Race and Ethnic Variation in Proximal Femur Structure and BMD Among Older Men

Authors

  • Lynn M Marshall ScD,

    Corresponding author
    1. Bone and Mineral Unit, Department of Medicine, Oregon Health and Science University, Portland Oregon, USA
    2. Department of Public Health and Preventive Medicine, Oregon Health and Science University, Portland Oregon, USA
    3. These authors contributed equally to the manuscript
    • Address reprint requests to: Bone and Mineral Unit, Oregon Health and Science University, 3181 SW Sam Jackson Park Road, Mailcode CR113, Portland, OR 97239-3098, USA
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  • Joseph M Zmuda,

    1. These authors contributed equally to the manuscript
    2. Department of Epidemiology, University of Pittsburgh, Pittsburgh Pennsylvania, USA
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  • Benjamin KS Chan,

    1. Bone and Mineral Unit, Department of Medicine, Oregon Health and Science University, Portland Oregon, USA
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  • Elizabeth Barrett-Connor,

    1. Department of Family and Preventive Medicine, University of California at San Diego, San Diego California, USA
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  • Jane A Cauley,

    1. Department of Epidemiology, University of Pittsburgh, Pittsburgh Pennsylvania, USA
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  • Kristine E Ensrud,

    1. Department of Medicine, Veterans Affairs Medical Center, Minneapolis Minnesota, USA
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  • Thomas F Lang,

    1. Department of Radiology, University of California at San Francisco, San Francisco California, USA
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  • Eric S Orwoll,

    1. Bone and Mineral Unit, Department of Medicine, Oregon Health and Science University, Portland Oregon, USA
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  • for the Osteoporotic Fractures in Men (MrOS) Research Group


  • Dr Barrett-Connor serves on advisory committees for and receives research support from Amgen, Eli Lilly, and Merck. Dr Cauley is a consultant for Merck, Merck Speakers Bureau, Eli Lilly, and Novartis and receives research support from Merck, Eli Lilly, Pfizer, and Novartis. All other authors state that they have no conflicts of interest.

Abstract

Femoral neck dimensions and vBMD from QCT were compared among 3305 black, Asian, Hispanic, and white men ≥65 yr of age. All had similar stature-adjusted mean femoral neck volume, but black and Asian men had thicker cortices and higher trabecular vBMD, which may increase bone strength.

Introduction: Hip fracture rates among elderly U.S. black and Asian men are lower than rates among white men. Structural characteristics or volumetric BMD (vBMD), which confer advantages for femoral neck bone strength, may vary by race/ethnicity. However, this topic has not been studied in detail.

Materials and Methods: In a cross-sectional study, dimensions and vBMD in the femoral neck and shaft were obtained from QCT scans among 3305 men ≥65 yr of age in the Osteoporotic Fractures in Men (MrOS) study. Femoral neck measures were cross-sectional area; integral, cortical, and medullary volumes and integral, cortical, and trabecular vBMD. Shaft measures were cross-sectional, cortical, and medullary areas and cortical vBMD. Self-reported race/ethnicity was classified as black, Asian, Hispanic, or white. We used multivariable linear regression models with adjustment for age, height, and body mass index to compare means of the outcome measures in black, Asian, and Hispanic men to those in whites.

Results: All groups had similar femoral neck integral volume. Among black and Asian men, mean cortical volume as a percent of integral volume was 6% greater, integral vBMD was 6-10% greater, and trabecular vBMD was 33-36% greater than means among whites. Shaft cross-sectional area was similar among blacks, but smaller among Asians, compared with whites. However, mean shaft cortical area was greater among blacks but similar among Asians and whites, resulting in mean cortical thickness being 5% greater among black and Asian men. Blacks also had greater mean cortical vBMD in both the femoral neck and shaft.

Conclusions: Black and Asian men ≥65 yr of age have features in the proximal femur that may confer advantages for bone strength. Specifically, greater cortical thickness and higher trabecular vBMD among black and Asian men could help explain the lower hip fracture rates in these populations. Discerning the mechanisms underlying these differences could provide advances for the prevention and treatment of osteoporosis.

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