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

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