Predictive accuracy of bioelectrical impedance equations corrected for fat‐free body size

Abstract

This study examined whether the predictive accuracy of agespecific bioelectrical impedance (BIA) equations was improved when estimated fat-free body (FFR,,,) was corrected for the influence of FFB size on whole body resistance (WBR) and residual errors of prediction for 152 women, ages 20-72 years. The criterion measure of FFB (FFBHU) was obtained from hydrostatic weighing at residual volume (RV). FFB,, was predicted from age-specific equations. Each subject's FFB,,, was then adjusted for the relationship between FFB and residual scores using the Lohman et al. (1990) Sample reference means were 45.0, 45.3, and 38.8 kg, respectively, for women 20-29 years, 3 0 4 9 years, and 50-70 years of age. The predictive accuracy of the unadjusted (FFBBTA) and adjusted (FFR,,) BIA estimates was analyzed for the total sample and each age group. For the total sample, r', standard error of estimate (SEE), and root mean square error (RMSE) were, respectively, 0.82,2.5 kg, and 2.5 kg for FFB,,.Corresponding values for FFB, , were, respectively, 0.81, 2.5 kg, and 2.6 kg. Across age groups, r2s ranged from 0.66-0.88, and the SEES and RMSEs were between 2.0 kg-2.8 kg. The relationship between FFRII, and residual scores (ry,reJ was significant (P < 0.05) for all age groups. The ry,rea for FFBRTA ranged from 0.37-0.41. For FFBAD,, the ry,y,res was higher (0.62-0.75). Thus, the overall predictive accuracy and systematic prediction error of the agespecific BIA equations were not improved by adjusting BIA estimates for the relationship between FFB size and residual scores. ~CI 1992 Wiley-Liss, Inc.Bioelectrical impedance analysis (BIA) is a rapid, non-invasive, and inexpensive field method for evaluating body composition. The BIA method is based on the relationship between whole body resistance (WBR) and the length (height) and volume (V) of the conductor, and assumes that the conductor (human body) is cylindrical (Lohman, 1989). The volume of total body water, or the fatfree body (FFB), is directly proportional to height squared (HT') and the specific resistivity (p) of the conductor, and inversely proportional to WBR, and is given by the following equation: V = (p)HT2/WBR (Nyboer et al., 1943). Segal et al. (1985) demonstrated that the FFB of men and women could be accurately estimated using the resistance index (HT2/WBR) in combination with body weight. Since 1985, many investigations have been undertaken to validate the BIA method for heterogeneous populations varying in age and levels of adiposity.This research has led t.0 the development of age-, gender-, and fat-specific BIA prediction equations (Boileau et al., 1989;Deurenberg et al., 1989Deurenberg et al., , 1990 Segal et al., 1985Segal et al., , 1988. Typically, hydrodensitometry (HD) has been used to derive criterion measures of FFB to develop and cross-validate these equations. The predictive accuracy of the equations is variable with standard errors of estimate (SEE) ranging from 1.97 kg (Gray

Predictive Accuracy of Bioimpedance Method for Assessing Body Composition of Brazilian Menopause Women

“…Now on the present study, due to a less signifi cant difference on the MLG (0.6 kg), this was sub estimated in a signifi cant way this signifi cant may be due to the size of the sample from this study (n=95). The studies by JERKINS et al, (1994) and WILSON et al, (1992) also had a good validation of prediction (EPE=2.1 to 2.4 kg, respectively), results very similar to the ones found on Brazilian women from this present study (EPE=2.1 kg). So, due the little signifi cant difference (EC=0.63 kg) of the MLG estimated by the equation by LOHMAN (1992), it may also be used to estimate the corporeal composition on Brazilian elderly women.…”

“…The equation by LOHMAN (1992) for elderly ones (from 50 to 70 years old) was developed using this module (multi components) estimating the MLG, adjusting for the bones mineral, with a grade acceptable of precision (EPE=3.0 kg on men and 2.8 kg on women). The validation crossed on the equations for elderly ones by LOHMAN (1992) in an additional sample on elderly women, varying among 50 and 70 years old, by JENKINS et al, (1994) and WILSON et al, (1992) resulted in a little difference which are not signifi cant on the MLG (<0.8 kg). Now on the present study, due to a less signifi cant difference on the MLG (0.6 kg), this was sub estimated in a signifi cant way this signifi cant may be due to the size of the sample from this study (n=95).…”

Seasonal and socioeconomic influences on thyroid function among the Yakut (Sakha) of Eastern Siberia

“…Changes in fat mass were measured using a Tanita digital bioelectrical impedance analysis (BIA) scale. A limitation of this method is that the predictive equations produce greater error when the reference population from which they were derived is more homogenous than the sample population (Wilson et al, ). Currently the Tanita BIA equations and reference population information are unpublished.…”

Predictive accuracy of bioelectrical impedance equations for women

“…In addition, these equations have been tested on independent samples of women (Gray et al, 1989;Jackson et al, 1988;Wilson et al, 1992). However, the equations of Durenberg et al (1990), Gray et al (1989), and Van Loan and Mayclin (1987) were not cross-validated in the original studies.…”