Predictive Accuracy of Glasgow Coma Scale and Pupillary Data on Presence of Traumatic Brain Injury

<b>Background/Objectives:</b> The GCS is widely used to assess a patient's level of consciousness after trauma. Although not a diagnostic tool for traumatic brain injury (TBI), prehospital clinicians frequently rely on GCS findings-along with pupil exam, mechanism of injury, and clinical presentation, to estimate the likelihood that TBI may be present before imaging is available. However, the GCS has known limitations and fails to identify a significant proportion of TBI patients. This study aimed to evaluate the association between GCS scores and the presence of TBI, and whether additional clinical variables improve its discriminatory value. <b>Methods:</b> This retrospective cohort study analyzed data from trauma patients registered in the TraumaRegister DGU^® between 2015 and 2017. TBI was defined as a head injury with an Abbreviated Injury Scale (AISHead) score of ≥2. Inclusion criteria consisted of trauma team activations with a maximum AIS ≥ 3 and/or the need for intensive care. Prognostic values were assessed using multivariable logistic regression analysis. <b>Results:</b> 40,216 patients were included of which 17,205 (42.8%) were diagnosed with TBI and 23,011 (57.2%) were non-TBI patients. In the TBI group, 36.4% (n = 6216) presented with an initial GCS of 15 prehospitally. 17.8% (n = 3059) of TBI patients had anisocoric or bilaterally dilated pupils, 22.1% (n = 3799) had sluggish or fixed light reactivity and 17% (n = 2934) had no motoric response in Eppendorf-Cologne Scale (ECS) motor component. GCS score by itself showed better TBI prediction value than pupil size or reactivity or motor component alone. Nevertheless, substantial misclassification was observed when using GCS alone: 25.7% of patients with a normal GCS (15) had TBI (AIS Head ≥ 2), while 19.1% of patients with GCS 3 had no TBI. In the non-TBI group, 2.7% (n = 622) had a GCS of 3, 2.9% (n = 685) had anisocoric or bilaterally dilated pupils, 4.2% (n = 960) had sluggish or fixed light reactivity and 3.3% (n = 751) had no motoric response. Even at the lowest GCS score of 3, 19.1% of patients did not have TBI, while a normal GCS of 15 still included 25.7% of patients with TBI. <b>Conclusions:</b> The expanded model combining GCS with pupillary assessment and the ECS motor component demonstrated superior performance in prehospital TBI detection compared with the GCS alone. Implementing an extended GCS incorporating pupillary and ECS assessment may facilitate earlier recognition of TBI and support timely triage decisions; however, potential effects on patient outcomes require confirmation in prospective studies.