Over-hydration as a key modifiable predictor of obstructive sleep apnea severity in dialysis patients with daytime sleepiness

Obstructive sleep apnea (OSA) is common yet frequently goes undiagnosed in end-stage kidney disease patients, contributing to morbidity and mortality. As standard polysomnography is burdensome for dialysis patients, this study aimed to evaluate the utility of the Epworth Sleepiness Scale (ESS) for screening for OSA and to identify modifiable risk factors in end-stage kidney disease patients with excessive daytime sleepiness (EDS). This single-center, cross-sectional study enrolled 40 dialysis patients (24 hemodialysis, 16 peritoneal dialysis [PD]) with EDS (ESS score > 10). Participants underwent level 4 polysomnography to determine the apnea-hypopnea index (AHI) and body composition monitoring to assess over-hydration (OH) status. Clinical characteristics, laboratory data, cardiothoracic ratio, and trachea-to-neck ratio were collected. OSA (AHI ≥ 5) was present in 75% (30/40) of participants. AHI severity correlated significantly with the oxygen desaturation index ( r = 0.62, P < .01) and OH ( r = 0.41, P = .009) in the overall OSA group. Multiple linear regression identified OH as an independent predictor of AHI severity in all patients ( P = .01) and specifically in PD patients ( P = .02), for whom dialysis vintage was also a predictor ( P = .002). Typical OSA symptoms like snoring did not significantly differ based on OSA presence or severity. The ESS is a potentially useful tool for screening OSA risk in dialysis patients experiencing EDS. OH is a significant and modifiable predictor of OSA severity, particularly in PD patients. Therefore, active volume management, guided by objective measures, should be considered a primary therapeutic target to mitigate OSA severity in dialysis patients.