van Beijsterveldt Inge A L P, Beunders Victoria A A, Bijlsma Alja, Vermeulen Marijn J, Joosten Koen F M, Hokken-Koelega Anita C S
Department of Pediatrics, Subdivision of Endocrinology, Erasmus Medical Center-Sophia Children's Hospital, 3015 CN Rotterdam, The Netherlands.
Department of Pediatrics, Division of Neonatology, Erasmus Medical Center-Sophia Children's Hospital, 3015 CN Rotterdam, The Netherlands.
J Clin Med. 2022 Mar 14;11(6):1604. doi: 10.3390/jcm11061604.
It is important to monitor body composition longitudinally, especially in children with atypical body composition trajectories. Dual-energy X-ray absorptiometry (DXA) can be used and reference values are available. Air-displacement plethysmography (ADP) is a relatively new technique, but reference values are lacking. In addition, estimates of fat-free mass density (Dffm), needed in ADP calculations, are based on children aged >8 years and may not be valid for younger children. We, therefore, aimed to investigate whether DXA and ADP results were comparable in young children aged 3−5 years, either born full-term or preterm, and if Dffm estimates in the ADP algorithm could be improved. In 154 healthy children born full-term and 67 born < 30 weeks of the inverse pressure-volume gestation, aged 3−5 years, body composition was measured using ADP (BODPOD, with default Lohman Dffm estimates) and DXA (Lunar Prodigy). We compared fat mass (FM), fat mass percentage (FM%) and fat-free mass (FFM), between ADP and DXA using Bland−Altman analyses, in both groups. Using a 3-compartment model as reference method, we revised the Dffm estimates for ADP. In full-term-born children, Bland−Altman analyses showed considerable fixed and proportional bias for FM, FM%, and FFM. After revising the Dffm estimates, agreement between ADP and DXA improved, with mean differences (LoA) for FM, FM%, and FFM of −0.67 kg (−2.38; 1.04), −3.54% (−13.44; 6.36), and 0.5 kg (−1.30; 2.30), respectively, but a small fixed and proportional bias remained. The differences between ADP and DXA were larger in preterm-born children, even after revising Dffm estimates. So, despite revised and improved sex and age-specific Dffm estimates, results of ADP and DXA remained not comparable and should not be used interchangeably in the longitudinal assessment of body composition in children aged 3−5 years, and especially not in very preterm-born children of that age.
纵向监测身体成分很重要，尤其是对于身体成分轨迹异常的儿童。可以使用双能X线吸收法（DXA），并且有参考值可用。空气置换体积描记法（ADP）是一种相对较新的技术，但缺乏参考值。此外，ADP计算中所需的去脂体重密度（Dffm）估计值是基于8岁以上儿童的，可能不适用于年幼儿童。因此，我们旨在研究DXA和ADP结果在3至5岁的足月或早产幼儿中是否具有可比性，以及ADP算法中的Dffm估计值是否可以改进。对154名足月出生的健康儿童和67名孕龄小于30周的早产儿进行了研究，这些儿童年龄在3至5岁，使用ADP（BODPOD，采用默认的Lohman Dffm估计值）和DXA（Lunar Prodigy）测量身体成分。我们在两组中使用Bland-Altman分析比较了ADP和DXA之间的脂肪量（FM）、脂肪量百分比（FM%）和去脂体重（FFM）。使用三室模型作为参考方法，我们修订了ADP的Dffm估计值。在足月出生的儿童中，Bland-Altman分析显示FM、FM%和FFM存在相当大的固定偏差和比例偏差。修订Dffm估计值后，ADP和DXA之间的一致性有所改善，FM、FM%和FFM的平均差异（一致性界限）分别为-0.67 kg（-2.38；1.04）、-3.54%（-13.44；6.36）和0.5 kg（-1.30；2.30），但仍存在较小的固定偏差和比例偏差。即使修订了Dffm估计值，早产儿童中ADP和DXA之间的差异仍然较大。因此，尽管修订并改进了按性别和年龄的Dffm估计值，但ADP和DXA的结果仍然不可比，在3至5岁儿童身体成分的纵向评估中不应互换使用，尤其是在该年龄段的极早产儿童中。
