Detection of symptom over-reporting on the Neurobehavioral Symptom Inventory in OEF/OIF/OND veterans with history of mild TBI

Abstract

Objective: As part of routine care at Veterans Affairs facilities, veterans with a service-related traumatic brain injury (TBI) are administered a self-report post-concussive symptom measure, the Neurobehavioral Symptom Inventory (NSI). Interpreting the NSI can be problematic given that over-reporting on self-report measures is often found in both civilian and military patient populations. This study investigates embedded scales on the NSI that identify possible and probable symptom exaggeration. Method: 183 veterans with a history of mild TBI were administered the Minnesota Multiphasic Personality Inventory, 2nd edition, Restructured Form (MMPI-2-RF) and the NSI. The participants were divided into symptom validity testing pass and fail groups based on their performance on the MMPI-2-RF symptom validity scales. Cut scores on the NSI Total and Validity-10 scores were then established and applied to two additional veteran populations. Results: Sensitivity and specificity values were derived for all NSI Total and Validity-10 values. Optimal cut scores were determined based on specificity levels of ≥95%. The NSI Total cut score was ≥57 for possible and ≥67 for probable symptom exaggeration and the Validity-10 cut score was ≥22 for possible and ≥27 for probable symptom exaggeration, with sensitivity ranging from 27 to 43%. Applying these cut scores to a broader clinical and research sample resulted in lower rates of suspected exaggeration. Conclusions: Both the NSI Total and Validity-10 cut scores consistently identified potential symptom exaggeration across three mild TBI samples. Clinicians and researchers who use the NSI are encouraged to utilize either embedded validity measure in their practice.

Keywords:

• NSI Validity-10
• symptom validity testing
• symptom exaggeration
• mild TBI
• veterans

Acknowledgements

We would like to acknowledge the support of: O1062-I (PI- Scheibel RS) VA RR&D, “A Longitudinal Study of Chronic TBI in OEF/OIF/OND Veterans and Service Members.”

Notes

1. The 4 TBI screen items are:

(1) Did you have any injury(ies) during your deployment from any of the following? (check all that apply: fragment, bullet, explosion, etc), (2) Did any injury you received while deployed result in any of the following? (check all that apply: being dazed, confused or “seeing stars,” not remembering the injury, losing consciousness, head injury, etc), (3) Did any of these begin or get worse afterward? (check all that apply: dizziness, headaches, memory problems, balance problems, ringing in the ears, irritability, sleep problems), and (4) In the past week, have you had any of the above symptoms? (check all that apply: dizziness, memory problems, etc). (Belanger et al., 2009, p. 6)