Abstract
Traumatic brain injury (TBI) is a complex injury that has a multi-faceted recovery process. The current "gold standard" for classifying severity of TBI symptoms is the Glasgow Outcome Scale (GOSE), a crude measure of overall dysfunction after TBI. Exploratory factor analysis performed on TRACK-TBI Pilot (N = 297) identified candidate multi-variate outcome measures of neuropsychological impairment and cognitive speed and flexibility at 6 months post-TBI that were confirmed in data from the COBRIT study (N = 645) using confirmatory factor analysis. These new outcome measures were used as the dependent variables in an ordinal logistic regression model, using common data elements (CDE) collected in the emergency department as independent variables, including basic demographics, socioeconomic status, medical history, and measures of blood alcohol and blood pressure. We directly compared these prediction models with the GOSE as the 6-month outcome variable and found that in both the TRACK-TBI pilot and COBRIT studies, both neuropsychiatric complications (approx. 36.0% and 22.3% variance explained) and cognitive speed and flexibility (approx. 33.9% and 24.5% variance explained) were better explained by the prediction model, compared with GOSE (approx. 19.9% and 14.4% variance explained), respectively. While differences in overall distributions of impairment between TRACK-TBI pilot and COBRIT exist and should be explored further for applications of these prediction models, we think these multi-variate end-points more accurately characterize patients' functioning at six-months post-TBI. A multi-variate assessment of end-points seems especially important for characterizing TBI outcomes in cases where gross impairment, such as those measured by the GOSE, may be less evident.