Adaptation of the 10-Item Functional Outcomes of Sleep Questionnaire to Iranian Patients with Obstructive Sleep Apnea

Purpose The purpose of this study was to evaluate the psychometric properties of the Farsi version of 10-item Functional Outcomes of Sleep Questionnaire (FOSQ-10) in Iranian patients with obstructive sleep apnea (OSA). Methods The FOSQ-10 was translated into Farsi using the standard forward-backward method. One hundred patients who fulfilled the inclusion criteria completed a series of questionnaires including IR-FOSQ-10, Medical Outcome Survey Short Form 12 (SF-12) and Epworth Sleepiness Scale (ESS). Internal consistency, test-retest reliability, concurrent validity, discriminant validity and responsiveness of IR-FOSQ-10 were investigated. Results The Cronbach's alpha coefficient was 0.85 in IRFOSQ-10 total score and ranged from 0.78 to 0.83 in each subscale. The test-retest reliability demonstrated by intraclass coefficient was 0.92. There were significant moderateto-good negative correlations between IR-FOSQ-10 subscales and ESS except for sexual relationship subscale. FOSQ-10 subscales generally correlated higher with related subscales of SF-12. The IR-FOSQ-10 was able to distinguish patients with abnormal sleepiness score from those with normal sleepiness score. The results of sensitivity to change proved that the IR-FOSQ-10 was able to detect changes after continuous positive airway pressure therapy. Conclusion The psychometric properties of the IRFOSQ-10 suggest that it is a reliable and valid measure among Iranian patients with OSA.