Declining kidney function increases the prevalence of sleep apnea and nocturnal hypoxia.
BACKGROUND
Sleep apnea is an important comorbidity in patients with chronic kidney disease (CKD) and end-stage renal disease (ESRD). Although the increased prevalence of sleep apnea in patients with ESRD is well established, few studies have investigated the prevalence of sleep apnea in patients with nondialysis-dependent kidney disease, and no single study, to our knowledge, has examined the full spectrum of kidney function. We sought to determine the prevalence of sleep apnea and associated nocturnal hypoxia in patients with CKD and ESRD. We hypothesized that the prevalence of sleep apnea would increase progressively as kidney function declines.


METHODS
Two hundred fifty-four patients were recruited from outpatient nephrology clinics and hemodialysis units. All patients completed an overnight cardiopulmonary monitoring test to determine the prevalence of sleep apnea (respiratory disturbance index ≥ 15) and nocturnal hypoxia (oxygen saturation < 90% for ≥ 12% of monitoring). Patients were stratified into three groups based on estimated glomerular filtration rate (eGFR) as follows: eGFR ≥ 60 mL/min/1.73 m(2) (n = 55), CKD (eGFR < 60 mL/min/1.73 m(2) not on dialysis, n = 124), and ESRD (on hemodialysis, n = 75).


RESULTS
The prevalence of sleep apnea increased as eGFR declined (eGFR ≥ 60 mL/min/1.73 m(2), 27%; CKD, 41%; ESRD, 57%; P = .002). The prevalence of nocturnal hypoxia was higher in patients with CKD and ESRD (eGFR ≥ 60 mL/min/1.73 m(2), 16%; CKD, 47%; ESRD, 48%; P < .001).


CONCLUSIONS
Sleep apnea is common in patients with CKD and increases as kidney function declines. Almost 50% of patients with CKD and ESRD experience nocturnal hypoxia, which may contribute to loss of kidney function and increased cardiovascular risk.
Department of Medicine, Foothills Medical Centre, University of Calgary, Calgary, AB, Canada.
David D M
DDM
Nicholl
Department of Medicine, Foothills Medical Centre, University of Calgary, Calgary, AB, Canada.
Sofia B
SB
Ahmed
Department of Medicine, Foothills Medical Centre, University of Calgary, Calgary, AB, Canada; Faculty of Medicine, and Sleep Centre, Foothills Medical Centre, University of Calgary, Calgary, AB, Canada.
Andrea H S
AHS
Loewen
Department of Medicine, Foothills Medical Centre, University of Calgary, Calgary, AB, Canada.
Brenda R
BR
Hemmelgarn
Department of Medicine, Foothills Medical Centre, University of Calgary, Calgary, AB, Canada.
Darlene Y
DY
Sola
Faculty of Medicine, and Sleep Centre, Foothills Medical Centre, University of Calgary, Calgary, AB, Canada.
Jaime M
JM
Beecroft
Department of Medicine, Foothills Medical Centre, University of Calgary, Calgary, AB, Canada.
Tanvir C
TC
Turin
Department of Medicine, Foothills Medical Centre, University of Calgary, Calgary, AB, Canada; Faculty of Medicine, and Sleep Centre, Foothills Medical Centre, University of Calgary, Calgary, AB, Canada. Electronic address: phanly@ucalgary.ca.
Patrick J
PJ
Hanly
D016009:Chi-Square Distribution; D003430:Cross-Sectional Studies; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D000860:Hypoxia / Q000453:epidemiology* / Q000209:etiology* / Q000503:physiopathology; D007676:Kidney Failure, Chronic / Q000150:complications*; D007677:Kidney Function Tests; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D018670:Monitoring, Ambulatory; D017286:Polysomnography; D015995:Prevalence; D012891:Sleep Apnea Syndromes / Q000453:epidemiology* / Q000209:etiology* / Q000503:physiopathology; D018709:Statistics, Nonparametric; D011795:Surveys and Questionnaires