title: Association of nocturnal hypoxemia with progression of CKD.
abstract: OBJECTIVE
  Nocturnal hypoxemia is highly prevalent among patients with CKD. Nocturnal hypoxemia contributes to systemic inflammation, oxidative stress, endothelial cell dysfunction, and activation of the renin-angiotensin system, which are common pathologic mechanisms of CKD progression. This study investigated whether nocturnal hypoxemia is independently associated with CKD progression.
  
  
  METHODS
  This two-center retrospective cohort study included 161 patients with stages 3-4 CKD enrolled from January of 2009 to July of 2011 with a body mass index less than 25.0 kg/m(2). The 4% oxygen desaturation index, the number of events per hour in which oxygen saturation decreases by >4% during sleep, was measured, and the declining rate of the estimated GFR was followed over 1 year. The severity of nocturnal hypoxemia was categorized as none (oxygen desaturation index<5.0), mild (5.0≤oxygen desaturation index<15.0), or moderate to severe (15.0≤oxygen desaturation index).
  
  
  RESULTS
  The mean estimated GFR of the total cohort at baseline was 31 ml/min per 1.73 m(2). Eighty patients (49.7%) were diagnosed with nocturnal hypoxemia; 64 patients were diagnosed with mild nocturnal hypoxemia, and 16 patients were diagnosed with moderate-to-severe nocturnal hypoxemia. The estimated GFR declined three- to fourfold faster in patients with moderate-to-severe nocturnal hypoxemia than patients with no or mild nocturnal hypoxemia (the mean values [95% confidence intervals] were -2.14 [-1.06 to -3.21], -3.02 [-1.31 to -4.74], and -8.59 [-2.00 to -15.2] ml/min per 1.73 m(2) per year in the no, mild, and moderate-to-severe nocturnal hypoxemia groups, respectively; P=0.003). Nocturnal hypoxemia remained a significant predictor of decline in estimated GFR after adjustment for various baseline clinical factors.
  
  
  CONCLUSIONS
  In nonobese patients with CKD, nocturnal hypoxemia is an independent risk factor of a rapid decline in kidney function.
authors.affiliation: Department of Geriatric Medicine and Nephrology, Osaka University Graduate School of Medicine, Japan. yusuke7771@gmail.com
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Sakaguchi
authors.forename: Tsuguru
authors.initials: T
authors.lastname: Hatta
authors.forename: Terumasa
authors.initials: T
authors.lastname: Hayashi
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Shoji
authors.forename: Akira
authors.initials: A
authors.lastname: Suzuki
authors.forename: Kodo
authors.initials: K
authors.lastname: Tomida
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Okada
authors.forename: Hiromi
authors.initials: H
authors.lastname: Rakugi
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Isaka
authors.forename: Yoshiharu
authors.initials: Y
authors.lastname: Tsubakihara
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D018450:Disease Progression; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D000860:Hypoxia / Q000150:complications / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood; D051436:Renal Insufficiency, Chronic / Q000150:complications / Q000503:physiopathology*; D012189:Retrospective Studies; D012720:Severity of Illness Index; D012891:Sleep Apnea Syndromes / Q000150:complications / Q000503:physiopathology*
chemical_list: D010100:Oxygen