Comparison of Phase Angle Using Bioelectrical Impedance Analysis According to Device Type and Examination Posture

Background: Bioelectrical impedance analysis (BIA) is gaining popularity as a body composition assessment tool for patients. Although it has been studied and validated in different populations, age groups, and clinical settings, including critically ill patients, there are concerns about BIA reproducibility and reliability in different device types and postures. This study aimed to evaluate the reliability of BIA according to different devices, postures, and lead types. Methods: Cross-sectional observational data of 74 healthy volunteers (32 women and 42 men) were collected. We used two types of devices, three types of postures (standing, sitting, and lying), and two lead types (clamp lead and adhesive lead) to measure the whole-body phase angle (phA) at a single frequency of 50 kHz. The measurements were validated using the intraclass correlation coefficient (ICC) and Bland-Altman plot analysis. Results: All phA measurements recorded with two types of devices, three different postures, and two types of leads were equivalent to each other (mean ICC = 0.9932, 95% confidence interval (CI) 0.9905-0.0053). The average mean difference in phA was 0.31 (95% CI 0.16-0.46). The largest phA value was measured using BWA with an adhesive-type lead in the lying position. There were no differences between standing and sitting positions. Conclusion: This is the first study to show the consistency and reliability of BIA in measuring phA using different devices, lead types, and postures. This could provide the confidence that BIA can be used in various clinical settings.