Baumgartner RN, Chumlea WC, Roche AF. Bioelectric impedance phase angle and body composition

Department of Pediatrics, Wright State University School of Medicine, Dayton, OH.
American Journal of Clinical Nutrition (Impact Factor: 6.92). 08/1988; 48(1):16-23.
Source: PubMed

ABSTRACT The use of bioelectric impedance phase angle for predicting body composition was determined in 53 males and 69 females 9-62 y of age. The phase angle describes the amount of reactance (Xc) in a conductor relative to the amount of resistance (R). Bioelectric resistance (R) and reactance (Xc) were determined for the whole body and separately for arm, leg, and trunk. Weight, stature, and skinfold thicknesses were measured. Body composition was determined from densitometry. Phase angles for the trunk (phi t), leg (phi 1), and whole body (phi w) had significant (p less than 0.05) negative correlations with percent body fat (%BF) in each sex, and positive correlations with fat-free mass (FFM) in males. In multiple regression analyses, phi t was associated significantly with %BF after controlling for age, mean skinfold thickness, and weight/stature2 in each sex. Bioelectric phase angle for the trunk may be useful for predicting %BF in clinical and survey research.

    • "Please cite this article in press as: Maddocks M, et al., Bioelectrical impedance phase angle relates to function, disease severity and prognosis in stable chronic obstructive pulmonary disease, Clinical Nutrition (2015), as a degree [4]. It provides information on hydration status, cellular mass and quality, and is not limited by the inherent assumptions when using BIA to estimate body compartments [4] [5]. "
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    ABSTRACT: Bioelectrical impedance analysis (BIA) provides a simple method to assess changes in body composition. Raw BIA variables such as phase angle provide direct information on cellular mass and integrity, without the assumptions inherent in estimating body compartments, e.g. fat-free mass (FFM). Phase angle is a strong functional and prognostic marker in many disease states, but data in COPD are lacking. Our aims were to describe the measurement of phase angle in patients with stable COPD and determine the construct and discriminate validity of phase angle by assessing its relationship with established markers of function, disease severity and prognosis. 502 outpatients with stable COPD were studied. Phase angle and FFM by BIA, quadriceps strength (QMVC), 4-m gait speed (4MGS), 5 sit-to-stand time (5STS), incremental shuttle walk (ISW), and composite prognostic indices (ADO, iBODE) were measured. Patients were stratified into normal and low phase angle and FFM index. Phase angle correlated positively with FFM and functional outcomes (r = 0.35-0.66, p < 0.001) and negatively with prognostic indices (r = -0.35 to -0.48, p < 0.001). In regression models, phase angle was independently associated with ISW, ADO and iBODE whereas FFM was removed. One hundred and seventy patients (33.9% [95% CI, 29.9-38.1]) had a low phase angle. Phenotypic characteristics included lower QMVC, ISW, and 4MGS, higher 5STS, ADO and iBODE scores, and more exacerbations and hospital days in past year. The proportion of patients to have died was significantly higher in patients with low phase angle compared to those with normal phase angle (8.2% versus 3.6%, p = 0.02). Phase angle relates to markers of function, disease severity and prognosis in patients with COPD. As a directly measured variable, phase angle offers more useful information than fat-free mass indices. Copyright © 2015 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.
    Clinical nutrition (Edinburgh, Scotland) 01/2015; DOI:10.1016/j.clnu.2014.12.020 · 3.94 Impact Factor
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    • "One must also consider whether changes in hydration status were relevant to the effect on PA changes and in parallel on IL-6 changes over time, observed in our study. An increase in extracellular fluid that is proportional to a decrease in body cell mass, can decrease PA [22]. A recent study reported that overhydration diagnosed on the basis of BIA-derived parameters is significantly related to inflammation (expressed as a high sensitivity CRP), natriuretic peptides, and cardiac biomarkers in HD patients [9]. "
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    ABSTRACT: We hypothesize that longitudinal changes in phase angle (PA) have independent associations with changes in inflammatory parameters over time and consequently with long-term survival in patients on maintenance hemodialysis (MHD). The aim of the present study was to determine the effect of change in nutritional and inflammatory parameters over time on change in PA and on subsequent mortality in patients on MHD. A 2-y prospective longitudinal study was performed on 91 prevalent HD patients (57 men and 34 women), followed by an additional 3 y of clinical observations. Dietary intake, biochemical markers of nutrition, body composition, and interleukin (IL)-6 levels were measured at baseline and at 6, 12, 18, and 24 mo following enrollment. In a linear mixed-effect model adjusted for baseline demographic and clinical parameters, each pg/mL increase in IL-6 over time was associated with a decrease in PA levels of 0.001°/2-y (P = 0.003 for IL-6 × time interaction). PA remained associated with the rate of change in IL-6 even after controlling for extracellular water and fat mass. Changes in PA over time were associated with inverse linear changes in IL-6 (adjusted r = -0.32; P = 0.005) and consequently with mortality risk. For each 1° increase in PA, the crude and adjusted mortality hazard ratios using Cox models with effect of time-varying risk were 0.62 (95% confidence interval [CI], 0.54-0.71) and 0.61 (95% CI, 0.53-0.71), respectively. Additionally, longitudinal changes in PA exhibited significant associations with slopes of changes over time in main nutritional markers. Longitudinal changes in PA appear to be reliable in detecting changes in nutritional and inflammatory parameters over time, a combination that may contribute to the understanding of its prognostic utility.
    Nutrition 03/2014; 30(3):297-304. DOI:10.1016/j.nut.2013.08.017 · 3.05 Impact Factor
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    • "The PA is the arc tangent relation of Xc/R converted to degrees. It describes the phase shift between the current and voltage that results from the electrochemical membrane [7]. Smaller PAs suggest cell death or decreased cell integrity, "
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    ABSTRACT: The main purpose of the present study was to assess the prognostic value of the bioelectrical phase angle (PA) in patients with heart failure independently of other parameters of a poor prognosis. This retrospective study included 389 patients with heart failure. Anthropometric, body composition, clinical, biochemical, and echocardiographic data were collected from all patients. The quartiles were obtained for the PA, and patients were classified according to the quartiles into four groups. The endpoint was all-cause mortality. A Cox proportional hazards regression analysis was performed to estimate the adjusted relative risks, and 95% confidence intervals were obtained for the potential predictors of death. Patients below the lowest quartile of PA (<4.2°) had decreased mean body mass index, handgrip strength, and hemoglobin values and a larger proportion of patients in New York Heart Association functional class III and renal failure. The Kaplan-Meier survival analysis among PA groups showed a better survival for patients above the highest quartile of PA (≥5.7°), and survival decreased as the PA decreased. The Cox regression analysis found that a PA <4.2 was an independent predictor of mortality (relative risk 3.08, 95% confidence interval 1.06-8.99), adjusting for age, hemoglobin levels, and diabetes, compared with a PA ≥5.7. In this study population, a smaller PA was associated with malnutrition markers such as decreased body mass index, handgrip strength, and hemoglobin values and with a poor New York Heart Association functional class and renal failure. Adjusting for age, hemoglobin levels, and diabetes, a PA <4.2 was found to be an independent predictor of all-cause mortality in chronic heart failure.
    Nutrition 03/2012; 28(9):901-5. DOI:10.1016/j.nut.2011.11.033 · 3.05 Impact Factor
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