Low Bioelectrical Impedance Phase Angle Is a Significant Risk Factor for Frailty

The phase angle, which is measured via bioelectrical impedance analysis (BIA), is a clinically important bioimpedance parameter used for nutritional assessment and evaluating the risk of various diseases, such as locomotive syndrome (LS). It remains unclear if the phase angle is associated with frailty (fragile state of physical and mental health). We therefore examined this association in a large prospective sample. Of 1081 individuals receiving health checkups, 550 (male; 235, female; 365) were enrolled in this study. We applied the Japanese version of the Cardiovascular Health Study criteria to evaluate frailty and administered the 25-Item Geriatric Locomotive Function Scale to diagnose LS. The phase angle was measured via BIA. Multiple logistic regression analysis was used to evaluate the relationship between the phase angle and frailty. For all participants and for each sex, the phase angle was significantly lower among individuals with frailty. After controlling for age, sex, and body mass index, we found that a low phase angle was a significant risk factor of frailty. As a result of multiple regression analysis including other confounding factors, among male participants, a low phase angle was significantly related with both frailty (P = 0.015) and LS (P < 0.001), whereas among female participants, the low phase angle had a stronger association with frailty (P = 0.001) than with LS (P = 0.52). Our findings suggest that a low angle is a risk factor of frailty. Furthermore, among female participants, frailty has a stronger relation with the phase angle than does LS. Therefore, the phase angle may be considered a useful indicator of frailty that does not require lengthy or costly assessment.