P056 Improvements in Daytime Function Items of the Insomnia Severity Index Are Correlated with a Positive Impact of Treatment on the Patient Global Impression Insomnia Scale

Introduction Items 4-7 (daytime function [DF]) of the 7-item Insomnia Severity Index (ISI) can assess daytime impairment. In Study E2006-G000-303 (Study 303; NCT02952820), lemborexant (LEM), a dual-orexin receptor antagonist, was associated at 6 months (6mo) with both significant improvement in ISI-DF items and significantly more subjects reporting positive effects on sleep, as assessed by the Patient Global Impression–Insomnia version (PGI-I), versus placebo (PBO). This analysis looked at the correlation between ISI-DF improvement and patient ratings on the PGI-I. Methods Study 303 was a 12-month, randomized, double-blind PBO-controlled (first 6mo) phase-3 study in adults with insomnia disorder. Subjects were randomized to PBO, LEM 5mg or 10mg for 6mo (2nd 6mo not reported here). ISI items are rated from 0 (no problem) to 4 (very severe problem). ISI-DF includes sleep satisfaction, extent symptoms are noticeable to others, cause worry/distress, and interfere with daily function. On the PGI-I, subjects assess positive, neutral or negative treatment impact on falling asleep, overall benefit on sleep, and total sleep time. Results A total of 739 subjects completed the ISI and PGI-I and were included in these analyses. At 6mo in all treatment groups, there were significant correlations (all P<0.001) between improvement in both ISI-DF items and PGI-I ratings regarding falling asleep, overall benefit on sleep, and total sleep time. Discussion These data suggest that the PGI-I may be a useful, quick tool to use in clinical practice, since an improvement in its score reflects improvements in daytime function. Sponsor Funded by Eisai Inc.