Malnutrizione proteico-energetica, sarcopenia e disidratazione nella popolazione senile sana e affetta da patologie

Background: Ageing is correlated with nutritional status imbalance. Protein Energy-Malnutrition (PEM) can lead to hydration balance impairment and sarcopenia, a loss of muscle mass. Sarcopenia syndrome can be worsened by the excess of fat mass leading to sarcopenic obesity. These conditions are associated with an increasing risk of morbidity, mortality and of cognitive, functional and psychological decline. Screening analysis features an important tool to prevent negative outcomes. The most accurate body composition assessment techniques, such as Computed Tomography, Magnetic Resonance Imaging and Dual energy X-ray Absorptiometry (DXA) are weakly invasive and not easily accessible to investigators because of their high operational costs. Among the other techniques (anthropometry and impedance), Bioelectrical Impedance Vector Analysis (BIVA) is easy to use, inexpensive, non invasive and can be used in biomedical field and clinical practice to evaluate hydration and nutritional status. However, its validity in assessing body composition was lacking. Objective: Ascertaining the accuracy of BIVA to assess body composition variations and validating an analytic variant, specific BIVA. Classic and specific BIVA will be applied in different samples of elderly subjects in order to evaluate body composition variations in relation to psycho-functional status and health condition. Design: Several samples of healthy (658 subjects, 60 y or older) and pathological elderly (227 subjects, 65 y or older, with Alzheimer’s disease or type 2 diabetes mellitus), and a sample of healthy adults from U.S. (1594 subjects, 21-49 y) were considered (NHANES 2003-2004). Six anthropometric measurements were taken (height, weight, calf, waist and arm circumferences, body mass index (BMI)). Classic BIVA and the new variant (specific BIVA), that adjust bioelectrical values for body geometry, were applied. DXA was used as the reference method. Classic and specific BIVA results were compared by Receiver Operating Curve (ROC curve) analysis and by a probit multiple-regression. The psycho-functional status was assessed by Mini Mental State Examination (MMSE), Geriatric Depression Scale (GDS), Activities of Daily Living (ADL) and Instrumental Activities of Daily Living (IADL). Muscle strength was measured by the Hand Grip Strength (HGS) and Short Physical Performance Battery (SPPB) tests. Results: Classic BIVA distinguished individuals with different amounts of fat and fat-free mass, according to DXA, but not those with different proportions of fat mass (FMDXA%). Specific bioelectrical values detected changes in body composition, resulting significantly more accurate than classic BIVA in evaluating FMDXA% (ROC areas: 0.84 - 0.92 and 0.49 - 0.61 respectively; p=0.002). The evaluation of extracellular water/intracellular water ratio was accurate (ROC areas between 0.83 and 0.96) and similarly performed by the two procedures (p=0.829). Classic and specific BIVA detected significant differences between sarcopenic and nonsarcopenic individuals. Moreover, specific BIVA recognized bioelectrical differences between sarcopenic and sarcopenic obese men. Classic BIVA showed that patients with Alzheimer's disease have a worse psycho-functional and nutritional status compared to a control group. Patients with diabetes showed greater body dimensions and a reduced muscular area, compared to healthy controls. Specific BIVA showed no association with muscular strength tests. The specific bioelectrical standards for the Italian elderly population have been proposed. Conclusions: Specific BIVA proved to be an accurate technique and a promising tool to assess age-related changes in body composition. Older patients with sarcopenia, sarcopenic obesity, Alzheimer’s disease, and type 2 diabetes were characterized by peculiar bioelectrical patterns, which can be related to their body composition characteristics. The newly proposed bioelectrical standards for the Italian elderly population allow the application of classic and specific BIVA in the geriatric routine.