienced, well-trained nurses. “ESI allows that training and experience to be superimposed on ESI, a published valid, and reliable system,” Rosenau says.

The patient’s condition and needs are in constant flux in the ED setting. “That does not change the initial ESI level nor make it invalid,” Rosenau adds.

Rosenau gives the example of two hypothetical patients who arrive with severe dehydration and diarrhea; a rapid, weak pulse; hypotension; and somewhat obtunded. Both are triaged as ESI level 2. The first patient is resuscitated with two liters of fluid, continues to improve, and is discharged with a diagnosis of viral gastroenteritis a few hours later. For the second hypothetical patient, a CT reveals ischemic bowel disease, requiring same-day surgery and ICU admission. At presentation, both received the correct ESI level and both received interventions and observations as to their test results and treatment response. “Both went on to different outcomes. Both were triaged and treated appropriately,” Rosenau says.


  1. McHugh M, Tanabe P, McClelland M, Khare RK. More patients are triaged using the Emergency Severity Index than any other triage acuity system in the United States. Acad Emerg Med 2012;19:106-109.
  2. Mistry B, Stewart De Ramirez S, Kelen G, et al. Accuracy and reliability of emergency department triage using the Emergency Severity Index: An international multicenter assessment. Ann Emerg Med 2018;71:581-587.
  3. Hinson JS, Martinez DA, Schmitz PSK, et al. Accuracy of emergency department triage using the Emergency Severity Index and independent predictors of under-triage and over-triage in Brazil: A retrospective cohort analysis. Int J Emerg Med 2018;11:3.