Psychometric properties of the Sleep Condition Indicator and Insomnia Severity Index in the evaluation of insomnia disorder

Mark Lawrence Wong; Kristy Nga Ting Lau; Colin A Espie; Annemarie I Luik; Simon D Kyle; Esther Yuet Ying Lau

doi:10.1016/j.sleep.2016.05.019

Psychometric properties of the Sleep Condition Indicator and Insomnia Severity Index in the evaluation of insomnia disorder

Sleep Med. 2017 May:33:76-81. doi: 10.1016/j.sleep.2016.05.019. Epub 2016 Oct 22.

Authors

Mark Lawrence Wong¹, Kristy Nga Ting Lau², Colin A Espie³, Annemarie I Luik³, Simon D Kyle³, Esther Yuet Ying Lau⁴

Affiliations

¹ Department of Clinical Psychology, Pamela Youde Nethersole Eastern Hospital, Hospital Authority, Hong Kong.
² Department of Psychology, The University of Hong Kong, Hong Kong.
³ Nuffield Department of Clinical Neurosciences, University of Oxford, UK.
⁴ Department of Psychological Studies, The Education University of Hong Kong, Hong Kong; Centre for Psychosocial Health, The Education University of Hong Kong, Hong Kong; Department of Psychiatry, The University of Hong Kong, Hong Kong. Electronic address: estheryylau@gmail.com.

PMID: 28449911
DOI: 10.1016/j.sleep.2016.05.019

Abstract

Objective: The Sleep Condition Indicator (SCI) and Insomnia Severity Index (ISI) are commonly used instruments to assess insomnia. We evaluated their psychometric properties, particularly their discriminant validity against structured clinical interview (according to DSM-5 and ICSD-3), and their concurrent validity with measures of sleep and daytime functioning.

Methods: A total of 158 young adults, 16% of whom were diagnosed with DSM-5 insomnia disorder and 13% with ICSD-3 Chronic Insomnia by structured interview, completed the ISI and SCI twice in 7-14 days, in addition to measures of sleep and daytime function.

Results: The Chinese version of the SCI was validated with good psychometric properties (ICC = 0.882). A cutoff of ≥8 on the ISI, ≤5 on the SCI short form, and ≤21 on the SCI achieved high discriminant validity (AUC > 0.85) in identifying individuals with insomnia based on both DSM-5 and ICSD-3 criteria. The SCI and ISI had comparable associations with subjective (0.18 < r < 0.51) and actigraphic sleep (0.31 < r < 0.43) and daytime functioning (0.34 < r < 0.53).

Conclusion: The SCI, SCI short form, and ISI were found to correctly identify individuals with DSM-5- and ICSD-3-defined insomnia disorder. Moreover, they showed good concordance with measures of daytime dysfunction, as well as subjective and objective sleep. The SCI and ISI are recommended for use in clinical and research settings.

Keywords: Actigraphy; Psychometrics; Sleep assessment; Sleep diary; Sleep–wake disorders.

MeSH terms

Actigraphy / methods
Female
Humans
Male
Medical Records
Psychometrics / methods*
Self Report
Severity of Illness Index
Sleep / physiology*
Sleep Initiation and Maintenance Disorders / diagnosis*
Sleep Initiation and Maintenance Disorders / physiopathology
Sleep Initiation and Maintenance Disorders / psychology
Sleep Wake Disorders / diagnosis*
Sleep Wake Disorders / physiopathology
Sleep Wake Disorders / psychology
Young Adult