Psychometric performance of the Oviedo Sleep Questionnaire in patients with severe mental disorder

Introduction: The prevalence of sleep disturbances among patients with severe mental disorder ranges from 30 to 80%. Since the impact of these disturbances on patients' lives is substantial, there is a need for their evaluation and management. The aim of this study was to examine the reliability and validity of the Oviedo Sleep Questionnaire (OSQ) in patients with severe mental disorder. Material and methods: We performed an observational, prospective (3-month), multicenter study. A total of 259 individuals (184 patients with severe mental disorder and 75 controls) were included. Evaluation: the OSQ, the sleep items of the Bech-Rafaelsen's Scales for Depression (MES item 3) and Mania (MAS item 5), and the Clinical Global Impression Scales for Severity of Mental Disorder (CGI-SMD) and Sleep Disorder (CGI-SSD). Results: a) Factorial structure: two factors accounted for 57.65% of the variance; factor 1 (insomnia) accounted for 44.65% and factor 2 (hypersomnia) for 13%; b) internal consistency: total OSQ = 0.90, insomnia scale = 0.91, hypersomnia scale = 0.88; c) test-retest reliability = 0.87; d) convergent validity: Pearson's correlation coefficients were 0.632 with item 3 of the MES, 0.619 with item 5 of the MAS, and 0.630 with the CGI-SS (p < 0.001); e) discriminant validity: the OSQ was able to differentiate between patients and controls (p = 0.018), and among distinct degrees of mental disorder severity (CGI-SMD) (p < 0.001) and sleep disorder severity (CGI-SSD) (p < 0.001); f) responsiveness: the OSQ, like the CGI-SSD (p = 0.004), identified a significant decrease in the insomnia severity score after 3 months (p = 0.005). Conclusions: The OSQ is a valid and reliable method for measuring the sleep/wake cycle in patients with severe mental disorder. (C) 2009 Sociedad Espanola de Psiquiatria and Sociedad Espanola de Psiquiatria Biologica. Published by Elsevier Espana, S.L. All rights reserved.