PART 2: Over Triage: Injury Classification Mistake or Hindsight Bias?
Event Type
Oral Presentations
TimeThursday, June 9th1:00pm - 1:30pm EDT
DescriptionThe injury severity score (ISS) is a method utilized by patient care teams to assess patient injuries after patient treatment via a standardized medium. The scoring method requires providers to input the patient’s most severe injuries for each of six anatomical regions using the Abbreviated Injury Scale (AIS). The anatomical regions include the head and neck, face, chest, abdomen, lower extremities, and upper extremities. Each injury from these regions is then scored by the Abbreviated Injury Scale (AIS) which uses a Likert-type scale from zero to six (no injury, minor, moderate, serious, severe, critical, unsurvivable). The ISS score is calculated by the sum of squares of the three highest injuries recorded. The resulting score of this calculation can range from 0 to 75. Any patient who receives one unsurvivable injury designation (i.e., a six on the AIS) automatically receives an ISS of 75, thus this score is often associated with a patient’s death.
The process of assigning an ISS is standardized for all patients according to the American College of Surgeons (2012). After a patient is assessed and treated, providers perform the ISS scoring and calculation and assign it to the patient’s records. This score is then utilized for a multitude of applications including the assessment of under- or over-triage within the hospital system. Triage is a system used by providers to allocate resources to patients based on their injury severity. The initial trauma triage stage is typically decided based on two factors and includes the information garnered from pre-hospital communication with emergency medical service (EMS) teams as well as patient assessments during the primary survey of the patient. The primary survey includes assessment of a patient’s airway, breathing, blood circulation and hemorrhage, disability or neurological status, and exposure. The initial triage assessment is, however, typically based upon only pre-hospital communication with EMS as the patient’s injury severity may necessitate expedited care resources upon arrival.
Triage is segmented into various severity types depending on what trauma triage system the healthcare facility uses. An example of a trauma triage criteria is from the Washington State Department of Health (2016) which classifies trauma triage into two categories which include 1) modified trauma team activation and 2) full trauma team activation. This triage system delegates resources based on standardized patient input guidelines. In this system, modified trauma teams consist of the emergency department (ED) physician and registered nurse (RN), respiratory therapist, radiology team, and the laboratory team. Full trauma teams include all providers from the modified team with the addition of the general surgeon, anesthesiologist-certified registered nurse (CRNA), and the trauma-ED RN. The additional resources provided by a fully activated trauma team allow for the more effective treatment of severely injured trauma patients. Patients who are under-triaged are believed to have had a lower activation level than needed, similarly, patients who are over-triaged are believed to have had a higher activation level than needed.
The Committee on Trauma American College of Surgeons (2014) reports that 25-35% of patients are over-triaged. This proportion significantly increases when considering other modes of emergency transportation such as helicopter emergency medical services (HEMS) whose patients are over-triaged 50-60% of the time. Both under- and over-triage have significant implications for patients, providers, and organizations. Patients who are under-triaged may not receive the care they require for survival or for receiving less adverse health outcomes. Alternatively, patients who are over-triaged may use resources unnecessarily. Some reports show that triage places a significant cost on both patients and organizations, costing up to $50,000 depending on the number of providers used. Therefore, using a standardized system to assist providers and researchers in adjusting the processes in place to provide more accurate methods of triage is paramount. The ISS is one such tool. Prior research using the ISS has found that while the scoring system itself relies on a numerical scale, the appropriate triage of a patient is associated with a dichotomous cut-off. Specifically, researchers have posited that an ISS of 16 or above indicates the patient should have received a full activation while any patients below 16 are generally associated with modified activations (Davis et al., 2017).
Prior research has provided evidence that the ISS as a form of assessing triage accuracy is inappropriate. Abback et al. (2021) found that a cohort of patients who were categorized as over-triaged according to the ISS were, in fact, appropriately triaged for trauma care resources based upon their severe injury outcomes. Additionally, Abback et al. (2021) and Hamada et al. (2014) suggest that the currently held thresholds of ISS in relation to the appropriateness of the trauma triage outcomes it is associated with are outdated. Specifically, Abback et al. (2021) propose that appropriate trauma triage decision-making and outcomes should not be assessed by the patient's subsequent ISS, rather, by the resources required at the time of assessment and in the context of the care facility for successful treatment of the patient.
This submission extends the arguments posited by Abback et al. (2021) and posits that the formation of the ISS in the context of estimating appropriate triage level or other care-related decision-making is a form of hindsight bias. Hindsight is a bias wherein information that was not available during an event or decision is available and used during a review of the process and subsequent outcome. The primary danger of hindsight bias is that it provides a level of overconfidence regarding an individual’s decision regarding modifications to current procedure based on hindsight (Roese & Vohs, 2012). In cases where organizations utilize the ISS to determine an appropriate amount of triage (e.g., 25-35% target), any subsequent adjustments to triage practices or policies will be affected by hindsight.
We propose that the ISS may still provide valuable insights to patient care; however, to mitigate subsequent bias’ in after-the-fact patient care, decision-making purposes should be considered within the system of patient care as a whole. One such mechanism may be via the Systems Engineering Initiative for Patient Safety (SEIPS; Holden et al., 2013). SEIPS is systems-oriented human factors framework approach to capturing the inputs, processes, and outputs that make up patient care through the lens of the patient, provider, and organizations involved. We propose that integrating the ISS into this framework as an output of patient care within the context of the tools, resources, and information available and utilized at the time of the patient's triage and care decisions is pertinent to better understand that factors that both contribute to the calculation of the ISS as well as its use in re-adapting the patient care processes based on up-to-date information and new emerging trends of patient injury. Thus, this submission serves to identify the inputs and processes that constitute triage decision-making and contextualize them in describing the triage decision-making process. This submission also serves to assess prior critiques of the ISS and its ability to appropriately assess triage decision-making and describe how framing these critiques through the framework of SEIPS may provide a stronger understanding of how to better integrate the ISS into the patient care process.