title: Cystatin-C, renal function, and incidence of hip fracture in postmenopausal women.
abstract: OBJECTIVE
  To evaluate the association between chronic kidney disease and incident hip fracture using serum cystatin-C as a biomarker of renal function calculated without reference to muscle mass.
  
  
  METHODS
  Case-control study nested within a prospective study.
  
  
  METHODS
  The Women's Health Initiative Observational Study conducted at 40 U.S. clinical centers.
  
  
  METHODS
  From 93,676 women aged 50 to 79 followed for an average of 7 years, 397 incident hip fracture cases and 397 matched controls were studied.
  
  
  METHODS
  Cystatin-C levels were measured on baseline serum using a particle-enhanced immunonepholometric assay. Estimated glomerular filtration rates (eGFR(cys-c)) were calculated using a validated equation and categorized into three groups (>or=90.0 mL/min per 1.73 m(2), 60.0-89.9 mL/min per 1.73 m(2), and <60.0 mL/min per 1.73 m(2) indicating chronic kidney disease Stages 3 to 4).
  
  
  RESULTS
  The odds ratio (OR) for hip fracture was 2.50 (95% confidence interval (CI)=1.32-4.72) for eGFR(cys-c) less than 60 mL/min per 1.73 m(2) compared with Stages 0 to 1, after adjustment for body mass, parental hip fracture, smoking, alcohol consumption, and physical function. No association was observed for eGFR(cys-c) of 60 to 90 mL/min per 1.73 m(2) (OR=1.04, 95% CI=0.66-1.64). Additional adjustment for poor health status, hemoglobin, serum 25-hydroxy vitamin D, and bone metabolism markers did not affect these associations. Adjustment for plasma homocysteine reduced the OR for eGFR(cys-c) less than 60 mL/min per 1.73 m(2) to 1.83 (95% CI=0.93-3.61).
  
  
  CONCLUSIONS
  Women with eGFR(cys-c) levels less than 60 mL/min per 1.73 m(2) have a substantially greater risk of hip fracture. Effects of renal function on homocysteine levels may partially mediate, or accompany, this association.
authors.affiliation: Division of Public Health Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109-1024, USA. alacroix@whi.org
authors.forename: Andrea Z
authors.initials: AZ
authors.lastname: LaCroix
authors.forename: Jennifer S
authors.initials: JS
authors.lastname: Lee
authors.forename: LieLing
authors.initials: L
authors.lastname: Wu
authors.forename: Jane A
authors.initials: JA
authors.lastname: Cauley
authors.forename: Michael G
authors.initials: MG
authors.lastname: Shlipak
authors.forename: Susan M
authors.initials: SM
authors.lastname: Ott
authors.forename: John
authors.initials: J
authors.lastname: Robbins
authors.forename: J David
authors.initials: JD
authors.lastname: Curb
authors.forename: Meryl
authors.initials: M
authors.lastname: Leboff
authors.forename: Douglas C
authors.initials: DC
authors.lastname: Bauer
authors.forename: Rebecca D
authors.initials: RD
authors.lastname: Jackson
authors.forename: Charles L
authors.initials: CL
authors.lastname: Kooperberg
authors.forename: Steven R
authors.initials: SR
authors.lastname: Cummings
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D016001:Confidence Intervals; D003430:Cross-Sectional Studies; D055316:Cystatin C; D015891:Cystatins / Q000097:blood*; D005260:Female; D005919:Glomerular Filtration Rate / Q000502:physiology; D006620:Hip Fractures / Q000097:blood / Q000453:epidemiology*; D006801:Humans; D015994:Incidence; D007676:Kidney Failure, Chronic / Q000097:blood / Q000453:epidemiology*; D007677:Kidney Function Tests; D008875:Middle Aged; D016017:Odds Ratio; D015663:Osteoporosis, Postmenopausal / Q000097:blood / Q000453:epidemiology*; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012307:Risk Factors; D014481:United States
chemical_list: C525030:CST3 protein, human; D055316:Cystatin C; D015891:Cystatins