Validating Body Fat Assessment by Bioelectric Impedance Spectroscopy in Taiwanese Hemodialysis Patients

Association of changes in body composition with all-cause mortality in patients undergoing hemodialysis: A prospective cohort study

OBJECTIVES

This study aimed to explore the effect of longitudinal body composition changes on mortality risk in patients undergoing hemodialysis and identify whether changes in body composition can more accurately predict mortality than baseline status.

METHODS

A prospective cohort study was conducted on 340 patients undergoing hemodialysis. Lean mass and body fat were determined using a bioimpedance spectroscopy (BIS) device and expressed as the lean tissue index (LTI) or fat tissue index (FTI), respectively. The patients were subjected to BIS at baseline and after 1 year. The hazard ratio (HR) for death was calculated using Cox regression analysis.

RESULTS

Among 340 patients, 289 were tested with a repeat BIS. LTI loss and FTI gain were observed in 51.2% and 47.1% of the patients, respectively. Low baseline LTI was a significant predictor of all-cause mortality after adjusting for demographic and biochemical parameters (HR, 2.41; P = 0.047), but not when comorbidities were included in the multivariate analysis. However, after adjusting for various confounding factors, LTI loss (HR, 3.40; P = 0.039) and FTI gain (HR, 4.06; P = 0.024) were independent risk factors for all-cause mortality, and the adjusted HR for LTI loss and FTI gain vs. no LTI loss and no FTI gain was 5.34 (P = 0.016).

CONCLUSIONS

LTI loss and FTI gain, particularly their combination, are important predictors of survival in patients undergoing hemodialysis. Our results emphasize that longitudinal changes in LTI and FTI are more strongly associated with all-cause mortality than single-point values. Therefore, it is important to dynamically assess the muscle and fat tissues and develop potential targeted treatment strategies for this population.

Fat mass as an important predictor of persistent hypertension in patients with primary aldosteronism after adrenalectomy

Aldosterone excess is present in obesity and is associated with involvement in the pathogenesis of obesity. We evaluate the impact of body obesity as measured by body composition monitor (BCM) on clinical outcomes in patients with unilateral primary aldosteronism (uPA) after adrenalectomy. The BCM device was used to assess body composition before and after adrenalectomy. We used fat mass (FM) and body mass index (BMI) to classify obesity and divided obesity into three groups: clinical overweight (BMI (kg/m2) ≥25); normal weight obesity (NWO, FM (%) ≥ 35 for women, >25 for men & BMI < 25); and no obesity (FM < 35 for women, <25 for men & BMI < 25). A total of 130 unilateral PA (uPA) patients received adrenalectomy, and 27 EH patients were identified; uPA patients with hypertension remission were found to have lower FM (p = 0.046), BMI (p < 0.001), and lower prevalence of overweight (p = 0.001). In the logistic regression model, patients with clinical overweight (OR = 2.9, p = 0.007), NWO (OR = 3.04, p = 0.041) and longer HTN duration (years, OR = 1.065, p = 0.013) were at the risk of persistent hypertension after adrenalectomy. Obesity status was strongly associated with persistent hypertension in uPA patients after adrenalectomy. However, patients in the NWO group also carried higher risk of persistent hypertension. Therefore, assessment of pre-obesity and overweight in uPA patients are extremely important, especially in those who have normal BMI.

Correlations among lean tissue index, physical activity, clinical parameters, diet quality, and nutritional status in patients receiving haemodialyses

INTRODUCTION

Poor diet quality and malnutrition accelerate protein and energy depletion. This can result in a diminished lean tissue index (LTI) and an inability to perform daily activities, both of which increase the risk of falls and affect the quality of life.

OBJECTIVE

This study investigated the correlations among LTI, physical activity (PA), clinical parameters, diet quality, and nutritional status.

METHODS

A cross-sectional study design was employed. Participants in stable conditions receiving haemodialyses were enroled. LTI was measured using a body composition monitor. Three-day dietary records and demographic and clinical parameters were collected.

RESULTS

In total, 104 patients receiving haemodialyses were recruited (53.8% men, aged 57.7 ± 11.78 years; dialysis duration, 7.3 ± 6.04 years). LTI was not associated with diet quality; LTI was positively correlated with sex and negatively correlated with age, dialysis duration, and fat tissue index (FTI); and lean tissue index was positively correlated with PA. Among patients with a normal LTI, the odds ratio for low-FTI was 31.04 times higher than that for high-FTI. In total, 80.8% of the participants had poor diet quality, which was mainly attributed to their excessive intake of saturated fatty acids and insufficient fruit intake.

CONCLUSIONS

Although diet quality was unrelated to the LTI, the results indicated that most patients receiving haemodialyses had poor diet quality. Therefore, this topic merits further investigation.

Estimation of Muscle Mass in the Integrated Assessment of Patients on Hemodialysis

Assessment of muscle mass (MM) or its proxies, lean tissue mass (LTM) or fat-free mass (FFM), is an integral part of the diagnosis of protein-energy wasting (PEW) and sarcopenia in patients on hemodialysis (HD). Both sarcopenia and PEW are related to a loss of functionality and also increased morbidity and mortality in this patient population. However, loss of MM is a part of a wider spectrum, including inflammation and fluid overload. As both sarcopenia and PEW are amendable to treatment, estimation of MM regularly is therefore of major clinical relevance. Whereas, computer-assisted tomography (CT) or dual-energy X-ray absorptiometry (DXA) is considered a reference method, it is unsuitable as a method for routine clinical monitoring. In this review, different bedside methods to estimate MM or its proxies in patients on HD will be discussed, with emphasis on biochemical methods, simplified creatinine index (SCI), bioimpedance spectroscopy (BIS), and muscle ultrasound (US). Body composition parameters of all methods are related to the outcome and appear relevant in clinical practice. The US is the only parameter by which muscle dimensions are measured. BIS and SCI are also dependent on either theoretical assumptions or the use of population-specific regression equations. Potential caveats of the methods are that SCI can be influenced by residual renal function, BIS can be influenced by fluid overload, although the latter may be circumvented by the use of a three-compartment model, and that muscle US reflects regional and not whole body MM. In conclusion, both SCI and BIS as well as muscle US are all valuable methods that can be applied for bedside nutritional assessment in patients on HD and appear suitable for routine follow-up. The choice for either method depends on local preferences. However, estimation of MM or its proxies should always be part of a multidimensional assessment of the patient followed by a personalized treatment strategy.

Agreement of Single-Frequency Electrical Bioimpedance in the Evaluation of Fat Free Mass and Fat Mass in Peritoneal Dialysis Patients

Background: Protein-energy wasting is related to impairment of quality of life and lower survival of end-stage kidney disease (ESKD) patients. The evaluation of body composition, especially fat free mass (FFM) and fat mass (FM), is important for the prediction of outcomes in these individuals. The aim of this study was to compare the FFM and FM measurements obtained by single-frequency bioimpedance (SF-BIA) and by a multiple frequency bioimpedance (MF-BIA) device, using dual energy X-ray absorptiometry (DXA) peritoneal dialysis (PD) patients. Methods: This was a cross-sectional study involving adult patients undergoing regular PD, in which we performed SF-BIA, MF-BIA, and DXA at the same visit. To compare the bioimpedance values with DXA, we used: Person correlation (r), intraclass correlation coefficient (ICC), and Bland-Altman concordance analysis. Results: The sample consisted of 50 patients in the PD, with mean age of 55.1 ± 16.3 years. Both bioimpedance methods showed a strong correlation (r > 0.7) and excellent reproducibility (ICC > 0.75) compared to DXA. According to the Bland-Altman diagram, SF-BIA showed agreement in body compartment measurements, with no proportionality bias (p > 0.05), without systematic bias for FFM (-0.5 ± 4.9, 95% CI -1.8 to 0.9, p = 0.506), and for FM (0.3 ± 4.6, p = 0.543). MF-BIA did not present a proportionality bias for the FFM, but it underestimated this body compartment by 2.5 ± 5.4 kg (p = 0.002). In addition, MF-BIA presented proportionality bias for FM. Conclusion: SF-BIA was a more accurate assessing method than MBIA for FFM and FM measurements in PD patients. Because it is a low-cost, non-evaluator-dependent measurement and has less systematic bias, it can also be recommended for fat mass and free-fat mass evaluation in PD patients.

Comparison of bioimpedance spectroscopy and dual energy X-ray absorptiometry for assessing body composition changes in obese children during weight loss

BACKGROUND

Obesity and age influence the reliability of dual energy X-ray absorptiometry scanning (DEXA) and bioimpedance spectroscopy (BIS). Both are used in clinical settings, but have not been compared for measurements in obese children. We compared DEXA and BIS for evaluating body composition and inherent changes in obese children before and after a 10-month weight loss programme.

METHODS

DEXA and BIS were used to evaluate 130 patients at baseline and 75 at follow-up. We tested agreement between the two techniques using Bland-Altman plots and proportional bias using Passing-Bablok regressions.

RESULTS

The Bland-Altman plots showed wide agreement limits before and after weight loss and when monitoring longitudinal changes. At baseline, the Passing-Bablok regressions revealed a proportional bias for all body compartments. After significant weight loss no proportional bias was found for fat mass and percentage, although BIS systematically underestimated fat mass by 2.9 kg. Longitudinally, no proportional bias was found in the measured changes of absolute fat, fat-free mass and fat-free percentage between both methods, although BIS systematically underestimated fat and fat-free mass by 2.6 and 0.7 kg, respectively.

CONCLUSION

While BIS and DEXA are not interchangeable at baseline, the agreement between the two improved after significant weight loss. Proportional changes in fat mass, fat-free mass and fat-free percentage were similar for both techniques. BIS is a viable alternative to DEXA for future paediatric obesity studies measuring treatment effect at group levels, but is not superior to DEXA and cannot be used for monitoring individual changes due to wide limits of agreement.

Effects of age and sex on the relationship between body fat area and kidney events in patients with chronic kidney disease

We examined the effects of age and sex on the relationship between body fat area and kidney events. We included 367 chronic kidney disease patients between 2011 and 2017. Patients' median age was 73.0 years; 262 (71.4%) patients were male. The median estimated glomerular filtration rate was 20.2 mL/min/1.73 m² . During the observation period, 187 patients developed kidney events. In males aged <75 years, high subcutaneous fat area was a risk factor for kidney events (hazard ratio: 1.06, 95% CI: 1.02-1.11). In females aged <75 years, high visceral fat area reduced kidney events (hazard ratio: 0.83, 95% CI: 0.71-0.97). In males and females ≥75 years, visceral fat area and subcutaneous fat area were not associated with kidney events. Body fat area was not a risk factor for chronic kidney disease progression in elderly patients. Opposite effects, in sex-related body fat and kidney events, were shown in young patients.

Design of Bio-Impedance Electrode Topologies for Specific Depth Sensing in Skin Layer

Bio-impedance analysis provides non-invasive estimation of body composition. Recently, applications based on bio-impedance measurement in skin tissue such as skin cancer diagnosis and skin composition monitoring have been studied. For scanning the electrical properties along the skin depth, the relationship between the electrode topologies and the depth sensitivity should be clarified. This work reports a systematic analysis on designing line electrode topologies to measure the bio-impedance of the skin layer at specific depth using a finite element method (FEM). Four electrodes consisting of two outer current electrodes and two inner voltage electrodes in the form of Wenner-Schlumberger array were employed on the top of a collagen layer as a skin model. The numerical results demonstrate a change in the effective depth of measurement depending on the electrode topologies, which also have a good agreement with an analytic solution. This study suggests a decision guideline for designing the electrode topologies to achieve target depth sensitivity in bio-impedance measurement of skin tissue.Clinical Relevance-This establishes the effect of electrode topologies on depth sensitivity in bio-impedance measurements in skin layer.

Vascular access as a survival factor for the hemodialysis population: a retrospective study

BACKGROUND

The creation of vascular access is an essential condition for providing hemodialysis, which remains the only option for most patients suffering from end-stage renal disease. Selection of the type of vascular access affects patients' clinical outcomes, access maintenance frequency, risk of infection and major adverse cardiac events during dialysis. To improve the decision-making process, we performed a retrospective clinical data analysis of dialyzed patients and critically compared the survival rates between two types of vascular access applied during dialysis therapy during a 5 years follow-up period.

METHODS

Using nationally representative data from 18 dialysis centers across Slovakia, we explore and compare survival rates of 960 adult patients undergoing hemodialysis using either a central venous catheter (CVC) or an arteriovenous fistula (AVF). Length of dialysis, protein malnutrition and comorbidities were examined as possible covariates that might influence survival rates.

RESULTS

Chances of surviving for a one-year period were higher by 52% in AVF patients compared to CVC patients (HR 1.52; 95% CI 1.27-1.83; P<0.001) regardless of age, sex, nutritional status, time spent on dialysis and comorbidities. The presence of cardiac congestion (HR 1.26 [95% CI 1.06-1.50], P<0.01) and malnutrition (protein malnutrition: HR 0.98 [95% CI 0.96-1.00], P<0.05; lean tissue index: HR 0.79 [95% CI 0.67-0.93], P<0.01) decreases chances for survival.

CONCLUSIONS

A functional arteriovenous fistula is a significant predictor of survival in the population dependent on hemodialysis, independently of sociodemographic parameters and serious comorbidities. Therefore, if various types of vascular accesses are applicable for the patient, AVF should be prioritized over CVC.

Correlation between body composition measurement by bioelectrical impedance analysis and intradialytic hypotension

OBJECTIVE

To explore the correlation between body composition measurement by bioelectrical impedance analysis (BIA) and intradialytic hypotension (IDH).

METHODS

The clinical data of 127 patients with end-stage renal disease (ESRD) who underwent regular dialysis in the Blood Purification Center of the Second Affiliated Hospital of Chongqing Medical University were retrospectively analyzed. According to the occurrence of IDH, the patients were divided into IDH group and intradialytic normotension group. The difference in body composition measured by BIA and its relationship with IDH were compared between the two groups.

RESULTS

Compared with intradialytic normotension group, the intracellular water (ICW) ratio (P = 0.009), extracellular water (ECW) ratio (P = 0.029), total body water (TBW) ratio (P = 0.012), protein ratio (P = 0.010), soft lean mass (SLM) ratio (P = 0.011), fat-free mass (FFM) ratio (P = 0.012) and skeletal muscle mass (SMM) ratio (P = 0.009) in IDH group were significantly decreased. However, the fat mass (FM) ratio (P = 0.016), percentage body fat (PBF) ratio (P = 0.001), extracellular water/total body water (ECW/TBW) ratio (P = 0.036), extracellular water/total body water in trunk (ECW/TBWT) ratio (P = 0.045) and visceral fat area (VFA) (P = 0.003) in IDH group were significantly increased when compared with intradialytic normotension group. In addition, there was a positive correlation between systolic blood pressure (SBP) during IDH and ECW ratio, ECW/TBW ratio, and ECW/TBWTR ratio before dialysis.

CONCLUSIONS

The body composition of dialysis patients is closely related to the occurrence of IDH. Strengthening the body composition management of dialysis patients outside the hospital may reduce the occurrence of IDH and improve the long-term prognosis of dialysis patients.

Three compartment bioimpedance spectroscopy in the nutritional assessment and the outcome of patients with advanced or end stage kidney disease: What have we learned so far?

Bioimpedance spectroscopy (BIS) is an easily applicable tool to assess body composition. The three compartment model BIS (3C BIS) conventionally expresses body composition as lean tissue index (LTI) (lean tissue mass [LTM]/height in meters squared) and fat tissue index (FTI) (adipose tissue mass/height in meters squared), and a virtual compartment reflecting fluid overload (FO). It has been studied extensively in relation to diagnosis and treatment guidance of fluid status disorders in patients with advanced‐stage or end‐stage renal disease. It is the aim of this article to provide a narrative review on the relevance of 3C BIS in the nutritional assessment in this population. At a population level, LTI decreases after the start of hemodialysis, whereas FTI increases. LTI below the 10th percentile is a consistent predictor of outcome whereas a low FTI is predominantly associated with outcome when combined with a low LTI. Recent research also showed the connection between low LTI, inflammation, and FO, which are cumulatively associated with an increased mortality risk. However, studies toward nutritional interventions based on BIS data are still lacking in this population. In conclusion, 3C BIS, by disentangling the components of body mass index, has contributed to our understanding of the relevance of abnormalities in different body compartments in chronic kidney disease patients, and appears to be a valuable prognostic tool, at least at a population level. Studies assessing the effect of BIS guided nutritional intervention could further support its use in the daily clinical care for renal patients.

Obesity and risk of end-stage renal disease in patients with chronic kidney disease: a cohort study

Background

Obesity is a risk factor for de novo chronic kidney disease (CKD) in the general population. Obesity has been increasingly prevalent in patients with CKD and may lead to further progression of pre-existing CKD. However, whether obesity is associated with the development of end-stage renal disease (ESRD) in patients with CKD is not well understood.

Objective

We investigated the impact of obesity on ESRD (needing chronic dialysis treatment or pre-emptive renal transplantation) or all-cause mortality in patients with moderate to advanced CKD.

Design

A total of 322 patients with stages 3-5 CKD who were not yet on dialysis were prospectively followed for a median of 4.9 y. Obesity was defined by body mass index (BMI, in kg/m2) ≥30 or body fat percentage (BF%) >25% in men and >35% in women. BF% was assessed with the use of the Body Composition Monitor, a multifrequency bioimpedance spectroscopy device.

Results

In total, 100 participants progressed to ESRD and 39 participants died. Obesity, whether defined by BMI or BF%, was not associated with a significantly increased risk of ESRD in Cox proportional hazards models that adjusted for age, sex, diabetes mellitus, cardiovascular disease, estimated glomerular filtration rate, urine protein:creatinine ratio, high-sensitivity C-reactive protein, and use of renin-angiotensin-aldosterone system inhibitors or statins, accounting for the competing risk for mortality (subdistribution HR: 1.15; 95% CI: 0.62, 2.14 for BMI-defined obesity and subdistribution HR: 0.84, 95% CI: 0.54, 1.29 for BF%-defined obesity, respectively). Results were similar when BMI and BF% were analyzed as continuous or time-dependent variables. Whereas higher BMI was protective, higher BF% appeared to be associated with increased all-cause mortality.

Conclusions

Obesity did not confer an increased risk of ESRD in patients with moderate to advanced CKD. This trial was registered at http://www.clinicaltrials.gov as NCT03285074.

Bioimpedance Spectroscopy Imprecisely Assesses Lean Body Mass in Pediatric Dialysis Patients

OBJECTIVES

Alterations in body compositions are strongly associated with poor outcomes in end-stage renal disease patients. Hence, assessment of lean body mass is crucial for clinically monitoring these patients. The use of multifrequency bioimpedance spectroscopy measurements has also been advocated, but their usefulness in children is questioned. We investigated whether their application is appropriate for lean body mass measurement in pediatric patients receiving chronic dialysis.

METHODS

Lean body mass estimates as assessed by multifrequency bioimpedance spectroscopy and by deuterium dilution were obtained for 15 patients (mean age 10.9 ± 3.6 years).

RESULTS

Lean body mass (mean ± standard deviation) determined by bioimpedance was 24.2 ± 10.7 and 24.4 ± 10.3 kg by deuterium technique. Bland-Altman analysis showed a mean (±standard deviation) difference between the 2 methods of -0.25 ± 2.30 kg with 95% limits of agreement of -4.80 to 4.25 kg. In a multiple linear regression model, the hydration status was associated with measurement bias after adjusting for age, sex, weight, and body surface area.

CONCLUSIONS

Our results show a high level of agreement between measurements by bioimpedance and deuterium technique, but the limits of agreement were wide. These findings do not support the use of bioimpedance to individually assess lean body mass in pediatric dialysis patients with and without overhydration.

Normal-weight obesity and clinical outcomes in nondiabetic chronic kidney disease patients: a cohort study

Background

Normal-weight obesity (NWO), defined by a normal body mass index (BMI) and high body fat percentage, has been shown to be associated with cardiometabolic dysfunction and an increased risk of cardiovascular disease and mortality in the general population. However, little is known about the clinical implications of NWO among patients with chronic kidney disease (CKD).

Objective

The aim of this study was to assess the characteristics and outcomes of nondiabetic CKD patients with NWO.

Design

A total of 178 nondiabetic patients with stages 3-5 CKD were prospectively followed for a median of 4.9 y. The patients were classified into 3 different adiposity phenotypes: nonobese [BMI (in kg/m2) <25 and fat mass percentage (FM%) ≤25% for men or ≤35% for women], NWO (BMI <25 and FM% >25% for men or >35% for women), and preobese-obese (BMI ≥25). FM% was determined using the Body Composition Monitor, a multifrequency bioimpedance spectroscopy device. The outcome was a composite of cardiovascular events or all-cause mortality.

Results

The prevalence of NWO was 28.1% among nondiabetic CKD patients with a normal BMI. NWO patients were older, had lower lean body mass, and had higher plasma interleukin-6 concentrations than nonobese patients. However, homeostatic model assessment for insulin resistance levels did not differ between the 2 groups. NWO patients showed a significant 3-fold higher risk of the composite outcome (HR 2.96, 95% CI: 1.13, 7.77; P < 0.05) than did nonobese patients in the fully adjusted model. Preobese-obese patients were not at increased risk compared to nonobese patients.

Conclusions

NWO was associated with the worst prognosis among the 3 different adiposity phenotypes in nondiabetic CKD patients. Our findings suggest the importance of using direct measures of adiposity for risk assessment in CKD patients who are normal-weight. This trial was registered at clinicaltrials.gov as NCT03285074.

Impact of Misclassification of Obesity by Body Mass Index on Mortality in Patients With CKD

Introduction

Unlike the general population, a higher body mass index (BMI) is associated with greater survival among patients with chronic kidney disease (CKD). This “obesity paradox” may be due to limitations of BMI as a measure of adiposity in CKD. Both BMI and body fat percentage (BF%) are used to classify obesity, but outcomes may vary. Therefore, we investigated the 2 different cutoffs for diagnosing obesity (BMI ≥28 kg/m² or BF% >25% for men and >35% for women) and the impact on all-cause mortality in CKD.

Methods

A total of 326 patients with non–dialysis-dependent CKD were prospectively followed for a median of 4.9 years (range 2.9–5.3). BF% and lean body mass were determined using the Body Composition Monitor, a novel multifrequency bioimpedance spectroscopy device. Covariates included age, gender, diabetes, cardiovascular disease, estimated glomerular filtration rate, proteinuria, and high-sensitivity C-reactive protein.

Results

Per the BMI definition, 27.9% of patients were obese. However, 48.8% of patients were obese according to the BF% definition. A BMI ≥28 kg/m² had a moderately high specificity of 83.2% but a low sensitivity of 39.6% for detecting BF%-defined obesity. In the fully adjusted models containing both BMI and BF%, obesity defined by BMI was associated with a significantly lower risk of death (hazard ratio [HR]: 0.23; 95% CI: 0.07–0.71; P = 0.011), whereas the result was reversed when obesity was defined by BF% (HR: 2.75; 95% CI: 1.28–5.89; P = 0.009). When patients were classified into 4 distinct groups based on both the BMI and BF% cutoffs for obesity, a considerable proportion of patients (29.4%) had excess body fat in the context of a normal BMI. These patients were more likely to have lower lean body mass (i.e., sarcopenic obesity) and had higher mortality compared with patients with obesity defined by both BMI and BF% (HR: 5.11; 95% CI: 1.43–18.26; P = 0.012).

Conclusion

Diagnostic discordance between BMI and BF% may partly explain the obesity paradox. Proper diagnosis of obesity in patients with CKD is required for both risk prediction and treatment.

Effect of Change in Fluid Status Evaluated by Bioimpedance Techniques on Body Composition in Hemodialysis Patients

OBJECTIVE

This prospective study uses calf bioimpedance spectroscopy (cBIS) to guide the attainment of dry weight (DW_cBIS) in chronic hemodialysis (HD) patients. The primary aim of this study was to evaluate whether body composition is altered when fluid status is reduced to DW_cBIS.

METHODS

Target post-HD weight was gradually reduced from baseline (BL) until DW_cBIS was achieved. DW_cBIS was defined as the presence of both flattening of the curve of extracellular resistance and the attainment calf normalized resistivity in the normal range during the dialysis treatment. Extracellular volume (ECV), intracellular volume, and total body water (TBW) were measured using whole body BIS (Hydra 4200). Fluid overload, lean body mass, and fat mass were calculated according to a body composition model.

RESULTS

Seventy-three patients enrolled and 60 completed the study (55 ± 13 years, 49% male). Twenty-eight patients (25% diabetes) achieved DW_cBIS, whereas 32 patients (47% diabetes) did not. Number of treatment measurements were 16 ± 10 and 12 ± 13 studies per patient in the DW_cBIS and non-DW_cBIS groups, respectively. Although significant decreases in body weight and ECV were observed, lean body mass and FM did not differ significantly in both groups from BL to the end of study. ECV, ECV/TBW, and fluid overload were higher in the non-DW_cBIS than in the DW_cBIS group both at BL and at the end of study. Ratios of intradialytic changes in calf normalized resistivity, ECV, and ECV/TBW to ultrafiltration volume were significantly lower in diabetic than in non-diabetic patients.

CONCLUSIONS

This study shows that decreasing fluid status by gradual reduction of post-HD weight in both DW_cBIS and Non-DW_cBIS groups did not affect body composition significantly over a period of about 4 weeks.

Intra-abdominal fat: Comparison of computed tomography fat segmentation and bioimpedance spectroscopy

Background

Intra-abdominal fat is an important factor in determining the metabolic syndrome/insulin resistance, and thus the risk of diabetes and ischaemic heart disease. Computed Tomography (CT) fat segmentation represents a defined method of quantifying intra-abdominal fat, with attendant radiation risks. Bioimpedance spectroscopy may offer a method of assessment without any risks to the patients. A comparison is made of these two methods.

Methods

This was a preliminary study of the utility of multifrequency bioimpedance spectroscopy of the mid abdomen as a measure of intra-abdominal fat, by comparison with fat segmentation of an abdominal CT scan in the −30 to −190 HU range.

Results

There was a significant (P < 0.01) correlation between intra-abdominal fat and mid-upper arm circumference, as well as the bioimpedance parameter, the R/S ratio. Multivariate analysis showed that these were the only independant variables and allowed the derivation of a formula to estimate intra-abdominal fat: IAF = 0.02 × MAC − 0.757 × R/S + 0.036.

Conclusions

Circumabdominal bioimpedance spectroscopy may prove a useful method of assessing intra-abdominal fat, and may be suitable for use in studies to enhance other measures of body composition, such as mid-upper arm circumference.