External Validation of the Simplified Motor Score in a Consecutive Cohort of Adult Patients with Traumatic Brain Injury: A Single-Center Retrospective Study

Abstract To externally validate the 3-point Simplified Motor Score (SMS) against the 15-point Glasgow Coma Scale (GCS) for predicting outcomes after traumatic brain injury (TBI). Retrospective cohort of consecutive adult patients with TBI evaluated at the Department of Neurosurgery, University Clinical Centre of Vojvodina, Serbia, in 2017. Discrimination for in-hospital mortality, emergency intubation, and non-home discharge was assessed using the area under the receiver operating characteristics (ROC) curve (AUC), with pairwise comparisons by the DeLong test. Agreement was quantified by Cohen's κ. Of 823 patients, with a median age of 58 years, 66.1% were male, 7.7% died, 9.7% required emergency intubation, and 16.5% had non-home discharge. The AUCs for GCS and SMS were 0.882 versus 0.837 for mortality; 0.967 versus 0.927 for intubation; and 0.835 versus 0.762 for non-home discharge respectively. The AUC differences between GCS and SMS ranged from 0.040 to 0.072. Agreement between SMS ≤ 1 and GCS ≤ 13 was high (κ = 0.84). The GCS was more accurate in patients aged ≥ 65 years. The SMS preserved most of the discriminative ability of the full GCS for acute outcomes but underperformed for disposition outcomes and in older patients. The SMS is best used as a rapid bedside complement to the GCS.