LAUSR

Research Objectives To perform a Rasch Analysis of the Behavioral Assessment Screening Tool (BAST) following the Rasch Reporting Guidelines in Rehabilitation Research (RULER) framework. Design Cross-sectional psychometric study. Setting Community. Participants A total of n=135 adult participants with a history of mild to severe TBI. Interventions Not Applicable. Main Outcome Measures The BAST is an established multidimensional measure of neurobehavioral symptoms with five subscales: Negative Affect, Fatigue, Executive Function, Impulsivity, and Substance Abuse. We assessed all subscales, except substance abuse (due to need for further development of this subscale), using the RULER framework. Results The BAST subscales all met the assumption of unidimensionality, with only one item from the Impulsivity scale displaying item misfit (MnSQ=1.40). Upon removing this item, we found a lower average domain measure (1.42 to -1.49) and larger standard error (0.34 to 0.43) so we retained the item. Items for each of the four subscales ranged in difficulty (i.e. endorsement of symptom frequency) with more severe symptoms endorsed in the Fatigue subscale and milder symptoms endorsed in the Impulsivity subscale. Though Negative Affect and Executive Function displayed appropriate targeting, the Fatigue and Impulsivity Subscales had larger average domain values (1.35 and -1.42) meaning that more items may need to be added to these subscales to capture differences across a wider range of symptom severity. Conclusions Overall, the BAST displayed excellent item and person separation indices and distinct strata for each of the four subscales assessed. Future work should examine the BAST using Rasch analysis in a larger, more representative sample, include more items for the Fatigue and Impulsivity subscale, and include the Substance Abuse subscale. Author(s) Disclosures All authors report no conflicts.