title: Hip Fractures Risk in Older Men and Women Associated With DXA-Derived Measures of Thigh Subcutaneous Fat Thickness, Cross-Sectional Muscle Area, and Muscle Density.
abstract: Mid-thigh cross-sectional muscle area (CSA), muscle attenuation, and greater trochanter soft tissue thickness have been shown to be independent risk factors of hip fracture. Our aim was to determine whether muscle and adipose tissue measures derived from dual-energy X-ray absorptiometry (DXA) scans would have a similar risk association as those measured using other imaging methods. Using a case-cohort study design, we identified 169 incident hip fracture cases over an average of 13.5 years among participants from the Health ABC Study, a prospective study of 3075 individuals initially aged 70 to 79 years. We modeled the thigh 3D geometry and compared DXA and computed tomography (CT) measures. DXA-derived thigh CSA, muscle attenuation, and subcutaneous fat thickness were found to be highly correlated to their CT counterparts (Pearson's r = 0.82, 0.45, and 0.91, respectively; p < 0.05). The fracture risk of men and women were calculated separately. We found that decreased subcutaneous fat, CT thigh muscle attenuation, and appendicular lean mass by height squared (ALM/Ht(2)) were associated with fracture risk in men; hazard ratios (HR) = 1.44 (1.02, 2.02), 1.40 (1.05, 1.85), and 0.58 (0.36, 0.91), respectively, after adjusting for age, race, clinical site, body mass index (BMI), chronic disease, hip bone mineral density (BMD), self-reported health, alcohol use, smoking status, education, physical activity, and cognitive function. In a similar model for women, only decreases in subcutaneous fat and DXA CSA were associated with hip fracture risk; HR = 1.39 (1.07, 1.82) and 0.78 (0.62, 0.97), respectively. Men with a high ALM/Ht(2) and low subcutaneous fat thickness had greater than 8 times higher risk for hip fracture compared with those with low ALM/Ht(2) and high subcutaneous fat. In women, ALM/Ht(2) did not improve the model when subcutaneous fat was included. We conclude that the DXA-derived subcutaneous fat thickness is a strong marker for hip fracture risk in both men and women, especially in men with high ALM/Ht(2).
authors: Bone and Breast Density Research Group, Department of Radiology, University of California, San Francisco, San Francisco, CA, USA.
authors: Serghei
authors: S
authors: Malkov
authors: California Pacific Medical Center Research Institute, San Francisco, CA, USA.
authors: Peggy M
authors: PM
authors: Cawthon
authors: California Pacific Medical Center Research Institute, San Francisco, CA, USA.
authors: Kathy Wilt
authors: KW
authors: Peters
authors: Department of Epidemiology, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA, USA.
authors: Jane A
authors: JA
authors: Cauley
authors: Laboratory of Epidemiology and Population Sciences, National Institute on Aging, Bethesda, MD, USA.
authors: Rachel A
authors: RA
authors: Murphy
authors: Department of Health Sciences, VU University Amsterdam, Amsterdam, The Netherlands.|Department of Epidemiology and Biostatistics, VU University Medical Center, Amsterdam, The Netherlands.
authors: Marjolein
authors: M
authors: Visser
authors: Bone and Breast Density Research Group, Department of Radiology, University of California, San Francisco, San Francisco, CA, USA.
authors: Joseph P
authors: JP
authors: Wilson
authors: Laboratory of Epidemiology and Population Sciences, National Institute on Aging, Bethesda, MD, USA.
authors: Tamara
authors: T
authors: Harris
authors: Department of Preventive Medicine, University of Tennessee Health Science Center, Memphis, TN, USA.
authors: Suzanne
authors: S
authors: Satterfield
authors: California Pacific Medical Center Research Institute, San Francisco, CA, USA.
authors: Steve
authors: S
authors: Cummings
authors: Bone and Breast Density Research Group, Department of Radiology, University of California, San Francisco, San Francisco, CA, USA.
authors: John A
authors: JA
authors: Shepherd
mesh_terms: D015502:Absorptiometry, Photon; D000368:Aged; D005260:Female; D006620:Hip Fractures / Q000000981:diagnostic imaging / Q000453:epidemiology / Q000378:metabolism; D006801:Humans; D008297:Male; D008954:Models, Biological; D018482:Muscle, Skeletal / Q000378:metabolism / Q000473:pathology; D011446:Prospective Studies; D012307:Risk Factors; D050151:Subcutaneous Fat / Q000378:metabolism / Q000473:pathology
keywords: AGING; BODY COMPOSITION; DUAL-ENERGY X-RAY ABSORPTIOMETRY; HIP FRACTURE; OSTEOPOROSIS; SKELETAL MUSCLE ATTENUATION
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