title: Creatinine clearance, walking speed, and muscle atrophy: a cohort study.
abstract: BACKGROUND
  Chronic kidney disease is associated with malnutrition and inflammation. These processes may lead to loss of skeletal muscle and reduced physical performance. Associations of kidney function with muscle composition and longitudinal measures of physical performance are unknown.
  
  
  METHODS
  Prospective cohort study.
  
  
  METHODS
  We evaluated 826 community-dwelling older adults enrolled in the Invecchiare in Chianti (InCHIANTI) Study who were free of baseline stroke or activities of daily living disability.
  
  
  METHODS
  Baseline creatinine clearance (Clcr) based on 24-hour urine collection.
  
  
  RESULTS
  Cross-sectional and longitudinal trajectories of physical performance measured by 7-m usual gait speed, 400-m fast gait speed, and knee extension strength using isometric dynamometry. Calf muscle composition assessed by quantitative computed tomography.
  
  
  RESULTS
  Mean age of participants was 74 ± 7 (SD) years, with 183 having Clcr < 60 mL/min/1.73 m(2). After adjustment, each 10-mL/min/1.73 m(2) decrement in Clcr was associated with 0.01 (95% CI, 0.004-0.017) m/s slower 7-m usual walking speed and 0.008 (95% CI, 0.002-0.014) m/s slower 400-m walking speed. Each 10-mL/min/1.73 m(2) decrement in Clcr was associated with 28 (95% CI, 0.8-55) mm(2) lower muscle area and 0.15 (95% CI, 0.04-0.26) mg/cm(3) lower muscle density. After adjustment, lower Clcr was associated with slower mean 7-m (P=0.005) and 400-m (P=0.02) walk and knee extension strength (P=0.001) during the course of follow-up. During a mean follow-up of 7.1 ± 2.5 years, each 10-mL/min/1.73 m(2) lower baseline Clcr was associated with 0.024 (95% CI, 0.01-0.037) kg/y greater decline in knee strength.
  
  
  CONCLUSIONS
  Single baseline measurement of Clcr and 3-year interval between follow-up visits may lead to nondifferential misclassification and attenuation of estimates.
  
  
  CONCLUSIONS
  Among older adults, lower Clcr is associated with muscle atrophy, reduced walking speed, and more rapid declines in lower-extremity strength over time.
authors.affiliation: Division of Nephrology, Department of Medicine, University of Washington Kidney Research Institute, Seattle, WA. Electronic address: broshanr@u.washington.edu.
authors.forename: Baback
authors.initials: B
authors.lastname: Roshanravan
authors.affiliation: Department of Anesthesiology and Pain Medicine, University of Washington, Seattle, WA.
authors.forename: Kushang V
authors.initials: KV
authors.lastname: Patel
authors.affiliation: Division of Nephrology, Department of Medicine, University of Washington Kidney Research Institute, Seattle, WA.
authors.forename: Cassianne
authors.initials: C
authors.lastname: Robinson-Cohen
authors.affiliation: Division of Nephrology, Department of Medicine, University of Washington Kidney Research Institute, Seattle, WA.
authors.forename: Ian H
authors.initials: IH
authors.lastname: de Boer
authors.affiliation: Veterans Affairs Puget Sound Healthcare System, University of Washington, Seattle, WA.
authors.forename: Ann M
authors.initials: AM
authors.lastname: O'Hare
authors.affiliation: Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, MD.
authors.forename: Luigi
authors.initials: L
authors.lastname: Ferrucci
authors.affiliation: Division of Nephrology, Department of Medicine, University of Washington Kidney Research Institute, Seattle, WA.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Himmelfarb
authors.affiliation: Division of Nephrology, Department of Medicine, University of Washington Kidney Research Institute, Seattle, WA.
authors.forename: Bryan
authors.initials: B
authors.lastname: Kestenbaum
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D015897:Comorbidity; D003404:Creatinine / Q000097:blood*; D005260:Female; D005684:Gait / Q000502:physiology; D005919:Glomerular Filtration Rate; D006801:Humans; D007719:Knee Joint / Q000503:physiopathology; D008297:Male; D053580:Muscle Strength; D009133:Muscular Atrophy / Q000097:blood / Q000453:epidemiology* / Q000503:physiopathology; D011446:Prospective Studies; D051436:Renal Insufficiency, Chronic / Q000097:blood / Q000453:epidemiology* / Q000503:physiopathology
chemical_list: D003404:Creatinine
keywords: Physical performance; chronic kidney disease (CKD); creatinine clearance (Clcr); longitudinal trajectory; mobility impairment; muscle atrophy; muscle strength; renal function; skeletal muscle composition