title: Nocturnal hypoxia and loss of kidney function.
abstract: BACKGROUND
  Although obstructive sleep apnea (OSA) is more common in patients with kidney disease, whether nocturnal hypoxia affects kidney function is unknown.
  
  
  METHODS
  We studied all adult subjects referred for diagnostic testing of sleep apnea between July 2005 and December 31 2007 who had serial measurement of their kidney function. Nocturnal hypoxia was defined as oxygen saturation (SaO2) below 90% for ≥12% of the nocturnal monitoring time. The primary outcome, accelerated loss of kidney function, was defined as a decline in estimated glomerular filtration rate (eGFR) ≥4 ml/min/1.73 m(2) per year.
  
  
  RESULTS
  858 participants were included and followed for a mean study period of 2.1 years. Overall 374 (44%) had nocturnal hypoxia, and 49 (5.7%) had accelerated loss of kidney function. Compared to controls without hypoxia, patients with nocturnal hypoxia had a significant increase in the adjusted risk of accelerated kidney function loss (odds ratio (OR) 2.89, 95% confidence interval [CI] 1.25, 6.67).
  
  
  CONCLUSIONS
  Nocturnal hypoxia was independently associated with an increased risk of accelerated kidney function loss. Further studies are required to determine whether treatment and correction of nocturnal hypoxia reduces loss of kidney function.
authors.affiliation: Department of Medicine, University of Calgary, Calgary, Alberta, Canada. sofia.ahmed@albertahealthservices.ca
authors.forename: Sofia B
authors.initials: SB
authors.lastname: Ahmed
authors.forename: Paul E
authors.initials: PE
authors.lastname: Ronksley
authors.forename: Brenda R
authors.initials: BR
authors.lastname: Hemmelgarn
authors.forename: Willis H
authors.initials: WH
authors.lastname: Tsai
authors.forename: Braden J
authors.initials: BJ
authors.lastname: Manns
authors.forename: Marcello
authors.initials: M
authors.lastname: Tonelli
authors.forename: Scott W
authors.initials: SW
authors.lastname: Klarenbach
authors.forename: Rick
authors.initials: R
authors.lastname: Chin
authors.forename: Fiona M
authors.initials: FM
authors.lastname: Clement
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Hanly
mesh_terms: D000328:Adult; D000368:Aged; D015331:Cohort Studies; D015897:Comorbidity; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D000860:Hypoxia / Q000150:complications* / Q000175:diagnosis; D007668:Kidney / Q000502:physiology*; D007674:Kidney Diseases / Q000150:complications* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000378:metabolism; D012119:Respiration; D012306:Risk; D020181:Sleep Apnea, Obstructive / Q000150:complications* / Q000175:diagnosis
chemical_list: D010100:Oxygen