Quality of Life Research

, Volume 23, Issue 2, pp 533–537

The Insomnia Severity Index: cross-cultural adaptation and psychometric evaluation of a Persian version

  • Khosro Sadeghniiat-Haghighi
  • Ali Montazeri
  • Ahmad Khajeh-Mehrizi
  • Saharnaz Nedjat
  • Omid Aminian
Brief Communication

DOI: 10.1007/s11136-013-0489-3

Cite this article as:
Sadeghniiat-Haghighi, K., Montazeri, A., Khajeh-Mehrizi, A. et al. Qual Life Res (2014) 23: 533. doi:10.1007/s11136-013-0489-3

Abstract

Purpose

The main purpose of this study was to describe the cultural adaptation of a Persian version of the Insomnia Severity Index and to evaluate its psychometric properties by testing internal consistency, construct validity, discriminant validity, and concurrent validity.

Methods

Cross-cultural adaptation was carried out according to guidelines and included forward and backward translations, expert committee, and field test. A sample of 1,037 sleep clinic patients filled in a questionnaire package including the Persian version of the Insomnia Severity Index (ISI-P), the Pittsburgh Sleep Quality Index (PSQI), the Epworth Sleepiness Scale (ESS), and the Beck Depression Inventory (BDI). In addition, 624 of these patients were assessed by polysomnography (PSG). A group of 50 members of hospital staff responded to the ISI-P as the control group. Internal consistency with Cronbach’s alpha, construct validity with principal component analysis, discriminant validity with assessing the ISI-P’s ability to differentiate patients from control group and concurrent validity with exploring the spearman correlation with the PSQI, ESS, BDI, and corresponding parameters in PSG were followed to examine the psychometric properties of the ISI-P.

Results

The ISI-P showed acceptable internal consistency (Cronbach’s alpha = 0.78) and a 2-factor solution in factor analysis. The ISI-P discriminated well between patients and control group (15.90 ± 6.12 vs 10.10 ± 5.76, P value <0.001). Items and total score of the ISI-P showed a weak correlation with the corresponding parameters in PSG. The ISI-P total score was significantly correlated with total score of the PSQI (r = 0.74, P value <0.001) and the BDI (r = 0.42, P value <0.001), while it was not significantly correlated with total score of the ESS (r = 0.12, P value = 0.72).

Conclusions

Cross-cultural adaptation was successful, and the ISI-P has good psychometric properties. Using the ISI-P is recommended to evaluate insomnia in research and clinical settings in Persian-speaking people.

Keywords

Insomnia Severity Index Persian Polysomnography Cross-cultural adaptation Psychometric properties 

Supplementary material

11136_2013_489_MOESM1_ESM.pdf (78 kb)
Supplementary material (PDF 77 kb)

Copyright information

© Springer Science+Business Media Dordrecht 2014

Authors and Affiliations

  • Khosro Sadeghniiat-Haghighi
    • 1
    • 2
  • Ali Montazeri
    • 3
  • Ahmad Khajeh-Mehrizi
    • 1
  • Saharnaz Nedjat
    • 4
  • Omid Aminian
    • 2
  1. 1.Occupational Sleep Research CenterTehran University of Medical SciencesTehranIran
  2. 2.Center for Research on Occupational DiseasesTehran University of Medical SciencesTehranIran
  3. 3.Mental Health Research Group, Health Metrics Research CentreIranian Institute for Health Sciences Research, ACECRTehranIran
  4. 4.Department of Epidemiology and Biostatistics, School of Public Health, Knowledge Utilization Research CenterTehran University of Medical SciencesTehranIran

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