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=3,197) and Sample 2 (n=247) individuals aged ≥60years 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=.97-.98). An ISI-3 score of ≥7 maximized sensitivity (.94-.97) and specificity (.88-.91) with kappa=.68-.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)