FOUR Score-Modified Trauma Scores for Mortality Prediction

Trauma is the leading cause of death worldwide, particularly in those younger than 35 years of age. Injuries and violence represent a major global public health, according to the World Health Organization (WHO), injuries and violence cause approximately 4.4 million deaths worldwide each year, accounting for nearly 8% of all deaths. Of these, about 3.16 million deaths are attributable to unintentional injuries and 1.25 million to violence-related injuries. Injuries and violence also contribute substantially to disability, with an estimated 10% of all years lived with disability attributed to these conditions.

Trauma severity scoring systems are important adjuncts to trauma care and are used to characterize the nature and extent of injury. They can support triage and assist in assessing and predicting patient outcomes, thereby helping to organize and improve trauma care systems. Trauma scoring systems can be divided into anatomical, physiological, and combined scores each with advantages and disadvantages. Anatomical scores describe the injuries recorded by clinical examination, imaging, surgery, or autopsy. While Physiologic Scores describe changes due to a trauma and translated by changes in vital signs and consciousness. The combination of anatomic scoring system and physiological scoring system is better than single scoring system for death prediction in patients with severe trauma in ICU, and it may be considered to be a new method for early identification of death risk in patients with severe trauma.

The Revised Trauma Score (RTS), a revision of the original Trauma Score developed by Champion et al., in 198, is a commonly used prehospital trauma triage tool. While there has been conceptual evolution of the core concept behind the RTS since its development, including the development of respiratory rate, pulse rate, and motor response (RPM) measure by Sacco et al., which may provide important mitigation of subjectivity of Glasgow Coma Scale (GCS) assessment, the RTS remains most prevalent in the literature. The RTS only requires three metrics to calculate: respiratory rate, systolic blood pressure, and GCS.

First introduced by Champion et al. in 1981, TRISS is a combination of the RTS and ISS with an age component. This system was to assess patients at the time of initial presentation to predict overall prognosis. Earlier studies had issues related to its applicability, but recent studies lend support to TRISS being a better scoring system when compared with others, such as ISS, NISS, and RTS. The past three decades have seen many international studies providing evidentiary support that it is, in fact, an accurate predictor of patient mortality.

More recent scoring systems, such as the Glasgow Coma Scale, Age, and Systolic Blood Pressure (GAP) score, have gained attention due to their simplicity and applicability in the field. The GAP score is especially relevant for traffic accident triage, as it can be quickly implemented at the scene, allowing for more efficient patient stratification and resource allocation. The New Trauma Score (NTS), which replaces the Respiratory Rate (RR) with arterial blood oxygen saturation percentage (SpO2), has shown improved performance over RTS in predicting mortality for trauma patients, including those from traffic accidents.

The Glasgow Coma Scale (GCS) provides an objective method for assessing the level of impaired consciousness in patients with acute medical conditions or trauma and is one of the most widely used neurological assessment scales. It evaluates three components of responsiveness: eye-opening, verbal, and motor responses, with each component reported separately to provide a detailed description of neurological status. The individual scores can also be combined into a total GCS score, providing a concise indication of overall severity. The GCS is widely used in trauma, emergency, and critical care settings and supports clinical assessment, triage, monitoring, and communication among healthcare professionals.

The Glasgow Coma Scale (GCS) has several limitations that can affect its reliability and clinical interpretation. The verbal component cannot be assessed reliably in patients who are intubated, pharmacologically sedated, or unable to speak, resulting in missing GCS values and limiting the use of the total score for prognostic models. The Glasgow Coma Scale (GCS) is limited in its ability to evaluate patients with concomitant head and spinal cord injury. Also, a comatose patient receives a GCS score of 3, which coincidentally matches the Glasgow Coma Scale (GCS) assigned to a deceased individual. Drug and alcohol intoxication can interfere with GCS assessment in trauma patients. DiGiorgio et al. found that intoxicated patients had greater changes in Glasgow Coma Scale (GCS) assigned scores than patients without detected substances, suggesting that intoxication may contribute to an initially depressed or variable Glasgow Coma Scale (GCS) assigned. The authors therefore recommended considering and addressing intoxicants when interpreting GCS scores to improve the accuracy of assessment and benchmarking. Painful stimuli used in the Best Eye and Best Motor Response assessments can complicate scoring, especially in polytrauma patients with spinal cord injuries.

The Full Outline of UnResponsiveness (FOUR) score is a coma scale consisting of four components: eye response, motor response, brainstem reflexes, and respiration, with each component assigned a maximum score of 4.

A study prospectively evaluated the Full Outline of UnResponsiveness (FOUR) score in 120 intensive care unit patients and compared it with the GCS among neuroscience nurses, neurology residents, and neurointensivists. The Full Outline of UnResponsiveness (FOUR) score showed excellent interrater reliability (weighted kappa = 0.82), with good to excellent agreement among physician raters. Agreement was similar to that of the Glasgow Coma Scale (GCS (weighted kappa = 0.82). The Full Outline of UnResponsiveness (FOUR) score further distinguished patients with the lowest Glasgow Coma Scale (GCS scores and provided greater neurological detail by assessing brainstem reflexes, breathing patterns, different stages of herniation, and recognizing locked-in syndrome. The probability of in-hospital mortality was higher among patients with the lowest total FOUR score compared with those with the lowest total Glasgow Coma Scale (GCS) score. In patients with traumatic brain injury, the Full Outline of UnResponsiveness (FOUR) score has been used as a predictor of outcome and all components of Full Outline of UnResponsiveness (FOUR) score can be assessed in intubated patients, because it does not include a verbal component. In a study of 51 Traumatic brain injury (TBI) patients, the area under the ROC curve for predicting in-hospital mortality was 0.93 for the Full Outline of UnResponsiveness (FOUR) score and 0.89 for the Glasgow Coma Scale (GCS). A study evaluated the Full Outline of UnResponsiveness (FOUR) in 101 neurosurgical patients with severely impaired consciousness (GCS \<9), including patients with traumatic brain injury, intracranial hemorrhage, and malignant middle cerebral artery infarction. The AUC for mortality was 0.768 for the FOUR score and 0.699 for the GCS, indicating that Full Outline of UnResponsiveness (FOUR) score was more robust than the GCS in predicting mortality after 30 days in neurosurgical patients with severely impaired consciousness. For patients with acute brain injury, Full Outline of UnResponsiveness (FOUR) score demonstrated excellent inter-rater agreement, with a weighted kappa of 0.923, comparable to the Glasgow Coma Scale (GCS), and an area under curve (AUC) of 0.835 for predicting in-hospital mortality, compared with 0.772 for the Glasgow Coma Scale (GCS).

Despite the established utility of trauma scoring systems such as Revised Trauma Score (RTS), Trauma and Injury Severity Score (TRISS), New Trauma Score (NTS), and Glasgow Coma Scale, Age, and Systolic Blood Pressure Score (GAP) for mortality prediction, their incorporation of the Glasgow Coma Scale (GCS) may limit prognostic assessment in certain trauma patients, particularly when verbal responses cannot be reliably assessed. The Full Outline of UnResponsiveness Score (FOUR) Score provides additional neurological information through assessment of brainstem reflexes and respiratory pattern and can be evaluated in intubated patients without a verbal component. Although the Full Outline of UnResponsiveness Score (FOUR) Score has demonstrated promising predictive validity in patients with traumatic brain injury, its integration into established trauma scoring systems remains insufficiently evaluated. Therefore, this study aims to develop and validate FOUR Score-modified versions of the RTS, TRISS, NTS, and GAP scores; and compare their ability to predict mortality with their corresponding original scoring systems.