Addo O Yaw, Himes John H, Zemel Babette S
Emory University Rollins School of Public Health and Global Health Institute, Atlanta, GA;
University of Minnesota, School of Public Health, Minneapolis, MN; and.
Am J Clin Nutr. 2017 Jan;105(1):111-120. doi: 10.3945/ajcn.116.142190. Epub 2016 Nov 2.
Midupper arm circumference (MUAC) has long been used in anthropometric assessments of nutritional status in field settings, especially in emergency situations, but percentile ranges for healthy, well-nourished children are currently unavailable.
We developed reference curves for MUAC and derived measures of arm muscle area (AMA) and arm fat area (AFA) on the basis of the population used in the current CDC body mass index growth charts.
We analyzed cross-sectional MUAC and triceps (triceps skinfold thickness) data from 32,952 US children aged 1-20 y. Generalized additive models for location, scale, and shape were used to calculate semiparametric smoothed percentiles and L, M, and S coefficients needed for z-score estimation by age and sex. Equations were developed with the use of the height-for-age z score (HAZ) to adjust for the associations of stature with upper arm measures.
MUAC increased with age steadily throughout the growing period. For children <5 y old, lower percentile ranges varied markedly across age and sex such that the single cutoff (<11.5 or 12.5 cm) for field screening of acute malnutrition did not track along the same percentile. AFA and AMA growth patterns exhibited sex-specific trends including multiple distinct age-related inflections that were more pronounced in males for AFA-for-age than in females. HAZ and age were substantially and independently related with all arm measures.
The new reference percentile ranges for midupper arm measures for healthy children provide a useful nutritional assessment tool in a wide variety of settings. Height status (HAZ) has complex independent associations with arm measures irrespective of the distributional ranking by age and sex. Prediction equations that account for these effects further extend the practical use of the new curves.
上臂中部周长（MUAC）长期以来一直用于现场环境中营养状况的人体测量评估，尤其是在紧急情况下，但目前尚无健康、营养良好儿童的百分位数范围。
我们基于美国疾病控制与预防中心（CDC）当前体重指数生长图表所使用的人群，制定了MUAC参考曲线，并得出了手臂肌肉面积（AMA）和手臂脂肪面积（AFA）的推导测量值。
我们分析了32952名1至20岁美国儿童的横断面MUAC和三头肌（三头肌皮褶厚度）数据。使用位置、尺度和形状的广义相加模型来计算年龄和性别的z分数估计所需的半参数平滑百分位数以及L、M和S系数。通过使用年龄别身高z分数（HAZ）来调整身高与上臂测量值之间的关联，从而建立方程。
在整个生长期间，MUAC随年龄稳步增加。对于5岁以下儿童，较低的百分位数范围在年龄和性别上差异显著，以至于用于急性营养不良现场筛查的单一临界值（<11.5或12.5厘米）并未沿着相同的百分位数分布。AFA和AMA的生长模式呈现出性别特异性趋势，包括多个不同的年龄相关拐点，其中AFA年龄别在男性中比在女性中更为明显。HAZ和年龄与所有上臂测量值均存在显著且独立的关联。
健康儿童上臂中部测量值的新参考百分位数范围在各种环境中提供了一种有用的营养评估工具。身高状况（HAZ）与上臂测量值存在复杂的独立关联，而与年龄和性别的分布排名无关。考虑到这些影响的预测方程进一步扩展了新曲线的实际应用。
