Bioelectrical Impedance Vector Analysis and Mini Nutritional Assessment in elderly nursing home residents.

OBJECTIVE: The aim of this study was to establish the presence of malnutrition in elderly institutionalized people through Mini Nutritional Assessment (MNA) scores and to observe the changes of nutritional status through the Bioelectrical Impedance Vector Analysis (BIVA).

DESIGN: Observational study.

SETTING: Nursing home located in the territory of Florence (Italy).

PARTICIPANTS: 463 elderly individuals from twelve nursing homes, all aged 65 yrs or over.

MEASUREMENTS: We carried out the MNA and measured the bioelectrical parameters of resistance (R) and reactance (Xc), with standard, tetrapolar analysis at 50 kHz frequency; these bioelectrical parameters were interpreted according to BIVA analysis.

RESULTS: According to the MNA score, 23.1% of the women and 20.4% of the males are malnourished (MNA < 17), 60.0% and 52.8%, respectively, are at risk for malnutrition (17 ≤ MNA ≤ 23.5). Malnourished, at-risk and well-fed subjects differ significantly (p < 0.05) in their mean scores obtained in each of the MNA areas. Fifteen of eighteen MNA items show a significant correlation to the total MNA score (p < 0.001). The items not significantly related to the MNA global score were those concerning protein intake, independence and number of medicinal drugs taken. In both genders, the decrease of the MNA score increases the proportion of subjects placed outside the 95% confidence ellipse on the BIVA tolerance graph.

CONCLUSION: A routine assessment of nutritional status through BIVA analysis combined with more "traditional" tools like the MNA could be useful for recognizing malnutrition and the risk of malnutrition in the elderly as these instruments provide complete information and are easy to use even with heavily impaired subjects.