Characterizing extreme values of body mass index-for-age by using the 2000 Centers for Disease Control and Prevention growth charts
Characterizing extreme values of body mass index-for-age by using the 2000 Centers for Disease Control and Prevention growth charts
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DOI：
10.3945/ajcn.2009.28335
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发表时间：
2009-11-01
影响因子：
7.1
通讯作者：
Curtin, Lester R.
中科院分区：
文献类型：
--
作者：
Flegal, Katherine M.;Wei, Rong;Curtin, Lester R.
背景资料：2000年美国疾病控制和预防中心（CDC）的生长图表中包含了用于计算第3至第97百分位数平滑曲线的LMS参数。目的：通过使用CDC生长图表的简单功能，评估不同的方法来描述不同年龄段的体重指数（BMI）的极端值。设计：根据用于构建生长图表的数据集计算第99和第1年龄BMI曲线的经验数据，并与CDC提供的LMS参数外推的估计值和其他平滑曲线的各种函数进行比较。一组重新估计的LMS参数，包括一个平滑的第99百分位数也evaluated.Results：极端的反推从CDC提供的LMS参数不匹配以及第99百分位数的经验数据。通过使用平滑的第95百分位数的120%获得了与经验数据的更好拟合。经验第一百分位数通过LMS值的外推合理地近似。重新估计的LMS参数有几个缺点，没有明显的优点。结论：几个近似值可以用来描述极高的值的BMI年龄与使用的CDC增长图表。CDC提供的LMS参数的外推法不能很好地拟合经验第99百分位值。简单地将高值近似为现有的平滑数据的百分比，与插补非常高的数据相比，具有一些实际优势。将高BMI值表示为第95百分位数的百分比可以提供描述和跟踪较重儿童的灵活方法。美国临床营养杂志2009; 90：1314-20。
Background: The 2000 Centers for Disease Control and Prevention (CDC) growth charts included lambda-mu-sigma (LMS) parameters intended to calculate smoothed percentiles from only the 3rd to the 97th percentile.Objective: The objective was to evaluate different approaches to describing more extreme values of body mass index (BMI)-for-age by using simple functions of the CDC growth charts.Design: Empirical data for the 99th and the 1st percentiles of BMI-for-age were calculated from the data set used to construct the growth charts and were compared with estimates extrapolated from the CDC-supplied LMS parameters and to various functions of other smoothed percentiles. A set of reestimated LMS parameters that incorporated a smoothed 99th percentile were also evaluated.Results: Extreme percentiles extrapolated from the CDC-supplied LMS parameters did not match well to the empirical data for the 99th percentile. A better fit to the empirical data was obtained by using 120% of the smoothed 95th percentile. The empirical first percentile was reasonably well approximated by extrapolations from the LMS values. The reestimated LMS parameters had several drawbacks and no clear advantages.Conclusions: Several approximations can be used to describe extreme high values of BMI-for-age with the use of the CDC growth charts. Extrapolation from the CDC-supplied LMS parameters does not provide a good fit to the empirical 99th percentile values. Simple approximations to high values as percentages of the existing smoothed percentiles have some practical advantages over imputation of very high percentiles. The expression of high BMI values as a percentage of the 95th percentile can provide a flexible approach to describing and tracking heavier children. Am J Clin Nutr 2009; 90: 1314-20.