Effects of sleep apnea and kidney dysfunction on objective sleep quality in non-dialyzed patients with chronic kidney disease: an ESADA study

Study Objectives: Patients with chronic kidney disease (CKD) often report poor sleep quality, but they commonly exhibit obstructive sleep apnea (OSA). The aim of this study was to evaluate the influence of OSA severity and estimated glomerular filtration rate (eGFR) impairment on objective sleep quality in non-dialyzed patients with CKD, defined as eGFR <60 ml/min/1.73m2. Methods: Polysomnographic sleep characteristics were compared between patients with (n=430) and without CKD (n=6,639) of the European Sleep Apnea Database (ESADA) cohort. Comparisons were repeated in 375 CKD patients and 375 non-CKD control subjects matched for sleep center, age, sex and apnea/hypopnea index (AHI), and in 310 matched cases and controls without psychiatric disturbances. Results: Among all patients with and without CKD, total sleep time was similar, but stage N1 (8.7 [4.8-18.0] vs 6.7 [3.6-12.7]%, respectively) and stage R (12.6 [6.8-17.7] vs 14.2 [8.819.8]%, respectively) significantly differed (p<0.0001). No difference in sleep characteristics was observed between matched cases and controls, either with or without psychiatric disturbances. After subdividing the matched subjects according to AHI tertile (<25, >=25 to <49, and >=49 events/h) and eGFR (>=60, 45 to <60, <45 ml/min/1.73m2), a significant effect of AHI on stages N2, N3 and R was found (p<0.001), but no effect of CKD. Conclusions: In non dialyzed CKD patients, objective sleep quality is influenced similarly by AHI as in non-CKD subjects, but is not affected by CKD severity. Previously reported poor sleep quality in CKD may partly be due to the high prevalence of OSA in CKD.