title: Sleep-disordered breathing and urinary albumin excretion in older men.
abstract: OBJECTIVE
  Sleep-disordered breathing (SDB) may be deleterious to the cardiovascular system and other organs, including the kidney. Although older men are at increased risk for both kidney disease and SDB, it is unknown whether SDB is associated with higher urinary albumin excretion in this population.
  
  
  METHODS
  We examined 507 community-dwelling men age ≥ 67 years (mean 76.0 ± 5.3) enrolled in the MrOS Sleep study who underwent overnight polysomnography and gave a spot urine sample. SDB severity was categorized using the respiratory disturbance index and percent total sleep time <90% oxygen saturation (%time O2<90). Urinary albumin excretion was expressed using the albumin-to-creatinine ratio (ACR).
  
  
  RESULTS
  There was a graded association between respiratory disturbance index and ACR (age- and race-adjusted mean ACR = 9.35 mg/gCr for respiratory disturbance index ≥ 30 versus 6.72 mg/gCr for respiratory disturbance index < 5, p = 0.007). This association was attenuated after further adjustment for body mass index (BMI), hypertension and diabetes and no longer reached significance (p = 0.129). However, even after adjustment for age, race, BMI, hypertension, and diabetes, greater %time O2<90 was associated with higher ACR (10.35 mg/gCr for ≥10%time O2<90 versus 7.45 mg/gCr for <1%time O2<90, p = 0.046).
  
  
  CONCLUSIONS
  SDB, measured by elevated respiratory disturbance index or nocturnal hypoxemia, was associated with higher ACR. The relationship between respiratory disturbance index and ACR was partially explained by higher BMI and greater prevalence of hypertension and diabetes among men with SDB. However, greater nocturnal hypoxemia was independently associated with higher ACR, suggesting that the hypoxia component of SDB may mediate any detrimental effect of SDB on the kidney.
authors.affiliation: Department of Medicine, Malcolm-Randall Veterans Affairs Medical Center, Gainesville, FL, USA. muna.canales@medicine.ufl.edu
authors.forename: Muna T
authors.initials: MT
authors.lastname: Canales
authors.forename: Misti L
authors.initials: ML
authors.lastname: Paudel
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; D000419:Albuminuria / Q000175:diagnosis / Q000503:physiopathology*; D015992:Body Mass Index; D015331:Cohort Studies; D015897:Comorbidity; D003404:Creatinine / Q000097:blood; D003924:Diabetes Mellitus, Type 2 / Q000175:diagnosis / Q000503:physiopathology; D006306:Health Surveys; D006801:Humans; D006973:Hypertension / Q000175:diagnosis / Q000503:physiopathology; D008297:Male; D008910:Minnesota; D017286:Polysomnography; D012307:Risk Factors; D012709:Serum Albumin / Q000378:metabolism; D020181:Sleep Apnea, Obstructive / Q000175:diagnosis / Q000503:physiopathology*; D013223:Statistics as Topic
chemical_list: D012709:Serum Albumin; D003404:Creatinine