Efficacy of specific bioelectrical impedance vector analysis (BIVA) for assessing body composition in the elderly.

OBJECTIVES: This study aimed to ascertain the efficacy of bioelectrical impedance vector analysis (BIVA) in assessing body composition in the elderly by comparing findings with the results of dual-energy X-ray absorptiometry (DXA), and to test an analytical variant of the method (specific BIVA). DESIGN: Cross-sectional study. PARTICIPANTS: The sample comprised 207 free-living elderly individuals (75 men and 132 women) aged 65 to 93 years. MEASUREMENTS: Anthropometric and bioelectrical measurements were taken according to standard criteria. BIVA was applied using the 'classic' procedure and correcting bioelectrical values for body geometry to obtain an estimate of the whole-body impedivity. DXA was used as a reference body composition assessment method. BIVA (classic and specific values) and DXA findings were compared using Student's t and Hotelling's T2 tests, and Pearson's correlation coefficient. RESULTS: In both sexes, BIVA distinguished between individuals with different amounts of fat and fat-free mass (lean mass including bone mineral content), according to DXA, but not between those with different proportions of fat mass (FM%). Specific bioelectrical values detected changes in body composition. CONCLUSION: BIVA should be used with caution for evaluating body composition in the elderly. Specific bioelectrical values proved effective, showing promise as a methodological variant of BIVA, suitable for identifying age-related changes in body fatness.

Nutritional and psycho-functional status in elderly patients with Alzheimer's disease.

OBJECTIVES: Analysis of variations of nutritional status in relation to psycho-functional conditions in elderly patients with mild to moderate Alzheimer's disease (AD) by means of bioelectrical impedance vector analysis (BIVA). DESIGN: Cross-sectional study. SETTING: Alzheimer Center, SS. Trinità Hospital, Cagliari (Italy). PARTICIPANTS: 83 free-living patients (29 men, 54 women) with mild-moderate Alzheimer's disease, aged 66 to 96 years, and 91 age-matched controls (37 men and 54 women). MEASUREMENTS: Nutritional status was evaluated by anthropometry (weight, height, waist and upper arm circumferences, triceps skinfold; body mass index, BMI; arm muscle area, AMA); Mini Nutritional Assessment, MNA®; bioelectrical impedance vector analysis, BIVA. Psycho-functional status was assessed by the Mini Mental State Examination (MMSE), Geriatric Depression Scale (GDS), Activities of Daily Living (ADL), and Instrumental Activities of Daily Living (IADL). RESULTS: Compared to the control groups, patients with Alzheimer's disease had a worse psycho-functional and nutritional status. BIVA detected lower body cell mass in Alzheimer's patients with respect to controls (men: T²= 23.4; women: T²=27.3; p<0.01), as well as in the female patients with lower levels of IADL and MMSE (respectively, T²= 8.0; T²=7.4; p<0.05). In patients with AD, a worse psycho-functional status was associated with obesity. CONCLUSION: The psycho-functional decline of patients with AD is related to body composition variations, with a relative increase of fat mass with respect to the muscle component. The BIVA technique distinguished patients from controls and patients with different levels of cognitive decline. Therefore, it is a suitable tool for the screening and monitoring of nutritional status in Alzheimer's disease.