title: Ethnic differences in composite indices of femoral neck strength.
abstract: Bone mineral density does not explain race/ethnicity differences in hip fracture risk. In this study, we demonstrated that race/ethnicity differences in composite hip strength indices were consistent with documented race/ethnicity differences in hip fracture risk, suggesting that unlike bone density, the composite indices may represent ethnicity-independent measures of bone strength.
  
  
  BACKGROUND
  African-American and Asian women have lower risks of hip fracture than Caucasian women, but such racial/ethnic variation in hip fracture risk cannot be explained by bone mineral density (BMD). The composite indices of femoral neck strength integrate femoral neck and body size with BMD and predict hip fracture risk in Caucasian women. We hypothesize that unlike race/ethnic differences in BMD, race/ethnic differences in the composite strength indices would be consistent with race/ethnic differences in hip fracture risk.
  
  
  METHODS
  We studied a community-based sample of Caucasian (n = 968), African-American (n = 512), Chinese (n = 221), and Japanese (n = 239) women, premenopausal or in early perimenopause, from the Study of Women's Health Across the Nation.
  
  
  RESULTS
  Unadjusted indices were similar in Caucasian and African-American women but higher in Asian women. After adjusting for age, body mass index, and menopause status, all three minority groups had higher composite strength indices than Caucasian women. Foreign-born Japanese women had higher unadjusted and adjusted composite strength indices than US-born Japanese women, but such differences by nativity were not observed in Chinese women.
  
  
  CONCLUSIONS
  We concluded that composite strength indices have the potential to explain racial/ethnic differences in hip fracture risk, suggesting that composite strength indices may represent ethnicity-independent measures of bone strength. This contention needs to be verified by further research on the fracture predictive ability of composite strength indices in multi-ethnic longitudinal cohorts.
authors.affiliation: Geriatric Research, Education and Clinical Center (GRECC), VA Greater Los Angeles Healthcare System, 11301 Wilshire Blvd, Building 220, Room 302, Los Angeles, CA 90073, USA. sishii@ucla.edu
authors.forename: S
authors.initials: S
authors.lastname: Ishii
authors.forename: J A
authors.initials: JA
authors.lastname: Cauley
authors.forename: G A
authors.initials: GA
authors.lastname: Greendale
authors.forename: M E
authors.initials: ME
authors.lastname: Danielson
authors.forename: N
authors.initials: N
authors.lastname: Safaei Nili
authors.forename: A
authors.initials: A
authors.lastname: Karlamangla
mesh_terms: D015502:Absorptiometry, Photon / Q000379:methods; D000328:Adult; D001741:Black or African American / Q000706:statistics & numerical data; D000886:Anthropometry / Q000379:methods; D044466:Asian People / Q000706:statistics & numerical data; D015519:Bone Density / Q000502:physiology; D005260:Female; D005272:Femur Neck / Q000503:physiopathology*; D006620:Hip Fractures / Q000208:ethnology* / Q000503:physiopathology; D006630:Hispanic or Latino / Q000706:statistics & numerical data; D006801:Humans; D008137:Longitudinal Studies; D008875:Middle Aged; D058866:Osteoporotic Fractures / Q000208:ethnology* / Q000503:physiopathology; D047648:Perimenopause / Q000208:ethnology / Q000502:physiology; D017697:Premenopause / Q000208:ethnology / Q000502:physiology; D044465:White People / Q000706:statistics & numerical data