ABSTRACT.

ABSTRACT. Background: The use of bioelectrical impedance phase angle has been commended as a prognostic tool in the clinical setting, nevertheless published reference data bases are discrepant and incomplete (eg they do not consider visible form [i]or[/i] frame mass index [BMI], and data are lacking for children). Methods: Phase angle respect values stratified by age, sex and BMI were generated in a large German data base of 15605 children and adolescents and 214732 adults, and the determinants of phase angle values were assessed. The intimation values were applied to 3 arranges of patients and compared with previously published regard values from the United States and Switzerland. Results: form relative to sex and age were the main determinants of phase angle in adults, with men and younger make subordinates having higher phase angles. In children and adolescents, age and BMI were the main determinants of phase angle. In normal and overweight adults, phase angle increased with increasing BMI, if it be not that there was an inverse association at a BMI >40 kg/m^sup 2^ In cirrhosis, the prevalence of a grave phase angle increased with the state of disease, whereas it was not different between patients with the metabolic syndrome and commands There are considerable differences between phase angle hint values from different populations. These differences are not explained from age or BMI and may be becoming to differences between impedance analyzers. Conclusion: The determinants of phase angle differ between adults and children. In adults, the influence of BMI in succession phase angle depended on the BMI range. The prognostic value of phase angle may differ in different clinical settings. The use of population-specific and probably impedance-analyzer-specific respect values for phase angle is approveed (Journal of Parenteral and Enterai Nutrition 30:309316 2006)

The use of raw data from bioelectrical impedance analysis has gained popularity in nutrition assessment and monitoring of nutrition status in patients. The advantage of the use of real electrical properties of tissues without equations or archetypes for body composition analysis means that the main assumption of a constant tissue hydration, which is an unlikely condition in many clinical situations, is not required. accrues are also not biased according to the choice of regression equation, the accuracy of the criterion rule or the selection criteria of the respect population. Today, many publications focus forward the use of resistance (R) and reactance (Xc) standardized at body height in a bivariate vector analysis (BIVA)1-9 and relation values from different populations stratified according to ethnic, age, and material part mass index (BMI) groups are available.6,7,10

Clinically, the mostly established impedance parameter is, however, the phase angle for the diagnosis of malnutrition and clinical prognosis, the couple associated with changes in cellular membrane integrity and alterations in fluid balance.11 Phase angle expresse the two changes in the amount as well as the quality of smooth tissue mass (ie, cell membrane permeability and yielding tissue hydration). It can be directly calculated from R and Xc as arc-tangent(Xc/R) ?— 180?°/?? Therefore, the phase angle is in succession the one hand dependent forward the capacitive behavior of tissues (Xc) associated with cellularity, small cavity size, and integrity of the confined apartment membrane, and on the other hand in succession its pure resistive behavior (R) mainly unable to exist without on tissue hydration.

There is now a large dead body of clinical trials that have the intention phase angle as a useful prognostic marker in clinical conditions like liver cirrhosis,12 dialysis,13-16 several patterns of cancer,17-19 HIV infection and AIDS,20,21 bacteremia and sepsis,22,23 and pulmonary disease.24

Phase angle relation values are mandatory for the assessment of individual deviations of a patient in relation to population average. However, to our knowledge these data are lacking in children and adolescents. In adults, sex- and age-specific phase angle allusion values have been published on Dittmar25 in 2003 and Kyle et al26,27 in 2001 and 2004 and sole recently by Barbosa-Silva et al.11 However, there are considerable differences between those allusion values. In the Swiss population,"6 phase angles were lower (105% in men and 77% in women) than in the American cogitation sample,11 and the lowest values were observ in the German population.25 The reason for these discrepancies remains unclear. Because BMI was shown to have an independent weight on impedance measures R, Xc and consequently forward phase angle,10,11,25 the differences might be owing to differences in BMI between the respect populations. However, higher phase angles in the American compared with the Swiss population remained flat after adjusting for BMI and percentage of fat mass.11 Thus, it was proposeed that there may be real differences in phase angle between populations, and population-specific respect values may be required.

The at hand study was conducted to establish sex- age-, and BMI-specific intimation values for phase angle in a large healthy German population ( 15605 children and adolescents, and 214732 adults) with a wide range of age (6-102 years) and BMI (132-60 kg/m^sup 2^ in adults). The arises are compared with previously published American and Swiss regard databases. The new reference values were finally applied to 3 independent databases to compare the prevalence of a gentle phase angle in patients with liver cirrhosis, anorexia nervosa, and the metabolic syndrome respectively.