Validation of dual energy X-ray absorptiometry measures of abdominal fat by comparison with magnetic resonance imaging in an Indian population

Fat Distribution and Urolithiasis Risk Parameters in Uric Acid Stone Formers and Patients with Type 2 Diabetes Mellitus

Key Points

Background

Uric acid (UA) nephrolithiasis affects approximately 10% of kidney stones, with a greater preponderance among patients with obesity and diabetes mellitus (DM). UA lithogenicity is driven by abnormally acidic urine pH. Distinguishing the contribution of intrinsic (e.g., body adiposity) versus external (e.g., dietary) factors to UA stone propensity is challenging because of uncontrolled diets in outpatients in previously published studies.

Methods

This compilation of metabolic studies with body composition examined by dual-energy x-ray absorptiometry scan and blood and urine biochemistry collected under a controlled metabolic diet was conducted across three distinct populations: 74 UA stone formers (UASF group), 13 patients with type 2 DM without kidney stones (DM group), and 51 healthy volunteers (HV group).

Results

Compared with HVs, both UASFs and patients with DM exhibited higher levels of net acid excretion (NAE) and significantly lower urine pH and lower proportion of NAE excreted as ammonium (NH4 +/NAE), all under controlled diets. UASFs exhibited significantly lower NH4 +/NAE compared with patients with DM. UASFs also showed higher total body and truncal fat compared with HVs. Among the HVs, lower NH4 +/NAE ratio correlated with higher truncal and total fat. However, this association was abolished in the UASF and DM groups who exhibit a fixed low NH4 +/NAE ratio across a range of body and truncal fat.

Conclusions

The findings suggest a dual defect of diet-independent increase in acid production and impaired kidney NH4 + excretion as major contributors to the risk of UA stone formation. There is an inverse physiologic association between body fat content and NH4 +/NAE in HVs, whereas NH4 +/NAE is persistently low in UASFs and patients with DM, regardless of body fat, representing pathophysiology.

Subscapular skinfold thickness, not other anthropometric and dual-energy X-ray absorptiometry-measured adiposity, is positively associated with the presence of age-related macular degeneration: a cross-sectional study from National Health and Nutrition Examination Survey 2005-2006

OBJECTIVE

Current literature reveals an association between anthropometric measures of adiposity (AnthM) and age-related macular degeneration (AMD), but few have explored the disease association with imaging methods. This study aimed to explore the relationship between AMD status and dual-energy X-ray absorptiometry measures (DEXAMs) among a representative sample of the US population, and compare the association with AnthM.

METHOD

Using a representative sample in the National Health and Nutrition Examination Study 2005-2006 (n=1632), DEXAMs across the whole body and waist (ie, android), and relative fat distributions (eg, percentage fat, android-to-total body ratio) were analysed between no AMD (baseline) and any AMD. Bivariate analyses across AMD status were similarly performed for AnthM (ie, body mass index, waist circumference and skinfold thicknesses) and potential confounders (ie, demographics and health-related variables). Significant adiposity measures were analysed using logistic regression, adjusting for confounders.

RESULTS

The participants in the sample were aged 40-69 years, were majority female (52%) and mainly Caucasian (76.5%). Bivariate analysis revealed having any AMD had positive significant associations with android-to-total fat ratio and subscapular skinfold thickness (SSFT). Other AnthM and DEXAMs were not significant. After adjusting age, gender and prescription of cholesterol-lowering medicine, only SSFT remained significantly associated.

CONCLUSION

SSFT represents an independent risk factor for AMD presence compared with other AnthM and DEXAMs. SSFT is an established method of measuring fat under the skin (ie, subcutaneous fat). Hence, subcutaneous fat may be more relevant in explaining the adiposity-AMD link due to physiological properties specific to the tissue. Limitations include the restricted age range and low numbers of participants with late AMD.

Development and Validation of a Method of Body Volume and Fat Mass Estimation Using Three-Dimensional Image Processing with a Mexican Sample

Body composition assessment using instruments such as dual X-ray densitometry (DXA) can be complex and their use is often limited to research. This cross-sectional study aimed to develop and validate a densitometric method for fat mass (FM) estimation using 3D cameras. Using two such cameras, stereographic images, and a mesh reconstruction algorithm, 3D models were obtained. The FM estimations were compared using DXA as a reference. In total, 28 adults, with a mean BMI of 24.5 (±3.7) kg/m2 and mean FM (by DXA) of 19.6 (±5.8) kg, were enrolled. The intraclass correlation coefficient (ICC) for body volume (BV) was 0.98-0.99 (95% CI, 0.97-0.99) for intra-observer and 0.98 (95% CI, 0.96-0.99) for inter-observer reliability. The coefficient of variation for kinetic BV was 0.20 and the mean difference (bias) for BV (liter) between Bod Pod and Kinect was 0.16 (95% CI, -1.2 to 1.6), while the limits of agreement (LoA) were 7.1 to -7.5 L. The mean bias for FM (kg) between DXA and Kinect was -0.29 (95% CI, -2.7 to 2.1), and the LoA was 12.1 to -12.7 kg. The adjusted R2 obtained using an FM regression model was 0.86. The measurements of this 3D camera-based system aligned with the reference measurements, showing the system's feasibility as a simpler, more economical screening tool than current systems.

Assessment of correlation between conventional anthropometric and imaging-derived measures of body fat composition: a systematic literature review and meta-analysis of observational studies

BACKGROUND

In studies of the association of adiposity with disease risk, widely used anthropometric measures of adiposity (e.g. body-mass-index [BMI], waist circumference [WC], waist-hip ratio [WHR]) are simple and inexpensive to implement at scale. In contrast, imaging-based techniques (e.g. magnetic resonance imaging [MRI] and dual x-ray absorptiometry [DXA]) are expensive and labour intensive, but can provide more accurate quantification of body fat composition. There is, however, limited evidence about the relationship between conventional and imaging-derived measures of adiposity.

METHODS

We searched Scopus and Web of Science for published reports in English of conventional versus imaging-derived measurements of adiposity. We identified 42 articles (MRI = 22; DXA = 20) that met selection criteria, involving 42,556 (MRI = 15,130; DXA = 27,426) individuals recruited from community or hospital settings. Study-specific correlation coefficients (r) were transformed using Fisher's Z transformation, and meta-analysed to yield weighted average correlations, both overall and by ancestry, sex and age, where feasible. Publication bias was investigated using funnel plots and Egger's test.

RESULTS

Overall, 98% of participants were 18 + years old, 85% male and 95% White. BMI and WC were most strongly correlated with imaging-derived total abdominal (MRI-derived: r = 0.88-; DXA-derived: 0.50-0.86) and subcutaneous abdominal fat (MRI-derived: 0.83-0.85), but were less strongly correlated with visceral abdominal fat (MRI-derived: 0.76-0.79; DXA-derived: 0.80) and with DXA-derived %body fat (0.76). WHR was, at best, strongly correlated with imaging-derived total abdominal (MRI-derived: 0.60; DXA-derived: 0.13), and visceral abdominal fat (MRI-derived: 0.67; DXA-derived: 0.65), and moderately with subcutaneous abdominal (MRI-derived: 0.54), and with DXA-derived %body fat (0.58). All conventional adiposity measures were at best moderately correlated with hepatic fat (MRI-derived: 0.36-0.43). In general, correlations were stronger in women than in men, in Whites than in non-Whites, and in those aged 18 + years.

CONCLUSIONS

In this meta-analysis, BMI and WC, but not WHR, were very strongly correlated with imaging-derived total and subcutaneous abdominal fat. By comparison, all three measures were moderately or strongly correlated with imaging-based visceral abdominal fat, with WC showing the greatest correlation. No anthropometric measure was substantially correlated with hepatic fat. Further larger studies are needed to compare these measures within the same study population, and to assess their relevance for disease risks in diverse populations.

Obesity marker trajectories and cognitive impairment in older adults: a 10-year follow-up in Taichung community health study for elders

BACKGROUND

Obesity and cognitive impairment prevalence increases as age increases. Recent growing evidence finds links between obesity and cognitive impairment in older adults. However, the association between the two is controversial. This study aims to identify obesity marker trajectory patterns, and to assess whether these patterns are associated with cognitive impairment and cognitive decline during a 10-year follow-up period among community-dwelling older adults.

METHODS

A total of 626 older adults aged 65 and older were involved in the study, with at least two repeated measurements at baseline, one-year or 10-year follow-up. Cognitive function was measured through the Mini Mental State Examination. Obesity markers included body mass index, waist circumference, waist-to-hip (WHR), fat mass (FM), and abdominal fat (AF) measured by dual-energy X-ray absorptiometry. Multivariate logistic regression analyses were performed to estimate the adjusted odds ratios (ORs) and 95% confidence intervals (CIs) of cognitive impairment and cognitive decline for obesity marker trajectory patterns.

RESULTS

After a 10-year follow-up, 168 older adults with incident cognitive impairment and 156 with rapid cognitive decline were defined as the top 25th percentile of cognitive decline. Four distinct trajectory groups of obesity markers were identified. In multivariate logistic regression analyses, a low likelihood of cognitive impairment was observed in the consistently high-level group from FM trajectory (ORs = 0.41, 95% CI = 0.20-0.85); the high-level U-shaped group from WHR trajectory (0.43, 0.22-0.84); and the median-level flat inverse U-shaped, consistently high-level, and low-level flat U-shaped groups from AF trajectory (0.44, 0.26-0.77; 0.33, 0.18-0.61; 0.39, 0.18-0.82). In addition, a low likelihood of rapid decline was found in the low-level, slightly increasing trend group from WHR trajectory (0.43, 0.22-0.85).

CONCLUSION

FM and AF trajectories with consistent high levels and WHR trajectory with high level with U-shaped group are associated with low risks of incident cognitive impairment in older adults. Similarly, WHR trajectory with a low but slowly increasing trend is associated with a decreased risk of cognitive decline.

Comparison between DXA and MRI for the Visceral Fat Assessment in Athletes

The use of dual-energy X-ray absorptiometry (DXA) may be invalid for assessing athletes with larger bodies, larger lean body mass, and thicker trunks. This study compared the athletes' visceral adipose tissue (VAT) assessed using DXA and magnetic resonance imaging (MRI). Eighty-two Japanese male collegiate athletes from 18 sports participated in this study. VAT was assessed using the dual-energy scan that coincided with the 4th lumbar vertebra. The sum of eight magnetic resonance slices corresponding to the region of the dual-energy scan was used for comparison. The VAT volume was higher with the dual-energy scan than with MRI (difference: 35 cm³, p<0.01). A significant correlation was noted between the volumes measured using both modalities (r=0.88, p<0.01). Magnetic resonance-derived volumes less than 600 cm³ showed a stronger significant correlation with dual-energy-derived volumes. However, magnetic resonance-derived VAT volumes exceeding 600 cm³ were not significantly correlated with dual-energy-derived volumes. In conclusion, VAT volumes derived from DXA were larger and significantly correlated with those derived from MRI across a wide range of values. Methods using DXA for assessing the visceral fat volume may require adjustment to estimate abdominal visceral fat volume in athletes, with care taken when using such methods for heavyweight athletes.

Validation of Global Diet Quality Score Among Nonpregnant Women of Reproductive Age in India: Findings from the Andhra Pradesh Children and Parents Study (APCAPS) and the Indian Migration Study (IMS)

BACKGROUND

In India, there is a need to monitor population-level trends in changes in diet quality in relation to both undernutrition and noncommunicable diseases.

OBJECTIVES

We conducted a study to validate a novel diet quality score in southern India.

METHODS

We included data from 3041 nonpregnant women of reproductive age (15-49 years) from 2 studies in India. Diet was assessed using a validated food frequency questionnaire (FFQ). The Global Diet Quality Score (GDQS) was calculated from 25 food groups (16 healthy; 9 unhealthy), with points for each group based on the frequency and quantity of items consumed in each group. We used Spearman correlations to examine correlations between the GDQS and several nutrient intakes of concern. We examined associations between the GDQS [overall, healthy (GDQS+), and unhealthy (GDQS-) submetrics] and overall nutrient adequacy, micro- and macronutrients, body mass index (BMI), midupper arm circumference, hemoglobin, blood pressure, high density lipoprotein (HDL), and total cholesterol (TC).

RESULTS

The mean GDQS was 23 points (SD, 3.6; maximum, 46.5). In energy-adjusted models, positive associations were found between the overall GDQS and GDQS+ and intakes of calcium, fiber, folate, iron, monounsaturated fatty acid (MUFA), protein, polyunsaturated fatty acid (PUFA), saturated fatty acid (SFA), total fat, and zinc (ρ = 0.12-0.39; P < 0.001). Quintile analyses showed that the GDQS was associated with better nutrient adequacy. At the same time, the GDQS was associated with higher TC, lower HDL, and higher BMI. We found no associations between the GDQS and hypertension.

CONCLUSIONS

The GDQS was a useful tool for reflecting overall nutrient adequacy and some lipid measures. Future studies are needed to refine the GDQS for populations who consume large amounts of unhealthy foods, like refined grains, along with healthy foods included in the GDQS.

Adiposity Is Related to Inflammatory Disease Activity in Juvenile Idiopathic Arthritis

OBJECTIVE

To identify factors associated with the higher proportion of fatty tissue and overweight/obesity observed in patients with juvenile idiopathic arthritis (JIA).

PATIENTS AND METHODS

We performed a cross-sectional study of 80 JIA patients aged 4-15 years with 80 age- and sex-matched healthy controls. Body composition was assessed using dual-energy x-ray absorptiometry. The 27-joint Juvenile Arthritis Disease Activity score (JADAS27) was calculated. Two multivariate models were constructed to identify factors associated with overweight/obesity and fat mass index (FMI).

RESULTS

No differences were found between cases and controls in body mass index (BMI) or body composition. However, compared with controls, patients with a high inflammatory activity (JADAS27 > 4.2 for oligoarticular JIA or >8.5 for polyarticular disease) had higher values for BMI (p = 0.006); total fat mass (p = 0.003); FMI (p = 0.001); and fat in the legs (p = 0.001), trunk (p = 0.001), and arms (p = 0.002). The factors associated with overweight/obesity in patients were the duration of therapy with biological drugs, measured in months (OR [95% CI] = 1.12 [1.02-1.04]; p = 0.037), and physical activity (OR [95% CI] = 0.214 [0.07-0.68]; p = 0.010), while the factors associated with FMI were age (β [95% CI] = 0.30 [0.17-1.41]; p = 0.014), JADAS27 (β [95% CI] = 0.45 [0.16-1.08]; p = 0.009), and physical activity (β [95% CI] = -0.22 [-5.76 to 0.29]; p = 0.031).

CONCLUSION

Our study revealed no differences between JIA patients with well-controlled disease and low disability and the healthy population in BMI or body composition. Furthermore, the association observed between inflammatory activity and adiposity could be responsible for poorer clinical course.

The Association of Upper Body Obesity with Insulin Resistance in the Newfoundland Population

Body-fat distribution is a primary risk factor for insulin resistance and cardiovascular disease. Visceral fat explains only a portion of this risk. The link between upper-body fat and insulin resistance is uncertain. Furthermore, upper-body fat is not clearly defined. Dual-energy X-ray absorptiometry (DXA) can accurately quantify body fat. In this study, we explored the relationship between non-visceral upper-body adiposity and insulin resistance and other markers of metabolic syndrome. Fat proportions in the upper body, leg, and visceral regions were quantified by using DXA in 2547 adult Newfoundlanders aged 19 and older. Adjusting for remaining fat regions, we performed partial correlation analysis for each body region and insulin resistance defined by the Homeostatic Model of Assessment (HOMA). Similarly, partial correlation analysis was also performed between each fat region and other markers of metabolic syndrome, including high-density lipoprotein cholesterol (HDL), triglycerides (TG), body mass index (BMI), and blood pressure. Major confounding factors, including age, caloric intake, and physical activity, were statistically controlled by using partial correlation analysis. Interactions between sex, menopausal status, and medication status were also tested. Arm adiposity was correlated with HOMA-IR (R = 0.132, p < 0.001) and HOMA-β (R = 0.134, p < 0.001). Visceral adiposity was correlated with HOMA-IR (R = 0.230, p < 0.001) and HOMA-β (R = 0.160, p < 0.001). No significant correlation between non-visceral trunk adiposity and insulin resistance was found. Non-visceral trunk adiposity was negatively correlated with HDL in men (R = −0.110, p < 0.001) and women (R = −0.117, p < 0.001). Non-visceral trunk adiposity was correlated with TG (total: R = 0.079, p < 0.001; men: R = 0.105, p = 0.012; women: R = 0.078, p = 0.001). In menopausal women, leg adiposity was negatively correlated with HOMA-IR (R = −0.196, p < 0.001) and HOMA-β (R = −0.101, p = 0.012). Upper-body adiposity in the arms is an independent contributor to insulin resistance. Upper-body adiposity in the non-visceral trunk region is an independent contributor to metabolic syndrome. Leg adiposity is protective against metabolic syndrome in women.

Cumulative inflammatory burden and obesity as determinants of insulin resistance in patients with established rheumatoid arthritis: cross-sectional study

OBJECTIVES

To describe the prevalence of insulin resistance (IR) in patients with established rheumatoid arthritis (RA) and to analyse the contribution of cumulative inflammatory burden and other factors to its development.

DESIGN

Observational cross-sectional study.

PARTICIPANTS

Patients with RA and controls matched for age, sex and Body Mass Index. We excluded patients with diabetes.

SETTINGS

Patients from an RA inception cohort at Hospital Regional Universitario de Málaga, Spain, were recruited between September 2016 and May 2018.

PRIMARY AND SECONDARY OUTCOME MEASURES

IR was evaluated using the homeostasis model assessment for IR and beta-cell function and the quantitative insulin sensitivity check index. Other variables included the cumulative 28-Joint Disease Activity Score (DAS28) with C reactive protein (CRP) body composition and cytokines. Two logistic regression models were constructed to identify factors associated with IR in patients with RA.

RESULTS

Eighty-nine patients with RA and 80 controls were included. The prevalence of IR was similar in both cases and controls. Inflammatory activity was controlled appropriately in patients during follow-up (mean DAS28 3.1 (0.8)). The presence of IR in patients with RA was associated with obesity (OR 6.01, 95% CI 1.9 to 8.7), higher cumulative DAS28-CRP values during follow-up (OR 2.8, 95% CI 1.3 to 6.0), and higher interleukin-1β levels (OR 1.6, 95% CI 1.1 to 2.4). The second model showed that the risk of IR increased by 10% for each kilogram of excess body fat.

CONCLUSION

In patients with well-controlled, established RA, IR is associated mainly with poorer control of inflammation from diagnosis and with obesity, specifically total fat mass.

Measuring Muscle Mass and Strength in Obesity: a Review of Various Methods

Lower muscle mass in populations with obesity is associated obesity-related diseases like hypertension and type 2 diabetes mellitus. Bariatric surgery leads to sustained weight loss. During the weight reduction, loss of muscle should be minimized. Thus reliable quantification of muscle mass is much needed and therefore the also the need for validated methods. Imaging methods, magnetic resonance imaging and computed tomography scan, have been the gold standard for many years. However, these methods are costly and have limitations such as the maximum weight. Dual-energy X-ray absorptiometry is currently the most used alternative. Other, less expensive methods are very limited in their validation in populations with morbid obesity. This narrative review summarizes the current knowledge regarding measuring muscle mass and strength in obesity.

Age and gender specific cut-off points for body fat parameters among adults in Qatar

Background

Excessive body fat is the leading cause of many metabolic disorders. Therefore, assessing levels of body fat associated with risk of disease in specific populations is crucial. The present study aimed to identify optimal cut-off values of body fat composition including total body fat, body fat percentage, visceral fat, and trunk fat, in order to predict metabolic risk in the Qatari population.

Methods

This cross-sectional study was based on Qatar Biobank data of 2407 Qatari adults (1269 male and 1138 female) aged 21–70 years old. Individuals’ height, weight and body fat percentage were obtained. Blood test data including lipid profile, blood glucose and HbA1c data were also obtained. The area under the curve was calculated using ROC analysis to obtain the body fat percentage associated with risk of disease.

Results

The cut-off points for total fat for those aged < 40 were 34.0 kg, and for those aged ≥40 were 30.7 kg and 35.6 kg in men and women, respectively. The cut-off for body fat percent for those aged < 40 were 35.1 and 45.1%, and for those aged ≥40 were 34.8 and 46.3% in men and women, respectively. The cut-off points for trunk fat percent for those aged < 40 were 19.5 and 22.4%, and for those aged ≥40 were 21.6 and 23.4% in men and women, respectively. The cut-off points for visceral fat percent for those aged < 40 were 1.4 and 1.0%, and for those aged ≥40 were 1.9 and 1.4% in men and women, respectively.

Conclusion

This study established Qatari adult-specific cut-off values of body fat for different age and gender groups.

Phenotyping of the Visceral Adipose Tissue Using Dual Energy X-Ray Absorptiometry (DXA) and Magnetic Resonance Imaging (MRI) in Pigs

The objective of this study was to phenotype visceral adipose tissue (VAT) in pigs. In this context, the ability to detect VAT by using the DXA CoreScan mode within the enCORE software, version 17 (GE Healthcare) was evaluated in comparison with MRI measurements (Siemens Magnetom C!) of the same body region. A number of 120 crossbred pigs of the F1 and F2 generation, with the parental breeds Large White, Landrace, Piétrain, and Duroc, were examined at an age of 150 days. A whole-body scan in two different modes ("thick", "standard") was carried out by a GE Lunar iDXA scanner. Very strong relationships (R² = 0.95, RMSE = 175cm³) were found for VAT between the two DXA modes. The comparison of VAT measured by MRI and DXA shows high linear relationships ("thick": R² = 0.76, RMSE = 399.25cm³/"standard": R² = 0.71, RMSE = 443.42cm³), but is biased, according to the Bland-Altman analysis. A variance analysis of VAT shows significant differences for both DXA modes and for MRI between male and female pigs, as well as between F1 and F2. In conclusion, DXA "CoreScan" has the ability to estimate VAT in pigs with a close relationship to MRI but needs bias correction.

Comparison of single-slice CT and DXA-derived measures of central adiposity in South African women

BACKGROUND

Visceral adipose tissue (VAT) accumulation is a known risk factor for cardiometabolic diseases. Efficient imaging modalities are necessary to quantify VAT. The study assessed the agreement between dual-energy x-ray absorptiometry (DXA) and single-slice computed tomography (CT) for abdominal fat quantification in mixed-ancestry South African women, and determined if this differed by body mass index (BMI) categories.

METHODS

VAT and abdominal subcutaneous adipose tissue (SAT) were measured using single-slice CT and DXA in 132 women aged 55 (45-64) years. Participants were categorised as normal weight (BMI < 25 kg/m²), overweight (BMI: 25-29.9 kg/m²) and obese (BMI ≥ 30 kg/m²). Pearson correlation coefficients and Bland-Altman analysis were used to determine agreement between the two measurements.

RESULTS

Two thirds of the participants were obese. DXA and CT-derived measurements of abdominal VAT and SAT were significantly correlated in the overall sample (r = 0.872 and r = 0.966, both p < 0.001, respectively) and within BMI categories. DXA overestimated VAT and SAT in the overall sample and across BMI categories. In the overall sample, the mean difference (DXA-CT estimates) was 75.3 cm² (95% CI: 68.8-81.8 cm², p ≤ 0.0001) for VAT and 54.7 cm² (47.1-62.3 cm², p ≤ 0.0001) for SAT. Within increasing BMI categories, the variance between the two modalities was fixed for VAT (p = 0.359 for obese), whereas the variance for SAT was heteroscedastic (p ≤ 0.0001).

CONCLUSIONS

DXA overestimated VAT and abdominal SAT in a sample of middle-aged mixed-ancestry South African women. VAT variance was fixed in the obesity category, an indication that DXA may be valid in measuring VAT in obese people.

Dual-Energy X-Ray Absorptiometry Compared to Computed Tomography for Visceral Adiposity Assessment Among Gastrointestinal and Pancreatic Cancer Survivors

Dual-energy x-ray absorptiometry (DXA) for visceral adipose tissue (VAT) assessment is used as an alternative to computed tomography (CT) for research purposes in apparently healthy and clinical populations. It is unknown whether DXA is comparable to CT among cancer survivors, especially in cases where VAT assessment may be affected by treatment history and side effects and become more challenging to assess, such as a history of surgical gastrointestinal resection and/or ascites. The purpose of this study was to determine the level of agreement between DXA and CT when assessing VAT area and volume among cancer survivors. One hundred Gastrointestinal and pancreatic cancer survivors underwent abdominal and pelvis CT and whole-body DXA within 48 hours. Bland-Altman analysis revealed that in women and men, DXA VAT-area estimates were larger and smaller, respectively, and was consistently smaller in estimates for VAT-volume. Correlations from linear regression analysis revealed statistically significant positive correlations between measurement methods. Overall, while DXA VAT estimates are highly correlated with CT VAT estimates, DXA estimates show substantial bias which indicates the two methods are not interchangeable in this population. Further research is warranted with a larger, more homogeneous sample to develop better estimates of the bias.

Comparison of a Wearable Tracker with Actigraph for Classifying Physical Activity Intensity and Heart Rate in Children

Introduction: To examine the validity and reliability of the Fitbit Charge HR (FCH), wrist-worn ActiGraph (AG) accelerometers were used for assessing the classification of physical activity (PA) into intensity categories in children. Methods: Forty-three children (n = 43) participated in the study. Each participant completed 3 min bouts of 12 PAs ranging from sedentary to vigorous intensity while simultaneously wearing FCH and AG on both hands, a Polar HR monitor, and a portable indirect calorimeter. Total time spent in different PA intensity levels measured by FCH and AG were compared to the indirect calorimetry. Results: The highest classification accuracy values of sedentary behavior was 81.1% for FCH. The highest classification (72.4%) of light intensity PA was observed with Crouter’s algorithm from the non-dominant wrist. Crouter’s algorithm also show the highest classification (81.8%) for assessing moderate to vigorous intensity PA compared to FCH (70.8%). Across the devices, a high degree of reliability was found in step measurements, ranging from an intra-class correlation (ICC) = 0.92 to an ICC = 0.94. The reliability of the AG and the FCH showed high agreement for each variable. Conclusion: The FCH shows better validity for estimating sedentary behavior and similar validity for assessing moderate to vigorous PA compared to the research-grade monitor. Across the devices, the reliability showed the strongest association.

Comparison of various anthropometric indices in predicting abdominal obesity in Chinese children: a cross-sectional study

Background

Former evidence regarding reference values of abdominal fat percentage (AFP) and optimal anthropometric indicators in predicting abdominal obesity measured by dual-energy X-ray absorptiometry (DXA) scan in Chinese children were scarce.

Methods

A total of 452 Chinese children aged 6–9 years were included in this cross-sectional study. Abdominal fat and lean mass were measured by a DXA scan, and AFP were calculated. Anthropometric indicators including body mass index (BMI), chest circumference (CC), waist circumference (WC) and hip circumference (HC) were measured, waist-to-hip ratio (WHR), waist-to-height ratio (WHtR) was also calculated.

Results

By defining abdominal obesity as those with an AFP ≥ 85th percentile, the cutoffs values are 24.80, 30.29, 31.58, 31.86% in boys, and 25.02, 30.32, 31.66, 31.79% in girls, for children aged 6, 7, 8, and 9 years old, respectively. All anthropometric indicators were independently and positively associated with AFP (P all < 0.01). In girls, BMI was found to be the optimal predictors of childhood abdominal obesity. The values of area under curves (AUCs) were significantly higher (P all < 0.05) than other anthropometric indicators, except for WHtR (AUCs value: 0.886). However, in boys, WHtR instead of BMI, provided the largest AUCs value (0.922) in predicting abdominal obesity, followed by BMI ((AUCs value: 0.913).

Conclusion

This study provides reference values of AFP measured by DXA in Chinese children aged 6–9 years. BMI and WHtR tend to be the optimal anthropometric indicators in predicting abdominal obesity in Chinese girls and boys, respectively.

Estimation of visceral fat in 9- to 13-year-old girls using dual-energy X-ray absorptiometry (DXA) and anthropometry

OBJECTIVES

Accumulation of visceral fat (VF) in children increases the risk of cardiovascular disease and type 2 diabetes, and measurement of VF in children using computed tomography and magnetic resonance imaging (MRI) is expensive. Dual-energy X-ray absorptiometry (DXA) may provide a low-cost alternative. This study aims to determine if DXA VF estimates can accurately estimate VF in young girls, determine if adding anthropometry would improve the estimate and determine if other DXA fat measures, with and without anthropometry, could be used to estimate VF in young girls.

METHODS

Visceral fat was measured at lumbar intervertebral sites (L1-L2, L2-L3, L3-L4 and L4-L5) using 3.0T MRI on 32 young girls (mean age 11.3 ± 1.3 years). VF was estimated using the GE CoreScan application. Measurement of DXA android and total body fat was performed. Weight, height and waist circumference (WC) measurements were also obtained.

RESULTS

Waist circumference and body mass index were both strongly correlated with MRI, although WC was the best anthropometric covariate. Per cent fat (%fat) variables had the strongest correlation and did best in regression models. DXA %VF (GE CoreScan) and DXA android %fat and total body %fat accounted for 65% to 74% of the variation in MRI VF.

CONCLUSION

Waist circumference predicted MRI VF almost as well as DXA estimates in this population, and a combination of WC and DXA fat improves the predictability of VF. DXA VF estimate was improved by the addition of WC; however, DXA android %fat with WC was better at predicting MRI VF.

Combined Oral Contraception and Bicalutamide in Polycystic Ovary Syndrome and Severe Hirsutism: A Double-Blind Randomized Controlled Trial

CONTEXT

Hirsutism often occurs in women with polycystic ovary syndrome (PCOS). The efficacy of oral contraceptive pill (OCP) plus antiandrogens in the treatment of its severe expression is controversial due to the lack of randomized, double-blind, long-term studies.

OBJECTIVE

The primary outcome was the reduction of hirsutism in PCOS women objectively measured by videodermoscopy on the androgen-sensitive skin areas assessed by the modified Ferriman and Gallwey (mF&G) total score, after 12 months of therapy with OCP + bicalutamide (BC) vs OCP plus placebo (P). The secondary outcomes were to evaluate tolerability of BC and body composition as well as the occurrence of adverse events.

DESIGN

An experimental, phase 3, prospective, multicenter, randomized, double-blind, P-controlled trial. Patients were evaluated at the baseline visit, at 6 and 12 months during treatment, and 6 months' posttreatment.

PARTICIPANTS

Seventy women with classic PCOS (severe hirsutism, oligoanovulation, and ovarian polycystic ovarian morphology).

INTERVENTION

Patients received OCP + BC (50 mg/d) or OCP + P for 12 months.

RESULTS

The repeated measures analysis of variance showed that both treatments were effective in reducing hirsutism: The OCP + BC group had a higher reduction compared with the OCP + P group. No adverse effects were described during treatment except an increase in total cholesterol and low-density lipoprotein in the OCP + BC group.

CONCLUSIONS

The association of OCP + BC is well tolerated and significantly more effective than OCP alone in treating severe hirsutism. We suggest a combined use of the videodermoscopic index and mF&G to evaluate the effects of androgen deprivation therapy for hirsutism.

Body Fat Distribution Ratios and Obstructive Sleep Apnea Severity in Youth With Obesity

STUDY OBJECTIVES

Obesity and regional fat distribution, measured by neck fat mass percentage using dual-energy X-ray absorptiometry (DXA), correlate with obstructive sleep apnea (OSA) severity in adults. In obese children, neck-to-waist-circumference ratio predicts OSA. This study examined associations between body fat percentage and distribution and sleep-disordered breathing (SDB) severity in obese youth, measured with DXA.

METHODS

Cross-sectional retrospective study conducted at a tertiary children's hospital. Participants were aged 6 to 18 years with obesity (body mass index [BMI] > 99th percentile [BMI z-score 2.35] or > 95th percentile with comorbidity). They underwent polysomnography and DXA to quantify body fat percentage and distribution ratios (neck-to-abdominal fat percentage [NAF % ratio]). SDB was defined as apnea-hypopnea index (AHI) > 5 and OSA as obstructive AHI (OAHI) > 1 event/h. Relationships of BMI z-score and NAF % ratio to log AHI and log OAHI were evaluated.

RESULTS

Thirty individuals participated; 18 male; median age 14.1 years. Twenty-four individuals had BMI z-scores > 2.35. Ten had AHI > 5 events/h. NAF % ratio was significantly associated with log AHI in males and with log OAHI in all, whereas total fat mass percent was not. The association between log OAHI and NAF % ratio was significant in males, but not females. NAF % ratio was significantly associated with log OAHI in those with BMI z-score above 2.35.

CONCLUSIONS

NAF % ratio was associated with OSA severity in males and youth with BMI > 99th percentile; however, total fat mass percentage was not, suggesting that body fat distribution is associated with OSA risk in youth.

Imaging methods for analyzing body composition in human obesity and cardiometabolic disease

Advances in the technological qualities of imaging modalities for assessing human body composition have been stimulated by accumulating evidence that individual components of body composition have significant influences on chronic disease onset, disease progression, treatment response, and health outcomes. Importantly, imaging modalities have provided a systematic method for differentiating phenotypes of body composition that diverge from what is considered normal, that is, having low bone mass (osteopenia/osteoporosis), low muscle mass (sarcopenia), high fat mass (obesity), or high fat with low muscle mass (sarcopenic obesity). Moreover, advances over the past three decades in the sensitivity and quality of imaging not just to discern the amount and distribution of adipose and lean tissue but also to differentiate layers or depots within tissues and cells is enhancing our understanding of distinct mechanistic, metabolic, and functional roles of body composition within human phenotypes. In this review, we focus on advances in imaging technologies that show great promise for future investigation of human body composition and how they are being used to address the pandemic of obesity, metabolic syndrome, and diabetes.

Is the Association between Vitamin D and Cardiovascular Disease Risk Confounded by Obesity? Evidence from the Andhra Pradesh Children and Parents Study (APCAPS)

Background

Evidence of an association between serum vitamin D and cardiovascular disease risk is inconsistent and comes predominantly from studies in high-income settings. We assessed the association between serum levels of 25-hydroxyvitamin D₃ (25(OH)D) and cardiovascular disease risk factors in a population of young Indian adults.

Methods

Cross-sectional analyses of data from APCAPS (Andhra Pradesh Children and Parents Study); a prospective birth cohort study in rural south India. Participants were 1038 (40.3% females) adults aged 18-24 years. Main outcome measures were blood pressures, fasting serum lipids (cholesterols and triglycerides), fasting glucose, insulin, measures of arterial stiffness (aortic augmentation index and aortic pulse wave velocity (aPWV)), carotid intima-media thickness, body mass index (BMI) and body fat (dual X-ray absorptiometry).

Results

Vitamin D deficiency (≤20ng/ml) was observed in 41.1% of this lean (mean BMI: 19.5) and active (mean minutes of moderate or vigorous physical activity per day: 186) population. Vitamin D deficiency was associated with higher median body fat in both males (15.9% body fat in vitamin D deficient males vs. 14.6% in non-deficient males, p<0.05) and females (29.1% body fat in vitamin D deficient females vs. 27.8% in non-deficient females, p<0.05) but no associations were observed between vitamin D deficiency and mean BMI or median fat mass index (FMI). Except a weak inverse association with fasting insulin in males, there was no clear association between serum vitamin D levels and cardiovascular disease risk factors in fully adjusted models.

Conclusions

We did not find clear evidence for an association between serum vitamin D levels and cardiovascular disease risk factors. Our results, consistent with the limited evidence from randomised trials of vitamin D supplementation and Mendelian randomisation experiments, suggest that the postulated link between serum vitamin D and cardiovascular disease may be non-causal. Instead, it may be attributable to confounding by lifestyle factors such as obesity and physical inactivity which may provide more fruitful targets for cardiovascular disease prevention.

Associations between diet, physical activity and body fat distribution: a cross sectional study in an Indian population

BACKGROUND

Obesity is a growing health problem in India and worldwide, due to changes in lifestyle. This study aimed to explore the independent associations between dietary and physical activity exposure variables and total body fat and distribution in an Indian setting.

METHODS

Individuals who had participated in the Indian Migration Study (IMS) or the Andhra Pradesh Children And Parents' Study (APCAPS), were invited to participate in the Hyderabad DXA Study. Total and abdominal body fat of study participants was measured using DXA scans. Diet and physical activity (PA) levels were measured using questionnaires.

RESULTS

Data on 2208 participants was available for analysis; mean age was 49 yrs in IMS, 21 yrs in APCAPS. Total energy intake was positively associated with total body fat in the APCAPS sample: a 100 kcal higher energy intake was associated with 45 g higher body fat (95% CI 22, 68). In the IMS sample no association was found with total energy intake, but there was a positive association with percent protein intake (1% higher proportion of energy from protein associated with 509 g (95% CI 138,880) higher total body fat). Broadly the same pattern of associations was found with proportion of fat in the abdominal region as the outcome. PA was inversely associated with total body fat in both populations (in APCAPS, one MET-hour higher activity was associated with 46 g (95% CI 12, 81) less body fat; in the IMS it was associated with 145 g less body fat (95% CI 73, 218)). An inverse association was observed between PA and percentage abdominal fat in the IMS but no association was seen in the APCAPS population.

CONCLUSIONS

In this Indian population, there was an inverse association between PA and body fat. Associations between body fat and dietary variables differed between the younger APCAPS population and older IMS population. Further longitudinal research is needed to elucidate causality and directions of these associations across the life course.

Abdominal obesity and metabolic syndrome burden in adolescents--Penn State Children Cohort study

To investigate the association between abdominal obesity and metabolic syndrome (MetS) burden in a population-based sample of adolescents, we used data from 421 adolescents who completed the follow-up examination in the Penn State Children Cohort study. Dual-energy x-ray absorptiometry (DXA) was used to assess abdominal obesity, as measured by android/gynoid fat ratio (A/G ratio), android/whole body fat proportion (A/W proportion), visceral (VAT) and subcutaneous fat (SAT) areas. Continuous metabolic syndrome score (cMetS), calculated as the sum of the age and sex-adjusted standardized residual (Z-score) of five established MetS components, was used to assess the MetS burden. Linear regression models were used to analyze the impact of DXA measures on cMetS components. All models were adjusted for age, race, sex, and general obesity. We found abdominal obesity is significantly associated with increased cMetS. With 1 standard deviation (SD) increase in A/G ratio, A/W proportion, VAT area, and SAT area, cMetS increased by 1.34 (SE=0.17), 1.25 (SE=0.19), 1.67 (SE=0.17), and 1.84 (SE=0.20) units, respectively. At individual component level, strongest association was observed between abdominal obesity and insulin resistance (IR) than lipid-based or blood pressure-based components. VAT and SAT had a stronger impact on IR than android ratio-based DXA measurements. In conclusion, abdominal obesity is associated with higher MetS burden in adolescent population. The association between abdominal obesity and IR measure is the strongest, suggesting the key impact of abdominal obesity on IR in adolescents MetS burden.

Determination of Cutoff Values for DEXA-Based Body Composition Measurements for Determining Metabolic and Cardiovascular Health

The two components of the body weight (i.e., fat mass and muscle mass) appeared to be of high interest to consider in predicting metabolic health related risks. We aimed to determine cutoff values for fat mass index (FMI) and muscle mass index (MMI), FM/MM, and BMI for metabolic and cardiovascular health. This study was a cross-sectional analysis study conducted in a center of preventive medicine. It included 616 consecutive outpatients: mean age was 56.0±10.0 years (74.6% aged ≥50), and 61.4% were female. Fat and muscle mass were obtained with dual energy X-ray absorptiometry scan analyses. Metabolically unhealthy individuals were defined as people with biological features of dyslipidemia, hyperuricemia, diabetes, and/or hepatitis steatosis. Documented hypertension and/or atherosclerosis of at least one major artery defined individuals with cardiovascular complications. Receiver-operating characteristic curve analysis revealed that the cutoff values for MMI, FMI, and FM/MM were respectively 18.8kg/m² (sensitivity [Se]=58%; specificity [Sp]=59%), 5.5kg/m² (Se=61%; Sp=62%), and 0.31 (Se=62%; Sp=62%) in men; and 14.1kg/m² (Se=52%; Sp=54%), 5.5kg/m² (Se=65%; Sp=67%), 0.39 (Se=73%; Sp=73%) in women for predicting metabolic health. Values were 19.3kg/m² (Se=58%; Sp=59%), 7.0kg/m² (Se=61%; Sp=62%) and 0.49 (Se=62%; Sp=62%) in men; and 15.7kg/m² (Se=58%; Sp=59%), 6.4kg/m² (Se=61%; Sp=62%) and 0.35 (Se=62%; Sp=62%) in women for cardiovascular complications. Whatever the outcomes considered, the Youden indexes for BMI values were systematically below 25 kg/m², except for cardiovascular complications in men, where the threshold for the best Se/Sp was 25.7 kg/m². These cutoff values for FMI, MMI, and FM/MM could be of practical value for the clinical evaluation of a deficit in MM with or without excess of FM. They complement the classical concept of BMI in a more qualitative manner and extend the analysis of its impact on health outcomes to all BMI categories.

Assessment of body composition in Indian adults: comparison between dual-energy X-ray absorptiometry and isotope dilution technique

Dual-energy X-ray absorptiometry (DXA) and isotope dilution technique have been used as reference methods to validate the estimates of body composition by simple field techniques; however, very few studies have compared these two methods. We compared the estimates of body composition by DXA and isotope dilution (¹⁸O) technique in apparently healthy Indian men and women (aged 19–70 years, n 152, 48 % men) with a wide range of BMI (14–40 kg/m²). Isotopic enrichment was assessed by isotope ratio mass spectroscopy. The agreement between the estimates of body composition measured by the two techniques was assessed by the Bland–Altman method. The mean age and BMI were 37 (sd 15) years and 23·3 (sd 5·1) kg/m², respectively, for men and 37 (sd 14) years and 24·1 (sd 5·8) kg/m², respectively, for women. The estimates of fat-free mass were higher by about 7 (95 % CI 6, 9) %, those of fat mass were lower by about 21 (95 % CI − 18, − 23) %, and those of body fat percentage (BF%) were lower by about 7·4 (95 % CI − 8·2, − 6·6) % as obtained by DXA compared with the isotope dilution technique. The Bland–Altman analysis showed wide limits of agreement that indicated poor agreement between the methods. The bias in the estimates of BF% was higher at the lower values of BF%. Thus, the two commonly used reference methods showed substantial differences in the estimates of body composition with wide limits of agreement. As the estimates of body composition are method-dependent, the two methods cannot be used interchangeably.

Markers of metabolic and cardiovascular health in adults: Comparative analysis of DEXA-based body composition components and BMI categories

OBJECTIVES

To investigate how body composition components fit body mass index (BMI) categories and whether they could be considered as markers of metabolic and cardiovascular health.

DESIGN

Prospective study.

SETTING

A center for preventive medicine.

PARTICIPANTS

Six hundred and sixteen consecutive outpatients: mean age of 56.0±10.0 years; 74.6% aged ≥50 years and 61.4% were females.

MEASUREMENTS

Fat mass (FM) and muscle mass (MM) were obtained by dual energy X-ray absorptiometry analyses. Metabolically unhealthy individuals were defined as people with biological features of dyslipidemia, hyperuricemia, diabetes, and/or hepatitis steatosis. Documented hypertension and/or atherosclerosis of one major artery, at least, defined individuals with cardiovascular complications.

RESULTS

According to BMI categories, 45.8% of the sample was of normal weight, while 19.2% and 16.5% were classified as overweight and obese. A total of 78.0% and 86.3% of overweight and obese individuals were metabolically unhealthy respectively, 46.8% and 52.6% of subjects classified into normal and underweight BMI categories were also diagnosed. Cardiovascular complications mainly concerned the two highest BMI groups (78.2%). In multifactorial analyses the overweight and obese BMI categories were predictive of health outcomes [respectively, odds ratio (OR)=8.05, 95% confidence interval (CI): 4.23-12.07 and 5.74, 95% CI: 3.41-8.98]. FM and MM indexes were significantly associated with metabolic (OR=1.30, 95% CI: 1.19-1.47; and 0.84, 95% CI: 0.78-0.91) and cardiovascular (OR=1.22, 95% CI: 1.13-1.32; and 0.72, 95% CI: 0.65-0.80) health respectively, and FM/MM (respectively, OR=15.45, 95% CI: 11.77-20.17; and 16.61, 95% CI: 10.49-21.33) as well.

CONCLUSION

Our findings suggest that FM and MM readouts are important measurements of nutritional status and they extend the analysis of its impact on health outcomes to all BMI categories. Moreover, they highlight the interest of measuring body composition in medical check-ups to predict metabolic and cardiovascular diseases.

Early Increase of Abdominal Adiposity in Patients with Spondyloarthritis Receiving Anti-tumor Necrosis Factor-α Treatment

Objective.

Patients with spondyloarthritis (SpA) receiving anti-TNF-α treatment have an increase in fat mass. This may be relevant to cardiovascular risk. The aim of this study was to estimate visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) changes by dual-energy x-ray absorptiometry (DEXA) in patients with SpA under anti-TNF-α therapy.

Methods.

We used an ancillary protocol to an open, prospective 2-year followup study of patients with SpA. Waist circumference (WC), body weight, body mass index, VAT, and SAT were measured at baseline, 6 months, and 1 and 2 years. Univariate and multivariate analyses were performed to assess variables associated with VAT and SAT changes.

Results.

A total of 85 patients were analyzed. Patients were 39.3 ± 11.4 years old and mean baseline Bath Ankylosing Spondylitis Disease Activity Index was 55.0 ± 20.2. Treatment was effective according to clinical and biological variables, and body weight increased by 0.9 ± 1.7 kg over 2 years. There was a significant gain in VAT after 6 months (13.7 ± 20.6 cm2, p < 0.0001), 1 year (21.0 ± 26.6 cm2, p < 0.0001), and after 2 years (29.1 ± 33.4 cm2, p < 0.0001); and in SAT after 6 months (12.5 ± 27.4 cm2, p < 0.0001), 1 year (27.1 ± 38.2 cm2, p < 0.0001), and after 2 years (31.9 ± 53.2 cm2, p < 0.0001). We could not find any determinant of these changes by multivariate analysis.

Conclusion.

In patients with SpA receiving anti-TNF-α therapy, there is an early significant increase in abdominal obesity with significant increase in both VAT and SAT after 1 and 2 years of treatment. Prospective studies are required to investigate the relationship between these changes and cardiovascular risk.

The Official Positions of the International Society for Clinical Densitometry: acquisition of dual-energy X-ray absorptiometry body composition and considerations regarding analysis and repeatability of measures

In preparation for the International Society for Clinical Densitometry Position Development Conference of 2013 in Tampa, Florida, Task Force 2 was created as 1 of 3 task forces in the area of body composition assessment by dual-energy X-ray absorptiometry (DXA). The assignment was to review the literature, summarize the relevant findings, and formulate positions covering (1) accuracy and precision assessment, (2) acquisition of DXA body composition measures in patients, and (3) considerations regarding analysis and repeatability of measures. There were 6 primary questions proposed to the task force by the International Society for Clinical Densitometry board and expert panel. Based on a series of systematic reviews, 14 new positions were developed, which are intended to augment and define good clinical practice in quantitative assessment of body composition by DXA.