Hudda M T, Nightingale C M, Donin A S, Fewtrell M S, Haroun D, Lum S, Williams J E, Owen C G, Rudnicka A R, Wells J C K, Cook D G, Whincup P H
Population Health Research Institute, St George's, University of London, London, UK.
Childhood Nutrition Research Centre, Population, Policy and Practice Programme, UCL Great Ormond Street Institute of Child Health, London, UK.
Int J Obes (Lond). 2017 Jul;41(7):1048-1055. doi: 10.1038/ijo.2017.75. Epub 2017 Mar 22.
BACKGROUND/OBJECTIVES: Body mass index (BMI) (weight per height) is the most widely used marker of childhood obesity and total body fatness (BF). However, its validity is limited, especially in children of South Asian and Black African origins. We aimed to quantify BMI adjustments needed for UK children of Black African and South Asian origins so that adjusted BMI related to BF in the same way as for White European children.
We used data from four recent UK studies that made deuterium dilution BF measurements in UK children of White European, South Asian and Black African origins. A height-standardized fat mass index (FMI) was derived to represent BF. Linear regression models were then fitted, separately for boys and girls, to quantify ethnic differences in BMI-FMI relationships and to provide ethnic-specific BMI adjustments.
We restricted analyses to 4-12 year olds, to whom a single consistent FMI (fat mass per height) could be applied. BMI consistently underestimated BF in South Asians, requiring positive BMI adjustments of +1.12 kg m (95% confidence interval (CI): 0.83, 1.41 kg m; P<0.0001) for boys and +1.07 kg m (95% CI: 0.74, 1.39 kg m; P<0.0001) for girls of all age groups and FMI levels. BMI overestimated BF in Black Africans, requiring negative BMI adjustments for Black African children. However, these were complex because there were statistically significant interactions between Black African ethnicity and FMI (P=0.004 boys; P=0.003 girls) and also between FMI and age group (P<0.0001 for boys and girls). BMI adjustments therefore varied by age group and FMI level (and indirectly BMI); the largest adjustments were in younger children with higher unadjusted BMI and the smallest in older children with lower unadjusted BMI.
BMI underestimated BF in South Asians and overestimated BF in Black Africans. Ethnic-specific adjustments, increasing BMI in South Asians and reducing BMI in Black Africans, can improve the accuracy of BF assessment in these children.
背景/目的：体重指数（BMI）（体重除以身高）是儿童肥胖和总体脂肪量（BF）最常用的指标。然而，其有效性有限，尤其是在南亚和非洲裔黑人儿童中。我们旨在量化英国非洲裔和南亚裔儿童所需的BMI调整值，以便调整后的BMI与欧洲裔白人儿童的BMI与BF的关系相同。
我们使用了英国最近四项研究的数据，这些研究对欧洲裔白人、南亚裔和非洲裔黑人儿童进行了氘稀释法BF测量。得出了一个身高标准化的脂肪量指数（FMI）来代表BF。然后分别对男孩和女孩拟合线性回归模型，以量化BMI-FMI关系中的种族差异，并提供特定种族的BMI调整值。
我们将分析限制在4至12岁的儿童，对他们可以应用单一一致的FMI（每身高的脂肪量）。BMI一直低估了南亚人的BF，所有年龄组和FMI水平的男孩需要将BMI正向调整+1.12kg/m²（95%置信区间（CI）：0.83，1.41kg/m²；P<0.0001），女孩需要将BMI正向调整+1.07kg/m²（95%CI：0.74，1.39kg/m²；P<0.0001）。BMI高估了非洲裔黑人的BF，非洲裔黑人儿童需要进行负向BMI调整。然而，这些调整很复杂，因为非洲裔黑人种族与FMI之间存在统计学上的显著交互作用（男孩P=0.004；女孩P=0.003），FMI与年龄组之间也存在交互作用（男孩和女孩P<0.0001）。因此，BMI调整因年龄组和FMI水平（以及间接的BMI）而异；调整最大的是未调整BMI较高的年幼儿童，最小的是未调整BMI较低的年长儿童。
BMI低估了南亚人的BF，高估了非洲裔黑人的BF。特定种族的调整，增加南亚人的BMI并降低非洲裔黑人的BMI，可以提高这些儿童BF评估的准确性。
