USDA/Agricultural Research Service Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX, USA.
Am J Clin Nutr. 2020 Sep 1;112(3):566-575. doi: 10.1093/ajcn/nqaa128.
Fat-free mass index (FFMI) and fat mass index (FMI) are superior to BMI and fat percentage in evaluating nutritional status. However, existing references fail to account for racial/ethnic differences in body composition among children.
Our goal was to produce age-based normative references for FFMI and FMI in children for specific racial/ethnic groups.
Body composition, weight, and height were measured in 1122 normal healthy children aged 2-21 y. Bone mineral content measured by DXA, total body water by deuterium dilution, and total body potassium by whole-body γ counting were combined to calculate fat-free mass (FFM) and fat mass (FM) using equations based on the Reference Child and Adolescent models. FFMI and FMI were calculated by dividing FFM and FM by height squared, respectively. After outlier removal, the LMS (Lambda-Mu-Sigma) function within R's GAMLSS package was used to produce age-based FFMI and FMI growth curves for black (B), white (W), and Hispanic (H) children for each sex. Combined models were produced in cases where outcomes did not differ by race/ethnicity. Resulting models were compared with previously published FFMI and FMI models.
FFMI and FMI models based on 1079 children, aged 2-21 y, were created for both sexes. FFMI models for B children showed higher values throughout. W and H children were combined to produce FFMI models for each sex. H boys were modeled individually for FMI, whereas W and B boys were combined. FMI models for girls were created for each race/ethnicity. Models agreed well with those based on children from the United Kingdom of comparable race/ethnicity.
Race/ethnicity-specific references for FFMI and FMI will increase the accuracy of health and nutrition status assessment in children over race/ethnicity-generic references. The models allow the calculation of SD scores to assess health and nutrition status in children.
与 BMI 和体脂百分比相比，去脂体重指数（FFMI）和脂肪量指数（FMI）更能评估营养状况。然而，现有的参考资料并未考虑到儿童身体成分的种族/民族差异。
我们的目标是为特定种族/民族的儿童生成基于年龄的 FFMI 和 FMI 正常参考值。
对 1122 名 2-21 岁的正常健康儿童进行身体成分、体重和身高测量。使用基于参考儿童和青少年模型的方程，通过 DXA 测量骨矿物质含量、用氘稀释法测量全身水、用全身γ计数法测量全身钾，将其结合起来计算去脂体重（FFM）和脂肪量（FM）。FFMI 和 FMI 分别通过将 FFM 和 FM 除以身高的平方来计算。去除异常值后，使用 R 中的 GAMLSS 包中的 LMS（Lambda-Mu-Sigma）函数为每个性别生成基于年龄的 FFMI 和 FMI 生长曲线。在结果不因种族/民族而异的情况下，生成综合模型。将得出的模型与以前发表的 FFMI 和 FMI 模型进行比较。
为男女分别创建了基于 1079 名 2-21 岁儿童的 FFMI 和 FMI 模型。B 组儿童的 FFMI 模型显示出更高的值。W 和 H 组儿童的 FFMI 模型进行了合并。H 组男孩的 FMI 模型单独建模，而 W 和 B 组男孩的 FMI 模型则进行了合并。为每个种族/民族创建了女孩的 FMI 模型。模型与来自英国具有类似种族/民族的儿童的模型吻合良好。
基于特定种族/民族的 FFMI 和 FMI 参考值将提高基于种族/民族通用参考值的儿童健康和营养状况评估的准确性。这些模型允许计算 SD 分数以评估儿童的健康和营养状况。
