B - 44 Examining Test–Retest Reliability and Mean Score Differences in Self-Reported Neuropsychological Symptoms in Active-Duty and Veterans with Mild Traumatic Brain Injury (Mtbi)

Abstract Objective Test–retest reliability is a foundational psychometric property of tests, providing a means through which tests may be assessed for time invariant interpretation. This study evaluated the test–retest reliability of several self-report instruments commonly employed in a veteran/military neurocognitive rehabilitation setting. Method Repeat administration of the Neurobehavioral Symptom Inventory (NSI), Key Behaviors Change Inventory (KBCI), Veterans RAND 12 Item Health Survey (VR12), C4 Inventory, Center for Epidemiologic Studies-Depression, Post-traumatic Checklist-DSM-5 (PCL-5), and the Epworth Sleepiness Scale (ESS) was collected across baseline, one, four, and twelve week timepoints. Interclass correlation coefficients and a two-way mixed ANOVA was conducted on 31 Veteran and 22 Active-duty participants (71.5% male). Results Most measures demonstrated a significant mean difference during follow-up, with reductions across the 1- and 4-week follow-ups. ICC ranged from good to excellent (0.76–0.93) across the measures. Correlations between time points on measures were high (e.g., PCL-5 Baseline/4wk r = 0.93), suggesting high reliability for measures despite changing scores after treatment completion. Conclusions This study found good test–retest reliability across the three follow-up timelines, supporting the use of the included measures in neurocognitive rehabilitation settings. Reliability and post-treatment changes in symptoms observed across these measures will be further discussed.