Frances Tylavsky

Computed Tomographic Measurements of Thigh Muscle Cross-Sectional Area and Attenuation Coefficient Predict Hip Fracture: The Health, Aging, and Body Composition Study

Fatty infiltration of muscle, myosteatosis, increases with age and results in reduced muscle strength and function and increased fall risk. However, it is unknown if increased fatty infiltration of muscle predisposes to hip fracture. We measured the mean Hounsfield unit (HU) of the lean tissue within the midthigh muscle bundle (thigh muscle HU, an indicator of intramuscular fat), its cross‐sectional area (CSA, a measure of muscle mass) by computed tomography (CT), bone mineral density (BMD) of the hip and total‐body percent fat by dual X‐ray absorptiometry (DXA), isokinetic leg extensor strength, and the Short Physical Performance Battery (SPPB) in 2941 white and black women and men aged 70 to 79 years. Sixty‐three hip fractures were validated during 6.6 years of follow‐up. Proportional hazards regression analysis was used to assess the relative risk (RR) of hip fracture across variations in thigh muscle attenuation, CSA, muscle strength, and physical function for hip fracture. In models adjusted by age, race, gender, body mass index, and percentage fat, decreased thigh muscle HU resulted in increased risk of hip fracture [RR/SD = 1.58; 95% confidence interval (CI) 1.10–1.99], an association that continued to be significant after further adjustment for BMD. In models additionally adjusted by CSA, muscle strength, and SPPB score, decreased thigh muscle HU but none of the other muscle parameters continued to be associated with an increased risk of hip fracture (RR/SD = 1.42; 95% CI 1.03–1.97). Decreased thigh muscle HU, a measure of fatty infiltration of muscle, is associated with increased risk of hip fracture and appears to account for the association between reduced muscle strength, physical performance, and muscle mass and risk of hip fracture. This characteristic captures a physical characteristic of muscle tissue that may have importance in hip fracture etiology.

Lower serum albumin concentration and change in muscle mass: the Health, Aging and Body Composition Study

BACKGROUND Low albumin concentrations in older persons increase the risk of poor health outcomes, including functional decline. OBJECTIVE The aim of the study was to investigate the association between serum albumin concentration and skeletal muscle loss (sarcopenia) in old age. DESIGN Serum albumin concentration was measured in 1882 black and white men and women aged 70-79 y participating in the Health, Aging and Body Composition Study. Five-year changes in appendicular skeletal muscle mass (ASMM), total-body fat-free mass (FFM), and trunk lean mass (TLM) were measured by using dual-energy X-ray absorptiometry. Confounders included health and lifestyle factors, which are markers of inflammation and protein intake. RESULTS A low albumin concentration (< 38 g/L) was observed in 21.2% of the study participants. After adjustment for confounders, the mean (+/-SE) change in ASMM was -82 +/- 26 g per 3-g/L lower albumin concentration (P = 0.002). This association remained after persons with a low albumin concentration (< 38 g/L) were excluded. The decline in ASMM in subjects with low albumin concentrations was almost 30% higher (-930 +/- 56 g) than that in those with albumin concentrations > or = 42 g/L (-718 +/- 38 g; P < 0.01). The association between albumin and change in ASMM remained after additional adjustment for weight change. A weak association was observed for FFM, whereas no association was observed for TLM, which suggests a specific role of albumin in skeletal muscle change. CONCLUSIONS Lower albumin concentrations, even above the clinical cutoff of 38 g/L, are associated with future loss of ASMM in older persons. Low albumin concentration may be a risk factor for sarcopenia.

Waist Circumference and Sagittal Diameter Reflect Total Body Fat Better Than Visceral Fat in Older Men and Women: The Health, Aging and Body Composition Study

Abstract: The validity of waist circumference and sagittal diameter as surrogate measures of visceral fat were assessed using preliminary cross‐sectional data from the Health, Aging and Body Composition Study, a cohort of 3,075 men and women aged 70–79. Weight, body mass index, waist circumference, waist/thigh ratio, and sagittal diameter were compared by correlation, graphical analysis, and regression to total body fat as measured by dual‐energy X‐ray absorptiometry (Hologic 4500A), and to visceral fat area as measured by computerized tomography. We included 2,830 persons, 1,439 women and 1,391 men with complete data on all measurements. For both men and women, all measurements were strongly correlated with both total body fat and visceral fat except the waist/thigh ratio. However, waist circumference, sagittal diameter, weight, and body mass index were more closely related to total body fat than to visceral fat area (R2 for the linear regression of waist circumference on total body fat was 0.69 in women and men; R2 for linear regression of waist circumference on visceral fat area was 0.40 in women, and 0.49 in men). These data suggest that the contribution of visceral fat to health risks will be better assessed by directly measuring this fat depot.

Relations of Dietary Magnesium Intake to Biomarkers of Inflammation and Endothelial Dysfunction in an Ethnically Diverse Cohort of Postmenopausal Women

OBJECTIVE Although magnesium may favorably affect metabolic outcomes, few studies have investigated the role of magnesium intake in systemic inflammation and endothelial dysfunction in humans. RESEARCH DESIGN AND METHODS Among 3,713 postmenopausal women aged 50–79 years in the Womens Health Initiative Observational Study and free of cardiovascular disease, cancer, and diabetes at baseline, we measured plasma concentrations of high-sensitivity C-reactive protein (hs-CRP), interleukin-6 (IL-6), turnor necrosis factor-α receptor 2 (TNF-α-R2), soluble intercellular adhesion molecule-1 (sICAM-1), soluble vascular cell adhesion molecule-1 (sVCAM-1), and E-selectin. Magnesium intake was assessed using a semiquantitative food frequency questionnaire. RESULTS After adjustment for age, ethnicity, clinical center, time of blood draw, smoking, alcohol, physical activity, energy intake, BMI, and diabetes status, magnesium intake was inversely associated with hs-CRP (P for linear trend = 0.003), IL-6 (P < 0.0001), TNF-α-R2 (P = 0.0006), and sVCAM-1 (P = 0.06). Similar findings remained after further adjustment for dietary fiber, fruit, vegetables, folate, and saturated and trans fat intake. Multivariable-adjusted geometric means across increasing quintiles of magnesium intake were 3.08, 2.63, 2.31, 2.53, and 2.16 mg/l for hs-CRP (P = 0.005); 2.91, 2.63, 2.45, 2.27, and 2.26 pg/ml for IL-6 (P = 0.0005); and 707, 681, 673, 671, and 656 ng/ml for sVCAM-1 (P = 0.04). An increase of 100 mg/day magnesium was inversely associated with hs-CRP (−0.23 mg/l ± 0.07; P = 0.002), IL-6 (−0.14 ± 0.05 pg/ml; P = 0.004), TNF-α-R2 (−0.04 ± 0.02 pg/ml; P = 0.06), and sVCAM-1 (−0.04 ± 0.02 ng/ml; P = 0.07). No significant ethnic differences were observed. CONCLUSIONS High magnesium intake is associated with lower concentrations of certain markers of systemic inflammation and endothelial dysfunction in postmenopausal women.

Low-fat, increased fruit, vegetable, and grain dietary pattern, fractures, and bone mineral density: the Women's Health Initiative Dietary Modification Trial

BACKGROUND The effects of dietary changes on osteoporosis, low bone density, and frequent falls are unestablished. OBJECTIVE We assessed the effect of the Womens Health Initiative Dietary Modification low-fat and increased fruit, vegetable, and grain intervention on incident hip, total, and site-specific fractures and self-reported falls, and, in a subset, on bone mineral density (BMD). DESIGN Postmenopausal women (n = 48,835) aged 50-79 y (18.6% of minority race-ethnicity) were randomly assigned to receive the Dietary Modification intervention (40%, n = 19,541) (daily goal: < or =20% of energy as fat, > or =5 servings of vegetables and fruit, and > or =6 servings of grains) or to a comparison group that received no dietary changes (60%; n = 29,294). RESULTS After a mean 8.1 y of follow-up, 215 women in the intervention group and 285 women in the comparison group (annualized rate: 0.14% and 0.12%, respectively) experienced a hip fracture (hazard ratio: 1.12; 95% CI: 0.94, 1.34; P = 0.21). The intervention group (n = 5423; annualized rate: 3.44%) had a lower rate of reporting > or =2 falls than did the comparison group (n = 8695; annualized rate: 3.67%) (HR: 0.92; 95% CI: 0.89, 0.96; P < 0.01). There was a significant interaction according to hormone therapy use; those in the comparison group receiving hormone therapy had the lowest incidence of hip fracture. In a subset of 3951 women, hip BMD at years 3, 6, and 9 was 0.4-0.5% lower in the intervention group than in the comparison group (P = 0.003). CONCLUSIONS A low-fat and increased fruit, vegetable, and grain diet intervention modestly reduced the risk of multiple falls and slightly lowered hip BMD but did not change the risk of osteoporotic fractures. This trial was registered at clinicaltrials.gov as NCT00000611.

Hospitalization and Change in Body Composition and Strength in a Population-Based Cohort of Older Persons

OBJECTIVES: To examine the association between hospitalization and annual changes in body composition and strength in older adults.

Utility of ultrasound to assess risk of fracture

Traditional assessments of bone properties have utilized densitometry techniques such as Dual Energy X‐ray Absorptiometry (DXA). Recently, quantitative ultrasound (QUS) has been introduced as an alternative method of assessing bone properties. Advantages of QUS over X‐ray techniques include low costs, portability, and nonionizing radiation. Proponents of QUS have claimed that this technology can provide information not only about the density but also about the structure and mechanical properties of bone. There are two major questions that need to be answered for those who seek to diagnose bone disorders with ultrasound: (1) what does quantitative ultrasound actually measure, and, even more importantly, (2) what is its clinical utility? In this review we will briefly examine the first question and will focus on the utility of ultrasound in clinical trials to discriminate between fractures and non‐fractures and to predict the risk of fractures. J Am Geriatr Soc 45:1382–1394, 1997.

Correlates and Prevalence of Insufficient 25-Hydroxyvitamin D Status in Black and White Older Adults: The Health, Aging and Body Composition Study

OBJECTIVES: To determine the prevalence and correlates of vitamin D insufficiency in black and white older adults.

Low volumetric BMD is linked to upper-limb fracture in pubertal girls and persists into adulthood: a seven-year cohort study.

The aetiology of increased incidence of fracture during puberty is unclear. This study aimed to determine whether low volumetric bone mineral density (vBMD) in the distal radius is associated with upper-limb fractures in growing girls, and whether any such vBMD deficit persists into adulthood. Fracture history from birth to 20 years was obtained and verified by medical records in 1034 Finnish girls aged 10-13 years. Bone density and geometry at distal radius, biomarkers and lifestyle/behavioural factors were assessed in a subset of 396 girls with a 7.5-year follow-up. We found that fracture incidence peaked during puberty (relative risk 3.1 at age of 8-14 years compared to outside this age window), and 38% of fractures were in the upper-limb. Compared to the non-fracture cohort, girls who sustained upper-limb fracture at ages 8-14 years had lower distal radial vBMD at baseline (258.9+/-37.5 vs. 287.5+/-34.1 mg/cm(3), p=0.001), 1-year (252.0+/-29.3 vs. 282.6+/-33.5 mg/cm(3), p=0.001), 2-year (258.9+/-32.2 vs. 289.9+/-40.1 mg/cm(3), p=0.003), and 7-year follow-ups (early adulthood, 307.6+/-35.9 vs. 343.6+/-40.9 mg/cm(3), p=0.002). There was a consistent trend towards larger bone cross-sectional area in the fracture cohort compared to non-fracture. In a logistic regression model, lower vBMD (p=0.001) was the only significant predictor of upper-limb fracture during the period of 8-14 years. Our results indicate that low BMD is an important factor underlying elevated upper-limb fracture risk during puberty, and that low BMD in pubertal girls with fracture persists into adulthood. Hence low vBMD during childhood is not a transient deficit. Methods to monitor vBMD and to maximise bone mineral accrual and reduce risks of falling in childhood should be developed.

Activity energy expenditure and change in body composition in late life

BACKGROUND Change in body composition, specifically loss of fat-free mass and gain in fat mass, in older adults is a major pathway leading to the onset of functional decline and physical disability. OBJECTIVE The objective was to determine the association of activity-related energy expenditure with change in body mass and composition among older men and women. DESIGN Total energy expenditure (TEE) was assessed over 2 wk by using the doubly labeled water method in 302 community-dwelling older adults aged 70-82 y. Resting metabolic rate (RMR) was measured by using indirect calorimetry, and the thermic effect of meals was estimated at 10% of TEE. Activity energy expenditure (AEE) was calculated as [TEE(0.9) - RMR]. Total body mass, fat-free mass (FFM), and fat mass (FM) were assessed by dual-energy X-ray absorptiometry annually over a mean (+/-SD) of 4.9 +/- 1.3 y. RESULTS In multivariate models adjusted for baseline age, smoking status, and race, men and women had a decline (in kg/y) in body mass (men: -0.34, 95% CI: -0.71, 0.02; women: -0.45, 95% CI: -0.71, -0.19) and FFM (men: -0.48, 95% CI: -0.67, -0.29; women: -0.14, 95% CI: -0.026, -0.03). No changes (in kg/y) were observed in FM (men: 0.14, 95% CI: -0.10, 0.38; women: -0.28, 95% CI: -0.49, -0.07). In men and women, higher AEE at baseline was associated with greater FFM. The average change in these outcomes (ie, slope), however, was similar across tertiles of AEE. CONCLUSIONS These data suggest that accumulated energy expenditure from all physical activities is associated with greater FFM, but the effect does not alter the trajectory of FFM change in late life.