Bioelectrical impedance may stand in for DXA in kids

While dual X-ray absorptiometry (DXA) remains the gold standard, bioelectrical impedance analysis (BIA) nevertheless gives reliable measurements of body composition among children, a recent study has found.

A total of 124 healthy children (mean age, 10±1 years; 58 boys) participated in the study and underwent body analysis using BIA, DXA, and quantitative ultrasound (QUS). Mean fat mass (FM), as measured by BIA and DXA, was 9.5±5.1 kg and 10.8±4.3 kg, respectively.

Lin’s concordance correlation coefficient (CCC) analysis found that BIA and DXA had nearly perfect concordance in terms of FM measurement, yielding a coefficient of 0.92. A similar, slightly stronger interaction was reported for fat-free mass (FFM), with respective mean measurements of 32.0±6.4 and 30.7±6.8 kg (CCC, 0.96).

The two body analysis techniques also showed substantial agreement in terms of the percentage of FM. BIA returned a value of 22.0±7.6 kg, while DXA measured 25.6±5.8 kg; the resulting CCC was 0.75. Stratifying participants according to sex did not meaningfully alter or weaken any of the above correlations.

QUS also agreed relatively well with DXA for the measurement of bone mineral density and content at the lumbar spine and for the total body less head. The correlation coefficient values ranged from 0.18–0.30. When considering QUS stiffness index instead, correlation coefficients improved, ranging from 0.30–0.45.

“Although BIA overestimates FFM as compared with DXA, BIA is an effective, portable, safe, and economically feasible alternative method for investigating body composition among children especially in large cohort field studies with a population that is similar to this study sample,” the researchers said.