The agreement between body composition indices measured by dual-energy X-Ray absorptiometry and bioelectrical impedance analysis in adults

Abstract

Background: Accurate assessment of body composition is fundamental for evaluating obesity or bone health. While Dual-energy X-ray absorptiometry (DXA) is a method with high and reliable accuracy for measuring body composition, bioelectrical impedance analysis (BIA) provides a rapid, non-invasive, and more accessible alternative. This study aimed to determine the correlation and agreement between multi-frequency BIA and DXA measurements among healthy Vietnamese adults.

Methods: A cross-sectional study was conducted on 456 adults (222 males, 234 females; mean age 37.0 ± 13.7 years). Body composition parameters including fat mass, body fat percentage, lean body mass, fat-free mass, and bone mineral content were measured using DXA (Hologic Horizon W) and BIA (Tanita MC-980MA PLUS). Bland-Altman plots were used to further assess the agreement between BIA and DXA results.

Results: Compared with DXA, BIA consistently underestimated body fat percentage (-6.19% for whole body, -4.88% for trunk; p < 0.001) and overestimated fat-free mass (+4.26 kg) and lean mass (+3.94 kg; p < 0.001). Correlations between BIA and DXA were strong (r = 0.95-0.97 for lean and fat-free mass; lowest for BMC, r = 0.81). Bland-Altman analyses revealed proportional bias by region - greater discrepancies in trunk and arms, while the legs showed more stable agreement.

Conclusion: Overall, the two methods demonstrated strong correlation but region-specific bias, indicating that agreement between BIA and DXA depends on body site.

Keywords: Bioelectrical impedance analysis; Body composition; Dual-energy X-ray absorptiometry; Validation; Vietnamese adults.