Definizione e applicazione di metodologie per la valutazione della composizione corporea e del volume dell’arto superiore

Background: Specific Bioelectrical Impedance Vector Analysis (BIVAsp) is an easy to use, inexpensive, non invasive, and accurate technique for the assessment of body composition (Buffa et al., 2013; Marini et al., 2013), which is promising for applications in many biomedical fields. Objective: This research had methodological and applicative objectives. The methodological purposes were related to define some aspects of BIVAsp not yet analyzed: the major information given with respect to body mass index (BMI), or phase angle (PA), or when considered in association with hand grip strength (HGS); the definition of new reference values. Also, a new instrument (SkanLab) for the estimation of arm volume was defined. In association with BIVAsp, it could be used to evaluate the relation between body composition and body volume changes. Total and segmental BIVAsp were applied to analyse body composition in patients with Alzheimer's disease (AD) and, in association with handgrip strength, to diagnose sarcopenic individuals. Methods: Firstly, literature on the efficacy of BIVA for assessing body composition and on the relationship between cognitive and nutritional status in patients with AD was systematically reviewed. Then, according to the different analyses, different samples have been considered. BIVAsp vs BMI: bioelectrical, dual-energy X-ray absorptiometry (DXA), and anthropometrics variables from a preexisting dataset on 1590 U.S. adults (21-49 y) (NHANES 2003-2004). BIVAsp vs PA: Bioelectrical and DXA variables from a preexisting dataset on 207 Italian elderly (65-93 y). New Specific references values: Anthropometric and bioelectrical variables from a new sample of 440 Italian-Spanish individuals (18–30 y). SkanLab: Anthropometric and bioelectrical variables from a new sample of 30 individuals (19-60 y); geometrical measures of 12 cylinders. Body composition in patients with AD: Anthropometric and bioelectrical variables, psycho-functional indicators, and muscle strength from a new sample of 134 patients with AD (50-93 y) and 135 healthy controls (70-97 y). Results: BIVAsp recognized differences in groups with different relative content of fat mass (FM%), but similar BMI values. Higher FM% corresponds to longer vectors, while higher fat-free mass (FFM) to higher phase angles. BIVAsp showed more information on body composition than PA alone, recognizing FM% variations in groups with equal PA. The specific bioelectrical values for the Italian-Spanish young population were: Rsp (332.7±41.7), Xcsp (44.4±6.8), Zsp (335.6±41.9), phase (7.6°±0.8) in men; Rsp (388.6±60), Xcsp (43.7±7.5), Zsp (391.0±60.3), phase (6.4°±0.7) in women. The sample showed lower FM% than U.S. adults and higher FFM than Italian elderly. SkanLab showed a low bias in measuring the cylinders (−5.7%; LOA: −18.1% to 6.7%) and arms volume (−0.6%; LOA: −2.6% to 1.4%); the intra- and inter-rater reliabilities were always very high (ICC>0.99). Patients with AD showed similar BMI, but peculiar bioelectrical characteristics (lower FFM and higher FM%), in comparison with the controls. The segmental and total approaches furnished consistent results. Sarcopenia was detected in the 26.8% of the patients. Conclusions: BIVAsp adds relevant information on body composition regarding BMI and PA, and should be considered with them in research and applications. The new specific tolerance ellipses can be used as reference for assessing body composition in young adults Italian-Spanish population. SkanLab is an accurate and reliable method for assessing arm volume. Patients with AD showed peculiar body composition characteristics. The segmental approach represents an alternative to the total body one that would be particularly useful in the elderly, especially if with cognitive impairment. In association with the information given by HGS, BIVAsp allows the diagnosis of sarcopenia in a simple way.