ISI-3: evaluation of a brief screening tool for insomnia

Abstract

Study objectives: We evaluated the performance of the Insomnia Severity Index-3 (ISI-3) as a short screening tool to identify clinically significant insomnia derived from the 7-item ISI in an older primary care population.

Methods: We used results from two surveys including the 7-item ISI: Sample 1 (n = 3197) and Sample 2 (n = 247) individuals aged ≥60 years with a diagnosis of osteoarthritis from electronic health records. The 7 items were: difficulty falling asleep, difficulty staying asleep, waking too early, sleep satisfaction, sleep interference with daytime functioning, noticeability of sleep problems by others, and worry about sleep. The ISI-3 included items with highest item-total correlations to the 7-item ISI from Sample 1. A 7-item ISI score ≥15 was defined as clinically significant insomnia and served as the primary criterion for the ISI-3. We derived operating characteristics to determine the diagnostic accuracy and cut-points to maximize sensitivity and specificity for both samples.

Results: The items with the highest item-total correlations were: sleep dissatisfaction, sleep interference with daily functioning, and worry about sleep problems (r = 0.78-0.81); while difficulty falling asleep, difficulty staying asleep, waking too early and noticeability of sleep problems by others showed lower correlations (r = 0.60-0.74). The ISI-3 achieved high discriminant validity in identifying insomnia (AUC = 0.97-0.98). An ISI-3 score of ≥7 maximized sensitivity (0.94-0.97) and specificity (0.88-0.91) with kappa = 0.68-0.71, 89.1-91.5% agreement.

Conclusions: The ISI-3 can effectively screen for insomnia to trigger a more thorough diagnostic evaluation including the 7-item ISI for research or clinical purposes. Future validation studies are needed in other community and clinical populations.

Clinical trial: This manuscript describes secondary analyses of data two National Institutes on Aging-funded clinical trials (ClinicalTrials.gov identifier: NCT01142349, NCT02946957).

Keywords: Difficulty sleeping; Insomnia Severity Index; Insomnia assessment; Insomnia symptoms; Sleep assessment; Sleep problems.

Conflict of interest statement

Conflicts of Interest:

Dr. Von Korff was the Principal Investigator of grants to Group Health Research Institute (GHRI) now Kaiser Permanente Washington Health Research Institute, from Pfizer and the Campbell Alliance Group. Dr. Morin has served as a consultant for Abbott, Merck, Pfizer, and Phillips, and received research support from Idorsia. The remaining authors have no conflicts of interest to report.

Copyright © 2020 Elsevier B.V. All rights reserved.

Figures

Figure 1.

ROC curve for the ability of ISI-3 score of 7 to identify clinically significant insomnia (ISI-7 score of 15)