Bioelectrical impedance analysis as an alternative to dual-energy x-ray absorptiometry in the assessment of fat mass and appendicular lean mass in patients with obesity.
Obesity is a challenge for bioelectrical impedance analysis (BIA) estimations of skeletal muscle and fat mass (FM), and none of the equations used for appendicular lean mass (ALM) have been developed for people with obesity. By using different equations and proposing a new equation, this study aimed to assess the estimation of FM and ALM using BIA compared with dual-energy x-ray absorptiometry (DXA) as a reference method in a cohort of people with severe obesity.
This cross-sectional study compared a multifrequency BIA (TANITA MC-780A) versus DXA for body composition assessment in adult patients with severe obesity (body mass index [BMI] of >35 kg/m2). Comparisons between measured (DXA) and predicted (BIA) data for FM and ALM were performed using the original proprietary equations of the device and the equations proposed by Kyle, Sergi, and Yamada. Bland-Altman plots were drawn to evaluate the agreement between DXA and BIA, calculating bias and limits of agreement (LOA). Reliability was analyzed using intraclass correlation coefficient (ICC). Stepwise multiple regression analysis was used to derive a new equation to predict ALM in patients with obesity and was validated in a subsample of our cohort.
In this study, 115 patients (72.4% women) with severe obesity (mean BMI of 46.1 [5.2] kg/m2) were included (mean age 43.5 [8.6] y). FMDXA was 61.4 (10.1) kg, FMBIA was 57.9 (10.3) kg, and ICC was 0.925 (P < 0.001). Bias was -3.4 (4.4) kg (-5.2%), and LOA was -14.0, +7.3 kg. Using the proprietary equations, ALMDXA was 21.8 (4.7) kg and ALMBIA was 29.0 (6.8) kg with an ICC 0.868, bias +7.3 (4.0) kg (+34.1%) and LOA -0.5, +15.1. When applying other equations for ALM, the ICC for Sergi, et al. was 0.880, the ICC for Kyle, et al. was 0.891, and the best ICC estimation for Yamada, et al. was 0.914 (P < 0.001). Bias was +2.8 (2.8), +4.1 (2.9), and +2.7 (2.8) kg, respectively. The best-fitting regression equation to predict ALMDXA in our population derived from a development cohort (n = 77) was: ALM = 13.861 + (0.259 x H2/Z) - (0.085 x age) - (3.983 x sex [0 = men; 1 = women]). When applied to our validation cohort (n = 38), the ICC was 0.864, and the bias was the lowest compared with the rest of the equations +0.3 (+0.5) kg (+2.7%) LOA -5.4, +6.0 kg.
BIA using multifrequency BIA in people with obesity is reliable enough for the estimation of FM, with good correlation and low bias to DXA. Regarding the estimation of ALM, BIA showed a good correlation with DXA, although it overestimated ALM, especially when proprietary equations were used. The use of equations developed using the same device improved the prediction, and our new equation showed a low bias for ALM.
Ballesteros-Pomar MD
，González-Arnáiz E
，Pintor-de-la Maza B
，Barajas-Galindo D
，Ariadel-Cobo D
，González-Roza L
，Cano-Rodríguez I
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Dual-Frequency Bioelectrical Impedance Analysis is Accurate and Reliable to Determine Lean Muscle Mass in The Elderly.
Dual-frequency bioelectrical impedance analysis (DF-BIA) devices are more accessible and affordable than dual-energy X-ray absorptiometry (DXA); however, no studies have reported the accuracy of DF-BIA in body composition measurement, especially in the Thai elderly. The aims of this study were to (1) compare the accuracies of lean muscle masses measured by DF-BIA devices and DXA and (2) assess the reliability of the DF-BIA device.
This cross-sectional study was conducted on participants older than 60 years who visited the Orthopedic Clinic of Siriraj Hospital. Whole-body and appendicular skeletal muscle masses (ASMs) were measured using DF-BIA (Tanita RD-545), with DXA (GE Lunar iDXA) as the standard reference. The test-retest reliability of the DF-BIA and the agreement between the devices were assessed using the intraclass correlation coefficient (ICC) and Bland-Altman plots. Regression analysis was used to develop an equation to estimate ASM values from BIA close to those from DXA.
The mean age of 88 participants was 73.8 (SD 8.0) years, with women predominating (84.1%). The agreement of BIA and DXA was very high for whole-body lean mass (ICC = 0.954) and ASM (ICC = 0.954), but the mean difference in muscle mass from DF-BIA was overestimated. The ICCs of test-retest reliability for whole-body muscle mass and ASM were 0.987 and 0.988, respectively. The equation for corrected ASM was formulated from a linear equation (R2 = 0.93).
Although lean muscle mass from DF-BIA was minimally overestimated relative to DXA, this device had high accuracy and reliability for lean muscle mass evaluation in the elderly. DXA and DF-BIA are interchangeable for the assessment of muscle mass.
Anusitviwat C
，Vanitcharoenkul E
，Chotiyarnwong P
，Unnanuntana A
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Body Composition Measurement in Bronchiectasis: Comparison between Bioelectrical Impedance Analysis, Skinfold Thickness Measurement, and Dual-Energy X-ray Absorptiometry before and after Pulmonary Rehabilitation.
In individuals with bronchiectasis, fat-free mass depletion may be common despite a low prevalence of underweight and is considered a risk factor for increased morbidity and mortality. Techniques to adequately estimate fat-free mass and its changes over time are needed.
The purpose of this study was to assess agreement among values obtained with three different body composition techniques: skinfold thickness measurement (STM), bioelectrical impedance analysis (BIA), and dual-energy x-ray absorptiometry (DXA).
The study was a secondary analysis of data from a randomized controlled trial.
A respiratory rehabilitation program was administered for 3 months to individuals with bronchiectasis from the bronchiectasis unit of the Regional University Hospital in Malaga, Spain, from September 2013 to September 2014. Individuals with a body mass index (calculated as kg/m2) >18.5 who were aged 65 years or younger and those with a body mass index >20 who were older than 65 years were included.
At baseline and at 3 and 6 months, body composition was determined by DXA and STM.
Statistical concordance was assessed with the intraclass correlation coefficient (ICC), kappa coefficient, and the degree of agreement using the Bland Altman method. For comparison of the quantitative variables at baseline vs at 3 months and 6 months, the paired sample t test (or the Wilcoxon test) was used.
Thirty participants were included. Strong agreement was observed between body composition values determined by BIA and DXA in fat mass (ICC: 0.92) and fat-free mass (ICC: 0.87). Strong agreement was observed between STM and DXA in the values for fat-free mass (ICC: 0.91) and fat mass (ICC: 0.94), and lower agreement was observed for the longitudinal data and in the regional values. The mean difference between fat-free mass determined by BIA and DXA was + 4.7 with a standard deviation of 2.4 kg in favor of BIA. The mean difference between fat-free mass determined by STM and DXA was +2.3 with a standard deviation of 2.7 kg in favor of STM. Six individuals were classified as having a low fat-free mass index (20%) by DXA vs four by STM (13%; kappa: 0.76) and only two by BIA (6.6%; kappa: 0.44) compared with DXA.
Despite good statistical agreement among values obtained with DXA, STM, and BIA, the study findings indicate that STM and BIA, above all, tended to overestimate fat-free mass compared with DXA.
Doña E
，Olveira C
，Palenque FJ
，Porras N
，Dorado A
，Martín-Valero R
，Godoy AM
，Espíldora F
，Contreras V
，Olveira G
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