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Psychometric properties and accuracy of the European Portuguese version of the Pittsburgh Sleep Quality Index in clinical and non-clinical samples

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Abstract

To assess the reliability and validity concerning the formal European Portuguese version of the Pittsburgh Sleep Quality Index [PSQI (EP)], its accuracy, and optimal cut-off point. N = 564 volunteers (18–80 years old) recruited in several settings (e.g., university campuses; work place; home; sleep consultations), agreed to complete the PSQI (EP). Subgroups completed additional measures: Insomnia Severity Index (ISI), STOP-Bang, Glasgow Sleep Effort Scale, or responded to a supplementary question about perceived sleep problems. As to internal consistency, Cronbach’s α = 0.75. Principal component analysis revealed a unidimensional structure. Six PSQI (EP) components and total scores were able to discriminate individuals who did versus did not describe having any sleep problem; all PSQI (EP) scores were significantly higher (denoting poorer quality) in participants suffering from a sleep disorder. Most Cohen’s d values showed large magnitude associations. PSQI (EP) and ISI scores were highly correlated, but no significant correlations were found considering STOP-Bang. ROC analysis confirmed an optimal cut-off point > 5 of the PSQI (EP) to detect self-reported poor/good sleepers in non-clinical settings. To discriminate non-clinical from clinical sleep patients, the optimal cutoff was > 7, and AUC = 0.94. The European Portuguese version of the PSQI performs as a reliable, valid, and accurate measure of overall sleep quality in Portuguese participants. Furthermore, results suggest that PSQI (EP) can discriminate poor sleepers in non-clinical settings, in addition to demonstrating high clinical accuracy in signaling potential sleep-disorder cases. In conclusion, the PSQI (EP) is a suitable tool to assess general sleep quality in Portuguese participants, both for clinical or non-clinical applications.

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Notes

  1. There are two standard forms of Portuguese language: the Portuguese for Portugal also termed European Portuguese (which is the reference for Portugal, the Portuguese-speaking African countries, East Timor and Macau), and the Brazilian Portuguese.

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Acknowledgements

Thanks are due to the Department of Education and Psychology of the University of Aveiro, which supported most printed materials for data collection. We also acknowledge the support from the R&D Unit IBILI (FM-UC), FCT Portugal (Portuguese Science and Technology Foundation). Manuscript preparation is presently supported by the corresponding author’s current institutional affiliations: Faculty of Psychology and Educational Sciences, University of Coimbra (FPCE-UC), and FCT R&D Unit CINEICC: Center for Research in Neuropsychology and Cognitive Behavioral Intervention, at the FPCE-UC. We are grateful to A. R. Salgueiro, C. T. Carlos, J. M. Ribeiro, and R. G. Dischler for their contribution to participant recruitment and database insertion of questionnaires.

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Author notes

  1. Ana Allen Gomes and Daniel Ruivo Marques have contributed equally for the present work.

Authors and Affiliations

  1. Faculty of Psychology and Educational Sciences, University of Coimbra, Rua Do Colégio Novo, 3000-115, Coimbra, Portugal

    Ana Allen Gomes

  2. FCT R&D Unit, Center for Research in Neuropsychology and Cognitive Behavioral Intervention, Faculty of Psychology and Educational Sciences, CINEICC, Rua Do Colégio Novo, 3001-802, Coimbra, Portugal

    Ana Allen Gomes, Daniel Ruivo Marques & Vanda Clemente

  3. Department of Education and Psychology, University of Aveiro, Campus Universitário De Santiago, 3810-193, Aveiro, Portugal

    Daniel Ruivo Marques, Ana Maria Meiavia & Filipa Cunha

  4. Sleep Medicine Centre, Coimbra University Hospital Centre (CHUC), Coimbra, Portugal

    Vanda Clemente

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  1. Ana Allen Gomes
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  2. Daniel Ruivo Marques
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  3. Ana Maria Meiavia
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Correspondence to Ana Allen Gomes.

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All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. This article does not contain any studies with animals performed by any of the authors.

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Informed consent was obtained from all individual participants included in the study.

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Gomes, A.A., Marques, D.R., Meiavia, A.M. et al. Psychometric properties and accuracy of the European Portuguese version of the Pittsburgh Sleep Quality Index in clinical and non-clinical samples. Sleep Biol. Rhythms 16, 413–422 (2018). https://doi.org/10.1007/s41105-018-0171-9

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