[Assessing nutritional status of severe malnutrition patients by bioelectrical impedance technique: a multicenter prospective study].

OBJECTIVE

To assess the nutritional status of severe malnutrition patients with anorexia nervosa by multi-frequency bioelectrical impedance technique, and to provide the basis for nutritional support therapy.

METHODS

A prospective study was conducted. Twenty-six severe malnutrition patients with anorexia nervosa, body mass index (BMI) ≤ 16 kg/m admitted to intensive care unit (ICU) of Peking University Third Hospital and general three ward of Peking University Sixth Hospital from June 1st to September 30th, 2017 were enrolled. The extracellular water (ECW), intracellular water (ICW), ECW/ICW ratio, adipose tissue mass (ATM), lean tissue mass (LTM), total body water/body weight (TBW/WT), ATM/WT, and LTM/WT were measured by multi-frequency bioelectrical impedance meter. Thirty-eighty healthy volunteers with normal nutritional status (23.0 kg/m > BMI > 18.5 kg/m) matched by gender and height were enrolled as healthy control group. The predictive value of main body composition for nutritional status were analyzed by receiver operating characteristic (ROC) curve.

RESULTS

All the patients were female. There was no significant difference in height between two groups, but WT and BMI in the severe malnutrition group were significantly higher than those in the healthy control group [WT (kg): 38.1±4.9 vs. 54.2±3.3, BMI (kg/m): 13.6±2.5 vs. 21.2±1.1, both P < 0.01]. Compared with the healthy control group, the ECW, ICW, ATM, LTM, ATM/WT and LTM/WT were significantly decreased in the severe malnutrition group [ECW (L): 9.02±0.42 vs. 10.19±0.77, ICW (L): 12.6±0.9 vs.19.1±1.3, ATM (kg): 9.3±1.1 vs. 16.6±1.9, LTM (kg): 16.5±1.5 vs. 26.1±1.7, ATM/WT: 0.26±0.02 vs. 0.30±0.02, LTM/WT: 0.22±0.02 vs. 0.26±0.01, all P < 0.01], the ECW/ICW and TBW/WT were significantly increased in the severe malnutrition group (ECW/ICW: 0.72±0.06 vs. 0.54±0.06, TBW/WT: 0.58±0.02 vs. 0.52±0.02, both P < 0.01). It was shown by ROC curve analysis that the area under ROC curve (AUC) of TBW/WT, ATM/WT, LTM/WT for evaluating severe malnutrition were 0.999, 0.919, 0.954 respectively; when the cut-off of TBW/WT, ATM/WT, LTM/WT were 0.58, 0.28, 0.24 respectively, the sensitivity were 100%, 85%, 80% respectively, and the specificity were 95%, 80%, 91% respectively.

CONCLUSIONS

Main body composition of severe malnutrition patients with anorexia nervosa changed significantly. Bioelectrical impedance technology can be an effective assessment tool for the nutritional status of such patients.