Validation of measurement of body composition by dual-energy X-ray absorptiometry and bioelectrical impedance analysis and body composition's profiling in Tibetan's adults

Abstract

Objective: We aimed to validate in-body bioelectrical impedance analysis (BIA) measures with dual-energy X-ray absorptiometry (DXA) as reference and describe the body composition (BC) profiling of Tibetan adults.

Design: This cross-sectional study included 855 participants (391 men and 464 women). Correlation and Bland-Altman analyses were performed for method agreement of in-body BIA and DXA. BC were described by obesity and metabolic status.

Setting: In-body BIA and DXA have not been employed to characterise the BC of the Tibetan population living in the Qinghai-Tibet Plateau.

Participants: A total of 855 Tibetan adults, including 391 men and 464 women, were enrolled in the study.

Results: Concordance correlation coefficient for total fat mass (FM) and total lean mass (LM) between in-body BIA and DXA were 0·91 and 0·89. The bias of in-body BIA for percentages of total FM and total LM was 0·91 % (2·46 %) and -1·74 % (-2·80 %) compared with DXA, respectively. Absolute limits of agreement were wider for total FM in obese men and women and for total LM in overweight men than their counterparts. Gradience in the distribution of total and regional FM content was observed across different BMI categories and its combinations with waist circumference and metabolic status.

Conclusions: In-body BIA and DXA provided overall good agreement at the group level in Tibetan adults, but the agreement was inferior in participants being overweight or obese.

Keywords: Bioelectrical impedance; Body composition; DXA; Tibetan; Validation.

Fig. 1

Bland–Altman plots for the comparison of total fat mass and total lean mass measured by dual-energy X-ray absorptiometry (DXA) and bioelectrical impedance analysis (in-body BIA) in Tibetan adults across BMI and sex. Values were obtained from 855 participants. Correlation coefficients derived from Spearman’s correlation. Individuals from different age groups, 18–44, 45–59 and ≥60 y, were represented by red, green and blue points, respectively.

Fig. 2

Density plots for body fat mass and lean body mass in Tibetan adults stratified by sex and BMI. Values were obtained by dual-energy X-ray absorptiometry (DXA) from 855 participants. Kruskal–Wallis H test was performed to compare variables across BMI groups.

Fig. 3

Body fat profiling of Tibetan adults based on sex, BMI categories and metabolic health conditions. Median percentages of fat in total and seven body regions were obtained by dual-energy X-ray absorptiometry (DXA) from 855 participants. Central obesity was defined as waist circumference ≥90 cm for men or ≥80 cm for women. Metabolic syndrome was defined if ≥3 criteria were fulfilled: (1) central obesity; (2) fasting plasma glucose ≥ 5·6 mmol/l or on medication for high blood glucose; (3) systolic blood pressure ≥130 mmHg or diastolic blood pressure ≥85 mmHg or on antihypertensive medication; (4) HDL cholesterol (HDL-C) <1·03 mmol/l for men and <1·30 mmol/l for women or on medication for reduced HDL-C; (5) TAG ≥ 1·7 mmol/l or on medication for elevated TAG. Independent t-test or Mann–Whitney U test was used for comparison between subjects with and without central obesity or metabolic syndrome. CO, central obesity; MetS, metabolic syndrome.