Phase Angle From Bioelectrical Impedance Analysis: Population Reference Values by Age, Sex, and Body Mass Index

Abstract

The determinants of phase angle differ between adults and children. In adults, the influence of BMI on phase angle depended on the BMI range. The prognostic value of phase angle may differ in different clinical settings. The use of population-specific and probably impedance-analyzer-specific reference values for phase angle is recommended.

Bioelectrical impedance vector analysis, phase-angle assessment and relationship with malnutrition risk in a cohort of frail older hospital patients in the United Kingdom

“…In aging, PA reduces due to the characteristic drop in the xC component. The mean PA values were lower here (Table 1 and Supplementary Table 1) than reference values for healthy white Swiss adults [21] (men ≥70 y, BMI 18.5-50 kg/m2, mean PA range 5.03°-5.50°; and women, ≥70 y, mean PA range 5.07°-5.27°); and lower than values for healthy white Italian men, 70 to 80 y (BMI 18.5 to ≥30 kg/m2, PA 5.8°-6.0°) [22]. In an American population of healthy adults, reference PA values for those ≥70 y were 6.19° ± 0.97° for men (BMI 25.6 ± 4.2 kg/m2), and 5.64° ± 1.02° for women (BMI 26 ± 6.4 kg/m2) [23].…”

“…A PA region of ∼5°-7° was chosen as a suitable range that is potentially linked to better health and lower risk for poor outcomes in this age range (e.g., nutritional risk, poor functional status, mortality, etc.). Region was selected based on previous data [14], [18], [19], [20], [21], [22] and [23]. Very high PA for older persons (e.g., 7°-10°) also may indicate abnormalities and poor outcomes [20].…”

“…The study groups were also categorized by BMI (18.5-24.9, 25-29.9, and ≥30 kg/m2, with two men omitted due to BMI <18.5) for patients ≥70 y (3 men and 1 women ages 60-69 y were omitted). These categories were chosen based on previous studies that have performed similar categorization (e.g., large studies have used the ≥70 age as a cut point [21] and [23]). BIVA showed a significant difference in two of the female groups (BMI 18.5-24.9 versus 25-29.9 kg/m2 and 18.5-24.9 versus ≥30 kg/m2; supplementary Table 1 and Fig.…”

“…In an American population of healthy adults, reference PA values for those ≥70 y were 6.19° ± 0.97° for men (BMI 25.6 ± 4.2 kg/m2), and 5.64° ± 1.02° for women (BMI 26 ± 6.4 kg/m2) [23]. It should be noted that the variation between PA reference measurements might be potentially due to differences in individual population groups and BIA analyzer differences [21], [22] and [23]. The mean/median PA values were lower in this study, which also might indicate the effects of disease and frailty ( [28].…”

Phase angle and World Health Organization criteria for the assessment of nutritional status in children with osteogenesis imperfecta

“…, 4 The PA is the arctangent of resistance and reactance ratio (Xc/R), that is, it derived from the bioelectrical impedance evaluation with the use of direct measurements of the components of the R and Xc vector; when used as nutritional status indicator and body cell mass (BCM), it considerably eliminates the errors of analysis by bioelectrical impedance 5. Its use has been recommended as an indicator of prognosis in clinical practice.…”