Measurement properties of the Neurobehavioral Cognitive Status Examination (Cognistat) in traumatic brain injury rehabilitation

Objective: Evaluate measurement properties of the Neurobehavioral Cognitive Status Examination (Cognistat) using Rasch analysis. Design: Calibration of item responses from 120 individuals admitted to a rehabilitation medicine service for traumatic brain injury (TBI) and 296 community-dwelling adults with TBI. Results: Three strata of performance were differentiated despite a skewed distribution toward high performance among the community sample. Elimination of easier items created a better targeted instrument (i.e., generated more spread among individuals) without a significant increase in error. Memory and verbal reasoning were the most difficult domains for each sample; however, analyses indicated significant measurement error. Conclusions: As a screening instrument, the Cognistat reliably classifies multiple levels of cognitive status in both acute and postacute TBI settings; however, this measure is unsuitable for generating a profile of neurocognitive strengths and weaknesses.