Correlations Between the Neurobehavioral Symptom Inventory and Other Commonly Used Questionnaires for Traumatic Brain Injury

Objective To evaluate the correlations between the Neurobehavioral Symptom Inventory (NSI) and other questionnaires commonly administered within military traumatic brain injury clinics. Setting Military outpatient traumatic brain injury clinics. Participants In total, 15,428 active duty service members who completed 24,162 NSI questionnaires between March 2009 and May 2020. Design Observational retrospective analysis of questionnaires collected as part of standard clinical care. Main Measures NSI, Post-Traumatic Stress Disorder Checklist for DSM-5 and Military Version, Patient Health Questionnaire (PHQ), Generalized Anxiety Disorder, Headache Impact Test (HIT-6), Insomnia Severity Index (ISI), Epworth Sleepiness Scale (ESS), Activities-Specific Balance Confidence Scale (ABC), Dizziness Handicap Inventory (DHI), Alcohol Use Disorders Identification Test (AUDIT), and the World Health Organization Quality of Life Instrument-Abbreviated Version. Only questionnaires completed on the same date as the NSI were examined. Results The total NSI score was moderately to strongly correlated with all questionnaires except for the AUDIT. The strongest correlation was between the NSI Affective Score and the PHQ9 (r  = 0.86). The NSI Vestibular Score was moderately correlated with the ABC (r = –0.55) and strongly correlated with the DHI (r = 0.77). At the item level, the HIT-6 showed strong correlation with NSI headache (r = 0.80), the ISI was strongly correlated with NSI difficulty sleeping (r = 0.63), and the ESS was moderately correlated with NSI fatigue (r = 0.39). Conclusion Clinicians and healthcare administrators can use the correlations reported in this study to determine if questionnaires add incremental value for their clinic as well as to make more informed decisions regarding which questionnaires to administer.