Bioelectrical impedance analysis and age-related differences of body composition in the elderly

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

“…However, after correction for body size and circumferences, there was no longer any significant effect of age on R; however, the downward reduction in xC remained. Data from this study shows in particular that the group of frail older hospitalized patients have significantly reduced mean xC/H values (e.g., Table 1, ∼24-26 ohm/m for the groups), compared with ∼28 to 35 previously observed [22], although note the individual differences in groups in Supplementary Table 1.…”

“…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].…”

“…A relative decrease in the xC/H component is understood to indicate a decrease in soft tissue mass/BCM, whereas a change in the R/H component indicates alterations in hydration status [14], [15] and [16]. Data from healthy white men, ages 50 to 80 y, and a BMI range from normal weight to obese [22] showed a relative reduction in xC/H and increase in R/H in aging, indicating reductions in BCM and fat-free mass (FFM). An increase in the R/H component indicates a reduction in hydration status and was also found in groups of healthy older people in an earlier study [26].…”

“…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].…”