Relationship between nutritional status and phase angle as a noninvasive method to predict malnutrition by sex in older inpatients

Phase angle has been suggested as a useful, noninvasive, and objective index to evaluate the nutritional status of older people. However, there are no studies analyzing the relationship between nutritional status and phase angle in older patients, according to sex. The aim of this study was to clarify the relationship between phase angle and malnutrition, and to calculate cut-off points of malnutrition with phase angle in older inpatients, according to sex. This study was a retrospective cross-sectional study. Participants were older inpatients of a rehabilitation unit, and data within 1 week of hospitalization were collected from the medical records. We collected data of demographics, phase angle, and the Geriatric Nutritional Risk Index. Phase angle was measured with InBody S10. To confirm whether phase angle is an important factor in predicting malnutrition, we conducted binary logistic regression analysis. In addition, to determine the cut-off points of malnutrition in older inpatients, we used the receiver operator characteristic (ROC) curve. Participants included 59 men (mean age 76.5 years) and 101 women (mean age 78.8 years). As a result of statistical analysis, phase angle was an important factor related to malnutrition in both male and female inpatients. Our findings showed that cut-off points of 4.03 degrees (sensitivity; 87.0%, specificity; 75.9%) in male patients and 3.65 degrees (sensitivity; 78.6%, specificity; 60.5%) in female patients could be used to predict malnutrition. The results of this study suggest that phase angle may be useful as an indicator to predict the nutritional status of older inpatients.