Validity and reliability of Sleep Quality Scale in subjects with obstructive sleep apnea syndrome

Abstract

Objective: The present study aimed to evaluate the validity and reliability of Sleep Quality Scale (SQS) in subjects with obstructive sleep apnea syndrome (OSAS). Methods: The known group technique was used for construct validity. The study sample was composed of 40 persons with OSAS and 37 normal subjects. OSAS was defined as an apnea-hypopnea index (AHI) of ≥5 plus an Epworth Sleepiness Scale (ESS) score of >10. Control group was composed of subjects who had no history of depression and sleep problems as identified by self-report and polysomnography. A Cronbach's alpha coefficient was used for internal consistency. Results: The total SQS score of the OSAS subjects was significantly higher than that of the normal subjects. The SQS score homogeneity was high with a Cronbach's alpha coefficient of 0.90 in all subjects, 0.87 in the OSAS subjects, and 0.70 in the normal subjects. Conclusion: SQS was confirmed to be an instrument with validity and high reliability for measuring sleep quality in OSAS subjects. © 2009 Elsevier Inc. All rights reserved.