title: Reduced renal function and sleep-disordered breathing in community-dwelling elderly men.
abstract: BACKGROUND
  Sleep-disordered breathing (SDB) may increase the risk of cardiovascular disease (CVD) and death in chronic kidney disease (CKD). However, the association between mild reductions in renal function and SDB is uncertain.
  
  
  METHODS
  We studied 508 community-dwelling men aged>or=67 years (mean 76.0+/-5.3) who were enrolled at the Minnesota site for the Minneapolis center of the Outcomes of Sleep Disorders in Older Men (MrOS) sleep study and had serum cystatin-C and creatinine measured coincident with overnight polysomnography. CKD was defined as estimated glomerular filtration rate (eGFR)<60 ml/min/1.73 m2 using Cockcroft-Gault (CG), modification of diet in renal disease (MDRD) and Mayo Clinic formulae. SDB was defined by a respiratory disturbance index (RDI)>or=15 events/h.
  
  
  RESULTS
  Mean cystatin-C was 1.21+/-0.30 mg/L, and mean creatinine was 1.09+/-0.23 mg/dL. Median RDI was 7.0 events/h (range 0-73). Higher quartiles of cystatin-C were associated with higher mean RDI (p for trend=0.007). This association persisted after adjustment for age and race (p for trend=0.03), but not after adjustment for body mass index (BMI, p for trend=0.34). After adjusting for age, race, BMI, diabetes, hypertension, and CVD, CKD defined by the Mayo Clinic formula, but not CG or MDRD, was associated with a higher odds of SDB [odds ratio (OR) 1.95, 95% confidence interval (CI) 1.04-3.65, p=0.04].
  
  
  CONCLUSIONS
  Older men with reduced renal function as defined by higher cystatin-C concentration have higher average RDI. This effect is explained by higher BMI in men with higher cystatin-C. CKD defined by the Mayo Clinic formula is independently associated with twofold higher odds for SDB. Therefore, reduced renal function may be associated with SDB in older men.
authors.affiliation: Division of Renal Diseases and Hypertension, Department of Medicine, University of Minnesota, Minneapolis, MN, USA. cana0033@umn.edu
authors.forename: Muna T
authors.initials: MT
authors.lastname: Canales
authors.forename: Brent C
authors.initials: BC
authors.lastname: Taylor
authors.forename: Areef
authors.initials: A
authors.lastname: Ishani
authors.forename: Reena
authors.initials: R
authors.lastname: Mehra
authors.forename: Michael
authors.initials: M
authors.lastname: Steffes
authors.forename: Katie L
authors.initials: KL
authors.lastname: Stone
authors.forename: Susan
authors.initials: S
authors.lastname: Redline
authors.forename: Kristine E
authors.initials: KE
authors.lastname: Ensrud
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D015331:Cohort Studies; D003404:Creatinine / Q000097:blood; D055316:Cystatin C / Q000097:blood; D005919:Glomerular Filtration Rate; D006801:Humans; D008297:Male; D017286:Polysomnography; D051436:Renal Insufficiency, Chronic / Q000097:blood / Q000150:complications* / Q000503:physiopathology; D012307:Risk Factors; D012891:Sleep Apnea Syndromes / Q000097:blood / Q000150:complications* / Q000503:physiopathology*
chemical_list: D055316:Cystatin C; D003404:Creatinine