Reference values for the phase angle of the electrical bioimpedance: Systematic review and meta-analysis involving more than 250,000 subjects

The science of bioelectrical impedance-derived phase angle: insights from body composition in youth

Despite bioelectrical impedance analysis (BIA)-derived phase angle (PhA) being recognized as a global marker of health, reflecting both cellular integrity and fluid distribution, its biological determinants still need to be described in youth. This narrative review provides a comprehensive framework examining to what extent dielectric properties shaping PhA are influenced by qualitative and quantitative determinants at multiple levels of body composition in healthy and clinical pediatric populations. At the atomic-molecular level, water content, glycogen, lipids, and ionic concentrations are expected to influence PhA by affecting electrical conductivity and/or capacitance. While the increase in the absolute values of intracellular (ICW) and extracellular water (ECW) enhances electric conductivity, an increase in the relative portion of ECW is expected to reflect hydration imbalances with an impact on electrical pathways. At the cellular level, body cell mass is a key determinant of PhA, mainly due to the presence of skeletal muscle cells favoring conductive and capacitive properties. At the tissue level, skeletal muscle architecture and orientation strongly influence conductivity, while increases in skeletal muscle mass positively impact PhA by enhancing electric conductivity and capacitance. Beyond the theoretical insights presented in this review, careful interpretation of dielectric data remains crucial due to the lack of methodological standardization. Future research should prioritize validated reference methods, investigate longitudinal changes, integrate localized BIA, and explore additional BIA models to refine the interpretation of PhA.

Segmental phase angle can predict incidence of severe exacerbation in male patients with COPD

OBJECTIVE

To investigate whether segmental phase angle (PhA) is a useful predictor of severe chronic obstructive pulmonary disease (COPD) exacerbation.

RESEARCH METHODS AND PROCEDURES

This prospective cohort study enrolled consecutive patients with COPD with a follow-up period of 3 years. The primary outcome was incidence of severe exacerbation. PhA was measured for the whole body and segmental body sites (trunk and upper and lower limbs). We used receiver operating characteristic (ROC) curves to determine the cut-off values and area under the curve (AUC) for predicting exacerbation based on PhA. We applied Cox proportional hazard regression analyses to estimate the independent prognostic effect of PhA on the incidence of severe exacerbation.

RESULTS

We analyzed 108 male participants (mean age 75.1±7.9 years) and the median follow-up period was 1082 [643-1103] days, with an annual severe exacerbation incidence rate of 0.23 per person-year. ROC analysis revealed that the AUC for Whole-body and segmental PhA were as follows: Whole-body: AUC = 0.69 (95% confidence interval [CI] = 0.59-0.79); right arm: AUC = 0.65 (95% CI = 0.53-0.77); left arm: AUC = 0.68 (95% CI = 0.56-0.79); right leg: AUC = 0.73 (95% CI = 0.64-0.82); left leg: AUC = 0.71 (95% CI = 0.62-0.81); trunk: AUC = 0.58 (95% CI = 0.46-0.69). Cox proportional hazard analysis demonstrated that PhA of the right leg (hazard ratio [HR]=3.50, 95% CI=1.33-9.20), left leg (HR=3.26, 95% CI=1.18-9.04), and left arm (HR=2.61, 95% CI=1.17-6.80) were independently and significantly associated with incidence of severe exacerbation. Whole and trunk PhA were not significantly associated with the incidence of severe exacerbation.

CONCLUSIONS

Segmental PhA may serve as a valuable predictive indicator of severe exacerbation in male patients with COPD. Notably, both leg PhA were strongly associated with the occurrence of severe exacerbations.

REGISTRY NUMBER

UMIN000044824.

The diagnostic performance of phase angle for sarcopenia among older adults: A systematic review and diagnostic meta-analysis

OBJECTIVE

Phase angle is a promising tool for diagnosing sarcopenia. This study aimed to summarize its diagnostic performance by performing a systematic review and meta-analysis.

METHODS

We conducted a systematic search of PubMed, Web of Science, Embase, and Scopus. The Quality Assessment of Diagnostic Accuracy Studies, Version 2, was used to evaluate the quality of the studies. A bivariate random effects model was employed for data synthesis, and diagnostic performance was reported in terms of pooled sensitivity, specificity, and the area under the summary receiver operating characteristic curve (AUC). Additionally, meta-regression, subgroup analyses, and sensitivity analyses were performed.

RESULTS

A total of 15 studies were included in this meta-analysis, involving 4,063 participants. The overall risk of bias in the included studies was high. The meta-analysis revealed that the pooled sensitivity and specificity across all studies were 0.74 [95 % confidence interval (CI): 0.71-0.78] and 0.75 (95 % CI: 0.70-0.79), respectively, with an AUC of 0.79 (95 % CI: 0.76-0.83). Meta-regression indicated that study design, country, population, sex-specificity, and age may influence the diagnostic performance of phase angle. The optimal diagnostic performance was observed in the cut-off interval of 4.20 to 4.50°.

CONCLUSION

The phase angle demonstrated moderate diagnostic performance for sarcopenia, and the possible cut-off interval is 4.20 to 4.50 °. However, large-scale, multicenter prospective studies are necessary to assess its clinical applicability at specific cut-off values.

Relationship between age and various muscle quality indices in Japanese individuals via bioelectrical impedance analysis (BIA)

BACKGROUND

Bioelectrical impedance analysis (BIA) is widely used as a convenient method of measuring body composition. The validity of the phase angle (PhA), impedance rate (IR), and resistance rate (RR) as indices of muscle quality using BIA has been suggested. This study aimed to investigate the relationship between these muscle quality indices and age, and to clarify their characteristics.

METHODS

The appendicular muscle mass (AMM), AMM corrected for body mass index (AMM/BMI), PhA, IR, and RR were determined using BIA in 1376 Japanese individuals (532 males and 844 females) aged 15-95 years. The PhA was determined from a 50-kHz current, and the IR and RR were determined from the impedance and resistance ratios between the 250- and 5-kHz currents.

RESULTS

AMM/BMI showed greater age-related changes than the other indices of muscle mass. Significant differences in PhA, IR, and RR were found for the whole body at age ≥ 50 years and for the lower limbs at age ≥ 30 years, compared to those in their 20 s. For the arms, age-related changes were small, and significant differences in PhA of females were only observed at aged ≥ 85 years, whereas significant differences in IR and RR were observed at aged ≥ 75 years, compared to those in their 20s.

CONCLUSION

These results suggest that although PhA, IR, and RR in the whole body and lower limbs showed age-related changes, the change in PhA in the upper body was small, especially in females. However, IR and RR in the upper limbs of females reflected age-related changes more than PhA.

Potential Determinants of Subjective Global Assessment Among Patients on Maintenance Hemodialysis

OBJECTIVE

The Subjective Global Assessment (SGA) is a validated tool for identifying nutritional status in patients receiving maintenance hemodialysis (MHD), but it is not without limitations. Current research identifies additional clinical characteristics such as phase angle (PhA) associated with SGA. This study aimed to assess the overall correlation between PhA and SGA; associations between PhA and SGA by body mass index, and to identify clinical characteristics associated with SGA.

DESIGN AND METHODS

This is a secondary analysis of the Rutgers Nutrition & Kidney Database, which enrolled participants from four primary studies that included adults diagnosed with chronic kidney disease who were receiving MHD. Multivariable binary logistic regression analyses were conducted to estimate odds ratio (OR) and corresponding 95% confidence intervals (CIs).

RESULTS

The study sample included 60.0% males with 81.1% of the sample identifying as African American. Additionally, 38.9% were obese according to the body mass index classification, and 57.0% were moderately malnourished. Patients with obesity had 44% lower odds of being moderately malnourished (OR = 0.56, 95% CI = 0.37, 0.85). In the model adjusted for age and ethnicity and other clinical characteristics, increasing PhA values by one unit was associated with 28% lower odds (OR = 0.72, 95% CI = 0.53, 0.97) of being moderately malnourished while increasing waist circumference (WC) values by one unit was associated with 12% higher odds (OR = 1.12; 95% CI = 1.06, 1.19) of being moderately malnourished than well-nourished. In this fully adjusted model, increasing fat free mass (FFM, OR = 0.95, 95% CI = 0.91, 0.99) and fat mass (FM, OR = 0.92, 95% CI = 0.87, 0.97) by 1 kg was also associated with 5% and 8% lower odds of being moderately malnourished, respectively.

CONCLUSION

PhA and SGA were significantly associated only among patients classified as obese. PhA, WC, FM, and FFM were identified as potential clinical determinants of SGA. Patients receiving MHD and who have obesity may benefit from utilizing SGA along with WC, PhA, FM, and FFM to assess nutritional status.

Phase angle is associated with nutritional risk in subacute stroke patients at the beginning of rehabilitation

OBJECTIVES

Malnutrition in stroke is associated with poor clinical outcomes. Bioelectrical impedance analysis-derived phase angle (PhA) is widely used for assessing nutritional status as an index of muscle quality. This study aimed to evaluate the associations between whole body and limb PhAs and nutritional risk in stroke patients. PhA predictors were also identified.

METHODS

Consecutive subacute stroke patients aged ≥50 y at the beginning of rehabilitation participated in this retrospective analysis. Nutritional risk was assessed using the Geriatric Nutritional Risk Index, the Prognostic Nutritional Index, and the Controlling Nutritional Status score. PhAs at 50 kHz for both whole body and limbs were measured. The associations between PhA and nutritional risk were examined through univariate/multivariate analyses.

RESULTS

Overall, 272 subacute stroke patients were studied (age, 70.1 ± 12.4 y, body mass index, 26.8 ± 3.9 kg/m²). Both whole body and limb PhAs were associated with Geriatric Nutritional Risk Index, Prognostic Nutritional Index, and Controlling Nutritional Status score, and this was also true in patients aged ≥75 y (P < 0.001). Low PhA values were observed in patients at high nutritional risk. The general linear model identified age, female sex, hypertension, diabetes, dysphagia, and time from stroke onset as independent predictors of PhA (R² = 0.468, P < 0.001). Furthermore, PhA emerged as a significant predictor of high nutritional risk according to each screening tool. Finally, optimal cutoffs of whole body PhA for predicting high nutritional risk were around 4.08°.

CONCLUSIONS

In stroke patients, low PhA values were associated with high nutritional risk. PhA at the beginning of rehabilitation may serve as a reliable parameter to be considered in the evaluation of nutritional status.

Disease modifies the dependency of percentiles of the phase angle distribution on age, sex, height and weight in hospitalized patients

BACKGROUND & AIMS

Phase angle (PhA) is viewed as a holistic indicator of quantity and quality of cellularity and hydration status and has emerged as a significant predictor of patient outcome in clinical medicine. We sought to analyze the impact of hospitalization as a surrogate for disease on the distribution of PhA and its dependency on influence variables age, sex, height and weight without any assumption as to the form of PhA-distribution.

METHODS

First PhA measurements obtained from 2418 women (median age 75 IQR[63; 82]) and 2541 men (median age 70 IQR[60; 79]) hospitalized in a Community General Hospital were analyzed. Multivariable quantile regression was applied for estimating percentiles P1 - P95 using parsimonious models including a dichotomous factor for sex and cubic polynomials for age (model A) and height and weight (model B) using only linear interaction terms between the four variables sex, age, height, and weight.

RESULTS

The association of PhA was strongest with age (women r = -0.48; men r = -0.47). In each age class average PhA values of hospitalized patients were below those reported for healthy individuals. In contrast to percentiles above the median showing a monotonous decrease with age as reported from healthy individuals the lower percentiles of patients showed a marked dip-and-plateau deformation. This deformation was associated with a change in the distribution span of PhA between P1 and P95 which was narrower at young age, expanded markedly due to a persisting fraction of patients with low PhA over the age range from 50 to 80 years and became narrower again at higher age due to the decreasing fraction of patients with high PhA. These distribution patterns were the same, irrespective of using either model A or model B. Furthermore, bootstrapping confirmed the estimated form of the percentile curves.

CONCLUSIONS

Disease modifies the PhA distribution pattern resulting not only in lower PhA in patients than in healthy individuals but also in a dip-and-plateau deformation of lower PhA percentile curves for the association with age. The dip-and-plateau pattern and the narrowing of the span between P1 and P95 with older age suggest that there is a low threshold value for PhA, below which life is impossible.

CLINICAL TRIAL REGISTRY

DRKS00025307, https://www.drks.de/DRKS00025307.

Phase angle in bioelectrical impedance analysis for assessing congestion in acute heart failure

BACKGROUND

The phase angle (PhA) in bioelectrical impedance analysis (BIA) reflects the cell membrane integrity or body fluid equilibrium. We examined how the PhA aligns with previously known markers of acute heart failure (HF) and assessed its value as a screening tool.

METHODS

PhA was measured in 50 patients with HF and 20 non-HF controls along with the edema index (EI), another BIA parameter suggestive of edema. Chest computed tomography-measured lung fluid content (LFC) was used to assess pulmonary congestion. A correlation analysis was conducted to evaluate the relationships between PhA and EI, NT-proBNP, and LFC. Receiver operating characteristic (ROC) curve analysis was used to determine the cut-off values for PhA and EI for classifying patients with HF. The area under the curve (AUC) was compared using the DeLong test to evaluate the performance of PhA and EI compared to that of LFC in correctly classifying HF.

RESULTS

The PhA levels were significantly lower in the HF group. Whole-body PhA was 4.49° in the HF group and 5.68° in the control group. Moderate and significant correlation was observed between PhA measured at 50-kHz and both NT-proBNP (-0.56 to -0.27, all p-values<0.05) and LFC (-0.52 to -0.41, all p-values <0.05). The AUC for whole-body PhA was 0.827 (confidence interval [CI] 0.724-0.931, p<0.01) and was 0.883 (CI 0.806-0.961, p<0.01) for EI, and the optimal cutoffs were estimated as 5° (sensitivity 0.84, specificity 0.80) and 0.394 (sensitivity 0.78, specificity 0.95), respectively. When both PhA and EI were included in the model, the AUC increased to 0.905, and this was comparable to that of LFC (AUC = 0.913, p = 0.857).

CONCLUSIONS

PhA exhibited a correlation with known markers of HF and demonstrated its potential as a non-invasive screening tool for the early detection of HF exacerbation. The combined use of PhA and EI can provide a robust alternative for routine self-monitoring in patients with HF, thereby enhancing early intervention.

Bioelectrical Impedance Analysis (BIA) detects body resistance increase in dogs undergoing blood donation

Using raw parameters of bioelectrical impedance analysis (BIA) and derived Phase Angle (PhA) has emerged as an alternative to conventional predictive BIA for body fluid volumes and body composition estimation in human patients, offering an approach independent of predictive equations. Classic predictive equation-based BIA remains unsuitable for veterinary clinical practice due to the high morphological variability within the canine species. This study aimed to validate the feasibility of BIA in dogs and assess its utility in detecting changes in body fluid volumes, particularly in blood donation. Sixty healthy blood donor dogs and ten controls were longitudinally assessed using BIA raw parameters with a portable analyzer at a 50 kHz frequency. Measurements were performed before and after blood donation in donor dogs, whereas in controls, they were carried out at two time points, approximating the timing of a donation. Significant increases in raw bioelectrical parameters were observed after blood donation in the donor group, while differences were not statistically significant in controls. Hematocrit values did not significantly differ between the two time points in both groups. These findings suggest the feasibility of using BIA to detect changes in body fluid volumes in dogs undergoing blood donation, highlighting its potential application in veterinary medicine. Further research should explore the applicability of BIA in spontaneous pathological conditions involving fluid loss or retention and investigate the potential utility of PhA as a prognostic or monitoring tool in veterinary clinical practice. This study provides valuable insights into using BIA in canine medicine, paving the way for enhanced diagnostic and monitoring strategies in clinical practice.

Bioelectrical impedance analysis (BIA) phase angle in stroke patients: A systematic review

BACKGROUND AND AIMS

Phase angle (PhA), a raw variable of bioelectrical impedance analysis (BIA), is an index of muscle structure and quality and might have a potential role in the evaluation of nutritional status. The aim of this systematic review was to evaluate in stroke patients: baseline PhA and its changes during hospital stay; the association of PhA with clinical features of patients, comorbidities, nutritional status or sarcopenia, and clinical outcomes.

METHODS

Systematic research on electronic databases (PubMed, Scopus, and Web of Science) up to June 14th, 2024 was performed according to PRISMA checklist. Using PECOS strategy, "P" (patients) = stroke patients, "E" (exposure) = lowest PhA values, "C" (comparison) = versus greatest PhA values, "O" (outcome) = nutritional and clinical outcomes, and "S" (study design) = all study types. Methodological quality was assessed using the Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies (NIH).

RESULTS

Eighteen papers met the inclusion criteria, with a low risk of bias. In stroke patients, evidence suggests that PhA was associated with malnutrition, sarcopenia and sarcopenic obesity, as well as with physical function. In addition, patients with low PhA had a longer hospital stay, higher inflammatory status and higher incidence of urinary tract infections and hospital-acquired pneumonia.

CONCLUSIONS

Selected papers, although not conclusive, show that in acute and subacute stroke patients PhA was inversely associated with malnutrition and poor physical function. PhA could be a marker of health status and disease progression. PhA may be useful in a more comprehensive evaluation of nutritional status to be used for diagnosis and implementing therapy.

Bioimpedance formalism: A new approach for accessing the health status of cell and tissues

This manuscript describes a novel methodology for studying relaxation dynamics in tissues and cells using characteristic frequency of bioimpedance spectroscopy measurements. The Bioimpedance Formalism allows for the simultaneous study of bioelectrical parameters in the frequency and time domains, providing insight into possible relaxation processes occurring in the tissue or cell of interest. Results from the Cole-Cole analysis showed no multiple relaxation processes associated with heterogeneity, with a visible age group separation in males compared with females. The study of the relaxation dynamic in the time domain revealed that the β parameter can be used to analyse the charge carriers in tissues, cells, or cancer cells, potentially leading to new diagnostic and therapeutic approaches for cancer and other diseases. Overall, this approach presents a promising area of research for gaining insights into the electrical properties of tissues and cells using bioimpedance methods.

Phase angle measured by bioelectrical impedance analysis in patients with chronic obstructive pulmonary disease: Associations with physical inactivity and frailty

BACKGROUND

Factors associated with early-stage frailty (pre-frailty) in patients with chronic obstructive pulmonary disease (COPD) remain unestablished. In addition to skeletal muscle quantity, skeletal muscle dysfunction can be estimated using an angular metric from bioelectrical impedance analyzer (BIA), termed the phase angle, that reflects cell membrane reactance representing the structural stability. This study examined whether the phase angle was more closely associated with pre-frailty compared with skeletal muscle quantity in patients with COPD.

METHODS

This cross-sectional analysis included stable smokers with and without COPD whose frailty status was assessed using the Japanese version of the Cardiovascular Health Study criteria. The phase angle and skeletal muscle index (SMI) were measured using BIA, and physical activity over one week was assessed using triaxial accelerometers.

RESULTS

A total of 159 patients were categorized into robust, pre-frail, and frail groups (n = 38, 92, and 29, respectively). The phase angle was significantly smaller in the pre-frail and frail groups than in the robust group after adjusting for age, sex, height, body mass index, smoking history, and lung function. In contrast, SMI did not differ between the robust and pre-frail groups. When combining the pre-frail and frail groups into a non-robust group, 4.8° was determined as the cutoff phase angle value to identify non-robust status. A phase angle <4.8° was associated with shorter durations of moderate-intensity physical activity but not with light physical activity.

CONCLUSIONS

A smaller phase angle was associated with pre-frailty and impaired moderate-intensity physical activity in smokers with and without COPD.

Variations in bioelectrical impedance devices impact raw measures comparisons and subsequent prediction of body composition using recommended estimation equations

BACKGROUND & AIMS

Bioelectrical impedance analysis (BIA) for body composition estimation is increasingly used in clinical and field settings to guide nutrition and training programs. Due to variations among BIA devices and the proprietary prediction equations used, studies have recommended the use of raw measures of resistance (R) and reactance (Xc) within population-specific equations to predict body composition.

OBJECTIVE

We compared raw measures from three BIA devices to assess inter-device variation and the impact of differences on body composition estimations.

METHODS

Raw R, Xc, impedance (Z) parameters were measured on a calibrated phantom and athletes using tetrapolar supine (BIASUP4), octapolar supine (BIASUP8), and octapolar standing (BIASTA8) devices. Measures of R and Xc were compared across devices and graphed using BIA vector analysis (BIVA) and raw parameters were entered into recommended athlete-specific equations for predicting fat-free mass (FFM) and appendicular lean soft tissue (ALST). Whole-body FFM and regional ALST were compared across devices and to a criterion five-compartment (5C) model and dual energy X-ray absorptiometry for ALST.

RESULTS

Data from 73 (23.2 ± 4.8 y) athletes were included in the analyses. Technical differences were observed between Z (range 12.2-50.1Ω) measures on the calibrated phantom. Differences in whole-body impedance were apparent due to posture (technological) and electrode placement (biological) factors. This resulted in raw measures for all three devices showing greater dehydration on BIVA compared to published norms for athletes using a separate BIA device. Compared to the 5C FFM, significant differences (p < 0.05) were observed on all three equations for BIASUP8 and BIASTA8, with constant error (CE) from -2.7 to -4.6 kg; no difference was observed for BIASUP4 or when device-specific algorithms were used. Published equations resulted in differences as large as 8.8 kg FFM among BIA devices. For ALST, even after a correction in the error of the published empirical equation, all three devices showed significant (p < 0.01) CE from -1.6 to -2.9 kg.

CONCLUSIONS

Raw bioimpedance measurements differ among devices due to technical, technological, and biological factors, limiting interchangeability of data across BIA systems. Professionals should be aware of these factors when purchasing systems, comparing data to published reference ranges, or when applying published empirical body composition prediction equations.

Associations between bioelectrical impedance analysis-derived phase angle, protein-energy wasting and all-cause mortality in older patients undergoing haemodialysis

AIM

Protein-energy wasting (PEW) is a common syndrome in patients undergoing haemodialysis (HD) and is associated with poor prognosis. Bioelectrical impedance analysis (BIA)-derived phase angle (PA) is useful for predicting PEW, but sex and age need to be considered. We aimed to reveal sex-specific cut-off values of PA predicting PEW in HD patients aged ≥65.

METHODS

This two-centre retrospective cohort study included patients on HD who underwent BIA. PEW was detected using the International Society of Renal Nutrition and Metabolism (ISRNM) criteria as a reference. The PA was measured using a multifrequency bioimpedance device. Sex-specific cut-off values of PA predicting PEW were detected by receiver-operator characteristic analysis. We investigated the association between PEW determined using sex-specific cut-off values for PA and all-cause mortality.

RESULTS

This study included 274 patients undergoing HD, with a median age of 75 (70-80) years, mean PA of 3.8 ± 1.1° and PEW of 43%. Over a median follow-up duration of 1095 (400-1095) days, 111 patients died. Cut-off values of PA predicting PEW were as follows: female, 3.00° (sensitivity, 87.3%; specificity, 77.5%), and male, 3.84° (sensitivity, 77.6%; specificity, 71.4%). The kappa coefficient between sex-specific cut-off values of the PA and ISRNM criteria had a moderate coincidence level of 0.55. PEW detected by PA was independently associated with all-cause mortality (hazard ratio: 2.40; 95% confidence interval: 1.51-3.85; p < .001).

CONCLUSIONS

Sex-specific cut-off values for PA in older HD patients may be useful as a screening tool for predicting PEW and mortality.

Effect of Oral Zinc Supplementation on Phase Angle and Bioelectrical Impedance Vector Analysis in Duchenne Muscular Dystrophy: A Non-Randomized Clinical Trial

Zinc plays a crucial role in cell structure and functionality. Neurodegenerative Duchenne muscular dystrophy (DMD) alters muscle membrane structure, leading to a loss of muscle mass and strength. The objective of this study was to evaluate the changes in phase angle (PA) and bioelectrical impedance vector analysis (BIVA) results in patients with DMD after oral zinc supplementation. This clinical trial included 33 boys aged 5.6 to 24.5 years diagnosed with DMD. They were divided into three groups according to age (G1, G2, and G3) and supplemented with oral zinc. The mean serum zinc concentration was 74 μg/dL, and 29% of patients had concentrations below the reference value. The baseline values (mean (standard deviation)) of the bioelectrical impedance parameters PA, resistance (R), and reactance (Xc) were 2.59° (0.84°), 924.36 (212.31) Ω, and 39.64 (8.41) Ω, respectively. An increase in R and a decrease in PA and lean mass proportional to age were observed, along with a negative correlation (r = -0.614; p < 0.001) between age and PA. The average cell mass in G1 was greater than that in G3 (p = 0.012). There were no significant differences in serum zinc levels or bioelectrical impedance parameters before and after zinc supplementation. We conclude that this population is at risk of zinc deficiency and the proposed dosage of zinc supplementation was not sufficient to alter serum zinc levels, PA and BIVA results.

Effectiveness of High-Protein Energy-Dense Oral Supplements on Patients with Malnutrition Using Morphofunctional Assessment with AI-Assisted Muscle Ultrasonography: A Real-World One-Arm Study

Background: User-friendly tools for assessing nutrition status and interventions in malnourished patients are crucial. This study evaluated the effectiveness of a personalised nutrition intervention using a novel oral nutritional supplement and AI-supported morphofunctional assessment to monitor clinical outcomes in patients with disease-related malnutrition (DRM). Methods: This prospective observational study involved patients receiving concentrated high-protein, high-calorie ONS (cHPHC-ONS), per usual clinical practice. Comprehensive assessments were performed at baseline (B0) and three months (M3) post-intervention. Results: 65 patients participated in the study. Significant decreases were observed in the percentage weight loss from B0 (-6.75 ± 7.5%) to M3 (0.5 ± 3.48%) (p < 0.01), in the prevalence of malnutrition (B0: 93.4%; M3: 78.9%; p < 0.01), severe malnutrition (B0: 60.7%; M3: 40.3%; p < 0.01), and sarcopenia (B0: 19.4%; M3: 15.5%; p < 0.04). Muscle area increased (p = 0.03), and there were changes in the echogenicity of the rectus femoris muscle (p = 0.03) from B0 to M3. In patients aged ≥60, an increase in muscle thickness (p = 0.04), pennation angle (p = 0.02), and handgrip strength (p = 0.04) was observed. There was a significant reduction in the prevalence of malnutrition (B0: 93.4%; M3: 78.9%; p < 0.01) and severe malnutrition (B0: 60.7%; M3: 40.3%; p < 0.01). Conclusions: In patients with DRM, a personalised intervention with cHPHC-ONS significantly reduces the prevalence of malnutrition, severe malnutrition, and sarcopenia and improves muscle mass and function.

Bioelectrical impedance phase angle and nutritional status in children with intestinal failure on prolonged parenteral nutrition

OBJECTIVE

To compare the phase angle (PhA) through bioelectrical impedance (BIA) of children with intestinal failure (IF) using prolonged parenteral nutrition (PN) followed by an Intestinal Rehabilitation Program, with a control group.

METHODS

Children under 10 years of age with IF using prolonged PN for >60 days (study group) were included. The control group consisted of healthy children without chronic pathologies, matched by sex and age. Anthropometric parameters evaluated were: weight, height, weight/age z-score (W/A), height/age z-score (H/A), BMI, BMI/A z-score, arm circumference, triceps skinfold, subscapular skinfold, mid-arm muscle circumference. BIA parameters were resistance (R), reactance (Xc), and phase angle (PhA).

RESULTS

Twenty-eight children were included in the study group, median (IQR) age was 11 (8-27) months, 53.6 % were male. In the control group, 28 children were included, median (IQR) age was 12.5 (8-24.7) months, 50 % were male. Children from the study group had W/A z-scores and H/A z-scores significantly lower than controls. There was no significant difference between PhA in the study group and controls, [median (IQR) 4.3° (3.8;4.6) vs 4.0° (3.8;5.4) respectively, p = 0.980]. Prematurity was significantly higher in the study group than in the controls, but there was no significant correlation between gestational age at birth and PhA of the children from the study group.

CONCLUSION

Children with IF using prolonged PN showed lower W/A and H/A compared to the control group, but without significant difference between the PhA of children with IF compared to controls.

Investigating the Association of Aortic Stiffness and Phase Angle with the Clinical Course of Rheumatoid Arthritis

Background

Aortic stiffness is an independent predictor of cardiovascular events which is increased in rheumatoid arthritis (RA). It can be measured by carotid-femoral pulse wave velocity (cfPWV). Phase angle (PhA) is lower in patients with cardiovascular disease and may be informative in assessing the clinical course of RA.

Materials and Methods

In this observational and cross-sectional study, all RA patients referred to the Imam Khomeini Hospital rheumatology clinic between September 2022 and March 2023 were included in the study. RA activity was assessed using the DAS28 criteria. In the patients, PhA and cfPWV were measured using Inbody-s10 and PulsePen tonometer instruments. The relationships between PhA, cfPWV, clinical course of RA, and CRP were evaluated using regression analysis.

Results

53 patients were included in the study (83% female, mean age 46.5 years). Significant inverse relationships existed between PhA, CRP, and age (P value = 0.003, 0.0001, R: 0.69, respectively). People with aortic stiffness had a lower mean PhA (P value = 0.05). In patients with RA duration of less than 10 years, the cfPWV percentile and the prevalence of rheumatoid factor (RF) and anti-cyclic citrullinated peptide (anti-CCP) positive cases were higher than in patients with RA duration >10 years (P values = 0.02, 0.01, respectively).

Conclusions

With increasing duration of RA, aortic stiffness and positive serology cases decreased. PhA and cfPWV may be useful in assessing the clinical course of RA to prevent cardiovascular events.

The Effect of Passive Dehydration on Phase Angle and Body Composition: A Bioelectrical Impedance Analysis

Bioelectrical impedance analysis (BIA) is a method used to estimate body composition, and it relies mainly on the body's water content. Insufficient body water can introduce bias to body composition scores.

PURPOSE

To determine the effect of body weight loss elicited by passive dehydration on body composition scores, including phase angle (PhA).

METHODS

Twenty-five euhydrated apparently healthy and physically active men's (age = 22.6 ± 3.3 yr.; body mass = 76.7 ± 15.9 kg; height = 172.0 ± 6.3 cm) body composition variables and PhA were measured before and after sitting quietly for 5 h in a controlled environment (26.6 ± 1.7 °C, 72 ± 4.9%RH).

RESULTS

It was found that five hours of passive dehydration caused a loss in body weight (Δ = 0.76 ± 0.34 kg, p < 0.05) and a decrease in body fat estimation (Δ = 0.90 ± 0.87 kg, p < 0.001). Additionally, an increase in ECW (Δ = 0.12 ± 0.30 L, p < 0.021) and PhA (Δ = 0.10 ± 0.15°, p < 0.005) was observed.

CONCLUSION

Body weight loss due to passive dehydration decreased BIA-derived fat mass, and increased extracellular water and PhA in physically active and apparently healthy men. Nonetheless, these changes had a negligible effect on the accuracy of the equipment, rendering them clinically insignificant.

Association between Physical Activity and Phase Angle Obtained via Bioelectrical Impedance Analysis in South Korean Adults Stratified by Sex

This cross-sectional study aimed to examine the association of various aspects of physical activity, including intensity, duration, type, and purpose, with the phase angle (PhA), an objective indicator of health, in Korean adults after stratification by sex. Data from the 2022 Korean National Health and Nutrition Examination Survey, a nationwide, representative, population-based survey, were used. In total, 3996 participants were included in the study. Participants self-reported their weekly intensity, frequency, duration of engagement in physical activity. PhA was categorized into two groups on the basis of sex-specific averages. Multiple logistic regression analysis was used to investigate the relationship between physical activity and PhA, and proportional odds logistic regression analysis was performed to determine the association between physical activity and different subclasses of PhA. A positive association was found between sufficiently active aerobic physical activity and PhA compared with inactive physical activity (sufficiently active, male: odds ratio = 1.952, 95% confidence interval = 1.373-2.776; female: odds ratio = 1.333, 95% confidence interval = 1.019-1.745). This association was further strengthened when aerobic physical activity was accompanied by muscle-strengthening activity (sufficiently active with muscle-strengthening activity, male: aOR = 2.318, 95% CI = 1.512-3.554; female: aOR = 1.762, 95% CI = 1.215-2.556) and vigorous-intensity activities (sufficiently active with sufficient vigorous-intensity activity, male: aOR = 2.785, 95% CI = 1.647-4.709; female: aOR = 2.505, 95% CI = 1.441-4.356) and when there was more leisure-time physical activity than occupational physical activity (sufficiently active with more leisure-time physical activity, male: aOR = 2.158, 95% CI = 1.483-3.140; female: aOR = 1.457, 95% CI = 1.078-1.969). Furthermore, the inclusion of muscle-strengthening activity made a significant difference in the values of PhA for males with insufficiently active physical activity (aOR = 2.679, 95% CI = 1.560-4.602). For females with highly active physical activity (aOR = 1.521, 95% CI = 1.068-2.166), the inclusion of muscle-strengthening and vigorous-intensity activities were significantly associated with higher values for PhA. This study can be utilized to provide specific suggestions for better health programs and can change perception that only occupational physical activity is enough. This study also indicated that PhA can be used for personalized health assessments.

Phase angle as an indicator of sarcopenia and malnutrition in patients with chronic obstructive pulmonary disease

BACKGROUND

Phase angle (PhA), which is measured using bioelectrical impedance analysis, is an indicator of muscle quality and malnutrition. PhA has been shown to be correlated with sarcopenia and malnutrition; however, studies on patients with chronic obstructive pulmonary disease (COPD) are limited. In this study, we investigated the correlation between PhA and sarcopenia and malnutrition and determined the cutoff values of PhA for those in patients with COPD.

METHODS

This study included 105 male patients with COPD (mean age 75.7 ± 7.7 years, mean forced expiratory volume in 1s % predicted [%FEV1] 57.0 ± 20.1%) and 12 male controls (mean age 74.1 ± 3.8 years) who were outpatients between December 2019 and March 2024. PhA was measured using the InBody S10, and its correlation with sarcopenia and malnutrition was assessed. The cutoff PhA values for sarcopenia and malnutrition were determined using receiver operating characteristic curves.

RESULTS

The prevalence rates of sarcopenia and malnutrition were 31% and 22%, respectively, in patients with COPD. PhA significantly correlated with sarcopenia- and malnutrition-related indicators. Multivariate logistic regression analysis independently correlated PhA with sarcopenia and malnutrition. The cutoff values of the PhA for sarcopenia and malnutrition were 4.75° (AUC = 0.78, 95% CI = 0.68-0.88) and 4.25° (AUC = 0.75, 95% CI = 0.63-0.86), respectively.

CONCLUSIONS

PhA was significantly correlated with sarcopenia and malnutrition in Japanese patients with COPD and may be a useful diagnostic indicator.

Phase angle and anthropometric indicators of cardiometabolic risk in children and adolescents

RATIONALE/OBJECTIVE

The phase angle (PhA) is a measurement obtained from the resistance and reactance found in the bioelectrical impedance examination and is useful in assessing nutritional status and in assessing cardiometabolic diseases. Therefore, the objective was to correlate the phase angle to the anthropometric variables of cardiometabolic risk (CMR) in children and adolescents.

SUBJECTS/METHODS

Weight, height, body mass index (BMI), waist circumference (WC) and neck circumference (NC), waist-to-height ratio (WHtR), and PhA of 1231 children and adolescents aged between 5 and 18 years were assessed. PhA was assessed in tertiles and CMR was identified using the anthropometric variables BMI, WC, NC, and WHtR. Linear regression models were used to verify the association between PhA tertiles and CMR anthropometric variables, stratified by sex.

RESULTS

No relationship was found between PhA and CMR variables in children. In adolescents, lower values of NC (β = -0.019, p = 0.005) and BMI (β = -0.025, p = 0.023) were found in boys, WC (β = -0.017, p = 0.020), WHtR (β = -0.017, p = 0.020), NC (β = -0.011, p = 0.027) and BMI (β = -0.026, p = 0.009) in girls when they were in tertile 1 when compared to tertile 3 of the PhA, even after adjusting for age.

CONCLUSION

The PhA was directly associated with CMR in the assessed adolescents.

Phase angle and its determinants among adolescents: influence of body composition and physical fitness level

To examine the association between levels of physical fitness, parameters of body composition and phase angle (PhA) amongst adolescents. A total of 152 adolescents (84 girls) aged 11-16 years were included in this study. Weight and height were measured and the body mass index (BMI) was calculated. Bioelectrical impedance analysis (BIA) provided resistance and reactance parameters to calculate fat-free mass (FFM), PhA and fat mass (%FM). The following physical fitness variables were analysed: flexibility, abdominal muscular endurance, upper and lower limb explosive strength, agility, speed and cardiorespiratory fitness. Generalized Linear Models were applied to verify differences across sexes. Stepwise linear regression was used to establish an association between the variables studied. The study established an association between PhA and weight, FFM, BMI, FM, %FM and medicine ball throw (MBT) for girls. As for the boys, an association was verified between PhA and weight, FFM, BMI, standing long jump (SLJ), MBT and the three allometric VO2peak variables analyzed. An association was found between PhA and the boys' 4-m shuttle run test (4SRT) and 20-m sprint test (20SRT). Boys showed a greater phase angle than girls; In girls, BMI and %FM, were determinant of 32.4% (r = 0.57). PhA variability which is influenced by physical fitness, body composition and, therefore, the tissues electrical conductivity. Furthermore, boys' height, FFM, upper limb strength, and agility account for 58.4% (r = 0.76) PhA variability. There was a positive correlation between the physical fitness tests and the PhA.

Using structural equation modeling to examine correlations between health-related physical fitness and cell health among Chinese college students

INTRODUCTION

College students' physical fitness is likely to be directly related to their cells' health. However, there is a lack of literature on whether the relationship between cell health and college students' physical fitness is direct or indirect. This study used a structural equation modeling (SEM) approach to investigate the connection between cell health and college students' physical fitness.

METHODS

This cross-sectional study collected data from 838 volunteers (502 males and 336 females, average age of 18.74 ± 1.5 years) who were college students from the Shandong province of China in July 2023. Initially, we obtained anthropometric measurements and conducted physical fitness tests on the students. Then, we performed Pearson correlation analysis and principal component analysis to screen variables and explore potentially influencing factors. Finally, we examined associations between the variables and determined whether there were direct or indirect influences among factors using SEM.

RESULTS

The results revealed a significant correlation between the cell health factor and the muscle strength factor (path coefficient = 0.97; p < 0.001) as well as the fat obesity factor (path coefficient = -0.52; p < 0.001). The cardiovascular factor exhibited a weak correlation with the cell health factor (path coefficient = 0.11; p < 0.01). Moreover, the cardiovascular factor acted as a mediating variable between the muscle strength factor and the cell health factor, with a positive correlation observed between the muscle strength factor and the cell health factor (path coefficient = 0.40; p < 0.001).

CONCLUSION

These findings suggest that cell health is indicative of muscle strength and cardiorespiratory fitness. Our findings demonstrate that assessing the cell health of college students can be a valuable method for evaluating their overall health.

Assessing the impact of early progressive mobilization on moderate-to-severe traumatic brain injury: a randomized controlled trial

INTRODUCTION

Traumatic brain injury (TBI) is a major cause of neurodisability worldwide, with notably high disability rates among moderately severe TBI cases. Extensive previous research emphasizes the critical need for early initiation of rehabilitation interventions for these cases. However, the optimal timing and methodology of early mobilization in TBI remain to be conclusively determined. Therefore, we explored the impact of early progressive mobilization (EPM) protocols on the functional outcomes of ICU-admitted patients with moderate to severe TBI.

METHODS

This randomized controlled trial was conducted at a trauma ICU of a medical center; 65 patients were randomly assigned to either the EPM group or the early progressive upright positioning (EPUP) group. The EPM group received early out-of-bed mobilization therapy within seven days after injury, while the EPUP group underwent early in-bed upright position rehabilitation. The primary outcome was the Perme ICU Mobility Score and secondary outcomes included Functional Independence Measure motor domain (FIM-motor) score, phase angle (PhA), skeletal muscle index (SMI), the length of stay in the intensive care unit (ICU), and duration of ventilation.

RESULTS

Among 65 randomized patients, 33 were assigned to EPM and 32 to EPUP group. The EPM group significantly outperformed the EPUP group in the Perme ICU Mobility and FIM-motor scores, with a notably shorter ICU stay by 5.9 days (p < 0.001) and ventilation duration by 6.7 days (p = 0.001). However, no significant differences were observed in PhAs.

CONCLUSION

The early progressive out-of-bed mobilization protocol can enhance mobility and functional outcomes and shorten ICU stay and ventilation duration of patients with moderate-to-severe TBI. Our study's results support further investigation of EPM through larger, randomized clinical trials. Clinical trial registration ClinicalTrials.gov NCT04810273 . Registered 13 March 2021.

Association between Physical Activity Level, Body Composition, and Phase Angle in University Students from Bioelectrical Impedance Analysis (BIA)

Background: The aim of this study is to determine the relationship between selected components of body composition and the phase angle specified by bioelectrical impedance analysis, depending on the level of physical activity among students. Materials and Methods: The study group consisted of 484 university students from Krosno. The diagnostic survey method (IPAQ-SF), measurements of highs, and analysis of body composition components (BIA) were used. The relationship between variables was determined using the χ2 test, the V-Kramer coefficient, and Spearman's rho coefficient. Results: University students in physical education demonstrated the highest level of physical activity and the lowest incidence of excessive body mass. Among the participants, 28.1% did not engage in any physical activity, or their level was insufficient. The PhA level was correlated with lean body mass and muscle mass. The correlation between higher levels of PA and PhA values was statistically significant, as was the relationship between self-assessment of physical fitness and the level of PA determined by IPAQ-SF. Conclusions: Preventive actions and educational programs, especially about spending leisure time in active ways, should be particularly targeted at students of disciplines with a significant amount of sedentary classes.

Prevalence of Malnutrition in a Group of Institutionalized Psychogeriatric Patients Using Different Diagnostic Criteria

Malnutrition (MN) is a highly prevalent condition in the elderly. It is associated with functional impairment, disability, frailty, and sarcopenia. The aim was to analyze the capacity of GLIM and ESPEN criteria to diagnose MN in a sample of institutionalized psychogeriatric patients. Clinical and anthropometric data were collected in a cross-sectional study. Patients' frailty, dependence, functional capacity, MNA, hand-grip strength (HS), and sarcopenia were evaluated. Body composition (BC) was estimated by conventional bioimpedance analysis. MN diagnosis was established using the ESPEN and the GLIM criteria based on fat-free mass index (GLIM-FFMI), appendicular skeletal muscle mass index (GLIM-ASMMI), skeletal muscle mass index (GLIM-SMMI), and HS (mGLIM). Ninety-two patients (57.6% men; mean age: 79.4 years) were studied. Depending on the diagnosis criteria, MN prevalence was between 25% (ESPEN) and 41.3% (GLIM-SMMI). Agreement between ESPEN and all GLIM criteria was poor, but it was excellent between all GLIM criteria (kappa > 0.8). Phenotypic criteria carried more weight in the diagnosis of MN than etiological ones. Depending on the parameter used, the prevalence of reduced muscle mass was notably different. Differences in BMI, BC, inflammation, and albumin are detected by the GLIM-FFMI criteria in the MN and non-MN subjects. Also, this criterion is the only one that identified differences in phase angle (PhA) between these groups. In the elderly, PhA can be very useful to monitor nutritional status.

Phase angle as a prognostic indicator in critically ill children: A systematic review

Phase angle (PhA) may reflect the integrity of cellular membranes, hydration status, and total body cell mass. Studies have shown that PhA can be used as a good predictor for evaluation of disease severity in critically ill adults. However, there is a lack of studies assessing the association between PhA and clinical outcomes in critically ill children. This systematic review described the association between PhA at pediatric intensive care unit (PICU) admission with clinical outcomes in critically ill children. The search was conducted using PubMed/Medline, Scopus, Web of Science, EMBASE and LILACS until July 22, 2022. Studies that evaluate the association between PhA at PICU admission in critically ill children and clinical outcomes were eligible. Data regarding population, study design, setting, bioelectrical impedance analysis (BIA) protocol used, PhA classification, and outcome analysis were extracted. Risk of bias was assessed by Newcastle-Ottawa Scale. Among the 4669 articles screened, five prospective studies were included. The studies have shown association between lower values of PhA at PICU admission with longer PICU and hospital length of stay, duration of mechanical ventilation, septic shock, and higher mortality risk. Small sample size, different clinical conditions, and methodological differences of the studies regarding BIA equipment and cutoffs of PhA were observed. Although the studies have limitations, the PhA has a potential role in predicting clinical outcomes in critically ill children. Larger studies with standardized PhA protocols and other relevant clinical outcomes are necessary.

Epicardial fat and insulin resistance in healthy older adults: a cross-sectional analysis

Insulin resistance (IR) and cardiovascular diseases (CVD) are relevant concerns in the elderly population; as the world's population ages, IR and CVD are two universal public health problems. While a link between IR a CVD has been established, the mediating mechanisms are uncertain and rigorous investigations are needed to fully elucidate them. The study aimed at assessing the relationship between epicardial fat (EF), an indicator of cardiovascular risk, and IR in Italian free-living elderly (n = 89). Baseline data from a previous cohort was used. Anthropometric measurements, EF, and IR-related variables, including the HOMA-IR index and other biochemical parameters were obtained. The correlation between EF and IR was explored. Further analysis was conducted to identify significant differences regarding IR variables among EF quartiles. EF correlated positively with glucose levels in females, males and the total population. The pairwise comparison among EF quartiles showed significant differences in glucose levels, HOMA-IR index, triglycerides, and total cholesterol levels. To our knowledge, this is the only study assessing the relationship between EF and IR in healthy elderly, while most of the studies have investigated EF and IR in diseased populations. Further research with a longitudinal approach should be conducted to design concrete conclusions about this relationship.

A meta-analysis on the impact of resistance training on phase angle in middle-aged and older individuals

PURPOSE

To determine the impact of resistance training (RT) on phase angle (PhA) in middle-aged and older individuals via meta-analysis, explore effects in subgroups, and identify optimal RT protocol.

MATERIALS AND METHODS

We searched five databases using predefined criteria, assessed literature quality per Cochrane 5.1 Handbook, and used Revman 5.3 for effect size aggregation, bias assessment, sensitivity analysis, and subgroup analysis.

RESULTS

RT improved PhA in middle-aged and older individuals (d = 0.34, 95 % CI: 0.27-0.40, P < 0.05). Effective subgroups included Suspension (d = 0.62, 95 % CI: 0.33-0.90, P < 0.05), free-weights and machine (d = 0.36, 95 % CI: 0.28-0.45, P < 0.05), equipment training (d = 0.24, 95 % CI: 0.13-0.36, P < 0.05), and moderate-intensity RT (d = 0.34, 95 % CI: 0.27-0.42, P < 0.05). RT was conducted 2-3 times/week (d = 0.20, 95 % CI: 0.01-0.38, P < 0.05) or (d = 0.38, 95 % CI: 0.30-0.47, P < 0.05). PhA improved after 8 weeks (d = 0.37, 95 % CI: 0.23-0.51, P < 0.05), 12 weeks (d = 0.35, 95 % CI: 0.26-0.44, P < 0.05), and ≥ 24 weeks (d = 0.26, 95 % CI: 0.11-0.41, P < 0.05) of RT in aged and older individuals. Low- and high-intensity RT, elastic band training, and weekly exercises did not significantly improve PhA.

CONCLUSIONS

RT enhances PhA in middle-aged and older adults. For optimal results, we recommend 2-3 weekly sessions of free weights and machine training lasting at least 8 weeks.

Use of Muscle Ultrasonography in Morphofunctional Assessment of Amyotrophic Lateral Sclerosis (ALS)

Amyotrophic lateral sclerosis (ALS) is a progressive disease with a high prevalence of malnutrition that can influence prognosis. The main objective of this study is to compare the validity of muscle ultrasonography in the diagnosis of malnutrition and the prognosis of patients with ALS.

METHODS

This is a prospective observational study that analyzes the nutritional status of patients at the beginning of nutritional monitoring. The morphofunctional assessment included the examination of anthropometric variables such as weight, height, body mass index (BMI), arm circumference, and calf circumference. Additionally, electrical bioimpedanciometry (BIA) was used to measure electrical parameters and estimate other relevant metrics. Muscle ultrasonography® (quadriceps rectus femoris (QRF)) assessed muscle mass parameters, including muscle area index (MARAI), anteroposterior diameter of the QRF (Y-axis) (cm), transverse diameter of the QRF (X-axis) (cm), and the sum of the quadriceps thickness (RF+VI) (cm), as well as muscle quality parameters such as echogenicity and the Y-X index.

RESULTS

A total of 37 patients diagnosed with amyotrophic lateral sclerosis (ALS) were included in this study. Of these patients, 51.4% were men. The mean age was 64.27 (12.59) years. A total of 54.1% of the patients had a bulbar onset of amyotrophic lateral sclerosis, and 45.9% had spinal onset. The percentage of subjects with malnutrition diagnosed by the Global Leadership Initiative on Malnutrition (GLIM) criteria was 45.9% of patients. There was a direct correlation between muscle mass parameters assessed by muscle ultrasonography (RF+VI) and active mass markers measured by bioimpedanciometry (body cellular mass index (BCMI) (r = 0.62; p < 0.01), fat-free mass index (FFMI) (r = 0.75; p < 0.01), and appendicular skeletal mass index (ASMI) (r = 0.69; p < 0.01)). There was a direct correlation between echogenicity and resistance (r = 0.44; p = 0.02), as well as between the fat-free mass index and the Y-X index (r = 0.36; p = 0.14). Additionally, there was a negative correlation between echogenicity and BCMI (r = -0.46; p < 0.01) and ASMI (r = 0.34; p = 0.06). Patients with low quadriceps thickness (male < 2.49 cm; female < 1.84 cm) showed an increased risk of hospital admission adjusted by age, sex, and presence of dysphagia (OR: 7.84 (CI 95%: 1.09-56.07); p-value = 0.04), and patients with low-quality mass (Y-X index < 0.35) had a higher risk of hospital admission adjusted by age, sex, and presence of dysphagia (OR: 19.83 (CI 95%: 1.77-222.46); p-value = 0.02).

CONCLUSIONS

In patients with ALS, ultrasonography echogenicity was inversely related to BCMI, FFMI, and ASMI, and the Y-X index was directly related to FFMI. The lowest quartiles of quadriceps thickness and Y-X index are risk factors for hospital admission.

Improvement of muscle quality assessed using the phase angle is influenced by recovery of knee extension strength in patients with hip fractures

BACKGROUND AND AIMS

Studies reported that knee extension strength on the operated side in patients with hip fractures was not recovered to the level on the non-operated side 6 months after surgery or later. In a cross-sectional study, we revealed that a reduction in isometric knee extension muscle strength on the operated side in patients with hip fractures approximately 6 months after surgery was associated with not only a reduction in skeletal muscle mass but also a reduction in muscle quality, characterized by a reduction in the phase angle (PhA). Furthermore, the mechanisms of knee extension strength improvement can be clarified in more detail using the minimal significant change as the index of recovery. However, no longitudinal studies have examined the factors for knee extension strength improvement based on the minimal significant change in patients with hip fractures 6 months after surgery. This study aimed to longitudinally examine the factors influencing the recovery of knee extension strength based on the minimal significant change in patients with hip fractures between 2 weeks and approximately 6 months after surgery.

METHODS

In this study, the outcomes used were basic and medical information, PhA, skeletal muscle index (SMI), pain, one-leg standing time, movement control during one-leg standing, and walking speed. For PhA, SMI, pain, one-leg standing time, movement control during one-leg standing, and walking speed, the amount of change was calculated by subtracting the data at 2 weeks from the data at 6 months. Group classification was determined by dividing the patients into two groups using a previous study as a reference: recovery group if the knee extension strength value approximately 6 months after surgery minus that 2 weeks after surgery was ≥3.3 kgf and non-recovery group if the value was <3.3 kgf. Logistic regression analysis was performed to explore the association between the recovery and non-recovery groups.

RESULTS

The recovery group contained 55 patients, while the non-recovery group comprised 35 patients. The only significant factor associated with knee extension muscle strength in the recovery group was the amount of change in PhA. The odds ratio for the amount of change in PhA was 2.26. The discrimination rate of the model was 62.5%.

CONCLUSIONS

Our results suggest that recovery of knee extension strength in patients with hip fractures after surgery was mainly because of improvements in muscle quality, not improvements in muscle mass or pain.

Relationship between cognitive function and phase angle measured with a bioelectrical impedance system

PURPOSE

The purpose of this study was to investigate the relationship between cognitive function and phase angle (PhA), an indicator of muscle quality.

METHODS

This cross-sectional study enrolled outpatients who visited a memory clinic at the Nagoya University hospital from January 2016 to June 2022. We enrolled 153 participants with body composition measurements. Inclusion criteria were a Mini-Mental State Examination score of 20-30 and a clinical diagnosis of Alzheimer's dementia (AD) or amnesic mild cognitive impairment (aMCI). The background characteristics of the participants were compared according to AD and aMCI. Next, linear regression analysis was performed with PhA as the objective variable. In addition, logistic regression analysis was performed for AD diagnosis.

RESULTS

PhA was lower in the AD group (P = 0.009). In linear regression analysis, PhA consistently decreased with worsening ADAS score. In logistic regression analysis, high PhA was associated with absence of AD. Gender-specific analyses showed these associations existed only in men.

CONCLUSIONS

Our study of patients with AD and aMCI found that PhA decreased with worsening of cognitive function. Compared with aMCI, AD was associated with significantly lower PhA. Our results strengthen the limited evidence in the literature showing that low muscle quality is associated with poor cognitive function.

Diagnostic Criteria and Measurement Techniques of Sarcopenia: A Critical Evaluation of the Up-to-Date Evidence

Sarcopenia, a geriatric syndrome characterized by progressive skeletal muscle mass and function decline, poses a significant health risk among the elderly, contributing to frailty, falls, hospitalization, loss of independence and mortality. The prevalence of sarcopenia varies significantly based on various factors, such as living status, demographics, measurement techniques and diagnostic criteria. Although the overall prevalence is reported at 10% in individuals aged 60 and above, disparities exist across settings, with higher rates in nursing homes and hospitals. Additionally, the differences in prevalence between Asian and non-Asian countries highlight the impact of cultural and ethnic factors, and variations in diagnostic criteria, cut-off values and assessment methods contribute to the observed heterogeneity in reported rates. This review outlines diverse diagnostic criteria and several measurement techniques supporting decision making in clinical practice. Moreover, it facilitates the selection of appropriate tools to assess sarcopenia, emphasizing its multifactorial nature. Various scientific groups, including the European Working Group of Sarcopenia in Older People (EWGSOP), the International Working Group on Sarcopenia (IWGS), the Asian Working Group on Sarcopenia (AWGS), the American Foundation for the National Institutes of Health (FNIH) and the Sarcopenia Definition and Outcomes Consortium (SDOC), have published consensus papers outlining diverse definitions of sarcopenia. The choice of diagnostic criteria should be aligned with the specific objectives of the study or clinical practice, considering the characteristics of the study population and available resources.

Association between fat-free mass and survival in critically ill patients with COVID-19: A prospective cohort study

BACKGROUND

Most critically ill patients with COVID-19 experience malnutrition and weight loss associated with negative clinical outcomes. Our primary aim was to assess body composition during acute and late phase of illness in these patients in relation to clinical outcome and secondary to tailored nutrition support.

METHODS

This prospective cohort study included adult critically ill patients with COVID-19. Body composition (fat-free mass [FFM] [exposure of interest], fat mass [FM], skeletal muscle mass [SMM], and phase angle [PA]) was determined with multifrequency bioelectrical impedance analyses in the acute and late phase. Nutrition support data were collected simultaneously. Clinical outcome was defined as intensive care unit (ICU) survival (primary outcome) and 30-90 days thereafter, duration of mechanical ventilation, and length of ICU stay and length of hospital stay (LOS). Nonparametric tests and regression analyses were performed.

RESULTS

We included 70 patients (73% male, median age 60 years). Upon admission, median BMI was 30 kg/m2 , 54% had obesity (BMI > 30 kg/m2 ). Median weight change during ICU stay was -3 kg: +3 kg FM and -6 kg FFM (-4 kg SMM). Body composition changed significantly (P < 0.001). Regarding clinical outcome, only low PA was associated with prolonged LOS (odds ratio = 0.83, 95% CI = 0.72-0.96; P = 0.015). Patients with optimal protein intake (>80%) during acute phase maintained significantly more FFM (2.7 kg, P = 0.047) in the late phase compared with patients who received <80%.

CONCLUSION

FFM decreased significantly during acute and late phase of illness, but we observed no association with ICU survival. Only low PA was associated with prolonged LOS. FFM wasting likely occurred because of disease severity and immobility.

A randomized controlled trial of propofol-remifentanil total intravenous anesthesia and sevoflurane-fentanyl anesthesia on early postoperative fatigue in patients undergoing laparoscopic colorectal surgery

PURPOSE

Even after uncomplicated surgery, postoperative fatigue prevalence has been reported to be 30-80% for various surgeries. We evaluated postoperative fatigue according to anesthetic technique in patients who underwent colorectal surgery.

METHODS

One hundred thirty patients who underwent colorectal surgery were randomly assigned to either propofol-remifentanil total intravenous anesthesia (propofol-remifentanil group, n = 65) or sevoflurane-fentanyl anesthesia (sevoflurane-fentanyl group, n = 65). The primary outcome was the prevalence of postoperative fatigue, as defined by the Chalder Fatigue Questionnaire (total score ≥ 16), at 24 h postoperatively. Secondary outcomes were early postoperative complications during hospitalization and laboratory examination.

RESULTS

The final analyses included 127 patients. The prevalence of postoperative fatigue on the 1st postoperative day was lower in the propofol-remifentanil group than the sevoflurane-fentanyl group: 56.3% (36/64) in the propofol-remifentanil group and 73.0% (46/63) in the sevoflurane-fentanyl group (relative risk [RR] = 0.77, 95% confidence interval [CI] 0.59-1.00; P = 0.048). However, there was no difference between the two groups in postoperative fatigue at postoperative day 3. Other postoperative outcomes including the severity of pain and the incidence of nausea/vomiting were not different between the two groups, but postoperative atelectasis on chest X-ray was higher in the sevoflurane-fentanyl group (2/64 [3.1%] vs. 9/63 [14.3%], P = 0.025). C-reactive protein change from preoperative to postoperative day 1 and 5 was significantly lower in the propofol-remifentanil group (P = 0.044).

CONCLUSION

Propofol-remifentanil total intravenous anesthesia was associated with reduced postoperative fatigue at the 1st postoperative day compared with sevoflurane-fentanyl anesthesia. Clinical trial The Korean Clinical Research Registry (study identifier: KCT0006917, principal investigator's name: MiHye Park, date of registration: January 12, 2022).

Associations of phase angle with platelet-activating factor metabolism and related dietary factors in healthy volunteers

Introduction

Phase angle (PA) is derived from bioelectrical impedance analysis (BIA). It reflects cell membrane function and decreases in disease. It is affected by inflammation, oxidative stress, and diet. Platelet-activating factor (PAF) is a potent inflammatory lipid mediator. Its levels, along with the activity of its metabolic enzymes, including CDP-choline:1-alkyl-2-acetyl-sn-glycerol-cholinephosphotransferase, acetyl-CoA:lyso-PAF-acetyltransferases, and PAF-AH/Lp-PLA2 are also related to dietary factors, such as the dietary antioxidant capacity (DAC). The aim of the study was to estimate whether the PAF metabolic circuit and related dietary factors are associated with PA in healthy volunteers.

Methods

In healthy subjects, PAF, its metabolic enzyme activity, and erythrocyte fatty acids were measured, while desaturases were estimated. Food-frequency questionnaires and recalls were used, and food groups, macronutrient intake, MedDietScore, and DAC were assessed. Lifestyle and biochemical variables were collected. DXA and BIA measurements were performed.

Results

Lp-PLA2 activity was positively associated with PA (rho = 0.651, p < 0.001, total population; rho = 0.780, p < 0.001, women), while PAF levels were negatively associated with PA only in men (partial rho = -0.627, p = 0.012) and inversely related to DAC. Estimated desaturase 6 was inversely associated with PA (rho = -0.404, p = 0.01, total sample). Moreover, the DAC correlated positively with PA (rho = 0.513, p = 0.03, women). All correlations were adjusted for age, body mass index, and sex (if applicable).

Conclusion

PA is associated with PAF levels and Lp-PLA2 activity in a gender-dependent fashion, indicating the involvement of PAF in cell membrane impairment. The relationship of PA with DAC suggests a protective effect of antioxidants on cellular health, considering that antioxidants may inhibit PAF generation.

Variations in phase angle and handgrip strength in patients undergoing cardiac surgery: Prospective cohort study

BACKGROUND

Bioimpedance phase angle (PA) is a measure of cell membrane integrity, whereas handgrip strength (HGS) is an evaluation of functional capacity. Although both are related to the prognosis of patients undergoing cardiac surgery, their changes over time are less known. This study followed variations in PA and HGS for 1 year in these patients, determining associations with clinical outcomes.

METHODS

This prospective cohort study included 272 cardiac surgery patients. PA and HGS were measured at six predetermined times. The evaluated outcomes were surgery type; bleeding; time of surgery, cardiopulmonary bypass, aortic cross-clamp, and mechanical ventilation; postoperative (PO) length of stay (LOS) in the intensive care unit (ICU) and hospital; and infections, hospital readmission, reoperation, and mortality.

RESULTS

There were reductions in PA and HGS values after surgery, with total recovery beginning at 6 months for PA and 3 months for HGS. In the PA area under the curve (AUC), age, combined surgery, and sex (β = -9.66, P < 0.001; β = -252.85, P = 0.005; β = -216.56, P < 0.001, respectively) were predictors for PA-AUC reduction. Stratified by sex, age (β = -93.54, P < 0.001) and PO LOS (β = -46.91, P = 0.003) were predictors for HGS-AUC reduction in women, but only age was a predictor in men (β = -77.02, P = 0.010). PA and HGS had an effect in hospital LOS and ICU LOS.

CONCLUSION

Age, combined surgery, and female sex were predictors of reduced PA-AUC, whereas reduced HGS-AUC was predicted by age in both sexes and PO hospital LOS in women, which suggests that these factors could interfere in prognosis.

Determinants of phase angle in Japanese patients with diabetes

Phase angle, obtained using bioelectrical impedance analysis, non-invasively reflects the whole-body cellular condition and nutritional status and may be helpful as a prognostic factor. Patients with diabetes had a smaller phase angle than healthy subjects. However, the clinical significance of phase angle has not yet been elucidated. Therefore, the purpose of this study was to clarify the relationship between phase angle and HbA1c in patients with diabetes and the clinical relevance of phase angle. A retrospective, multicenter, cross-sectional study was conducted with Japanese patients with diabetes. Body composition was determined with bioelectrical impedance analysis, and this was used to obtain phase angle. Phase angle was assessed in relation to clinical parameters, body composition parameters, and HbA1c levels. A total of 655 patients were enrolled (400 men and 255 women, aged 57.1 ± 14.8 years, body mass index 25.6 ± 5.2 kg/m2, HbA1c 8.1 ± 1.9%). Even in patients with diabetes, the phase angle was higher in men than in women and did not differ between the types of diabetes. Multiple regression analysis, performed with phase angle as the objective variable, and age, sex, diabetes type, HbA1c, albumin level, and body mass index as explanatory variables, revealed that phase angle was negatively affected by HbA1c (B = - 0.043, 95% Confidence interval: - 0.07 to - 0.02, p < 0.001). HbA1c, age, sex, albumin level, and body mass index were independent determinants of phase angle in participants with diabetes.

New bioelectrical impedance vector references and phase angle centile curves in 4,367 adults: The need for an urgent update after 30 years

BACKGROUND & AIMS

The bioelectrical impedance vector analysis (BIVA) represents a qualitative analysis of body composition. The vector, defined by resistance (R) and reactance (Xc) standardized by stature, can be evaluated compared to the 50%,75%, and 95% tolerance ellipses representative of the reference populations. The tolerance ellipses for healthy adults have been provided in 1995 and were developed by mixing underage, adult, and elderly subjects, possibly misrepresenting the actual adult population. The current multicentric, cross-sectional study aimed to provide new tolerance ellipses specific for the general adult population and as a secondary aim to present centile curves for the bioelectrical phase angle.

METHODS

R, Xc, and phase angle were measured in 2137 and 2230 males and females using phase-sensitive foot-to-hand analyzers at 50 kHz. A minimum of 35 subjects were included for each sex and age category from 18 to 65 years.

RESULTS

The new mean vectors showed a leftward shift on the R-Xc graph with respect to the former reference values (males: F = 75.3; p < 0.001; females: F = 36.6, p < 0.001). The results provided new 3rd, 5th, 10th, 25th, 50th, 75th, 90th, 95th, and 97th percentile curves for phase angle, identifying time point phases of decrement (males: -0.03° per year at 33.0-51.0 years and -0.05° per year after 51 years; females: -0.03° per year from 37.2 to 57.9 years).

CONCLUSIONS

Compared to the original references, the new data are characterized by a different distribution within the R-Xc graph with a higher phase angle. Thirty years after the BIVA invention, the current study presents new tolerance ellipses and phase angle reference values for the adult population.

The Impact of Nutritional Markers and Dietary Habits on the Bioimpedance Phase Angle in Older Individuals

Low phase angle (PhA), as determined via bioelectrical impedance analysis, reflects unhealthy aging and mortality. In this study, we assessed whether nutritional status, including serum nutritional markers and dietary habits, is related to PhA in older individuals. We recruited 212 participants (aged ≥ 65 years) who underwent medical health checkups. PhA was measured using a multi-frequency impedance body composition analyzer. Habitual food and nutrient intake was evaluated using a brief, self-administered diet history questionnaire. Low PhA values were defined as ≤4.95 in males and ≤4.35 in females. Males with low PhA had poor exercise habits (p = 0.0429) and a lower body mass index (p = 0.0024). PhA was significantly correlated with serum cholinesterase levels, a nutritional status marker (r = 0.3313, p = 0.0004 in males; r = 0.3221, p = 0.0070 in females). The low-PhA group had significantly lower total energy and carbohydrate intake per ideal body weight (IBW) than the high-PhA group in males (total energy intake:30.2 ± 9.8 and 34.5 ± 9.3 kcal/kg/day, p = 0.0307; carbohydrate intake:15.2 ± 4.9 and 18.0 ± 5.8 kcal/kg/day, p = 0.0157). Total energy intake per IBW (adjusted odds ratio [95% confidence interval], 0.94 [0.89-1.00] per 1 kcal/kg/day increase) was independently associated with a low PhA in males. Our study revealed that lower total energy intake independently impacted low PhA in older males.

Phase angle as a marker of outcome in hospitalized pediatric patients. A systematic review of the evidence (GRADE) with meta-analysis

Phase angle (PhA) is a valuable tool for evaluating the nutritional and inflammatory status, which can accompany acute and severe disorders. PhA is a cellular health biomarker, whose value is particularly substantial due to the negative consequences of these situations in the pediatric population. Relevant literature was collected with the aim of comprehensively analysing the evidence on the association between an altered PhA can serve as a predictive-marker for mortality and poor-outcomes in at-risk-pediatric patients. Understanding this relationship could have significant implications for identifying high-risk individuals and implementing timely interventions. A systematic review with meta-analysis was conducted in the primary electronic databases from inception until January 2023. Overall, four studies with a total of 740 patients were eligible for our analysis. Evidence demonstrates that PhA is associated with nutritional status, reflecting undernutrition and changes in body composition related to illness. This review suggests that PhA can indeed be used as an indicator of nutritional status and a tool for predicting prognosis, including mortality and poor-outcomes, in hospitalized pediatric patients. A low PhA was associated with a significant mortality risk [RR:1.51;95%CI (1.22-1.88),p = 0.0002;I2 = 0%,(p = 0.99)] and an increased complications risk [OR:8.17;95%CI (2.44-27.4),p = 0.0007;I2 = 44%,(p = 0.18)]. These findings highlight the importance of taking a comprehensive approach to clinical nutrition, integrating multiple evaluation aspects to establish an accurate diagnosis and personalized therapeutic plans. While PhA emerges as a valuable tool for assessing the risk of malnutrition and as a prognostic-indicator for poor-outcomes in pediatric patients. Further future studies are needed to focus on investigating this relationship in larger and diverse population to strengthen the evidence base.

Segmental bioelectrical impedance analysis can detect differences between the affected and non-affected limbs in individuals with hip osteoarthritis

OBJECTIVE

To analyze the bioelectrical impedance parameters of the lower limbs of individuals with hip osteoarthritis and healthy individuals.

DESIGN

Cross-sectional study.

SETTING

The study was carried out at the Hip Surgery Outpatient Clinic.

PARTICIPANTS

The volunteers had to be between 45 and 70 years of age, of both sexes, with a clinical and radiological diagnosis of hip osteoarthritis for at least three years, unilateral involvement, or a significant complaint in one hip.

METHODS

This was a cross-sectional study. Fifty-four individuals were recruited for the study, 31 individuals with hip osteoarthritis (OA group) and 29 healthy individuals for the control group (C group). Demographic and anthropometric data were collected and then the Numerical Pain Rating Scale, WOMAC, Harris Hip Score, and bioimpedance assessment were applied.

MAIN OUTCOME MEASURE(S)

Electrical bioimpedance parameters. Phase angle (PhA), impedance, reactance, and muscle mass.

RESULTS

There was a significant difference in phase angle (PhA), impedance, and muscle mass at 50 kHz frequency on the side affected by OA when compared to the contralateral side. In the OA group, there was a significant decrease in phase angle (PhA) -0.54 (-0.85 to -0.23) and muscle mass - 0.29 (-0.40 to -0,19), as well as an increase in impedance at the 50 kHz frequency on the side affected by OA when compared to contralateral side 21.71 (13.69 to 29.74). In the C group, there was no difference between the dominant and non-dominant sides (P > 0.05).

CONCLUSION

The segmental electrical bioimpedance equipment can detect differences between limbs affected and unaffected by hip osteoarthritis.

Phase Angle as a Prognostic Indicator of Survival in Institutionalized Psychogeriatric Patients

Phase angle (PhA) has been evidenced to be a useful survival indicator and predictor of morbi-mortality in different pathologies, but not in psychogeriatric patients. The aim of this study was to evaluate the clinical utility of PhA as a prognostic indicator of survival in a group of institutionalized psychogeriatric patients. A survival study was conducted on 157 patients (46.5% dementia, 43.9% schizophrenia). Functional impairment stage, frailty, dependence, malnutrition (MNA), comorbidity, polypharmacy, BMI, and waist circumference were registered. Body composition was analyzed using a 50-kHz whole-body BIA; PhA was recorded. The association between mortality and standardized-PhA was evaluated through univariate and multivariate Cox regression models and ROC-curve. The risk of death decreased when Z-PhA, BMI, and MNA were higher. Mortality increases with age, frailty, and dependence. The risk of death was statistically significantly lower (56.5%) in patients with schizophrenia vs. dementia (89%). The Z-PhA cut-off point was -0.81 (Sensitivity:0.75; Specificity:0.60). Mortality risk was multiplied by 1.09 in subjects with a Z-PhA < -0.81, regardless of age, presence of dementia, and BMI. PhA presented a remarkable clinical utility as an independent indicator of survival in psychogeriatric patients. Moreover, it could be useful to detect disease-related malnutrition and to identify subjects eligible for an early clinical approach.

Bioelectrical impedance analysis in the BaSAlt cohort-study: the phase angle as an additional parameter for sarcopenia quantification among German nursing home residents?

PURPOSE

Sarcopenia is characterized by the loss of muscle mass, strength, and physical functioning. The bioelectrical impedance analysis (BIA) is a simplify method for the measurement of muscle quantity and quality. But there is a lack of evidence in the interpretation of the muscle quality parameter phase angle (PhA), which was recommended by the European Working Group on Sarcopenia in Older People 2 (EWGSOP2). We hypothesize that the PhA shows differences between sarcopenia categorized groups and can be used as an additional parameter for sarcopenia quantification among residents of nursing homes (NH).

METHODS

Based on EWGSOP2 specifications, 78 residents from five German NH was categorized into sarcopenia groups. Group comparisons with Kruskal-Wallis tests, Dunn-Bonferroni post-hoc-Tests, and correlations with Spearman coefficients were conducted with the muscle quality parameter PhA.

RESULTS

Significant group differences by Kruskal-Wallis test for PhA was detected (H = 8.150, p = 0.017). The Dunn-Bonferroni post-hoc-Test showed significant results by group comparison for "confirmed/ severe sarcopenia" (4.1° [3.1-5.0]) with "no sarcopenia" (4.6° [3.7-11.2]; p =0 .049) and "probable sarcopenia" (4.7° [3.4-13.5]; p = 0.016), respectively.

CONCLUSIONS

There is a limitation for differentiation in preliminary stage of sarcopenia among multimorbid NH residents by PhA. Moreover, further research for specific cut-off-values and the individual sarcopenia progression monitoring by PhA are needed.

TRIAL REGISTRATION

No. AZ A2.5.4-096_aa (Date of approval: July 2019).

Future lines of research on phase angle: Strengths and limitations

Bioelectrical impedance analysis (BIA) is the most widely used technique in body composition analysis. When we focus the use of phase sensitive BIA on its raw parameters Resistance (R), Reactance (Xc) and Phase Angle (PhA), we eliminate the bias of using predictive equations based on reference models. In particular PhA, have demonstrated their prognostic utility in multiple aspects of health and disease. In recent years, as a strong association between prognostic and diagnostic factors has been observed, scientific interest in the utility of PhA has increased. In the different fields of knowledge in biomedical research, there are different ways of assessing the impact of a scientific-technical aspect such as PhA. Single frequency with phase detection bioimpedance analysis (SF-BIA) using a 50 kHz single frequency device and tetrapolar wrist-ankle electrode placement is the most widely used bioimpedance approach for characterization of whole-body composition. However, the incorporation of vector representation of raw bioelectrical parameters and direct mathematical calculations without the need for regression equations for the analysis of body compartments has been one of the most important aspects for the development of research in this area. These results provide new evidence for the validity of phase-sensitive bioelectrical measurements as biomarkers of fluid and nutritional status. To enable the development of clinical research that provides consistent results, it is essential to establish appropriate standardization of PhA measurement techniques. Standardization of test protocols will facilitate the diagnosis and assessment of the risk associated with reduced PhA and the evaluation of changes in response to therapeutic interventions. In this paper, we describe and overview the value of PhA in biomedical research, technical and instrumental aspects of PhA research, analysis of Areas of clinical research (cancer patients, digestive and liver diseases, critical and surgical patients, Respiratory, infectious, and COVID-19, obesity and metabolic diseases, Heart and kidney failure, Malnutrition and sarcopenia), characterisation of the different research outcomes, Morphofunctional assessment in disease-related malnutrition and other metabolic disorders: validation of PhA with reference clinical practice techniques, strengths and limitations. Based on the detailed study of the measurement technique, some of the key issues to be considered in future PhA research. On the other hand, it is important to assess the clinical conditions and the phenotype of the patients, as well as to establish a disease-specific clinical profile. The appropriate selection of the most critical outcomes is another fundamental aspect of research.

Raw bioelectrical impedance measurements are not different between White and Black adults when matched for sex, age, BMI, and other physical characteristics

Raw bioelectrical impedance measurements are often used as a prognosticator of health status because of their association with disease states and malnutrition. Although studies consistently show the effect of physical characteristics on bioelectrical impedance, few investigations describe the effect of race, particularly for Black adults, and many bioelectrical impedance standards were produced from primarily White adults almost 2 decades ago. Therefore, this study sought to evaluate the racial differences in bioelectrical impedance measurements using bioimpedance spectroscopy between non-Hispanic White and non-Hispanic Black adults matched for age, sex, and body mass index. We hypothesized that Black adults would have a lower phase angle from higher resistance and lower reactance compared with White adults. One hundred non-Hispanic White (n = 50) and non-Hispanic Black (n = 50) males (n = 34) and females (n = 66) matched for sex, age, and body mass index completed this cross-sectional study. Participants underwent several anthropometric assessments, including height, weight, waist circumference, hip circumference, bioimpedance spectroscopy, and dual-energy X-ray absorptiometry. Bioelectrical impedance measures of resistance, reactance, phase angle, and impedance were all collected at frequencies of 5, 50, and 250 kHz and bioelectrical impedance vector analysis was performed using 50-kHz data. There were no significant differences for any anthropometric variable between Black and White participants in the total sample or by sex groups. In addition, there were no significant racial differences for any bioelectrical impedance assessment, including bioelectrical impedance vector analysis. Differences in bioelectrical impedance are likely not a function of race between Black and White adults and concerns regarding its utility should not be based on this characteristic.