基于GAMLSS模型的我国3~6岁幼儿BMI百分位数曲线参考标准及超重、肥胖临界值的研制

Construction BMI Percentile Standard Curve and Cut-off Points for Overweight and Obesity of 3~6 Years Children Based on GAMLSS Model in China

目的:建立我国3~6岁幼儿BMI百分位曲线参考标准和超重、肥胖临界值。方法:1)以2010年和2014年国家国民体质监测中心得到的全国除港澳台外的31个省(自治区、直辖市)101861名幼儿体质数据为建模对象,采用包含中位数、标准差、峰度和偏度4个参数的GAMLSS模型构建BMI的百分位数曲线。2)运用百分位曲线接轨法,与中国肥胖问题工作组(WGOC)推荐的7岁儿童超重、肥胖临界值接轨,划分我国3~6岁幼儿超重、肥胖临界线。结果:1)男女幼儿最优模型均为BCTo分布模型,自变量的幂转换系数ξ分别为0.6017和0.2501,参数总自由度分别为18.11和16.26,模型的拟合优度检验较优;以2018—2019年监测数据回代检验显示,各年龄组百分位标准曲线下的百分数与实际百分数的差异均在2%以内,说明模型有效性良好。研究最终得到了光滑度优良的我国3~6岁幼儿BMI百分位标准曲线及参考值。2)男幼儿超重、肥胖百分位曲线分别为C79.6和C91.5,女幼儿超重、肥胖百分位曲线分别为C85.4和C94.6。计算得出了表格和公式两种形式呈现的超重、肥胖临界值。结论:所建3~6岁幼儿BMI百分位曲线参考标准和超重、肥胖临界值代表性广、有效性高,可为我国幼儿生长发育评价和超重、肥胖的识别提供参考依据。

Objective:To establish the BMI percentile curve reference standard and the critical value of overweight and obesity for children aged 3~6 years in China.Methods:1)The physical fitness data of 101861 children from 31 provinces in 2010 and 2014 were used for analysis.The percentile curve of BMI was constructed by using GAMLSS model with four parameters:Median,standard deviation,kurtosis and skewness.2)The percentile integration method was used to establish the borderline between overweight and obesity in children aged 3~6 years in China by connecting with the borderline for 7-year old children recommended by WGOC.Results:1)The optimal model for male and female children were all BCTo distribution models with excellent results of goodness-fit-test.In this model,the power conversion coefficients of independent variable were 0.6017 and 0.2501,respectively;and the total degrees of freedom of the parameters were 18.11 and 16.26,respectively.Based on the 2018—2019 physical fitness data,the regression test showed that the difference between the percentage under the standard percentile curve and the actual percentage in each age group was within 2%,which showed the model was effective.Finally,a reference standard for BMI percentile curves of 3~6 years old children in China with excellent smoothness was obtained.2)The percentile curves of cut-off values of overweight and obesity in male children were C79.6 and C91.5,respectively and that in female children were C85.4 and C96.4,respectively.The critical values of overweight and obesity presented in the forms of table and formula were obtained.Conclusions:The reference standard of BMI percentile curve and the cut-off values of overweight and obesity established in this study were widely representative and high effective.The results of this study provided references for the evaluation of growth and development and the identification of overweight and obesity in 3~6 years Chinese children.