Accuracy Of Bioelectrical Impedance Analysis Research Articles

Effect of peritoneal dialysate on bioelectrical impedance analysis variability in pediatric patients receiving peritoneal dialysis.

Previous adult studies have yielded conflicting results regarding whether the presence (D +) or absence (D-) of peritoneal dialysate affects the accuracy of bioelectrical impedance analysis (BIA) measurements. The aim of this study was to investigate whether the accuracy of BIA data varies between D + and D- measurements in children. This cross-sectional study recruited chronic kidney disease stage 5 patients aged 3 to 18years who received peritoneal dialysis. Body composition was assessed by multifrequency BIA, and values were compared between D + and D- measurements using the intraclass correlation coefficient (ICC). Fifty paired BIA measurements were collected from 18 patients with a mean age of 13.6 ± 4.1years and a mean dialysate fill volume of 1,006 ± 239.7ml/m2. Sixteen out of 17 BIA parameters (94.1%) exhibited excellent correlations between D + and D- measurements (ICC values = 0.954, 0.998). There was a trend of increased fluid status, including extracellular water, edema index, and overhydration, in D + measurements, with mean differences (95% CIs) of 0.5 (0.4, 0.6) L, 0.002 (0.001, 0.002), and 0.1 (0.1, 0.2) L, respectively. Soft lean mass and fat-free mass were higher in D + measurements, with mean differences (95% CIs) of 1.4 (1.2, 1.6), and 1.6 (1.4, 1.8) kg, respectively. In addition, patients older than 10years had a stronger correlation between D + and D- measurements than younger patients. A total of 94.1% of BIA parameters exhibited excellent correlations between D + and D- measurements, especially patients older than 10years. We recommend that BIA measurements be collected from children regardless of the presence of peritoneal dialysate.

Development of bioelectrical impedance-based equations for the prediction of body composition of Malawian adolescents aged 10–18 years: a cross-sectional study

ObjectivesThe accuracy of bioelectrical impedance analysis (BIA) depends on population-specific prediction equations and there is no population-specific equation for predicting fat-free mass (FFM) in Malawian adolescents. This study aimed at...

Bioelectrical impedance analysis versus reference methods in the assessment of body composition in athletes.

The present systematic review aimed to compare the accuracy of Bioelectrical Impedance Analysis (BIA) and Bioelectrical Impedance Vector Analysis (BIVA) vs. reference methods for the assessment of body composition in athletes. Studies were identified based on a systematic search of internationally electronic databases (PubMed and Scopus) and hand searching of the reference lists of the included studies. In total, 42 studies published between 1988 and 2021 were included. The methodological quality was assessed using the Quality Assessment Tool for Observational Cohort and Cross-sectional Studies as recommended by the National Institute of Health. Twenty-three studies had an overall good rating in terms of quality, while 13 were rated as fair and 6 as poor, resulting in a low to moderate risk of bias. Fat mass was inconsistently determined using BIA vs. the reference methods, regardless of the BIA-technology. When using the foot to hand technology with predictive equations for athletes, a good agreement between BIA and the reference methods was observed for fat-free mass, total body, intra and extra cellular water. However, an underestimation in fat-free mass and body fluids was found when using generalized predictive equations. Classic and Specific BIVA represented a valid approach for assessing body fluids (Classic BIVA) and percentage of fat mass (Specific BIVA). The present systematic review suggests that BIA and BIVA can be used for assessing body composition in athletes, provided that foot-to-hand technology, predictive equations, and BIVA references for athletes are used.

P274 Bioelectrical impedance analysis identifies low skeletal muscle index in patients with Inflammatory Bowel Disease

Abstract Background Low skeletal muscle index (SMI) has been associated with increased need for surgery and post-surgical complications in patients with Inflammatory Bowel Disease (IBD). On dual energy X-ray absorptiometry (DXA), SMI is routinely calculated by dividing limb skeletal muscle mass (kg) by the square of the height (m2). Bioelectrical impedance analysis (BIA) provides a quick, inexpensive and radiation-free method to measure body composition. The aim of this study was to compare BIA with DXA to identify patients with low skeletal muscle mass and to show change over 14 weeks. Methods This single-centre prospective study recruited adult patients with IBD and adult controls, matched for gender. Active disease was defined as a faecal calprotectin of ≥150 μg/g. Active IBD patients undergoing biologic induction had repeat body composition measurements at least 14 weeks apart. All patients underwent single-frequency segmental BIA (Tanita BC-418) and DXA (GE Lunar Prodigy). A BIA-predicted SMI was calculated by dividing limb fat-free mass (kg) by the square of the height (m2). Results Of 48 patients with IBD, 54% had Crohn’s disease, 56% were male and median age was 29 (IQR 23–40) years. 28 had active disease, 16 inactive disease and 4 had no faecal calprotectin available. Patients with IBD and controls (n=30) had similar total body water, measured by BIA, and differed in albumin levels (39 vs 40.1 g/L, p=0.011). In IBD patients and controls, BIA total fat-free mass correlated strongly with DXA-derived fat-free mass (0.96 and 0.93, both p<0.0001). The BIA-predicted SMI also correlated well with DXA-derived SMI (0.89 and 0.91, both p<0.0001). The correlation was stronger for Ulcerative Colitis (0.96) compared to Crohn’s disease (0.84). In patients with IBD, the mean difference between BIA-predicted SMI and DXA-derived SMI was 1.1 ± 0.6 kg/m2 with 95% limits of agreement, -0.1 to 2.3 kg/m2. Controls followed a similar trend with a mean difference of 0.5 ± 0.6 kg/m2 and 95% limits of agreement, -0.5 to 1.6 kg/m2. The BIA-predicted SMI demonstrated a strong ability to identify low DXA-derived SMI for women with IBD (AUC: 0.98) and less so for men (AUC: 0.79). In 14 patients undergoing biologic treatment, change in DXA-derived SMI correlated with BIA-derived SMI (0.76, p=0.003). Conclusion An accurate estimate of SMI can be obtained with BIA as point-of-care in clinical practice. Further prospective studies with larger sample sizes are needed to determine the accuracy of BIA in monitoring changes of SMI during IBD treatment.

Precision and accuracy of bioelectrical impedance analysis devices in supine versus standing position with or without retractable handle in Caucasian subjects.

Bioelectrical impedance analysis (BIA) could be facilitated in subjects who are able to stand by using scales without (BIAstd4) or with a retractable handle (BIAstd8), provided that they are as precise as BIA devices commonly used in the supine position in the hospital setting (BIAsup). This observational prospective cross-sectional study aimed to compare the precision and accuracy of BIAstd4, BIAstd8 and BIAsup in a Caucasian population. Fat mass percentage (FM%) was measured in 160 healthy Caucasian subjects (80 men/80 women) aged 20-60 years, with a body mass index (BMI) ≥18.5 and<30kg/m2, using the HAGRID Body Fat Scales (Huawei Technologies Co., Ltd., China) in BIAstd4 or BIAstd8 mode, and the Nutriguard-M (Data Input GmbH, Germany) as BIAsup. Intra-unit and inter-unit precisions of each device were evaluated by calculating the coefficients of variation (CV%) of 3 measurements with 3 different units of each device. Inter-device precisions were evaluated with Pearson correlations, Bland-Altman plots, and repeated measures ANOVA followed by post-hoc Bonferroni tests. Accuracy of these BIA devices was estimated in a subgroup of 16 subjects, using comparison with dual-energy X-ray absorptiometry (DXA). The study population was 40±12 years old, with a body height and weight of 171±10cm and 72.2±11.5Kg, respectively. All three devices were very precise with intra-unit CV% of 0.5%, 0.9%, and 0.3% and inter-unit CV% of 0.5%, 1.1%, and 0.4% for BIAstd4, BIAstd8 and BIAsup, respectively. Inter-device precision was ±2.1% for BIAstd4/BIAsup, ±1.9% for BIAstd8/BIAsup, and ±1.3% for BIAstd8/BIAstd4. Bland-Altman plots showed bias ±1.96 SD of 0.3±5.2% for BIAstd4/BIAsup,-0.4±4.5% for BIAstd8/BIAsup and-0.6±3.1% for BIAstd8/BIAstd4. Compared to DXA, all three devices tended to underestimate FM% in men with low BMI, while only BIAstd4 and BIAstd8 tended to overestimate FM% in women with high BMI. FM% measurement accuracy was ±2.6% for BIAsup/DXA, ±3.3% for BIAstd4/DXA, and ±3.4% for BIAstd8/DXA. Both BIAstd4 and BIAstd8 show a good intra- and inter-unit precision close to BIAsup, making them suitable for rapid body composition assessment in non-bedridden subjects. However, all these three devices should not be used interchangeably, because BIAstd4 and BIAstd8 tend to accentuate FM% changes during body composition monitoring compared to BIAsup and DXA. ClinicalTrial.gov no. NCT04504799.

Accuracy of bioelectrical impedance analysis and skinfold thickness in the assessment of body composition in people with chronic spinal cord injury.

Cross-sectional study. This study: (1) investigated the accuracy of bioelectrical impedance analysis (BIA) and skinfold thickness relative to dual-energy X-ray absorptiometry (DXA) in the assessment of body composition in people with spinal cord injury (SCI), and whether sex and lesion characteristics affect the accuracy, (2) developed new prediction equations to estimate fat free mass (FFM) and percentage fat mass (FM%) in a general SCI population using BIA and skinfolds outcomes. University, the Netherlands. Fifty participants with SCI (19 females; median time since injury: 15 years) were tested by DXA, single-frequency BIA (SF-BIA), segmental multi-frequency BIA (segmental MF-BIA), and anthropometry (height, body mass, calf circumference, and skinfold thickness) during a visit. Personal and lesion characteristics were registered. Compared to DXA, SF-BIA showed the smallest mean difference in estimating FM%, but with large limits of agreement (mean difference = -2.2%; limits of agreement: -12.8 to 8.3%). BIA and skinfold thickness tended to show a better estimation of FM% in females, participants with tetraplegia, or with motor incomplete injury. New equations for predicting FFM and FM% were developed with good explained variances (FFM: R2 = 0.94; FM%: R2 = 0.66). None of the measurement techniques accurately estimated FM% because of the wide individual variation and, therefore, should be used with caution. The accuracy of the techniques differed in different subgroups. The newly developed equations for predicting FFM and FM% should be cross-validated in future studies.

Comparison of Bioelectrical Impedance Analysis and Computed Tomography on Body Composition Changes Including Visceral Fat After Bariatric Surgery in Asian Patients with Obesity.

The accuracy of bioelectrical impedance analysis (BIA) in patients with obesity has been controversial. This study aimed to validate the use of BIA in detecting body composition changes, especially for visceral fat, before and after bariatric surgery using computed tomography (CT) as a reference method. This retrospective study included Korean patients with a BMI of ≥ 35, or ≥ 30 with metabolic comorbidities. All patients underwent bariatric surgery, and underwent BIA and CT evaluation before and 6 months after the operation. The skeletal muscle index (SMI) and visceral fat index (VFI), variables corrected for height, were compared between BIA and CT. Forty-eight patients (18 men, 30 women) demonstrated a mean weight loss of 27.5 kg. Significant decreases in both VFI and SMI were observed in both BIA and CT (all p<0.001), with greater VFI change compared to SMI (48.2% vs. 10.4% in CT, respectively). Both pre- and post-operative measurements of VFI and SMI were significantly correlated between BIA and CT (all p<0.05). However, the percent decrease was significantly correlated only with VFI (ρ=0.71, p<0.001). The Bland-Altman analysis showed that BIA underestimated VFI, with a greater degree of underestimation in subjects with higher VFI. Despite the underestimation of BIA in measuring visceral fat, BIA VFI was associated with CT VFI. The SMI values showed significant correlations before and after surgery, but not with the percent decrease. Our results suggest that BIA can be a reliable tool for measuring body composition, especially for visceral fat, after bariatric surgery.

Relative Accuracy of Bioelectrical Impedance Analysis for Assessing Body Composition in Children With Severe Obesity.

The accuracy of different bioelectrical impedance analysis (BIA) devices for assessing body composition in children with obesity is unclear. We determined the relative accuracy of 2 BIA devices compared to dual x-ray absorptiometry (DXA) in obese and severely obese children. We measured body composition in a cross-sectional study of 78 obese children by a handheld single frequency tetrapolar BIA device (Omron), a stationary multifrequency octopolar BIA device (InBody 370) and DXA. Intermethod agreement was assessed by intraclass correlations, paired t tests, and Bland-Altman analyses. Participants (37% female, age 14.8 ± 2.7 years) had mean (±standard deviation) body mass index of 36.7 ± 7.5 kg/m, body fat percentage of 46.4% ± 5.2%, and appendicular lean mass of 22.5 ± 6.0 kg by DXA. Intraclass correlations with DXA for body fat percentage were 0.39 and 0.87 for single frequency tetrapolar and multifrequency octopolar BIA devices, respectively. The single frequency tetrapolar BIA underestimated body fat percentage by 5.5% ± 2.9% (P < 0.0001). Differences between the multifrequency octopolar BIA and DXA for body fat percentage (-1.1% ± 2.8%) and appendicular lean mass (-0.3 ± 1.4 kg) were small, and 95% limits of agreement were approximately ±5%. BIA machines vary in relative accuracy in measuring body composition in children who are obese and severely obese. The multifrequency octopolar BIA device accurately estimated body fat percentage and appendicular lean mass relative to DXA and has the advantage of point of care performance.

Comparison of Bioelectrical Impedance Analysis, Slaughter Skinfold-Thickness Equations, and Dual-Energy X-ray Absorptiometry for Estimating Body Fat Percentage in Colombian Children and Adolescents with Excess of Adiposity.

Dual-energy X-ray absorptiometry (DXA) has been considered a reference method for measuring body fat percentage (BF%) in children and adolescents with an excess of adiposity. However, given that the DXA technique is impractical for routine field use, there is a need to investigate other methods that can accurately determine BF%. We studied the accuracy of bioelectrical impedance analysis (BIA) technology, including foot-to-foot and hand-to-foot impedance, and Slaughter skinfold-thickness equations in the measurement of BF%, compared with DXA, in a population of Latin American children and adolescents with an excess of adiposity. A total of 127 children and adolescents (11–17 years of age; 70% girls) from the HEPAFIT (Exercise Training and Hepatic Metabolism in Overweight/Obese Adolescent) study were included in the present work. BF% was measured on the same day using two BIA analysers (Seca® 206, Allers Hamburg, Germany and Model Tanita® BC-418®, TANITA Corporation, Sportlife Tokyo, Japan), skinfold measurements (Slaughter equation), and DXA (Hologic Horizon DXA System®, Quirugil, Bogotá, Columbia). Agreement between measurements was analysed using t-tests, Bland–Altman plots, and Lin’s concordance correlation coefficient (ρc). There was a significant correlation between DXA and the other BF% measurement methods (r > 0.430). According to paired t-tests, in both sexes, BF% assessed by BIA analysers or Slaughter equations differ from BF% assessed by DXA (p < 0.001). The lower and upper limits of the differences compared with DXA were 6.3–22.9, 2.2–2.8, and −3.2–21.3 (95% CI) in boys and 2.3–14.8, 2.4–20.1, and 3.9–18.3 (95% CI) in girls for Seca® mBCA, Tanita® BC 420MA, and Slaughter equations, respectively. Concordance was poor between DXA and the other methods of measuring BF% (ρc < 0.5). BIA analysers and Slaughter equations underestimated BF% measurements compared to DXA, so they are not interchangeable methods for assessing BF% in Latin American children and adolescents with excess of adiposity.

Accuracy of Bioelectrical Impedance Analysis in Estimated Longitudinal Fat-Free Mass Changes in Male Army Cadets.

Bioelectrical impedance analysis (BIA) is a practical and rapid method for making a longitudinal analysis of changes in body composition. However, most BIA validation studies have been performed in a clinical population and only at one moment, or point in time (cross-sectional study). The aim of this study is to investigate the accuracy of predictive equations based on BIA with regard to the changes in fat-free mass (FFM) in Brazilian male army cadets after 7 mo of military training. The values used were determined using dual-energy X-ray absorptiometry (DXA) as a reference method. The study included 310 male Brazilian Army cadets (aged 17-24 yr). FFM was measured using eight general predictive BIA equations, with one equation specifically applied to this population sample, and the values were compared with results obtained using DXA. The student's t-test, adjusted coefficient of determination (R2), standard error of estimation (SEE), Lin's approach, and the Bland-Altman test were used to determine the accuracy of the predictive BIA equations used to estimate FFM in this population and between the two moments (pre- and post-moment). The FFM measured using the nine predictive BIA equations, and determined using DXA at the post-moment, showed a significant increase when compared with the pre-moment (p < 0.05). All nine predictive BIA equations were able to detect FFM changes in the army cadets between the two moments in a very similar way to the reference method (DXA). However, only the one BIA equation specific to this population showed no significant differences in the FFM estimation between DXA at pre- and post-moment of military routine. All predictive BIA equations showed large limits of agreement using the Bland-Altman approach. The eight general predictive BIA equations used in this study were not found to be valid for analyzing the FFM changes in the Brazilian male army cadets, after a period of approximately 7 mo of military training. Although the BIA equation specific to this population is dependent on the amount of FFM, it appears to be a good alternative to DXA for assessing FFM in Brazilian male army cadets.

Bioelectrical Impedance for Accuracy Detecting Body Composition Changes during an Activity Intervention

ABSTRACT Body composition is an important component of an individual's health and fitness profile. The purpose of this study was to assess the accuracy of bioelectrical impedance analysis (BIA) in detecting percent body fat (%BF) changes throughout a physical activity intervention in previously sedentary, overweight men and women. Fourteen men (mean ± SD; 46 ± 7 yr) and 22 women (47 ± 5 yr) with a body mass index of ≥25 kg·m−2 participated in an intervention of 10,000 steps per day for 36 wk. %BF was measured by air displacement plethysmography (ADP; criterion measure) and BIA at baseline, 20 wk, and 36 wk. During the 36-wk intervention, the women lost 1.6 ± 4.8 kg and the men lost 3.9 ± 4.2 kg. There was a significant three-way interaction for %BF across time points, device, and sex (P = 0.019). Among women, ADP and BIA detected %BF changes of −1.9% ± 2.0% and 0.5% ± 1.8%, respectively, from baseline to 20 wk, and −1.5% ± 2.3% and 0.3% ± 2.5%, respectively, from baseline to 36 wk. Among men, ADP and BIA detected %BF changes of −1.9% ± 1.8% and −1.5% ± 1.9%, respectively, from baseline to 20 wk, and −2.8% ± 3.7% and −2.3% ± 2.6%, respectively, from baseline to 36 wk. There was a significant difference in the accuracy of BIA in detecting %BF changes compared with ADP in women but not men on a group level. However, on an individual level, there was greater variation in BIA's accuracy in tracking %BF changes in both sexes. Compared with ADP, BIA is a suitable method for detecting %BF changes in a group of overweight men, but not women. However, caution should be exercised when using BIA to track body composition changes in either sex on an individual level.

Which method to use for a fast assessment of body fat percentage?

Body position affects body water distribution and in turn the accuracy of bioelectrical impedance analysis (BIA), which may consequently distort conclusions about an individual’s body composition.We compared body fat percentage (BFP) obtained with leg-to-leg-BIA (LL) and hand-to-leg-BIA (HL) with the reference values.The BFPs of 97 individuals were determined with an LL- (Tanita TBF 215GS, Japan) and HL- (Akern, STA/BIA, Italy) BIA-analyser and with reference skinfold thickness (SF) measurements. Each subject was measured upright with the LL-analyser, and upright and supine with the HL-analyser, both before and after 20 min of supine rest. The one-way ANOVA for repeated measures (HL-BIA), Student’s t-test (LL-BIA), intraclass correlation coefficients, and Bland–Altman’s plots were used for statistical analysis.BFPs determined with HL/LL BIA in upright/supine positions differ significantly. Compared to the SF method, HL-BIA mostly overestimates, while LL-BIA mostly underestimates BFP. Agreement between anthropometrically determined BFP and HL/LL-BIA determined BFP is better with HL for both sexes, and generally better in females than males.HL-BIA-determined estimates of BFP are more similar to reference values than LL-BIA. However, for both BIA methods, BIA-determined estimates of BFP are significantly affected by body position. Consequently, different BIA methods will classify approximately one fifth of subjects into the erroneous body-fat-content category, which calls for urgent standardization.

A Bedside Measure of Body Composition in Duchenne Muscular Dystrophy

BackgroundIn clinical practice, monitoring body composition is a critical component of nutritional assessment and weight management in boys with Duchenne muscular dystrophy. We aimed to evaluate the accuracy of a simple bedside measurement tool for body composition, namely bioelectrical impedance analysis, in boys with Duchenne muscular dystrophy. MethodsMeasures of fat-free mass were determined using a bioelectrical impedance analysis machine and compared against estimations obtained from a reference body composition model. Additionally, the use of raw impedance values was analyzed using three existing predictive equations for the estimation of fat-free mass. Accuracy of bioelectrical impedance analysis was assessed by comparison against the reference model by calculation of biases and limits of agreement. ResultsBody composition was measured in 10 boys with Duchenne muscular dystrophy, mean age 9.01 ± 2.34 years. The bioelectrical impedance analysis machine values of fat-free mass were on average 2.3 ± 14.1 kg higher than reference values. Limits of agreement (based on 95% confidence interval of the mean) were −7.4 to 2.9 kg. There was a significant correlation between the mean fat-free mass and difference in fat-free mass between the bioelectrical impedance analysis machine and the reference model (r = −0.86; P = 0.02) suggesting that the bias was not consistent across the range of measurements. The most accurate predictive equation for the estimation of fat-free mass using raw impedance values was the equation by Pietrobelli et al. (mean difference, −0.7 kg; 95% limits of agreement, −3.5 to 2.0 kg). ConclusionsIn a clinical setting, where a rapid assessment of body composition is advantageous, the use of raw impedance values, combined with the equation by Pietrobelli et al., is recommended for the accurate estimation of fat-free mass, in boys with Duchenne muscular dystrophy.

Re: Effects of Resistance Versus Multicomponent Training on Body Composition and Functional Fitness in Institutionalized Elderly Women

To the Editor: We read with great interest the study by Sousa and Mendes,1 who reported that 12 weeks of training protocol was not enough to induce changes in the body composition of institutionalized elderly women. The results of that study are particularly important because body composition changes with aging even in weight-stable elderly men and women.2 Beyond these, we would like to comment on some points. Body composition measurement in the study was made using bioelectrical impedance analysis (BIA). For body composition analysis in elderly adults, accuracy of BIA is under discussion.3 The theory of BIA measurement relies on the capacity of hydrated tissues to conduct electrical energy, which allows estimation of total body water (TBW). Calculation of lipid and fat-free mass with BIA was made using equations on TBW,4 so changes in TBW may easily affect BIA results, and pretest preparation is mandatory to minimize the effect of the confounders. The pretest protocol was not reported. Moreover, a recent study showed that a 12-week training program had a significant effect on changes in body fat, total lean mass, and total fat mass in an elderly population.5 In Sousa and Mendes's study, body composition was measured using dual-energy X-ray absorptiometry, which is the recommended alternative to criterion standard methods. We believe that these problems may have affected the results. Conflict of Interest: The editor in chief has reviewed the conflict of interest checklist provided by the authors and has determined that the authors have no financial or any other kind of personal conflicts with this paper. Author Contributions: Umut Safer and Vildan Binay Safer discussed and prepared the manuscript. Sponsor's Role: None.

Validity of Bioelectrical Impedance Analysis for Measuring Changes in Body Water and Percent Fat After Bariatric Surgery

Few studies have validated bioelectrical impedance analysis (BIA) following bariatric surgery. We examined agreement of BIA (Tanita 310) measures of total body water (TBW) and percent body fat (%fat) before (T0) and 12 months (T12) after bariatric surgery, and change between T0 and T12 with reference measures: deuterium oxide dilution for TBW and three-compartment model (3C) for %fat in a subset of participants (n = 50) of the Longitudinal Assessment of Bariatric Surgery-2. T0 to T12 median (IQR) change in deuterium TBW and 3C %fat was -6.4 L (6.4 L) and -14.8% (13.4%), respectively. There were no statistically significant differences between deuterium and BIA determined TBW [median (IQR) difference: T0 -0.1 L (7.1 L), p = 0.75; T12 0.2 L (5.7 L), p = 0.35; Δ 0.35 L(6.3 L), p = 1.0]. Compared with 3C, BIA underestimated %fat at T0 and T12 [T0 -3.3 (5.6), p < 0.001; T12 -1.7 (5.2), p = 0.04] but not change [0.7 (8.2), p = 0.38]. Except for %fat change, Bland-Altman plots indicated no proportional bias. However, 95% limits of agreement were wide (TBW 15-22 L, %fat 19-20%). BIA may be appropriate for evaluating group level response among severely obese adults. However, clinically meaningful differences in the accuracy of BIA between individuals exist.

Estimation of thigh muscle cross-sectional area by single- and multifrequency segmental bioelectrical impedance analysis in the elderly

Bioelectrical impedance analysis (BIA) has been used to estimate skeletal muscle mass, but its application in the elderly is not optimal. The accuracy of BIA may be influenced by the expansion of extracellular water (ECW) relative to muscle mass with aging. Multifrequency BIA (MFBIA) can evaluate the distribution between ECW and intracellular water (ICW), and thus may be superior to single-frequency BIA (SFBIA) to estimate muscle mass in the elderly. A total of 58 elderly participants aged 65-85 years were recruited. Muscle cross-sectional area (CSA) was obtained from computed tomography scans at the mid-thigh. Segmental SFBIA and MFBIA were measured for the upper legs. An index of the ratio of ECW and ICW was calculated using MFBIA. The correlation between muscle CSA and SFBIA was moderate (r = 0.68), but strong between muscle CSA and MFBIA (r = 0.85). ECW/ICW index was significantly and positively correlated with age (P < 0.001). SFBIA tends to significantly overestimate muscle CSA in subjects who had relative expansion of ECW in the thigh segment (P < 0.001). This trend was not observed for MFBIA (P = 0.42). Relative expansion of ECW was observed in older participants. The relative expansion of ECW affects the validity of traditional SFBIA, which is lowered when estimating muscle CSA in the elderly. By contrast, MFBIA was not affected by water distribution in thigh segments, thus rendering the validity of MFBIA for estimating thigh muscle CSA higher than SFBIA in the elderly.

The application of bioelectrical impedance analysis in live tropical hair sheep as a predictor of body composition upon slaughter

Animal management for breeding and marketing can be improved by precise measurement of desirable traits. Live animal body composition analysis facilitates the selection of animals that are best suited for the intended purpose. This study was designed to assess the accuracy of bioelectrical impedance analysis (BIA) predicted live body tissue composition, as a proxy for the estimation of carcass quality in Barbados Black Belly lambs. Thirty-four Barbados Black Belly lambs were placed on an 8-week feeding regime and then slaughtered. A randomized experimental design was used to allocate diets to animals, which had been stratified into eight groups by initial live weight. The lambs were fed a basal diet of Brachiaria arrecta fresh forage ad libitum and subjected to one of four diets; NS-non-supplemented diet, TG-Trichantera gigantea-supplemented, C100-concentrate supplemented for maintenance, and C400-concentrate supplemented for growth. Diets NS, TG, C100, and C400 had 7, 9, 11, and 7 animals, respectively. The average age and weight at the time of slaughter were 206days and 23.7kg, respectively. A 4-terminal impedance analyzer (RJL Systems®) was used to generate BIA data from live animals immediately before slaughter. The chilled carcasses were then subject to chemical analysis for crude fat, crude protein, and dry matter. Live animal and carcass traits predicted by BIA included fat and fat-free mass, crude fat, crude protein, protein to fat ratio, and tissue distribution. Regression equations were developed from BIA data obtained from the live animal to predict all carcass composition traits measured. Bioelectrical impedance analysis generated favorable results as a practical application to carcass composition evaluation in live tropical hair sheep.

Comparison of bioelectrical impedance analysis, body mass index and waist circumference in evaluating growth and development of children

Objective To compare body mass index(BMI), bioelectrical impedance analysis(BIA) and waist circumference(WC) for the assessment of the growth and development of the children, and to explore the accuracy of BIA and WC for the assessment of the growth and development of the children. Methods Children were surveyed in Department of Child Health Care of Nanjing Children's Hospital from Aug.2011 to Aug.2012.BIA was used to measure body fat, skeletal muscles and bone minerals of these children, and WC was measured by meterstick.According to BMI and body fat parameters, the study subjects were classified into lower weight, normal weight, overweight and obese groups.According to the WC, the subjects were divided into the normal group and the abnormal group. Results There were 2313 children in this survey, 1528 boys of them, median age 7.7 years old(ranged from 3.0 to 16.8 years old), and 785 girls of all the children, median age 7.2 years old(ranged from 3.0 to 17.5 years old). Bone mineral content of skeletal muscles increased with age in boys and girls(P<0.001). According to BMI, there were 484(20.9%) obese children and 266(11.5%) lower weight children; according to the BIA, there were 663(28.7%) obese children and 481(20.8%) lower weight children; according to the WC, there were 597(25.8%)abnormal children.The sensitivity and specificity of WC and BIA were both higher in the evaluation of overweight and obesity status.When overweight and obesity were analyzed by BIA as well as WC, girls showed a higher specificity, while the boys showed a higher sensitivity.The sensitivity of BMI was higher than BIA in evaluating weight loss. Conclusions BIA as a commonly used indicator is reliable for population census, and it is more desirable if the measurement of WC is done at the same time.The high sensitivity of BIA makes it more suitable for screening overweight and obesity of children. Key words: Bioelectrical impedance analysis; Body mass index; Waist circumference; Child

Comparison of DEXA-derived body fat measurement to two race-specific bioelectrical impedance equations in healthy Indians

AimPrevalence of obesity is increasing in Asian Indians. Reliable, precise and convenient methods to estimate body composition are required. This study aimed to test the accuracy of bioelectrical impedance analysis (BIA) estimates of body composition among Asian Indians according to two BIA equations – one developed for Asians, the other for Caucasians. MethodsTwo hundred apparently healthy Asian Indians (100 males, 100 females; mean age 36.6±7.6 years; mean BMI 16.6–46.7kg/m2) underwent BIA assessment of fat mass (FM), fat free mass (FFM) and percentage body fat (%BF) using Tanita Multi-Frequency Body Composition Analyzer MC-180MA (Tanita Corporation, Tokyo, Japan). One set of BIA values was automatically calculated by the analyzer (Caucasian figures), the other set by Tanita (Japanese Asian figures). Results were compared to dual X-ray absorptiometry (DEXA) as the standard measure. ResultsA moderate level of relative agreement was found between the DEXA-derived measurement of %BF and the estimate from both the Caucasian (r2=0.75; p<0.001) and Asian equation (r2=0.7; p<0.001). Despite this, the level of absolute agreement was poor, with large bias and wide limits of agreement. According to the Caucasian equation the mean difference between methods was −8.3±3.9 (95% limits of agreement −20.10 to 9.40), for the Asian equations mean difference was −5.4±4.3 (95% limits of agreement −20.63 to 11.41). Interpretation and conclusionsWhen compared to DEXA, the current Asian and Caucasian Tanita formulae significantly under-estimate the %BF of Asian Indians.

The novel application of artificial neural network on bioelectrical impedance analysis to assess the body composition in elderly

BackgroundThis study aims to improve accuracy of Bioelectrical Impedance Analysis (BIA) prediction equations for estimating fat free mass (FFM) of the elderly by using non-linear Back Propagation Artificial Neural Network (BP-ANN) model and to compare the predictive accuracy with the linear regression model by using energy dual X-ray absorptiometry (DXA) as reference method.MethodsA total of 88 Taiwanese elderly adults were recruited in this study as subjects. Linear regression equations and BP-ANN prediction equation were developed using impedances and other anthropometrics for predicting the reference FFM measured by DXA (FFMDXA) in 36 male and 26 female Taiwanese elderly adults. The FFM estimated by BIA prediction equations using traditional linear regression model (FFMLR) and BP-ANN model (FFMANN) were compared to the FFMDXA. The measuring results of an additional 26 elderly adults were used to validate than accuracy of the predictive models.ResultsThe results showed the significant predictors were impedance, gender, age, height and weight in developed FFMLR linear model (LR) for predicting FFM (coefficient of determination, r2 = 0.940; standard error of estimate (SEE) = 2.729 kg; root mean square error (RMSE) = 2.571kg, P < 0.001). The above predictors were set as the variables of the input layer by using five neurons in the BP-ANN model (r2 = 0.987 with a SD = 1.192 kg and relatively lower RMSE = 1.183 kg), which had greater (improved) accuracy for estimating FFM when compared with linear model. The results showed a better agreement existed between FFMANN and FFMDXA than that between FFMLR and FFMDXA.ConclusionWhen compared the performance of developed prediction equations for estimating reference FFMDXA, the linear model has lower r2 with a larger SD in predictive results than that of BP-ANN model, which indicated ANN model is more suitable for estimating FFM.