Objectives The simplified motor score (SMS) is a three-point measure of traumatic brain injury (TBI) severity, which is easier to calculate than the 15-point Glasgow coma scale (GCS). Using a state trauma registry, the accuracy of the emergency medical services (EMS)-obtained SMS was compared with the GCS for predicting neurological outcomes and mortality.

Methods A retrospective, observational analysis was performed of patients aged 16 years and older in the 2002–7 Ohio Trauma Registry. Those not initially transported by EMS or with incomplete EMS GCS scores were excluded. Outcomes included inhospital mortality, TBI, neurosurgical intervention, any emergency intubation and emergency department intubation. Discriminatory ability was compared using area under the receiver-operating characteristic curves (AUC). Sensitivity and specificity for each outcome were calculated at a SMS cutoff of one or less (any abnormal SMS) and a GCS cutoff of 13 or less.

Results 52 412 patients were identified. Sensitivity, specificity and AUC were similar between the SMS and GCS for all outcomes. Sensitivity for mortality was 72.2% for SMS and 74.6% for GCS. Sensitivity for TBI was 40.8% for SMS and 45.4% for GCS. Sensitivity for neurosurgical intervention was 52.9% for SMS and 60.0% for GCS. Sensitivity for any intubation was 72.7% for SMS and 75.5% for GCS. Specificity was less than 2% different for all outcomes. Discriminatory ability was similar with the difference in AUC between SMS and GCS no greater than 6% for any outcome.

Conclusions In a state trauma registry including both trauma and non-trauma centres, the EMS-obtained SMS performs as well as the 15-point GCS.