title: Renal function and nonvertebral fracture risk in multiethnic women: the Women's Health Initiative (WHI).
abstract: To examine the association between renal function and fracture in multiethnic women, we studied postmenopausal women enrolled in the Women's Health Initiative. Postmenopausal White women with mild renal dysfunction were at increased risk of nonvertebral fracture; this association was at least partially explained by effects of renal dysfunction on chronic inflammation. Reduced renal function appeared to increase fracture risk among Black women, but there was little evidence to support this association among other racial/ethnic groups.
  
  
  BACKGROUND
  The purpose of this study was to determine whether renal function is associated with fracture risk within racial/ethnic groups.
  
  
  METHODS
  A nested case-control study was conducted among 93,673 postmenopausal women; incident nonvertebral fractures were identified in 362 Black, 183 Hispanic, 110 Asian, and 45 American-Indian women. A random sample of 395 White women with incident nonvertebral fracture was chosen. One nonfracture control for each case was selected (matched on age, race/ethnicity, and blood draw date). Cystatin C levels were measured using baseline serum, and estimated glomerular filtration rate calculated (eGFR(cys-c)).
  
  
  RESULTS
  Each 1 SD increase in cystatin C was associated with a 1.2-fold increased risk of fracture among White women (adjusted odds ratios [OR], 1.23; 95% confidence intervals [CI], 1.04-1.46). The OR of fracture was 1.16 (95% CI, 0.85-1.58) among women with eGFR(cys-c) 60-90 mL/min/1.73 m(2) and 2.46 (95% CI, 1.16-5.21) among those with eGFR(cys-c) <60 mL/min/1.73 m(2) compared to the reference group (eGFR(cys-c) >90 mL/min/1.73 m(2)) (p trend = 0.05). The association was reduced after adjustment for cytokine TNFα soluble receptors (OR, 1.62; 95% CI, 0.59-4.46 for eGFR(cys-c) <60 mL/min/1.73 m(2)). Among Blacks, there was an association between cystatin C and fracture risk (OR per 1 SD increase, 1.15; 95% CI, 1.00-1.32); after adjustment, this association was only modestly attenuated, but no longer statistically significant. There was no evidence of significant associations among Hispanic, Asian, or American-Indian women.
  
  
  CONCLUSIONS
  Postmenopausal White women with mild renal dysfunction are at increased risk of nonvertebral fracture. Effects of renal function on chronic inflammation may mediate this association. Reduced renal function may increase fracture risk among Black women, but there was little evidence to support this association among other racial/ethnic groups.
authors.affiliation: Department of Medicine, University of Minnesota, One Veterans Drive 111-0, Minneapolis, MN 55417, USA. ensru001@umn.edu
authors.forename: K E
authors.initials: KE
authors.lastname: Ensrud
authors.forename: K
authors.initials: K
authors.lastname: Barbour
authors.forename: M T
authors.initials: MT
authors.lastname: Canales
authors.forename: M E
authors.initials: ME
authors.lastname: Danielson
authors.forename: R M
authors.initials: RM
authors.lastname: Boudreau
authors.forename: D C
authors.initials: DC
authors.lastname: Bauer
authors.forename: A Z
authors.initials: AZ
authors.lastname: Lacroix
authors.forename: A
authors.initials: A
authors.lastname: Ishani
authors.forename: R D
authors.initials: RD
authors.lastname: Jackson
authors.forename: J A
authors.initials: JA
authors.lastname: Robbins
authors.forename: J A
authors.initials: JA
authors.lastname: Cauley
mesh_terms: D000368:Aged; D015415:Biomarkers / Q000097:blood; D016022:Case-Control Studies; D055316:Cystatin C / Q000097:blood; D005260:Female; D050723:Fractures, Bone / Q000097:blood / Q000208:ethnology / Q000209:etiology*; D005919:Glomerular Filtration Rate; D006801:Humans; D018836:Inflammation Mediators / Q000097:blood; D008875:Middle Aged; D017698:Postmenopause / Q000097:blood / Q000208:ethnology / Q000502:physiology; D011446:Prospective Studies; D051436:Renal Insufficiency, Chronic / Q000097:blood / Q000150:complications* / Q000208:ethnology; D018570:Risk Assessment / Q000379:methods; D014481:United States / Q000453:epidemiology
chemical_list: D015415:Biomarkers; D055316:Cystatin C; D018836:Inflammation Mediators