In medicine, triage is a process by which care providers such as medical professionals and those with first aid knowledge determine the order of priority for providing treatment to injured individuals and/or inform the rationing of limited supplies so that they go to those who can most benefit from it.[1] Triage is usually relied upon when there are more injured individuals than available care providers (known as a mass casualty incident), or when there are more injured individuals than supplies to treat them.
The methodologies of triage vary by institution, locality, and country but have the same universal underlying concepts. In most cases, the triage process places the most injured and most able to be helped as the first priority, with the most terminally injured the last priority (except in the case of reverse triage). Triage systems vary dramatically based on a variety of factors, and can follow specific, measurable metrics, like trauma scoring systems, or can be based on the medical opinion of the provider. Triage is an imperfect practice, and can be largely subjective, especially when based on general opinion rather than a score. This is because triage needs to balance multiple and sometimes contradictory objectives simultaneously, most of them being fundamental to personhood: likelihood of death, efficacy of treatment, patients' remaining lifespan, ethics, and religion.
The term triage comes directly from French, where the term means to pick or to sort,[2] it itself coming from the Old French verb, meaning to separate, sort, shift, or select; with in turn came from late Latin tritare, to grind.[3] Although the concept existed much earlier, at least as far back as the reign of Maximillian I,[4] it was not until the 1800s that the Old French trier was used to describe the practice of triage.[5] That year, Baron Dominique-Jean Larrey, the Surgeon in Chief of Napoleon's Imperial Guard laid the groundwork for what would eventually become modern triage[6] introducing the concept of "treat[ing] the wounded according to the observed gravity of their injuries and the urgency for medical care, regardless of their rank or nationality".[7]
Simple triage is usually used in a scene of an accident or "mass-casualty incident" (MCI), in order to sort patients into those who need critical attention and immediate transport to a secondary or tertiary care facility to survive, those who require low-intensity care to survive, those who are uninjured, and those who are deceased or will be so imminently.[8] In the United States, this most commonly takes the form of the START triage model, in Canada, the CTAS model, and in Australia the ATS model.[9] Assessment often begins with asking anyone who can walk to walk to a designated area, labeling them the lowest priority, and assessing other patients from there. Upon completion of the initial assessment by the care provider, which is based on the so-called ABCDE approach,[10] patients are generally labelled with their available information, including "patient’s name, gender, injuries, interventions, care-provider IDs, casualty triage score, and an easily visible overall triage category".[11]
See main article: ABC (medicine). An ABCDE assessment (other variations include ABC,[12] ABCD,[13] ABCDEF,[14] and many others, including those localized to non-English) is rapid patient assessment designed to check bodily function in order of importance.
| A | Airway | Checking for airway obstruction | |
| B | Breathing | Checking if the patient is breathing and if the breathing is normal | |
| C | Circulation | Checking to see if the heart rate and capillary refill time is normal | |
| D | Disability | Checking the patient’s alertness, awareness, and response to painful stimuli | |
| E | Exposure | Checking the patient for trauma, bleeding, temperature, and other skin signs |
See main article: Triage tag.
A triage tag is a premade label placed on each patient that serves to accomplish several objectives:
Triage tags take a variety of forms. Some countries use a nationally standardized triage tag,[15] while in other countries commercially available triage tags are used, which vary by jurisdictional choice.[16] In some cases, international organizations also have standardized tags, as is the case with NATO. The most commonly used commercial systems include the METTAG,[17] the SMARTTAG,[18] E/T LIGHT[19] and the CRUCIFORM systems.[20] More advanced tagging systems incorporate special markers to indicate whether or not patients have been contaminated by hazardous materials, and also tear off strips for tracking the movement of patients through the process.[21]
In advanced triage, those with advanced training, such as doctors, nurses and paramedics make further care determinations based on more in-depth assessments, and may make use of advanced diagnostics like CT scans.[22] This can also be a form of secondary triage, where the evaluation occurs at a secondary location like a hospital,[23] or after the arrival of more qualified care providers.
There are a three primary concepts referred to as Reverse Triage. The first is concerned with the discharge of patients from hospital often to prepare for an incoming mass casualty. The second concept of Reverse Triage is utilized for certain conditions such as lightning injuries, where those appearing to be dead may be treated ahead of other patients, as they can typically be resuscitated successfully.[24] The third is the concept of treating the least injured, often to return them to functional capability. This approach originated in the military, where returning combatants to the theatre of war may lead to overall victory (and survivability).[25]
Undertriage is underestimating the severity of an illness or injury. An example of this would be categorizing a Priority 1 (Immediate) patient as a Priority 2 (Delayed) or Priority 3 (Minimal). The rate of undertriage generally varies by the location of the triage, with a 2014 review of triage practices in emergency rooms finding that in-hospital undertriaging occurred 34% of the time in the United States,[26] while reviews of pre-hospital triage finding undertriage rates of 14%.[27]
Overtriage is the overestimating of the severity of an illness or injury. An example of this would be categorizing a Priority 3 (Minimal) patient as a Priority 2 (Delayed) or Priority 1 (Immediate). Acceptable overtriage rates have been typically up to 50% in an effort to avoid undertriage. Some studies suggest that overtriage is less likely to occur when triaging is performed by hospital medical teams, rather than paramedics or EMTs.[28]
In telephone triage, care providers like nurses assess symptoms and medical history, and make a care recommendation over the phone.[29] A review of available literature found that these services provide accurate and safe information about 90% of the time.[30]
In triage, palliative care takes on a wider applicability, as some conditions which may be survivable outside of extreme circumstances become unsurvivable due to the nature of a mass casualty incident.[31] For these patients, as well as those who are deemed to be unsavable, palliative care can mean the difference of a painful death, and a relatively peaceful one.[32] During the COVID-19 pandemic issues of palliative care in triage became more obvious as some countries were forced to deny care to large groups of individuals due to lack of supplies and ventilators.[33]
In the field, evacuation of all casualties is the ultimate goal,[34] so that the site of the incident can ultimately be cleared, if necessary investigated, and eventually rendered safe. Additional considerations must be made to avoid overwhelming local resources,[35] and in some extreme cases, this can mean evacuating some patients to other countries.
Alternative care facilities are places that are set up for the care of large numbers of patients, or are places that could be so set up. Examples include schools, sports stadiums, and large camps that can be prepared and used for the care, feeding, and holding of large numbers of victims of a mass casualty or other type of event.[36] Such improvised facilities are generally developed in cooperation with the local hospital, which sees them as a strategy for creating surge capacity. While hospitals remain the preferred destination for all patients, during a mass casualty event such improvised facilities may be required in order to divert low-acuity patients away from hospitals in order to prevent the hospitals becoming overwhelmed.
The general concept was first described in a 17th-century BCE Egyptian document, the Edwin Smith Papyrus.[37] Discovered in 1862, outside of modern-day Luxor, Egypt,[38] the Edwin Smith Papyrus contains descriptions of the assessment and treatment of a multitude of medical conditions, and divides injuries into three categories:
During the reign of Emperor Maximilian I, during wartime, a policy was implemented where soldiers were prioritized over all others in hospitals, and the sickest soldiers received treatment first.
Modern triage grew out of the work of Baron Dominique-Jean Larrey and Barron Francois Percy during the reign of Napoleon. Larrey in particular introduced the concept of a "flying ambulance" (flying in this case meaning rapidly moving) or in its native French, Ambulance Volante.
In 1914, Antoine Depage developed the five-tiered Ordre de Triage, a triage system which set specific benchmarks on evacuation, described staged evacuation.[39] [40] French and Belgian doctors began using these concepts to inform the treatment of casualties at aid stations behind the front.[41] Those responsible for the removal of the wounded from a battlefield or their care afterwards would divide the victims into three categories:[42] [43]
From that delineation, aid workers would follow the Ordre de Triage:
In the first order of triage, the injured would be evacuated to clearing stations in the night, when darkness offered maximum protection from the German forces.[44]
Once at a casualty clearing station, wounds were dressed, and anyone requiring immediate surgical intervention was placed in a cart and brought immediately to an ambulance pickup area. If the wounded could wait, they would be evacuated by ambulance during the night.
Ambulances, driven by YMCA and American Red Cross trained drivers then removed the casualties to mobile surgical centers, called postes avances des hospitaux du front or outposts of the frontline hospitals.
At the mobile surgical hospitals, the most severe cases were treated, specifically those who were likely to die before reaching a permanent, more equipped hospital. Anyone who could survive the trip was transported to a farther away, often costal, hospital.
Upon reaching a permanent hospital, casualties received appropriate care to treat all of their injuries.
By the onset of World War II, American and British forces had adopted and adapted triage, with other global powers doing the same.[45] [46] The increased availability of airplanes allowed rapid evacuation to a hospital outside of the warzone to become a part of the triage process. Although the basic practices remained the same as in World War I, with initial evacuation to an aid station, followed by transitions to higher levels of care, and eventual admission to a permanent hospital, more advanced care was provided at each stage, and the mindset of treating only what was absolutely necessary fell away.[47] Although triage almost certainly occurred in the days after the atomic bombings of Hiroshima and Nagasaki, the pandemonium caused by the attack left records of such action non-existent until after the fifth day, at which point they are largely without historical use.[48]
In 1947, the Texas City Disaster occurred when the SS Grandcamp exploded in Texas City, Texas, killing 600 people and injuring thousands more.[49] The entire fire department was killed in the blast, and what followed was a massive informal triage of the victims.[50] Drug stores, clinics, and homes were opened as makeshift triage stations. As the city has no hospital, they had to evacuate casualties to area facilities, including those in Galveston and Houston, with at least one doctor relying on skills he had learned in World War II to inform care decisions.[51]
The Korean War saw the advent of the tiered triage, wherein care providers sorted people into categories defined ahead of time.[52] These categories, immediate, delayed, minimal and expectant are still the basis for most triage systems today. The time period was also marked by improvements in medical understanding, including shock, which allowed effective interventions to be administered earlier in the Triage process, which in turn significantly improved outcomes.[53] At the same time, Mobile Army Surgical Hospitals (MASH) were introduced along with helicopters for evacuation. These helicopters, however were used for evacuation only, and care was not provided in the air during the evacuation. These advances reduced fatalities for injured soldiers by up to 30%, and changed the nature of battlefield medicine significantly.
The conditions of the Vietnam War drove further development on the concepts created during the Korean War. Advances in helicopters allowed the introduction of the first helicopter medics, who were able to provide fluid resuscitation, and other interventions mid-flight. This made it so that the average time from injury to definitive care was less than two hours. This evolution also flowed into the everyday life, with air ambulances emerging in the civilian world by the mid-1960's. The use of triage in emergency departments and ambulance services also quickly followed.
In 1993, the north tower of the World Trade Center was bombed, in a plot with a similar intended outcome as the later September 11th attacks.[54] While search, rescue and triage operations immediately following were ordinary, the attack itself represented one of the first terrorist attacks affecting the United States directly. The fact that the U.S. was no longer seen as untouchable, along with the later Oklahoma City bombing in 1995, and the September 11th attack lead to long term changes in triage practices to be more focused on operational safety and the risk of secondary attacks designed to kill care providers.[55]
In June 1994, emergency crews began responding to calls related to symptoms of toxic gas exposure in a neighborhood. Without proper personal protective equipment, more than 253 residents were evacuated and 50 were hospitalized.[56] 20 vehicles were called to the scene, and a mobile operating center was setup nearby, likely within the zone of contamination. Unaware of the presence of Sarin, triage was performed following the standard system of the time, which ultimately resulted in eight care givers experiencing mild sarin poisoning, and an unknown amount of additional staff experiencing general malaise.[57]
At the time, no decontamination procedures or gas masks were available for incidents involving contaminants. In response, the Japan Self-Defense Forces created a decontamination team, which was then instrumental to the response of the Tokyo subway sarin attack which occurred only seven months later.
As medical technology has advanced, so have modern approaches to triage, which are increasingly based on scientific models. The categorizations of the victims are frequently the result of triage scores based on specific physiological assessment findings. Some models, such as the START model may be algorithm-based. As triage concepts become more sophisticated, and to improve patient safety and quality of care, several human-in-the-loop decision-support tools have been designed on top of triage systems to standardize and automate the triage process (e.g., eCTAS, NHS 111) in both hospitals and the field.[58] Moreover, the recent development of new machine learning methods offers the possibility to learn optimal triage policies from data and in time could replace or improve upon expert-crafted models.[59]
Most simply, the general purpose of triage is to sort patients by level of acuity to inform care decisions; so that the most people possible can be saved.[60] Although a multitude of systems, color codes, codewords, and categories exist to help direct it, in all cases, triage follows the same basic process.[61] [62] In all systems, patients are first assessed for injuries, then, they are categorized based on the severity of those injuries. Although the number of categories differs from system to system, all have at least three in common; high severity, low severity, and deceased. Some systems involve features like scoring systems, such as the Revised Trauma Score, the Injury Severity Score, and the Trauma and Injury Severity Score, the latter of which has been shown to be most effective at determining outcome.
See main article: Simple triage and rapid treatment. S.T.A.R.T. (Simple Triage and Rapid Treatment) is a simple triage system that can be performed by lightly trained lay and emergency personnel in emergencies.[63] It was developed at Hoag Hospital in Newport Beach, California for use by emergency services in 1983.[64]
Triage separates the injured into four groups:
Triage also sets priorities for evacuation and transport as follows:
See main article: JumpSTART triage. The JumpSTART pediatric triage MCI triage tool is a variation of the S.T.A.R.T. model. Both systems are used to sort patients into categories at mass casualty incidents (MCIs). However, JumpSTART was designed specifically for triaging children in disaster settings. Though JumpSTART was developed for use in children from infancy to age 8, where age is not immediately obvious, it is used in any patient who appears to be a child (patients who appear to be young adults are triaged using START).[65]
In hospital settings, Australia and New Zealand rely on the Australasian Triage Scale (abbreviated ATS and formally known as the National Triage Scale).[66] [67] [68] The scale has been in use since 1994.[69] The scale consists of 5 levels, with 1 being the most critical (resuscitation), and 5 being the least critical (nonurgent).
| 1 | Resuscitation | 0 minutes | |
| 2 | Emergency | 10 minutes | |
| 3 | Urgent | 30 minutes | |
| 4 | Semi-Urgent | 60 minutes | |
| 5 | Nonurgent | 120 minutes |
In 1995, the CAEP Triage and Acuity scale was launched in Canada relying on a simplified version of the Australian National Triage Scale.[71] This scale used three categories, emergent, urgent, and non-urgent.[72] This scale was deprecated in 1999 with the introduction of the Canadian Triage and Acuity Scale (CTAS),[73] which is used across the country to sort incoming patients.[74] The system categorizes patients by both injury and physiological findings, and ranks them by severity from 1–5 (1 being highest).[75] The model is not currently used for mass casualty triage, and instead the START protocol and METTAG triage tags is used.[76]
| 1 | Resuscitation | 0 minutes | |
| 2 | Emergency | 15 minutes | |
| 3 | Urgent | 30 minutes | |
| 4 | Less Urgent | 60 minutes | |
| 5 | Non Urgent | 120 minutes |
In France, the Prehospital triage in case of a disaster uses a multi-tier scale:
This triage is performed by a physician called médecin trieur (sorting medic).[80] [81]
The German triage system uses four color codes:[82]
| Acute, life-threatening condition | Immediate, highest priority treatment | Arterial lesions, internal haemorrhage, major amputations | ||
| Severe injury requiring urgent treatment | Rapid transport and treatment | Minor amputations, flesh wounds, fractures and dislocations | ||
| Minor injury or no injury | Physician examination, clearance and discharge as soon as possible | Minor lacerations, sprains, abrasions | ||
| Already dead, or expectant | No/low priority. Identification, guarding and evacuation as possible | Death, injuries not compatible with life |
In Hong Kong, triage in Accident & Emergency Departments is performed by experienced registered nurses, patients are divided into five triage categories: Critical, Emergency, Urgent, Semi-urgent and Non-urgent.[83] In mass casualty incidents, the START triage system is used.[84] [85]
In Japan, the triage system is mainly used by health professionals. The categories of triage, in corresponding color codes, are:
All public hospitals in Singapore use the Patient Acuity Category Scale (PACS) to triage patient in Emergency Departement. PACS is a symptom-based differential diagnosis approach that triages patients according to their presenting complaints and objective assessments such as vital signs and Glasgow Coma Scale, allowing acute patients to be identified quickly for treatment. PACS classifies patients into four main categories: P1, P2, P3, and P4.[86]
| Category (Priority Level) | Category Name | Description | Example | |
|---|---|---|---|---|
| P1 | Critically ill and requires resuscitation | State of cardiovascular collapse or in imminent danger of collapse and require immediate medical attention. | Multiple major trauma, head injury with loss of consciousness, shortness of breath, unconsciousness from any cause | |
| P2 | Major emergency | unable to walk and are in some form of distress, appear stable on initial examination, and are not in imminent danger of collapse, requires very early attention | Chest pain, major limb fractures, major joint dislocations, spinal cord injury, trunk injury with stable vital signs | |
| P3 | Minor emergency | able to walk, have mild to moderate symptoms and require early treatment | All sprains, mild constant abdominal pain, fever with cough for several days, insect stings or animal bites (not in severe distress), superficial injuries with or without mild bleeding, minor head injury (alert, no vomiting), foreign object in ear, nose, or throat, urinary tract infections, headaches. | |
| P4 | Nonemergency | Old injury or condition that has been present for a long time. | Chronic lower back pain, high cholesterol, acne. |
In Spain, there are 2 models which are the most common found in hospitals around the country:
In mass casualty incidents, the Modelo Extrahospitalario de Triaje Avanzado (META)/Advanced Triage Out of Hospital Model system is used.[90] [91] META is a seven-stage system, classifying patients as: Red 1st, Red 2nd, Red 3rd, Yellow 1st, Yellow 2nd, Green, and Deceased. The system aligns with the ABCDE framework.
| Compromised airway | ||
| Not breathing, or abnormally breathing | ||
| Asystole, arrhythmia, or hemorrhage | ||
| Injury requiring urgent care | ||
| Injury requiring delayed care | ||
| Mildly or non-injured | ||
| Deceased | Dead |
In April 2023, the NHS and ambulance services adopted two new triage tools to be used in major incidents, replacing the NASMeD Triage Sieve.[92] [93] These new tools resulted from a multi-stakeholder review led by the NHS but its implementation became more urgent after the Manchester Arena Inquiry made it a monitored recommendation for the NHS and National Ambulance Resilience Unit to adopt.[94]
The Ten Second Triage Tool (TST) was introduced as a way for all emergency services, including the police and fire service, to assess and prioritise mass casualties to provide lifesaving intervention. The tool allows for rapid assessment by removing the need to measure physiological vital signs focusing on what the emergency responder can see.[95]
The Major Incident Triage Tool (MITT) serves as the more advanced triage tool for emergency medial responders to triage casualties. The tool, derived from the Modified Physiological Triage Tool, can be used on both adults and children, and also includes the assessment of physiological vital signs.[96]
A multitude of triage systems exist in the United States, and there is no national standard.[97] Among local, regional, state, and interstate systems, the START triage method is most commonly used.
The U.S. armed forced utilize a four-stage system,[98] A battlefield situation, care providers rank casualties for precedence, treat those who they can safely, and transport casualties who need it to a higher level of care, either a Forward Surgical Team or Combat Support Hospital.[99]
The triage categories (with corresponding color codes), in order of priority, are:[100]
| Life-threatening injury | Airway or breathing issues, hemorrhage | ||
| Potentially life-threatening injury | Shock, Fractures and dislocations, abdominal, spinal, thoracic, or head injuries, uncomplicated major burns | ||
| Not life-threatening injuries | Cuts, bruises, abrasions, small bone fractures, minor burns, strains/sprains, frostbite | ||
| Non-survivable injuries | Cardiac arrest, massive head or brain trauma, Second or third degree burns over 70% or more of body |
Notions of mass casualty triage as an efficient rationing process of determining priority based upon injury severity are not supported by research, evaluation and testing of current triage practices, which lack scientific and methodological bases. START and START-like (START) triage that use color-coded categories to prioritize provide poor assessments of injury severity and then leave it to providers to subjectively order and allocate resources within flawed categories.[101] Some of these limitations include:
Research indicates there are wide ranges and overlaps of survival probabilities of the Immediate and Delayed categories, and other START limitations. The same physiologic measures can have markedly different survival probabilities for blunt and penetrating injuries. For example, a START Delayed (second priority) can have a survival probability of 63% for blunt trauma and a survival probability of 32% for penetrating trauma with the same physiological measures – both with expected rapid deterioration, while a START Immediate (first priority) can have survival probabilities that extend to above 95% with expected slow deterioration. Age categories exacerbate this. For example, a geriatric patient with a penetrating injury in the Delayed category can have an 8% survival probability, and a pediatric patient in the Immediate category can have a 98% survival probability. Issues with the other START categories have also been noted. In this context, color-coded tagging accuracy metrics are not scientifically meaningful.
Poor assessments, invalid categories, no objective methodology and tools for prioritizing casualties and allocating resources, and a protocol of worst first triage provide some challenges for emergency and disaster preparedness and response. These are clear obstacles for efficient triage and resource rationing, for maximizing savings of lives, for best practices and National Incident Management System (NIMS) compatibilities,[103] [104] [105] and for effective response planning and training.
Inefficient triage also provides challenges in containing health care costs and waste. Field triage is based upon the notion of up to 50% overtriage as being acceptable. There have been no cost-benefit analyses of the costs and mitigation of triage inefficiencies embedded in the healthcare system. Such analyses are often required for healthcare grants funded by taxpayers, and represent normal engineering and management science practice. These inefficiencies relate to the following cost areas:
Because treatment is intentionally delayed or withheld from individuals under this system, triage has ethical implications that complicate the decision-making process. Individuals involved in triage must take a comprehensive view of the process to ensure fidelity, veracity, justice, autonomy, and beneficence are safeguarded.[108]
Ethical implications vary between different settings and the type of triage system employed, culminating in no single gold-standard approach to triage. Emergency departments are advised to preemptively plan strategies in attempts to mitigate the emotional burden on these triage responders.[109] While doing so, standards of care must be maintained to preserve the safety of both patients and providers.
There is widespread agreement among ethicists that, in practice, during the COVID-19 pandemic triage should prioritize "those who have the best chance of surviving" and follow guidelines with strict criteria that consider both short-term and long-term survivability.[110] Likewise, the triage of other health services has been adjusted during the pandemic to limit resource strain on hospitals.
Under the utilitarian model, triage works to maximize the survival outcomes of the most people possible. This approach implies that some individuals may likely suffer or die, in order for the majority to survive. Triage officers must allocate limited resources and weigh an individual's needs along with the needs of the population as a whole.
Some ethicists argue the utilitarian approach to triage is not an impartial mechanism, but rather a partial one that fails to address the social conditions that prevent optimal outcomes in marginalized communities, rendering it a practical but inadequate means of distributing health resources.[111]
There is wide discussion regarding how VIPs and celebrities should be cared for in the emergency department. It is generally argued that giving special considerations or deviating from the standard medical protocol for VIPs or celebrities is unethical due to the cost to others. However, others argue that it may be morally justifiable as long as their treatment does not hinder the needs of others after assessing overall fairness, quality of care, privacy, and other ethical implications.[112]
A variety of logistical challenges complicate the triage and ultimate provision of care in conflict situations. Humanitarian actors acknowledge challenges like disruptions in food and medical supply chains, lack of suitable facilities, and existence of policies that prohibit administration of care to certain communities and populations as elements that directly impede the successful delivery of care. The logistical realities of humanitarian emergencies and conflict situations threatens the bioethical principle of beneficence, the obligation to act for the benefit of others.[113]
To address the ethical concerns that underpin triage in conflict situations and humanitarian crises, new triage frameworks and classification systems have been suggested that aim to uphold human rights. Scholars have argued that new frameworks must prioritize informed consent and rely on established medical criteria only in order to respect the human rights considerations set forth by the Geneva Convention of 1864 and the Universal Declaration of Human Rights,[114] but no comprehensive triage model has been adopted by international bodies.
Emergency veterinarian Jessica Fragola wrote in 2022 about the ethics of animal triage. She said that pressures on veterinarians having been exacerbated by staffing shortages that resulted from the Covid pandemic, coupled with growth in spending on veterinary care and on pet insurance.[115]