Laboratory of Experimental Medicine and Paediatrics, University of Antwerp, Universiteitsplein 1, Wilrijk, Belgium.
Department of Paediatrics, University Hospital of Antwerp, Wilrijkstraat 10, Edegem, Belgium.
Eur J Clin Nutr. 2021 Jan;75(1):73-84. doi: 10.1038/s41430-020-00738-9. Epub 2020 Sep 11.
Obesity and age influence the reliability of dual energy X-ray absorptiometry scanning (DEXA) and bioimpedance spectroscopy (BIS). Both are used in clinical settings, but have not been compared for measurements in obese children. We compared DEXA and BIS for evaluating body composition and inherent changes in obese children before and after a 10-month weight loss programme.
DEXA and BIS were used to evaluate 130 patients at baseline and 75 at follow-up. We tested agreement between the two techniques using Bland-Altman plots and proportional bias using Passing-Bablok regressions.
The Bland-Altman plots showed wide agreement limits before and after weight loss and when monitoring longitudinal changes. At baseline, the Passing-Bablok regressions revealed a proportional bias for all body compartments. After significant weight loss no proportional bias was found for fat mass and percentage, although BIS systematically underestimated fat mass by 2.9 kg. Longitudinally, no proportional bias was found in the measured changes of absolute fat, fat-free mass and fat-free percentage between both methods, although BIS systematically underestimated fat and fat-free mass by 2.6 and 0.7 kg, respectively.
While BIS and DEXA are not interchangeable at baseline, the agreement between the two improved after significant weight loss. Proportional changes in fat mass, fat-free mass and fat-free percentage were similar for both techniques. BIS is a viable alternative to DEXA for future paediatric obesity studies measuring treatment effect at group levels, but is not superior to DEXA and cannot be used for monitoring individual changes due to wide limits of agreement.
肥胖和年龄会影响双能 X 射线吸收法扫描（DEXA）和生物阻抗谱（BIS）的可靠性。这两种方法都在临床环境中使用，但尚未在肥胖儿童中比较其测量结果。我们比较了 DEXA 和 BIS 在肥胖儿童减肥 10 个月前后评估身体成分和固有变化的效果。
DEXA 和 BIS 分别在基线时和随访时评估了 130 例患者和 75 例患者。我们使用 Bland-Altman 图和 Passing-Bablok 回归的比例偏差来测试两种技术之间的一致性。
Bland-Altman 图显示，在减肥前后和监测纵向变化时，一致性界限较宽。在基线时，Passing-Bablok 回归显示所有身体部位都存在比例偏差。在显著减肥后，虽然 BIS 系统地低估了脂肪量 2.9kg，但未发现脂肪量和脂肪百分比存在比例偏差。纵向来看，两种方法之间绝对脂肪、去脂体重和去脂百分比的测量变化均未发现比例偏差，尽管 BIS 系统地低估了脂肪和去脂体重分别为 2.6kg 和 0.7kg。
虽然 BIS 和 DEXA 在基线时不能互换，但在显著减肥后两者的一致性有所提高。脂肪量、去脂体重和去脂百分比的比例变化在两种技术中相似。BIS 是未来儿童肥胖研究测量组水平治疗效果的一种可行替代方法，但由于一致性界限较宽，不能优于 DEXA，也不能用于监测个体变化。
