Glasgow coma scale motor score and pupillary reaction to predict six-month mortality in patients with traumatic brain injury: comparison of field and admission assessment

Abstract

The Glasgow Coma Scale (GCS) and pupillary reactivity are well-known prognostic factors in traumatic brain injury (TBI). The aim of this study was to compare the GCS motor score and pupillary reactivity assessed in the field and at hospital admission and assess their prognostic value for 6-month mortality in patients with moderate or severe TBI. We studied 445 patients with moderate or severe TBI from Austria enrolled to hospital in 2009-2012. The area under the curve (AUC) and Nagelkerke's R(2) were used to evaluate the predictive ability of GCS motor score and pupillary reactivity assessed in the field and at admission. Uni- and multi-variable analyses-adjusting for age, other clinical, and computed tomography findings-were performed using combinations of field and admission GCS motor score and pupillary reactivity. Motor scores generally deteriorated from the field to admission, whereas pupillary reactivity was similar. GCS motor score assessed in field (AUC=0.754; R(2)=0.273) and pupillary assessment at admission (AUC=0.662; R(2)=0.214) performed best as predictors of 6-month mortality in the univariate analysis. This combination also showed best performance in the adjusted analyses (AUC=0.876; R(2)=0.508), but the performance of both predictors assessed at admission was not much worse (AUC=0.857; R(2)=0.460). Field GCS motor score and pupillary reactivity at hospital admission, compared to other combinations of these parameters, possess the best prognostic value to predict 6-month mortality in patients with moderate-to-severe TBI. Given that differences in prognostic performance are only small, both the field and admission values of GCS motor score and pupillary reaction may be reasonable to use in multi-variable prediction models to predict 6-month outcome.

Keywords: Glasgow Coma Scale; assessment at admission; prehospital assessment; pupillary reactivity; traumatic brain injuries.

FIG. 1.

Six-month mortality in subsets of patients created based on their GCS motor score (A) and pupillary reactivity (B) assessed in field or at admission. GCS, Glasgow Coma Scale.

FIG. 2.

Performance of GCS and pupillary reaction assessed in field and at admission in univariate analysis. AUC, area under the receiver-operating curve; GCSf, Glasgow Coma Scale-Motor Score assessed in field; GCSa, Glasgow Coma Scale-Motor Score assessed at admission; PUPf, pupillary reactivity assessed in field; PUPa, pupillary reactivity assessed at admission.

FIG. 3.

Performance of the combinations of GCS and pupillary reaction with age (IMPACT core model) and with hypoxia, hypotension, and computed tomography (CT) characteristics (IMPACT extended model). The IMPACT core models uses age, pupillary reaction and GCS motor score as additional predictors; The IMPACT extended model uses age, pupillary reaction, GCS motor score, CT classification, hypoxia, hypotension, traumatic subarachnoid hemorrhage and epidural mass as additional predictors. AUC, area under the receiver-operating curve; CI, confidence interval; GCSf, Glasgow Coma Scale-Motor Score assessed in field; GCSa, Glasgow Coma Scale-Motor Score assessed at admission; IMPACT, the International Mission for Prognosis and Analysis of Clinical Trials; PUPf, pupillary reactivity assessed in field; PUPa, pupillary reactivity assessed at admission.

FIG. 4.

Availability of the set of GCS motor score and pupillary reaction values at different points of assessment. *Based on our analysis, this is the combination of GCS motor score assessed in field and pupillary reactivity assessed at admission, which had the best prognostic performance of all combinations analyzed. **Refers to the availability of either the set of values assessed in field or the set of values assessed at admission.