Factors affecting fatigue severity in patients with obstructive sleep apnea

Abstract Objectives A limited number of studies have investigated the relationships among fatigue, insomnia and obstructive sleep apnea (OSA). This study evaluated the factors affecting fatigue severity in patients with OSA. Methods We investigated 633 OSA patients who were diagnosed by polysomnography. All patients completed sleep questionnaires including self‐reported sleep duration, the Fatigue Severity Scale (FSS), the Korean version of Epworth Sleepiness Scale (K‐ESS), Insomnia Severity Index (ISI), Korean version of Pittsburgh Sleep Quality Index (K‐PSQI) and Beck Depression Inventory‐2 (BDI‐2). Results The subjects had a mean age of 48.7 ± 10.5 years and 72.5% (n = 459) were men. The subjects were distributed as follows: 160 with mild, 168 with moderate and 305 with severe OSA. A multiple regression model found that age (β = −0.146, P = .005), K‐ESS (β = 0.689, P < .001), 8 ≤ ISI score < 15 (β = 3.801, P = .006), 15 ≤ ISI score (β = 4.565, P = .009), and K‐PSQI (β = 0.684, P = .002) were predictors of a higher FSS score. BDI‐2 (β = 0.007, P = .918), apnea‐hypopnea index (AHI) (β = −0.006, P = .895), arousal index (β = 0.034, P = .415), and nadir O 2 saturation (β = −0.044, P = .655) were not associated with FSS score. Conclusion Our findings indicate that fatigue severity is more likely to be associated with younger age, sleepiness and insomnia, but less likely to be directly related to OSA severity.