title: Prevalence of chronic kidney disease in patients with suspected sleep apnoea.
abstract: BACKGROUND
  Little is known about the epidemiology of chronic kidney disease (CKD) in patients with suspected sleep apnoea (SA).
  
  
  METHODS
  Glomerular filtration rate (eGFR) was calculated in consecutive patients referred for full-night observed in-hospital polysomnography. SA was defined as the respiratory disturbance index (RDI) > 5.
  
  
  RESULTS
  One hundred and fifty-eight patients were studied. The age (mean +/- SD) was 61.2 +/- 12.7 years, body mass index 29.5 +/- 5.9 kg/m(2) and eGFR 86.1 +/- 21.7 mL/min/1.73 m(2). SA was present in 133 patients (85%). The eGFR was 94.6 7 mL/min/1.73 m(2) in patients without SA and 84.5 7 mL/min/1.73 m(2) in patients with SA [mean difference (95% confidence interval) 10.0 (0.6-19.4) mL/min/1.73 m(2); P = 0.037]. Seventy patients had eGFR > or = 90 mL/min/1.73 m(2) (group 1), and 70 patients had between 60 and 89 mL/min/1.73 m(2) (group 2), and 18 patients had 30-59 mL/min/1.73 m(2) (CKD 3). Although the prevalence of SA did not differ among the groups (group 1: 80%; group 2: 86%; CKD 3: 94%), the number of central sleep apnoeas (CSA) per hour was 5.9 +/- 12.2 in CKD 3, six times greater compared to patients with eGFR > or = 60 mL/min/1.73 m(2) (1.0 +/- 2.1; P = 0.01). The prevalence of obstructive SA did not differ between the groups. After adjustment for age, gender, BMI, hypertension, diabetes mellitus and smoking status, CKD 3 (P = 0.0004) and New York Heart Association class > or =3 (P = 0.0001) remained predictive of CSA events per hour.
  
  
  CONCLUSIONS
  eGFR is reduced in patients with SA, particularly in those with episodes of CSA.
authors.affiliation: Department of Internal Medicine, Krankenhaus der Barmherzigen Brüder, Graz, Austria.
authors.forename: Georg
authors.initials: G
authors.lastname: Fleischmann
authors.forename: Gundula
authors.initials: G
authors.lastname: Fillafer
authors.forename: Heike
authors.initials: H
authors.lastname: Matterer
authors.forename: Falko
authors.initials: F
authors.lastname: Skrabal
authors.forename: Peter
authors.initials: P
authors.lastname: Kotanko
mesh_terms: D000368:Aged; D002908:Chronic Disease; D003430:Cross-Sectional Studies; D005260:Female; D005919:Glomerular Filtration Rate / Q000502:physiology; D006801:Humans; D007674:Kidney Diseases / Q000453:epidemiology* / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D017286:Polysomnography; D015995:Prevalence; D012891:Sleep Apnea Syndromes / Q000150:complications*