Introduction: The Glasgow Coma Scale (GCS) and pupil response to light are commonly used to assess brain injury severity and predict outcomes. The aim of this study was to investigate whether the GCS combined with pupil response (GCS-P), compared to the GCS alone, could be a better predictor of hospital mortality for patients with traumatic brain injury (TBI).
Methods: A retrospective cohort study was undertaken at an adult level one trauma centre including patients with isolated TBI of Abbreviated Injury Scale above three. The GCS and pupil response were combined to an arithmetic score (GCS score (range 3-15) minus the number of nonreacting pupils (0, 1, or 2)), or by treating each factor as separate categorical variables. The association of in-hospital mortality with GCS-P as a categorical variable was evaluated using Nagelkerke's R2 and compared using areas under the receiver operating characteristic (AUROC) curve.
Results: There were 392 patients included over the study period of 1 July 2014 and 30 September 2017, with an overall mortality rate of 15.2%. Mortality was highest at GCS-P of 1 (79%), with lowest mortality at a GCS-P 15 (1.6%). Nagelkerke's R2 was 0.427 for GCS alone and 0.486 for GCS-P. The AUROC for GCS-P to predict mortality was 0.87 (95%CI: 0.82-0.72), higher than for GCS alone (0.85; 95%CI: 0.80-0.90; p < .001).
Discussion: GCS-P provided a better predictor of mortality compared to the GCS. As both the GCS and pupillary response are routinely recorded on all patients, combination of these pieces of information into a single score can further simplify assessment of patients with TBI, with some improvement in performance.
Keywords: Glasgow Coma Scale; Wounds and injuries; brain injury; mortality; pupil constriction.