Reliability and Validity of the Thai Version of the Pittsburgh Sleep Quality Index
Tullaya Sitasuwan MD*, Sontuss Bussaratid MD**, Pimon Ruttanaumpawan MD*, Wattanachai Chotinaiwattarakul MD*
Affiliation : * Department of Medicine, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand ** Department of Psychiatry, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
Objective : To assess the internal consistency, test-retest reliability, and validity of the Thai version of the Pittsburgh Sleep
Quality Index (Thai-PSQI), which was recently translated using a standardized method, in Thai patients with major sleep
disorders.
Material and Method: The Thai-PSQI was developed under a standard translation protocol and administered to “bad”
sleepers (i.e. patients with suspected obstructive sleep apnea [OSA], depression, or insomnia) and “good” sleepers in an
academic tertiary care setting. All participants were asked to complete the same questionnaire after 2-4 weeks.
Results : A total of 138 participants consisting of 69 patients with OSA, 28 with major depression, 11 with primary insomnia,
and 30 controls completed the questionnaire. The global scores of the Thai-PSQI revealed that it had excellent internal
consistency (Cronbach’s alpha = 0.837) and test-retest reliability (intraclass correlation coefficient = 0.89). An analysis of
covariance demonstrated a significant difference in Thai-PSQI global score between good sleepers and bad sleepers (p<0.001).
A cut-off point of 5 out of 6 on the global score resulted in a sensitivity of 77.78% and specificity of 93.33%.
Conclusion : The Thai-PSQI is a valid and reliable tool for screening and identifying the presence of significant sleep
disturbances, and is comparable to the original English version.
Keywords : Pittsburgh sleep quality index, Sleep quality, Sleep questionnaire, Thai sleep quality index
