The Brain Injury Functional Outcome Measure (BI-FOM): A single instrument capturing the range of recovery in moderate-severe traumatic brain injury.

Abstract Objective To develop a measure of global functioning after moderate-severe TBI with similar measurement precision but a longer measurement range than the FIM. Design Phase 1: Retrospective analysis of 5 data sets containing FIM, DRS, and other assessment items, to identify candidate items for extending the measurement range of the FIM; Phase 2. Prospective administration of 49 candidate items from phase 1, with Rasch analysis to identify a unidimensional scale with an extended range. Setting Six TBI Model System rehabilitation hospitals. Participants 184 individuals with moderate-severe injury recruited during inpatient rehabilitation or at 1-year telephone follow up. Interventions Participants were administered the 49 assessment items in person or via telephone. Main Outcome Measure(s) IRT parameters: item monotonicity, infit/outfit statistics, and Factor 1 variance. Results After collapsing misordered rating categories and removing misfitting items, we derived the Brain Injury Functional Outcome Measure (BI-FOM), a 31-item assessment instrument with high reliability, greatly extended measurement range, and improved unidimensionality in comparison to the FIM. Conclusions The BI-FOM improves global measurement of function after moderate-severe brain injury. Its high precision, relative lack of floor and ceiling effects, and feasibility for telephone follow up, if replicated in an independent sample, are substantial advantages.