The European Portuguese version of the insomnia severity index

Abstract

Summary Insomnia is the most prevalent sleep complaint, but remains largely an unidentified public health issue. The Insomnia Severity Index (ISI) is a brief self‐report questionnaire to assess insomnia, long‐established both in clinical and research settings. The present study aimed to analyse the reliability, validity, and accuracy of the ISI European Portuguese version. After the translation protocol, 1,274 participants (65.54% female), with a mean (SD, range) age of 37.52 (16.82, 18–95) years, completed the ISI. This sample included 250 patients with insomnia from a Sleep Medicine Centre, presenting a diagnosis of insomnia disorder (Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition; International Classification of Sleep Disorders, Third Edition), and 1,024 individuals from the community. A group of 30 patients with obstructive sleep apnea (OSA) was also recruited. Cronbach’s α was 0.88 (internal consistency), and corrected item‐total correlations ranged from 0.56 to 0.83. An exploratory factor analysis (oblique rotation) revealed a two‐factor solution for both clinical and community samples. The ISI total score significantly differentiated insomnia disorder, no insomnia, and OSA subgroups with a large effect size (η 2 = 0.42). The correlation between ISI and Pittsburgh Sleep Quality Index supported concurrent validity (0.82), and discriminant validity was confirmed by a moderate correlation between ISI and Beck Depression Inventory Second Edition (0.32). The area under the curve was 0.88, and the optimal cut‐off to detect clinical insomnia was 14 (82.1% sensitivity, 79.5% specificity). In conclusion, the Portuguese version of the ISI is a reliable and valid measure of insomnia in clinical and non‐clinical populations. Our present study also contributes to relevant data for the international literature regarding the cut‐off score of the scale for the detection of clinical insomnia.

Psychometric Properties of the Insomnia Severity Index Among Arabic Chronic Diseases Patients

“…The CFA of the current study found that a two-factor model which was labeled as “Factor I: Impact (2, 3, 4, and 5)” and “Factor II: Severity (1a, 1b, and 1c)” showed absolute fit indices. A similar model was found to have the best fit in studies involving a Portuguese clinical sample ( Clemente et al, 2021 ), and an American sickle cell disease sample ( Moscou-Jackson et al, 2016 ). In terms of clinical samples, previous studies conducted to evaluate the structure of the ISI show different model structures within the seven items.…”

Psychometric Properties of the Sleep Locus of Control (SLOC) Scale in a Portuguese Sample

“…Higher scores are associated with a greater severity of insomnia (Bastien et al, 2001 ; Morin, Belleville, et al, 2011 ; Morin, Leblanc, et al, 2011 ). For this study, the European Portuguese version by Clemente et al ( 2021 ) was used and had acceptable internal consistency (Cronbach’s alpha = .83).…”

A Course on Cognitive and Behavioural Interventions for Sleep Disorders within a Master Degree Programme in Clinical and Health Psychology

“…In addition to an individual end-of-semester examination (comprising ~ 50 multiple choice questions), there is a practical written assignment developed by students in small groups. More specifically, for the practical assignment, students are invited to complete individually and in an anonymous way a sleep diary (Consensus Sleep Diary) for one to two weeks (Carney et al, 2012;Portuguese translation: Marques & Gomes, 2012), the Pittsburgh Sleep Quality Index [PSQI] (Buysse et al, 1989; Portuguese version validation study: Gomes et al, 2018), a questionnaire on sleep quality plus sleep-wake schedules and durations devised by the responsible for the unit (Gomes et al, 2015;Miller-Mendes et al, 2019); the Insomnia Severity index [ISI] (Morin, 1993;Bastien et al, 2001;Portuguese version/validation: Clemente, 2007;Clemente et al, 2017;Clemente et al, 2021); the Glasgow Sleep Effort Scale (Broomfield & Espie, 2005;Portuguese version: Meia-via et al, 2016), the Epworth Sleepiness Scale [ESS] (Johns, 1991;Portuguese version and main studies: Santos et al, 2001;Guimarães et al, 2012;Sargento et al, 2015); the Stop-Bang (Chung et al, 2008;Portuguese version/validation: Pereira et al, 2013;Reis et al, 2015); and the Composite Morningness Scale [CMS] (Smith et al, 1989; Portuguese version/successive psychometric studies: Silva et al, 1995/ Buekenhout et al, 2019Gomes, 2005;Gomes et al, 2016;Silva et al, 2016), among other possibilities. These tools are introduced gradually, accompanying the contents addressed in class, each week (e.g., the CMS is administrated following the normal inter-individual differences in sleep-wake patterns topic; the ISI is introduced during the insomnia classes).…”