Identifying Unique Symptom Groups Following Mild Traumatic Brain Injury Using the Neurobehavioral Symptom Inventory and PTSD Checklist-5 in Military Personnel: A Bifactor Analysis

To identify both shared and unique groups of posttraumatic stress and postconcussive symptoms using bifactor analysis.Two large military outpatient traumatic brain injury (TBI) rehabilitation clinics in the Southwestern United States.A sample of 1476 Active Duty Service Members seeking treatment for a mild TBI sustained more than 30 days previously, without history of moderate or severe TBI, who completed measures of postconcussive and posttraumatic stress symptoms assessed at clinic intake.Observational, correlational study with data taken from an institutional review board-approved clinical registry study.Neurobehavioral Symptom Inventory (NSI) and Posttraumatic Stress Disorder (PTSD) Checklist for Diagnostic and Statistical Manual of Mental Disorders (Fifth Edition) ( DSM-V ) (PCL-5). Concurrent measures were Patient Health Questionnaire (PHQ-8), Pittsburgh Sleep Quality Index (PSQI), and Headache Impact Test (HIT-6).Results identified a bifactor model demonstrating unique posttraumatic stress, depressive, cognitive, and neurological/somatic symptom groups that were still evident after accounting for a universal factor representing general distress. These symptom groups were differentially related to concurrently measured clinical outcomes.Use of a bifactor structure may help derive clinically useful signals from self-reported symptoms among Active Duty Service Members seeking outpatient treatment for mild TBI.