Psychometric Characteristics of the Insomnia Severity Index in Veterans With History of Traumatic Brain Injury

ABSTRACT

Objective/Background: The Insomnia Severity Index (ISI) is a widely used self-report measure of insomnia symptoms. However, to date this measure has not been validated or well-characterized in veterans who have experienced traumatic brain injury (TBI). This study assessed the psychometric properties and convergent, divergent, construct, and discriminate validity of the ISI in veterans with a history of TBI. Participants: Eighty-three veterans with history of TBI were seen in the VA San Diego Healthcare System as part of a research protocol. Methods: Measures included the ISI, Pittsburgh Sleep Quality Index (PSQI), Epworth Sleepiness Scale, Neurobehavioral Symptom Inventory, Beck Depression Inventory-II, Beck Anxiety Inventory, and PTSD Checklist–Military Version. Results: The ISI demonstrated moderate to strong or excellent convergent and divergent validity. A principal component analysis indicated a single construct with excellent internal consistency (Cronbach’s alpha = 0.92). In exploratory analyses, the ISI discriminated well between those with (73%) and without (27%) sleep disturbance based on the PSQI. Conclusions: Results from this study indicate validity of the ISI in assessing insomnia in veterans with history of TBI and suggest a cutoff score not dissimilar from non-TBI populations. Findings from this study can help inform clinical applicability of the ISI, as well as future studies of insomnia in TBI.

SUPPLEMENTAL MATERIAL

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Additional information

Funding

This work was supported in part by Clinical Sciences R&D (DMS: CDA-2-065-10S, LDW: CX000842-01A2 & 829-CDMH-13858) and Rehabilitation Research R&D (HJO: CDA-1 IK2 RX001512-01A2) from the U.S. Department of Veterans Affairs, Department of Defense (LDW: W81XWH-10-2-0169), and National Institute of Mental Health (CNK: T32MH019934, RCM: K23MH107260).