The IDSIQ showed score changes that correlated with clinically meaningful improvement on various responder definition estimates following triangulation.
Using a randomized, double-blind, placebo-controlled phase 3 trial (NCT03545191) of daridorexant (Quviviq; Idorsia) in adults with insomnia, the incorporation of the Insomnia Daytime Symptoms and Impacts Questionnaire (IDSIQ), a patient-reported outcome instrument, was found to be sensitive to changes in patients who experience daytime impacts of insomnia.1
The findings, presented at the 2022 SLEEP Annual Meeting, June 4-8, in Charlotte, North Carolina, also showed that the tool is effective in evaluating treatment efficacy on daytime functioning in such patients. Originally modified from the Daytime Insomnia Symptom Scale, an existing 20-item instrument for assessing daytime functioning, IDSIQ is comprised of 14 items grouped into domains such as Alert/Cognition, Mood, and Sleepiness.
Senior author Dalma S. Kinter, PhD, global medical director, Medical Affairs, Idorsia, and colleagues analyzed data on 930 adults with insomnia who completed the ISDIQ daily during treatment with daridorexant. Spearman correlations were calculated for changes in IDSIQ scores and potential anchors: Insomnia Severity Index, Patient Global Assessment of Disease Severity, Patient Global Impression of Severity, and Patient Global Impression of Change, applying a prespecified threshold of 0.30 (moderate association).
At month 1 (95% CI, 0.36-0.44) and month 3 (95% CI, 0.45-0.57), the score change correlations for the potential anchors and IDSIQ were all above 0.30. Anchor-based analyses of weekly average IDSIQ total and domain scores were used to estimate responder definitions (RD), which were then triangulated to identify values that converge. Triangulated mean IDSIQ score changes in patients with clinically relevant improvement on the different anchors that supported RD thresholds for a clinically relevant improvement were 17 points for the total score, 9 points for the Alert/Cognition domain, 4 points for the Mood domain, and 4 points for the Sleepiness domain.
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Distribution-based and receiver operating characteristic analyses calculated standard error of measurement (SEM), 0.5 standard deviation (SD), and Youden index as supportive evidence for anchor-based RD estimates. At the conclusion of the study, Kinter et al saw SEM and 0.5 SD values that were within ranges of anchor-based IDSIQ score changes. Additionally, the Youden index was maximized or near-maximized when the RD estimates were used as thresholds for identifying responders based on the anchors.
The validation of the IDSIQ in 2020 was done using individuals from an interventional study (NCT03056053) in which patients with insomnia (n = 114) received zolpidem 5- or 10-mg daily for 2 weeks and an observational study (n = 103) that included subjects with no diagnosis of insomnia, considered “good sleepers.” Participants in both studies completed the IDSIQ daily for 2 weeks, with exit interviews conducted for those who completed the interventional study.2
Results showed that those who completed exit interviews (n = 41) demonstrated a good understanding of the IDSIQ response scales. Day 1 mean scores were higher (worse) in those with insomnia compared with good sleepers. After removing 4 items, the final 14 items showed strong, consistent, reliability. This was evidenced by day 1 Chronbach’s alpha of 0.917 for IDSIQ total score and 0.806-0.918 for the domains. Test-retest reliability, assessed for subjects with insomnia with no change on the Patient Global Assessment of Disease Severity scale between day 1 and day 8, was also good (intra-class correlation coefficient 0.856-0.911).2
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