The Association Between Health-Related Quality of Life and Bioelectrical Impedance-Derived Phase Angle in...

Background and objective The phase angle (PhA) obtained using bioelectrical impedance analysis is a highly reliable indicator that reflects the quality of skeletal muscle, as it is calculated directly from reactance and resistance when an electric current is applied and does not use an estimation formula. Although PhA is a useful indicator of nutritional status and prognosis, its relationship with health-related quality of life (HRQoL) in older adults from the general population has not been fully investigated. In this study, we aimed to assess the relationship between HRQoL and PhA in community-dwelling older adults to determine whether PhA is a useful indicator of decreased HRQoL. Methods The study included 162 older adults (114 women; average age: 77.8 ± 5.5 years) who were independent in their daily activities and did not have serious musculoskeletal or internal disorders. The EuroQol 5-Dimension 5-Level (EQ-5D-5L) was used to evaluate HRQoL, and PhA was measured using a body composition analyzer (MC-780A-N; TANITA Corporation, Tokyo, Japan), with the left and right values averaged. In addition, we evaluated sex, BMI, appendicular skeletal muscle mass (ASM), skeletal muscle index, and physical function (grip strength, walking speed, knee extension strength, and five-times sit-to-stand test). We examined the relationship between PhA and each evaluation item using Spearman's rank correlation test, with HRQoL as the objective variable, using multiple regression analysis. Results The Spearman rank correlation test showed a significant correlation between HRQoL and PhA (ρ=0.2550), as well as with ASM, grip strength, and knee extension strength (ρ=0.1580, 0.1610, and 0.1670, respectively). In the multiple regression analysis, PhA was a significant independent factor explaining HRQoL (t=2.8097, p=0.0056); however, no association was found with the other evaluation items. Conclusions Based on our findings, PhA is an independent factor associated with HRQoL in community-dwelling older adults. Hence, PhA may be a useful indicator of the risk of decreased HRQoL. Compared with other physical function and muscle strength indicators, PhA may serve as a more useful complementary evaluation tool in maintaining health and improving HRQoL in older adults.