Reduced renal function and sleep-disordered breathing in community-dwelling elderly men.
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.
Canales
Muna T
MT
Division of Renal Diseases and Hypertension, Department of Medicine, University of Minnesota, Minneapolis, MN, USA. cana0033@umn.edu
Taylor
Brent C
BC
Ishani
Areef
A
Mehra
Reena
R
Steffes
Michael
M
Stone
Katie L
KL
Redline
Susan
S
Ensrud
Kristine E
KE
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*
D055316:Cystatin C; D003404:Creatinine