Depressive symptoms and obesity as predictors of sleepiness and quality of life in patients with REM-related obstructive sleep apnea: Cross-sectional analysis of a large clinical population

Background: The clinical significance of rapid eye-movement (REM)-related obstructive sleep apnea (OSA) is unknown. Moreover, it is unclear what the determinants of sleepiness and quality of life (QoL) are among these patients. Our aim was to identify whether the apnea-hypopnea index during REM sleep (AHI _REM), AHI during NREM sleep (AHI _NREM), depressive symptoms, or obesity are independent predictors of excessive daytime sleepiness and reduced QoL in patients with REM-related OSA. We also assessed if these characteristics were predictors of sleepiness and QoL in all patients with OSA (AHI≥5) as well as in non-stage specific OSA. Methods: This was a cross-sectional analysis of a clinic-based population with OSA. In order to minimize the contribution of AHI _NREM, we defined REM-related OSA using the following criteria: an overall AHI≥5, AHI _REM/AHI _NREM≥2, AHI _NREM<lowest quartile, and REM sleep in minutes>the lowest quartile of the entire cohort. We examined the predictors of subjective sleepiness using the Epworth Sleepiness Scale (ESS) and QoL using the short-form quality of life questionnaire-12 (SF-12). Results: Of 1019 consecutive adults that were referred for their first in-laboratory polysomnogram for suspicion of OSA over a 10month period, 931 had OSA. REM-related OSA was present in 126 patients. In adjusted linear regression models, AHI _NREM was a significant predictor of sleepiness in the entire cohort of patients with OSA as well as non-stage specific OSA, but not in the REM-related OSA group. AHI _REM was not a significant predictor of ESS or QoL in any of the three groups. However, greater depressive symptoms and body mass index were significant independent predictors of ESS and reduced QoL in the REM-related OSA group. Conclusion: Higher depression scores and obesity, rather than the severity of OSA (as measured by AHI _NREM and AHI _REM), were predictive of sleepiness and QoL scores in patients with REM-related OSA.