To develop and cross-validate internal validity scales for the Neurobehavioral Symptom Inventory (NSI).
Four existing data sets were used: (1) outpatient clinical traumatic brain injury (TBI)/neurorehabilitation database from a military site (n = 403), (2) National Department of Veterans Affairs TBI evaluation database (n = 48 175), (3) Florida National Guard nonclinical TBI survey database (n = 3098), and (4) a cross-validation outpatient clinical TBI/neurorehabilitation database combined across 2 military medical centers (n = 206).
Secondary analysis of existing cohort data to develop (study 1) and cross-validate (study 2) internal validity scales for the NSI.
The NSI, Mild Brain Injury Atypical Symptoms, and Personality Assessment Inventory scores.
Study 1: Three NSI validity scales were developed, composed of 5 unusual items (Negative Impression Management [NIM5]), 6 low-frequency items (LOW6), and the combination of 10 nonoverlapping items (Validity-10). Cut scores maximizing sensitivity and specificity on these measures were determined, using a Mild Brain Injury Atypical Symptoms score of 8 or more as the criterion for invalidity. Study 2: The same validity scale cut scores again resulted in the highest classification accuracy and optimal balance between sensitivity and specificity in the cross-validation sample, using a Personality Assessment Inventory Negative Impression Management scale with a T score of 75 or higher as the criterion for invalidity.
The NSI is widely used in the Department of Defense and Veterans Affairs as a symptom-severity assessment following TBI, but is subject to symptom overreporting or exaggeration. This study developed embedded NSI validity scales to facilitate the detection of invalid response styles. The NSI Validity-10 scale appears to hold considerable promise for validity assessment when the NSI is used as a population-screening tool.
Departments of Mental Health and Behavioral Sciences (Drs Vanderploeg, Belanger, and Donnell), and Physical Medicine and Rehabilitation (Dr Scott) and Health Services Research and Development (HSR&D)/Rehabilitation Research and Development (RR&D) Center of Excellence: Maximizing Rehabilitation Outcomes (Drs Vanderploeg, Belanger, and Scott), James A. Haley Veterans' Hospital, Defense and Veterans Brain Injury Center (Drs Vanderploeg, Belanger, Donnell, and Scott), and Department of Psychology (Drs Vanderploeg and Belanger) and Psychiatry and Neurosciences (Dr Vanderploeg), University of South Florida, Tampa, Florida; Defense and Veterans Brain Injury Center (Drs Cooper and Kennedy) and Neurology Service, Department of Medicine (Drs Cooper and Kennedy), San Antonio Military Medical Center, Fort Sam Houston, San Antonio, Texas; and Traumatic Brain Injury Clinic, Darnall Army Medical Center, Fort Hood, Killeen, Texas (Dr Hopewell).
Corresponding Author: Rodney D. Vanderploeg, PhD, James A. Haley Veterans' Hospital Psychology Service (116B), 13000 Bruce B. Downs Blvd, Tampa, FL 33612 (Rodney.email@example.com).
This research was supported by the Department of Veterans Affairs, Veterans Health Administration, and Defense and Veterans Brain Injury Center and by a Department of Veterans Affairs Health Service Research & Development grant CCN 06-164 to Steven G. Scott, DO. Further support was provided by the James A. Haley Veterans' Hospital and its HSR&D/RR&D center of excellence.
The views expressed herein are those of the authors and do not necessarily reflect the views or the official policy of the Department of Veterans Affairs or the US government. No potential conflict of interest relevant to this article was reported.
The authors declare no conflicts of interest.