Abstract: Objective To analyze the trend of height(length) for age Z score [HAZ(LAZ)] of Chinese children under 5 years old in 2002 and 2013, so as to provide scientific evidence for determining critical window period for improving stunting. Methods Data were extracted from Chinese national nutrition and health survey in 2002 and Chinese National Nutrition and Health Surveillance in 2013. Two-sample t-test was used to analyze the difference of HAZ(LAZ) between 2002 and 2013, and restricted cubic spline regression was used to analyze the trend of HAZ(LAZ) of Chinese children under 5 years old in 2002 and 2013. Results The HAZ(LAZ) were-0.31±1.54 and 0.03±1.36 in 2002 and 2013, respectively, and the difference was significant(t=-23.72, P<0.001). The differences of HAZ(LAZ) were significant between 2002 and 2013 in 0—1 month,6—23 months and 24—59 months groups(t=2.68,-11.21,-18.69,P<0.01). In 2002, the HAZ (LAZ) of children under 5 years old fell to the trough firstly, and then increased slowly. In 2013, the HAZ(LAZ) of children under 5 years old reached the peak firstly, and then declined, especially among 6—23 months. Conclusions Compared with 2002, the HAZ (LAZ) values of Chinese children under 5 years old increase significantly in 2013. And 6 to 23 months old is the critical window for stunting intervention because of the continuously downward trend.

Key words: height(length) for age Z score, children under 5 years old, trend analysis, restricted cubic spline regression

摘要： 目的 分析2002年和2013年中国5岁以下儿童年龄别身高(身长)Z评分[HAZ(LAZ)]的变化趋势,为下一步筛选儿童生长迟缓干预的窗口期提供科学依据。 方法 利用“2002年中国居民营养与健康状况调查”和“2010-2013年中国居民营养与健康状况监测”项目中5岁以下儿童身高(身长)、年龄等数据,采用t检验方法比较2002年和2013年HAZ(LAZ)的差异,采用限制性立方样条回归方法分别分析2002年和2013年5岁以下儿童HAZ(LAZ)的变化趋势。 结果 2002年5岁以下儿童HAZ(LAZ)为-0.31±1.54,2013年为0.03±1.36。2013年比2002年提高0.34,差异有统计学意义(t=-23.72, P<0.001)。0～＜1、6～23、24～59月龄组2002年和2013年HAZ(LAZ)均值比较,差异均有统计学意义(t值分别为2.68、-11.21、-18.69,P<0.01)。2002年5岁以下儿童的HAZ(LAZ)呈先下降至最低值后缓慢上升并逐渐趋于平稳的趋势,2013年呈先上升至最高值后下降并逐渐趋于平稳的趋势,特别是6～23月龄组下降趋势明显。 结论 2013年中国5岁以下儿童HAZ(LAZ)的平均水平较2002年有显著提高,但6～23月龄儿童HAZ(LAZ)仍处于持续下降趋势,该阶段可作为改善儿童生长迟缓的窗口期。

关键词: 年龄别身高(身长)Z评分, 5岁以下儿童, 趋势分析, 限制性立方样条回归