Identification of Sarcopenia Components That Discriminate Slow Walking Speed: A Pooled Data Analysis.

BACKGROUND: The Sarcopenia Definitions and Outcomes Consortium (SDOC) sought to identify cut points for muscle strength and body composition measures derived from dual-energy x-ray absorptiometry (DXA) that discriminate older adults with slow walking speed. This article presents the core analyses used to guide the SDOC position statements. DESIGN: Cross-sectional data analyses of pooled data. SETTING: University-based research assessment centers. PARTICIPANTS: Community-dwelling men (n = 13,652) and women: (n = 5,115) with information on lean mass by DXA, grip strength (GR), and walking speed. MEASUREMENTS: Thirty-five candidate sarcopenia variables were entered into sex-stratified classification and regression tree (CART) models to agnostically choose variables and cut points that discriminate slow walkers (<0.80 m/s). Models with alternative walking speed outcomes were also evaluated (<0.60 and <1.0 m/s and walking speed treated continuously). RESULTS: CART models identified GR/body mass index (GRBMI) and GR/total body fat (GRTBF) as the primary discriminating variables for slowness in men and women, respectively. Men with GRBMI of 1.05 kg/kg/m2 or less were approximately four times more likely to be slow walkers than those with GRBMI of greater than 1.05 kg/kg/m2 . Women with GRTBF of less than 0.65 kg/kg were twice as likely to be slow walkers than women with GRTBF of 0.65 kg/kg or greater. Models with alternative walking speed outcomes selected only functions of GR as primary discriminators of slowness in both men and women. DXA-derived lean mass measures did not consistently discriminate slow walkers. CONCLUSION: GR with and without adjustments for body size and composition consistently discriminated older adults with slowness. CART models did not select DXA-based lean mass as a primary discriminator of slowness. These results were presented to an SDOC Consensus Panel, who used them and other information to develop the SDOC Position Statements. J Am Geriatr Soc 68:1419-1428, 2020.

Association Between Abdominal Aortic Calcification, Bone Mineral Density, and Fracture in Older Women.

Although a relationship between vascular disease and osteoporosis has been recognized, its clinical importance for fracture risk evaluation remains uncertain. Abdominal aortic calcification (AAC), a recognized measure of vascular disease detected on single-energy images performed for vertebral fracture assessment, may also identify increased osteoporosis risk. In a prospective 10-year study of 1024 older predominantly white women (mean age 75.0 ± 2.6 years) from the Perth Longitudinal Study of Aging cohort, we evaluated the association between AAC, skeletal structure, and fractures. AAC and spine fracture were assessed at the time of hip densitometry and heel quantitative ultrasound. AAC was scored 0 to 24 (AAC24) and categorized into low AAC (score 0 and 1, n = 459), moderate AAC (score 2 to 5, n = 373), and severe AAC (score >6, n = 192). Prevalent vertebral fractures were calculated using the Genant semiquantitative method. AAC24 scores were inversely related to hip BMD ( r s = -0.077, p = 0.013), heel broadband ultrasound attenuation ( r s = -0.074, p = 0.020), and the Stiffness Index ( r s = -0.073, p = 0.022). In cross-sectional analyses, women with moderate to severe AAC were more likely to have prevalent fracture and lumbar spine imaging-detected lumbar spine fractures, but not thoracic spine fractures (Mantel-Haenszel test of trend p < 0.05). For 10-year incident clinical fractures and fracture-related hospitalizations, women with moderate to severe AAC (AAC24 score >1) had increased fracture risk (HR 1.48; 95% CI, 1.15 to 1.91; p = 0.002; HR 1.46; 95% CI, 1.07 to 1.99; p = 0.019, respectively) compared with women with low AAC. This relationship remained significant after adjusting for age and hip BMD for clinical fractures (HR 1.40; 95% CI, 1.08 to 1.81; p = 0.010), but was attenuated for fracture-related hospitalizations (HR 1.33; 95% CI, 0.98 to 1.83; p = 0.073). In conclusion, older women with more marked AAC are at higher risk of fracture, not completely captured by bone structural predictors. These findings further support the concept that vascular calcification and bone pathology may share similar mechanisms of causation that remain to be fully elucidated © 2019 American Society for Bone and Mineral Research.

Adding Lateral Spine Imaging for Vertebral Fractures to Densitometric Screening: Improving Ascertainment of Patients at High Risk of Incident Osteoporotic Fractures.

The current diagnosis of osteoporosis is limited to a T-score ≤-2.5. However, asymptomatic vertebral fractures (VF) are known to predict a high risk of subsequent fractures and pharmaceutical intervention is known to reduce future fracture risk in these individuals. In a prospective, population-based cohort of ambulant older women, we sought to evaluate the role of VF detection by screening densitometric lateral spine imaging (LSI) for VF at time of bone density testing to the effect on the magnitude of fracture risk. A total of 1084 women (mean age 75 years ± SD 3 years) had baseline LSI that identified 100 (9%) women with VFs and 89 (8%) with femoral neck (FN) T-score osteoporosis ≤-2.5. Follow-up identified incident clinical spine fracture in 73 (7%), 305 (28%) with any fracture-related hospitalization, and 121 (11%) with a hip fracture-related hospitalization. Compared with those without baseline VF, in those with baseline VF, relative risk (RR) for incident clinical spine, hip, and any fracture were 3.46 (95% confidence interval [CI] 2.14-5.60, p < 0.001); 1.72 (95% CI 1.09-2.71, p = 0.02), and 1.4 (95% CI 1.07-1.84, p = 0.02), respectively. In 675 (62%) of women with femoral neck osteopenia (T-score <-1 to >-2.5), 61 (9%) also had a VF. Compared with those without baseline VF, RR for any incident fragility fractures and fractures at spine and hip in those with baseline VF were 1.6 (95% CI 1.2-2.1, p < 0.01), 3.9 (95% CI 2.2-6.9, p < 0.01), and 1.6 (95% CI 0.9-2.8, p = 0.10), respectively. On basis of the prognosis, older women with LSI VF with osteopenia should be diagnosed with osteoporosis and should be considered for pharmaceutical intervention. © 2018 American Society for Bone and Mineral Research.

Validation of rapid 4-component body composition assessment with the use of dual-energy X-ray absorptiometry and bioelectrical impedance analysis.

Background: The 4-component (4C) model is a criterion method for human body composition that separates the body into fat, water, mineral, and protein, but requires 4 measurements with significant cost and time requirements that preclude wide clinical use. A simplified model integrating only 2 measurements-dual-energy X-ray absorptiometry (DXA) and bioelectrical impedance analysis (BIA)-and 10 min of patient time has been proposed. Objective: We aimed to validate a rapid, simplified 4C DXA + BIA body composition model in a clinical population. Design: This was a cross-sectional observational study of 31 healthy adults. Participants underwent whole-body DXA, segmental BIA, air displacement plethysmography (ADP), and total body water (TBW) measurement by deuterium (D2O) dilution. 4C composition was calculated through the use of the Lohman model [DXA mineral mass, D2O TBW, ADP body volume (BV), scale weight] and the simplified model (DXA mineral mass and BV, BIA TBW, scale weight). Accuracy of percentage of fat (%Fat) and protein measurements was assessed via linear regression. Test-retest precision was calculated with the use of duplicate DXA and BIA measurements. Results: Of 31 participants, 23 were included in the analysis. TBWBIA showed good test-retest precision (%CV = 5.2 raw; 1.1 after outlier removal) and high accuracy to TBWD2O [TBWD2O = 0.956*TBWBIA, R2= 0.92, root mean squared error (RMSE) = 2.2 kg]. %Fat estimates from DXA, ADP, D2O, and BIA all showed high correlation with the Lohman model. However, only the 4C simplified model provides high accuracy for both %Fat (R2 = 0.96, RMSE = 2.33) and protein mass (R2= 0.76, RMSE = 1.8 kg). %Fat precision from 4C DXA + BIA was comparable with DXA (root mean square-SD = 0.8 and 0.6 percentage units, respectively). Conclusions: This work validates a simplified 4C method that measures fat, water, mineral, and protein in a 10-min clinic visit. This model has broad clinical application to monitor many conditions including over/dehydration, malnutrition, obesity, sarcopenia, and cachexia.

Long-Term Atherosclerotic Vascular Disease Risk and Prognosis in Elderly Women With Abdominal Aortic Calcification on Lateral Spine Images Captured During Bone Density Testing: A Prospective Study.

Lateral spine images are captured using bone densitometers for vertebral fracture assessment (VFA) in older women. Abdominal aortic calcification (AAC) is commonly seen on these images; however, the long-term prognosis in women with AAC remains uncertain. In a prospective study of 1052 community-dwelling ambulant white women over 70 years old abdominal aortic calcification 24 scale (AAC24) scores were calculated from digital lateral spine images captured during bone density testing in 1998 or 1999. Cardiovascular risk factors were assessed in 1998, whereas 14.5-year atherosclerotic vascular disease (ASVD)-related hospitalizations and deaths (events) were available through linked health records. Using established cut points for AAC 471 women (45%) had low AAC (AAC24 score 0 or 1), 387 (37%) moderate AAC (AAC24 score 2-5), and 197 (19%) had high AAC (AAC24 score ≥6). Over 14.5 years, 420 women experienced an ASVD event. Increasing severity of AAC was associated with increased absolute risk of ASVD events (37%, 39%, and 49%, respectively, p = 0.008 for trend), ASVD deaths (15%, 21%, and 27%, respectively, p < 0.001 for trend), and all-cause mortality (30%, 38%, and 44%, respectively, p < 0.001 for trend). After adjusting for Framingham risk scores, women with high AAC had increased relative hazard for ASVD events, HR 1.37 (95% CI, 1.07 to 1.77; p = 0.013) compared to women with low AAC. Similarly, women with moderate AAC and high AAC had increased relative hazards for ASVD deaths HR 1.41 (95% CI, 1.03 to 1.94; p = 0.034) and HR 1.80 (95% CI, 1.26 to 2.57; p = 0.001), or any deaths HR 1.30 (95% CI, 1.03 to 1.64; p = 0.026) and HR 1.53 (95% CI, 1.17 to 2.00; p = 0.002), compared to women with low AAC. In conclusion, more advanced AAC on images captured for VFA is associated with long-term ASVD hospitalizations and deaths before and after adjusting for Framingham risk scores. AAC assessment could be considered in addition to VFA to identify individuals who may benefit for more aggressive cardiovascular primary prevention strategies. © 2018 American Society for Bone and Mineral Research.

Abdominal Aortic Calcification Identified on Lateral Spine Images From Bone Densitometers Are a Marker of Generalized Atherosclerosis in Elderly Women.

OBJECTIVE: Dual-energy x-ray absorptiometry is a low-cost, minimal radiation technique used to improve fracture prediction. Dual-energy x-ray absorptiometry machines can also capture single-energy lateral spine images, and abdominal aortic calcification (AAC) is commonly seen on these images. APPROACH AND RESULTS: We investigated whether dual-energy x-ray absorptiometry-derived measures of AAC were related to an established test of generalized atherosclerosis in 892 elderly white women aged >70 years with images captured during bone density testing in 1998/1999 and B-mode carotid ultrasound in 2001. AAC scores were calculated using a validated 24-point scale into low (AAC24 score, 0 or 1), moderate (AAC24 scores, 2-5), and severe AAC (AAC24 scores, >5) seen in 45%, 36%, and 19%, respectively. AAC24 scores were correlated with mean and maximum common carotid artery intimal medial thickness (rs=0.12, P<0.001 and rs=0.14, P<0.001). Compared with individuals with low AAC, those with moderate or severe calcification were more likely to have carotid atherosclerotic plaque (adjusted prevalence ratio (PR), 1.35; 95% confidence interval, 1.14-1.61; P<0.001 and prevalence ratio, 1.94; 95% confidence interval, 1.65-2.32; P<0.001, respectively) and moderate carotid stenosis (adjusted prevalence ratio, 2.22; 95% confidence interval, 1.39-3.54; P=0.001 and adjusted prevalence ratio, 4.82; 95% confidence interval, 3.09-7.050; P<0.001, respectively). The addition of AAC24 scores to traditional risk factors improved identification of women with carotid atherosclerosis as quantified by C-statistic (+0.075, P<0.001), net reclassification (0.249, P<0.001), and integrated discrimination (0.065, P<0.001). CONCLUSIONS: AAC identified on images from a dual-energy x-ray absorptiometry machine were strongly related to carotid ultrasound measures of atherosclerosis. This low-cost, minimal radiation technique used widely for osteoporosis screening is a promising marker of generalized extracoronary atherosclerosis.

Assessment of abdominal fat compartments using DXA in premenopausal women from anorexia nervosa to morbid obesity.

OBJECTIVE: To test a newly developed dual energy X-ray absorptiometry (DXA) method for abdominal fat depot quantification in subjects with anorexia nervosa (AN), normal weight, and obesity using CT as a gold standard. DESIGN AND METHODS: 135 premenopausal women (overweight/obese: n = 89, normal-weight: n = 27, AN: n = 19); abdominal visceral adipose tissue (VAT), subcutaneous adipose tissue (SAT), and total adipose tissue (TAT) areas determined on CT and DXA. RESULTS: There were strong correlations between DXA and CT measurements of abdominal fat compartments in all groups with the strongest correlation coefficients in the normal-weight and overweight/obese groups. Correlations of DXA and CT VAT measurements were strongest in the obese group and weakest in the AN group. DXA abdominal fat depots were higher in all groups compared to CT, with the largest % mean difference in the AN group and smallest in the obese group. CONCLUSION: A new DXA technique is able to assess abdominal fat compartments including VAT in premenopausal women across a large weight spectrum. However, DXA measurements of abdominal fat were higher than CT, and this percent bias was most pronounced in the AN subjects and decreased with increasing weight, suggesting that this technique may be more useful in obese individuals.

Dual-energy X-ray performs as well as clinical computed tomography for the measurement of visceral fat.

Visceral adipose tissue (VAT) is associated with adverse health effects including cardiovascular disease and type 2 diabetes. We developed a dual-energy X-ray absorptiometry (DXA) measurement of visceral adipose tissue (DXA-VAT) as a low cost and low radiation alternative to computed tomography (CT). DXA-VAT was compared to VAT assessed using CT by an expert reader (E-VAT). In addition, the same CT slice was also read by a clinical radiographer (C-VAT) and a best-fit anthropomorphic and demographic VAT model (A-VAT) was developed. Whole body DXA, CT at L4-L5, and anthropometry were measured on 272 black and white South African women (age 29 ± 8 years, BMI 28 ± 7 kg/m(2), waist circumference (WC) 89 ± 16 cm). Approximately one-half of the dataset (n = 141) was randomly selected and used as a training set for the development of DXA-VAT and A-VAT, which were then used to estimate VAT on the remaining 131 women in a blinded fashion. DXA-VAT (r = 0.93, standard error of the estimate (SEE) = 16 cm(2)) and C-VAT (r = 0.93, SEE = 16 cm(2)) were strongly correlated to E-VAT. These correlations with E-VAT were significantly stronger (P < 0.001) than the correlations of individual anthropometry measurements and the A-VAT model (WC + age, r = 0.79, SEE = 27 cm(2)). The inclusion of anthropometric and demographic measurements did not substantially improve the correlation between DXA-VAT and E-VAT. DXA-VAT performed as well as a clinical read of VAT from a CT scan and better than anthropomorphic and demographic models.

Volumetric DXA (VXA): A new method to extract 3D information from multiple in vivo DXA images.

Three-dimensional geometric and structural measurements of the proximal femur are of considerable interest in understanding the strength of the femur and its susceptibility to fracture. Quantitative computed tomography (QCT) with a small voxel size (≤1 mm per side) is the current "gold standard" to examine the macrostructure of the femur, but it has a high effective radiation dose (approximately 2 to 5 mSv) and cost. Volumetric dual-energy X-ray absorptiometry (VXA) uses a commercially available DXA system (Hologic Discovery A) to reconstruct the proximal femur from four DXA scans delivering an effective radiation dose of 0.04 mSv. VXA was compared with QCT (voxel size of 0.29 × 0.29 × 1 mm) in 41 elderly women (age 82 ± 2.4 years) at slices located at the femoral neck and trochanteric regions of interest. For parameters of shape, the femoral neck axis length (FNAL) and the cross-sectional slice area (SA), accuracy and strong linear correlations (r = 0.84 to 0.98) were demonstrated. Similar correlations (r = 0.81 to 0.97) were observed for the density parameters, the cross-sectional bone area (CSA) and volumetric bone mineral density (vBMD). VXA also demonstrated strong correlations (r = 0.76 to 0.99) for the engineering parameters of the minimum, maximum, and polar cross-sectional moments of inertia (CSMIs) and the section modulus (Z). We conclude that VXA is capable of generating a variety of 3D geometric and structural measurements that are highly correlated with QCT in elderly subjects in vivo. Moreover, the VXA measurements can be made with a commercially available DXA device at a very low radiation dose.

Dual energy X-Ray absorptiometry body composition reference values from NHANES.

In 2008 the National Center for Health Statistics released a dual energy x-ray absorptiometry (DXA) whole body dataset from the NHANES population-based sample acquired with modern fan beam scanners in 15 counties across the United States from 1999 through 2004. The NHANES dataset was partitioned by gender and ethnicity and DXA whole body measures of %fat, fat mass/height(2), lean mass/height(2), appendicular lean mass/height(2), %fat trunk/%fat legs ratio, trunk/limb fat mass ratio of fat, bone mineral content (BMC) and bone mineral density (BMD) were analyzed to provide reference values for subjects 8 to 85 years old. DXA reference values for adults were normalized to age; reference values for children included total and sub-total whole body results and were normalized to age, height, or lean mass. We developed an obesity classification scheme by using estabbody mass index (BMI) classification thresholds and prevalences in young adults to generate matching classification thresholds for Fat Mass Index (FMI; fat mass/height(2)). These reference values should be helpful in the evaluation of a variety of adult and childhood abnormalities involving fat, lean, and bone, for establishing entry criteria into clinical trials, and for other medical, research, and epidemiological uses.

Abdominal aortic calcification detected on lateral spine images from a bone densitometer predicts incident myocardial infarction or stroke in older women.

UNLABELLED: Among a cohort of elderly women, abdominal aortic calcification scored on baseline lateral spine densitometric images intended for vertebral fracture assessment was associated with subsequent myocardial infarction or stroke over a median 4-yr period, independent of clinical cardiovascular disease risk factors. INTRODUCTION: Cardiovascular disease (CVD) risk among older women is not adequately captured by traditional CVD risk factors. Lateral spine images obtained on bone densitometers for vertebral fracture assessment (VFA) can detect abdominal aortic calcification (AAC), an important marker of subclinical CVD. Our objective was to estimate the association between AAC scored on VFA images and subsequent myocardial infarction (MI) or stroke in elderly women. MATERIALS AND METHODS: Among participants in a randomized controlled trial (women; age > 75 yr) of clodronate versus placebo, those who sustained an MI or stroke during the median 4-yr follow-up study period were selected as cases (n = 408), and 408 controls were randomly selected from the remainder of the parent study population. Baseline VFA images were scored for AAC with a previously validated 24-point scale and a newer, simpler 8-point scale. RESULTS: The OR of incident MI or stroke for those in the middle and top tertiles, respectively, compared with the bottom tertile of AAC score were 1.14 (95% CI, 0.79-1.66) and 1.74 (95% CI, 1.19-2.56) for the 24-point scale and 1.42 (95% CI, 0.98-2.05) and 1.77 (95% CI, 1.22-2.55) for the 8-point scale, adjusted for age, high-density lipoprotein and low-density lipoprotein cholesterol, triglycerides, blood pressure, smoking, renal function, health status, and baseline diagnoses of diabetes mellitus, hypertension, angina, and prior stroke. CONCLUSIONS: AAC scored on VFA images is independently associated with incident MI or stroke. Because bone densitometry is indicated for all women > or = 65 yr of age, VFA imaging offers an opportunity to capture this CVD risk factor in postmenopausal women undergoing bone densitometry at very little additional cost.

Detection of aortic calcification during vertebral fracture assessment (VFA) compared to digital radiography.

BACKGROUND: Cardiovascular disease is the most common cause of mortality among post-menopausal women. Our objective was to determine whether or not lateral spine images obtained on a bone densitometer to detect prevalent vertebral fracture can also accurately detect radiographic abdominal aortic calcification (AAC), an important risk factor for cardiovascular disease independent of clinical risk factors. METHODOLOGY/PRINCIPAL FINDINGS: One hundred seventy four postmenopausal women had bone densitometry, lateral spine densitometry imaging (called vertebral fracture assessment, or VFA), and lateral spine digital radiographs. Radiographs and VFA images were scored for AAC using a previously validated 24 point scale and a simplified, new 8 point scale (AAC-8). One hundred fifty six (90%) of the VFA images were evaluable for AAC. The non-parametric intraclass correlation coefficient between VFA and radiographic 24 point and AAC-8 readings, respectively, were 0.80 (95% C.I. 0.68-0.87) and 0.76 (95% C.I. 0.65-0.84). Areas under receiver operating characteristics (ROC) curves for VFA to detect those with a radiographic 24-point AAC score >or=5 were 0.86 (95% C.I. 0.77-0.94) using the 24 point scale and 0.84 (95% C.I. 0.76-0.92) using the AAC-8 scale. CONCLUSION/SIGNIFICANCE: VFA imaging intended to detect prevalent vertebral fracture can also detect radiographic AAC, an important cardiovascular disease risk factor. Since bone densitometry is recommended for all women age 65 and older, VFA imaging at the time of bone densitometry offers an opportunity to assess this risk factor in the post-menopausal female population at very little incremental time and expense.

Emerging trends in dual energy X-ray absorptiometry.

The risk of osteoporosis and cardiovascular disease increase significantly with age. Because of the long silent latency of these diseases, there is the opportunity for primary prevention before clinical symptoms occur. The newer fan beam dual energy x-ray absorptiometry (DXA) systems can detect vertebral fractures with fast, low dose lateral scans of the vertabrae from T4 to L4 in as little as 10 s. The next generation of DXA imaging technology will image the hip in 3D and is expected to give a more accurate picture of bone density as well as the geometry and underlying strength of a bone. Visualizing abdominal aortic calcifications (AAC) as a part of a standard vertebral fracture assessment exam is a particularly valuable measurement since it is an independent measure of cardiovascular disease risk, including heart attacks and strokes.

Detection of abdominal aortic calcification with lateral spine imaging using DXA.

Radiographic abdominal aortic calcification (AAC) is associated with incident cardiovascular disease and mortality independent of other risk factors. Lateral spine imaging using dual-energy X-ray absorptiometry (DXA) is now available to detect prevalent vertebral fracture (called vertebral fracture assessment), but its potential utility to detect radiographic AAC has not been investigated. Fifty-seven of 205 women age 65 or older who had participated in a prior study of the detection of prevalent vertebral fracture with lateral DXA had technically adequate radiographs and lateral DXA images to assess AAC. Two readers scored both the radiographic and lateral DXA images for AAC using a previously validated 24-point scale, blinded to both of each other's readings and also to their own readings on the other technology. The agreement between radiograph and lateral DXA AAC scores was very good (intra-class correlation coefficient [ICC] of 0.81 (95% confidence interval [CI]: 0.66-0.90) for reader 1 and 0.82 (95% CI: 0.69-0.90) for reader 2). The ICC between the two reader's AAC scores on radiographs was 0.92 (95% CI: 0.88-0.95) and on lateral DXA images was 0.89 (95% CI: 0.80-0.94). Lateral spine imaging with DXA shows very good agreement with standard radiography in the detection of AAC. Lateral imaging of the spine with DXA intended to detect vertebral fracture is a promising technology for the simultaneous assessment of a risk factor for cardiovascular disease incidence and death.