Trauma scores are standardized tools used by medical professionals in emergency and trauma care to quickly assess the severity of a patient’s injuries. They provide a numerical measure of the physiological derangement and anatomical damage resulting from trauma. The primary goal is to offer a rapid, reliable estimate of injury severity and the associated risk of mortality. By converting complex clinical data into a simple number, these systems guide immediate treatment decisions and predict patient outcomes for research and quality assurance.
Core Physiological Assessment: The Revised Trauma Score
The Revised Trauma Score (RTS) is a widely used physiological scoring system designed for rapid assessment in pre-hospital or emergency department settings. This score is based entirely on the patient’s immediate, measurable vital signs, reflecting their current physiological status and response to injury. A lower RTS indicates greater injury severity and a poorer prognosis.
The RTS calculation relies on three main components: the Glasgow Coma Scale (GCS) score, the Systolic Blood Pressure (SBP), and the Respiratory Rate (RR). Each parameter is converted into a coded value ranging from zero to four points, with four representing a normal or optimal finding. For example, a GCS score between 13 and 15 is coded as four points, as is a systolic blood pressure greater than 89 mmHg.
To arrive at the final weighted score, these coded values are multiplied by specific weighting factors and then summed. The formula heavily weights the GCS component to account for severe head injuries that might not initially present with major changes in blood pressure or breathing. The final RTS is a decimal number ranging from zero to 7.8408, with zero representing the worst possible prognosis. Due to the complexity of this weighted calculation, a simpler, unweighted version, the Triage-RTS (T-RTS), is often used by first responders for quick field decision-making.
Quantifying Physical Harm: The Injury Severity Score
The Injury Severity Score (ISS) is an anatomical scoring system that quantifies the total physical damage sustained by a patient, typically calculated after hospital arrival. Unlike the RTS, the ISS is based on a detailed review of injuries, often informed by imaging studies or surgical findings. The ISS is highly predictive of mortality and defines “major trauma” when the score exceeds 15.
The calculation of the ISS begins with the Abbreviated Injury Scale (AIS), which assigns a severity code from one (minor) to six (maximal, untreatable) to every specific injury. The body is divided into six distinct regions for the ISS calculation. Only the single most severe injury score from each of these six regions is considered for the ISS calculation.
The ISS is determined by identifying the three most severely injured body regions, based on their highest AIS score. The AIS score for each of these three regions is squared, and the three resulting numbers are added together to produce the final ISS. This squaring mechanism ensures that multiple severe injuries in different body areas result in a significantly higher score than a single severe injury. The ISS ranges from one to 75. If any single injury has an AIS score of six, the ISS is automatically set to 75, recognizing the unsurvivable nature of the trauma.
Guiding Emergency Response: Triage and Resource Allocation
Trauma scores are action-oriented tools that directly influence the immediate treatment path of an injured person. Scores like the RTS are used in structured field triage decision schemes to determine the most appropriate destination for the patient. A low physiological score, such as an RTS below 11, immediately flags the patient as requiring transfer to a designated high-level trauma center.
This immediate decision triggers a “trauma center activation,” mobilizing specialized surgical teams and resources before the patient arrives. The goal is to minimize the time between injury and definitive surgical care, often referred to as the “golden hour.” Using a combination of physiological scores and anatomical injury criteria, the system aims to achieve the optimal balance between overtriage and undertriage.
Overtriage occurs when a patient with minor injuries is transported to a high-level trauma center, which can strain resources. Undertriage is the more concerning scenario, where a severely injured patient is taken to a facility that cannot provide the necessary specialized care. Trauma systems prioritize minimizing undertriage to prevent avoidable mortality, often accepting a higher rate of overtriage as a necessary trade-off. These scores allow the system to efficiently sort and allocate resources, ensuring the most seriously injured patients receive the highest level of care.
Interpreting Scores Across Different Patient Populations
While trauma scores provide objective data, their interpretation must be flexible and consider the patient’s individual characteristics. Age is a significant factor that modifies the predictive power of both the RTS and ISS. Elderly patients often have decreased physiological reserve and may be taking medications that mask their body’s response to injury.
An older patient’s blood pressure may appear normal or deceptively high despite significant internal bleeding, leading to an acceptable RTS that could result in undertriage. Conversely, children often maintain physiological stability until a rapid decline, meaning a good score may not accurately reflect the underlying severity of their injury. Therefore, some systems use age-specific scores or lower threshold scores to ensure these vulnerable populations are not missed.
The mechanism of injury can also override a moderate score, demanding a higher level of care regardless of the initial metrics. Injuries resulting from high-speed motor vehicle crashes, falls from significant heights, or penetrating trauma, such as gunshot wounds to the torso, are often automatic triggers for trauma center activation. These specific mechanisms are recognized risk factors suggesting a high probability of occult, life-threatening injuries that the initial physiological or anatomical assessment might miss.