Short sleep duration and poor sleep quality have been reported in chronic kidney disease (CKD). Additionally, sleep disordered breathing (SDB), a well-known cause of disturbed sleep, is highly prevalent in CKD. The majority of studies on sleep quality in CKD were focussed on dialysed patients, were based on subjective reports, and did not consider possible coexistence of SDB.1 Only a small number of studies assessed sleep quality on polysomnographic data in non-dialysed patients with CKD.2
The aim of this study was to evaluate objective sleep quality based on electroencephalographic (EEG) recordings during nocturnal polysomnography in non-dialysed patients with CKD, taking into account coexisting SDB and psychiatric diagnoses.
The European Sleep Apnea Database (ESADA) cohort includes patients studied for suspected obstructive sleep apnea from numerous European sleep centres. From this cohort, 375 non-dialysed CKD patients who had undergone full polysomnography were matched one-by-one with 375 non-CKD patients. CKD was defined as an estimated glomerular filtration rate (eGFR) of <60 mL/min/1.73m2. Matching criteria were sleep centre, age, sex, and apnea-hypopnea index (AHI). Total sleep time and percentage duration of each sleep stage were compared between cases and controls. The analysis was repeated in 310 patients and controls with no psychiatric diagnosis and who did not use psycholeptic or psychoanaleptic drugs.
CKD patients (eGFR=48.3±11.4 mL/min/1.73m2) were marginally more obese, exhibited worse sleep hypoxaemia, and displayed more comorbidities than controls, including arterial hypertension, Type 2 diabetes mellitus, and congestive heart failure. However, these patients did not differ from controls in any evaluated objective sleep parameter. The sample was subdivided into three groups, each of which included patients and matched controls, according to AHI tertiles. The duration of each sleep stage differed depending on AHI tertile (all p<0.001); whereas, no difference was detected between CKD patients and controls within each AHI tertile. Exclusion of patients with a psychiatric diagnosis did not modify the results.
Objective sleep quality is not affected by CKD in patients with moderate reduction of eGFR, independent of SDB and psychiatric diagnosis. Varying AHI is associated with parallel changes in sleep stage distribution in patients with and without CKD. Previously reported poor sleep quality and duration in CKD may partly be because of the high prevalence of SDB in CKD.