Psychometric properties of the Persian version of the Pittsburgh Sleep Quality Index addendum for PTSD (PSQI-A)

Abstract

Considering the frequent occurrence of natural disasters in Iran, the need for an inventory assessing the quality of sleep in the posttraumatic stress disorder (PTSD) patients is clearly evident. The Pittsburgh Sleep Quality Index addendum for PTSD (PSQI-A) has been recently developed to assess the disruptive nocturnal behaviors in the PTSD patients. This study was aimed to explore the reliability and validity of the Persian version of the PSQI-A. Eighty-five PTSD patients related to the two recent major earthquakes of Kerman Province were enrolled in the study, and 133 healthy subjects were conveniently selected as the control group. The inventory was translated and then back-translated according to standard methods. The reliability was checked by computing the Cronbach;s alpha coefficient and corrected item-total correlation. The sensitivity and specificity were assessed by comparing the PSQI-A score with the DSM-IV-TR diagnosis. Convergent validity was checked against the General Health Questionnaire 12 (GHQ-12). The mean (+/-SD) of the two groups were 42.1(+/-13.8) and 34.2 (+/-9.8), respectively. The sex distribution was comparable in the two groups (females consisted 55% and 58% of the PTSD and control groups, respectively). There were significant differences between the items comparing the two groups except for the "acting out dreams". Overall the Cronbach;s alpha coefficient was 0.89, and the item-total correlation of all the seven items were over 0.4 except for the acting out dreams. At cut-off of 7/8, the sensitivity and specificity were 100% and 93%, respectively. The sum score showed a correlation of 0.66 with the GHQ-12. Although the psychometric properties of one of the seven items of the inventory were to some extent unsatisfactory, the overall reliability and validity of the questionnaire were acceptable.