Psychometric properties of the Kurdish version of Pittsburgh Sleep Quality Index

Background: The Pittsburgh Sleep Quality Index (PSQI) is a standardized questionnaire that used for subjective assessment of sleep quality. It has been translated into several languages and is widely used in clinical research settings. Since there is no sleep-related scale standardized in the Kurdish language, the present study aimed to translate and validate the PSQI into Kurdish.

Methods: First, the PSQI was successfully translated into Kurdish then back-translated into English by independent professional bilingual translators. The translated version of PSQI was tested with 230 participants, 150 healthy subjects, 40 subjects with insomnia, and 40 subjects with physical symptoms. Internal consistency was calculated by the Cronbach Alpha method using SPSS-20 software. Spearman correlation via a test-retest process was used for reliability. The General Health Questionnaire (GHQ28) was used to analyze criterion validity. The construct validity of the scale was tested by exploratory factor analysis (EFA). Factor weight was checked by confirmatory factor analysis (CFA) using LISREL software version 8.8.

Results: The internal consistency and reliability for PSQI global score was acceptable (Cronbach's alpha = 0.70). The result showed a strong correlation between test and retest after six weeks (r = 0.83). Correlations between the global score and components of the PSQI with the GHQ28 were all statistically significant (r = 0.23-0.72, p < 0.05). Exploratory factor analysis revealed three factors with a significant correlation between the PSQI global score and these factors. All factor weights were above 0.40.

Conclusion: The results of this study support the PSQI's validity and reliability. This study offers a foundation for further studies in Kurdish populations.