The Glasgow Outcome Scale-Extended (GOSE) is one of the most widely used measures of functional limitations after traumatic brain injury (TBI), and is the primary outcome measure used in clinical trials of acute TBI treatment. However, the GOSE appears insensitive to the full spectrum of TBI-related functional limitations, which may limit its potential to capture treatment effects or correlate with other variables that impact outcome. The Functional Status Examination (FSE) was designed to improve on the assessment of injury-related functional limitations using a standardized assessment and wider possible score range. The aim of this pilot study was to employ item response theory (IRT) to test the hypothesis that the FSE yields more precise estimation of functional outcome than the GOSE. Traumatically injured patients (n = 100, 77 TBI, 23 orthopedic injuries) were interviewed at 3 months post-injury using both the GOSE and FSE structured interviews. IRT was used to quantify and compare the tests' information functions, which reflect the degree to which each instrument precisely measures functional limitations across the severity spectrum. Findings were consistent with predictions: the FSE yielded stronger measurement of functional limitations (i.e., higher test information) across a wider range of severity than the GOSE, whether scoring the GOSE from all interview items or using the traditional GOSE overall score. Although the FSE appears to be a promising alternative measure to the GOSE, further research is needed to cross-validate these findings in a larger sample and understand how to best deploy it in clinical and translational research.
Keywords: FSE; GOSE; IRT; TBI; outcome measurement.