Reliability and validity of the Persian version of the Pittsburgh Sleep Quality Index (PSQI-P)

There is a high worldwide prevalence of sleep quality disturbances, and sleep disturbances have been associated with numerous diseases. Thus, it is important to assess sleep quality. The Pittsburgh Sleep Quality Index (PSQI) is a self-rating questionnaire that can be completed within 5 min, but no Persian language version is available.

We translated the PSQI into Persian and then back into English to ensure the accuracy of the translation. A total of 125 psychiatric patients (generalized anxiety disorder, n = 37; major depression, n = 35; schizophrenia, n = 28; primary insomnia, n = 25) and 133 controls completed our Persian version of this questionnaire. Internal consistency, construct validity, and sensitivity and specificity of the PSQI were assessed.

The mean ages (±SD) of the patient and control groups were 36.8 years (±13.9) and 34.2 years (±9.8), respectively (p = 0.08). Cronbach's alpha coefficient for all subjects was 0.77 and was 0.52 for the patient group and 0.78 for the control group. The corrected item-total correlations ranged from 0.30 to 0.75 for the seven component scores of the PSQI. When the general health questionnaire-12 was used as a measure of psychiatric morbidity, it was well correlated with the PSQI scores (r = 0.54, p < 0.001). The sensitivity and specificity of discrimination of insomniac patients from control subjects were 94% and 72% for a PSQI cutoff value of 5 and 85% and 84% for a PSQI cutoff value of 6.

The psychometric properties of the Persian version of the PSQI were acceptable.