Chronic kidney disease and functional limitation in older people: health, aging and body composition study.
OBJECTIVE
To assess whether chronic kidney disease (CKD) is independently associated with incident physical-function limitation.


METHODS
Prospective cohort study.


METHODS
Two sites: Pittsburgh, Pennsylvania, and Memphis, Tennessee.


METHODS
Two thousand one hundred thirty-five men and women aged 70 to 79 without functional limitation at baseline from the Health, Aging and Body Composition Study.


METHODS
Functional limitation was defined as difficulty in walking one-quarter of a mile or climbing 10 steps on two consecutive reports 6 months apart (in the same function). Kidney function was measured using serum cystatin C. Estimated glomerular filtration rate (eGFR), using the Modification of Diet in Renal Disease formula (<60 versus > or =60 mL/min per 1.73 m(2)), was a secondary predictor. Muscle strength, lean body mass according to dual energy x-ray absorptiometry, comorbidity, medication use, and inflammatory markers were evaluated as covariates.


RESULTS
Persons in the highest (> or =1.13 mg/L) quartile of cystatin C experienced a significantly higher risk of developing functional limitation than those in the lowest (<0.86 mg/L) quartile (hazard ratio (HR)=1.70, 95% confidence interval (CI)=1.40-2.07). The association between the fourth cystatin C quartile and functional limitation remained after adjustment for demographics, lean body mass, comorbidity, muscle strength, and gait speed (HR=1.41, 95% CI=1.13-1.75), although the association was attenuated after adjustment for markers of inflammation (HR=1.15, 95% CI=0.90-1.46). Similar results were found for eGFR less than 60 mL/min per 1.73 m(2), although the association with functional limitation remained after adjustment for inflammatory markers (HR=1.30, 95% CI=1.08-1.56).


CONCLUSIONS
CKD is associated with the development of functional impairment independent of comorbidity, body composition, and tests of strength and physical performance. The mechanism may be related to a heightened inflammatory state in CKD.
Fried
Linda F
LF
Department of Veterans Affairs Pittsburgh Healthcare System, University Drive, Pittsburgh, PA 15240, USA. Linda.Fried@med.va.gov
Lee
Jung Sun
JS
Shlipak
Michael
M
Chertow
Glenn M
GM
Green
Christie
C
Ding
Jingzhong
J
Harris
Tamara
T
Newman
Anne B
AB
D000368:Aged; D000375:Aging / Q000502:physiology*; D001823:Body Composition; D002908:Chronic Disease; D015331:Cohort Studies; D055316:Cystatin C; D015891:Cystatins / Q000097:blood; D005080:Exercise Test; D005260:Female; D006304:Health Status; D006801:Humans; D007674:Kidney Diseases / Q000097:blood / Q000150:complications / Q000503:physiopathology*; D007677:Kidney Function Tests; D008297:Male; D051346:Mobility Limitation; D016138:Walking / Q000502:physiology*
C525030:CST3 protein, human; D055316:Cystatin C; D015891:Cystatins