title: Validation study of the Italian version of the Insomnia Severity Index (ISI).
abstract: To test the factorial structure of the Italian version of the Insomnia Severity Index (ISI) using a confirmatory approach and to assess its psychometric properties. ISI questionnaire was completed by 272 patients (average age 41.28, range 18-73) with insomnia diagnosis performed by a sleep medicine physician and retrospectively enrolled in the study. All patients underwent Cognitive Behavioral Treatment for Insomnia (CBT-I) and completed sleep diaries before starting the treatment. Data from sleep diaries were analyzed for assessing concurrent validity of the ISI. Confirmatory factor analysis (CFA) for ordinal Likert-type items was applied to compare four competing models proposed in the literature. 244 patients, out of the 272, completed the ISI at the end of CBT-I. A comparison of ISI score before and after treatment was performed. The CFA analysis confirmed the presence of three main factors conceptualized as severity and impact of the disease along with sleep satisfaction. Significant correlations of the first three items of the questionnaire, investigating three different subtypes of insomnia, and the subjective measures from the sleep diaries were found, thus supporting the concurrent validity of the test. Sleep efficiency (SE) had a significant inverse correlation with the severity and satisfaction factors and with ISI's total score. After CBT-I treatment, a significant reduction of ISI's scores was observed, thus confirming the effectiveness of the CBT-I treatment. The internal reliability coefficient was 0.75. The ISI questionnaire maintains good psychometric properties in the Italian version, thus confirming that this instrument is reliable for detecting insomnia severity and identifying patients' symptoms.
authors.affiliation: Department of Clinical Neurosciences, Neurology, OSR-Turro, Sleep Disorders Center, University San Raffaele, Milan, Italy.
authors.forename: Vincenza
authors.initials: V
authors.lastname: Castronovo
authors.affiliation: Department of Clinical Neurosciences, Neurology, OSR-Turro, Sleep Disorders Center, University San Raffaele, Milan, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Galbiati
authors.affiliation: Department of Clinical Neurosciences, Neurology, OSR-Turro, Sleep Disorders Center, University San Raffaele, Milan, Italy.
authors.forename: Sara
authors.initials: S
authors.lastname: Marelli
authors.affiliation: University Centre of Statistics in the Biomedical Sciences (CUSSB), Vita-Salute San Raffaele University, Milan, Italy.
authors.forename: Chiara
authors.initials: C
authors.lastname: Brombin
authors.affiliation: University Centre of Statistics in the Biomedical Sciences (CUSSB), Vita-Salute San Raffaele University, Milan, Italy.
authors.forename: Federica
authors.initials: F
authors.lastname: Cugnata
authors.affiliation: Department of Clinical Neurosciences, Neurology, OSR-Turro, Sleep Disorders Center, University San Raffaele, Milan, Italy.
authors.forename: Laura
authors.initials: L
authors.lastname: Giarolli
authors.affiliation: Department of Clinical Neurosciences, Neurology, OSR-Turro, Sleep Disorders Center, University San Raffaele, Milan, Italy.
authors.forename: Matteo Mario
authors.initials: MM
authors.lastname: Anelli
authors.affiliation: Department of Clinical Neurosciences, Neurology, OSR-Turro, Sleep Disorders Center, University San Raffaele, Milan, Italy.|Neurology Clinic, Spedali Civili di Brescia Hospital, University of Brescia, Brescia, Italy.
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Rinaldi
authors.affiliation: Department of Clinical Neurosciences, Neurology, OSR-Turro, Sleep Disorders Center, University San Raffaele, Milan, Italy. ferinistrambi.luigi@hsr.it.
authors.forename: Luigi
authors.initials: L
authors.lastname: Ferini-Strambi
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D015928:Cognitive Behavioral Therapy; D005163:Factor Analysis, Statistical; D005260:Female; D006801:Humans; D007558:Italy; D008297:Male; D008875:Middle Aged; D017063:Outcome Assessment, Health Care; D011594:Psychometrics; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012720:Severity of Illness Index; D007319:Sleep Initiation and Maintenance Disorders / Q000175:diagnosis* / Q000534:rehabilitation; D014175:Translating; D055815:Young Adult
keywords: Cognitive behavioral therapy for insomnia; Confirmatory factor analysis; Insomnia; Insomnia Severity Index; Sleep diary