Supplementary information for Socio-economic disparities in child-to-adolescent growth trajectories in China: Findings from the China Health and Nutrition Survey 1991-2015

Supplementary information files for article Socio-economic disparities in child-to-adolescent growth trajectories in China: Findings from the China Health and Nutrition Survey 1991-2015

Backgrounds: Socio-economic disparities in growth trajectories of children from low-/middle-income countries are poorly understood, especially those experiencing rapid economic growth. We investigated socio-economic disparities in child growth in recent decades in China.
Methods: Using longitudinal data on 5,095 children/adolescents (7-18y) from the China Health and Nutrition Survey (1991-2015), we estimated mean height and BMI trajectories by socio-economic position (SEP) and sex for cohorts born in 1981-85, 1986-90, 1991-95, 1996-2000, using random-effects models. We estimated differences between high (urbanization index ≥median, household income per capita ≥median, parental education ≥high school, or occupational classes I-IV) and low SEP groups.
Findings: Mean height and BMI trajectories have shifted upwards across cohorts. In all cohorts, growth trajectories for high SEP groups were above those for low SEP groups across SEP indicators. For height, socio-economic differences persisted across cohorts (e.g. 3.8cm and 2.9cm in earliest and latest cohorts by urbanization index for boys at 10y, and 3.6cm and 3.1cm respectively by household income). For BMI, trends were greater in high than low SEP groups, thus socio-economic differences increased across cohorts (e.g. 0.5 to 0.8kg/m2 by urbanization index, 0.4 to 1.1kg/m2 by household income for boys at 10y). Similar trends were found for stunting and overweight/obesity by SEP. There was no association between SEP indicators and thinness.
Interpretation: Socio-economic disparities in physical growth persist among Chinese youth. Short stature was associated with lower SEP, but high BMI with higher SEP. Public health interventions should be tailored by SEP, in order to improve children’s growth while reducing overweight/obesity.

补充信息文件：关于中国1991-2015年中国儿童至青少年成长轨迹中的社会经济差异：来自中国健康与营养调查的研究发现

背景：对于来自低收入/中等收入国家的儿童成长轨迹中的社会经济差异，理解甚微，尤其是在经历快速经济增长的情况下。我们调查了近年来中国在儿童成长方面的社会经济差异。

方法：利用来自1991-2015年中国健康与营养调查的5,095名儿童/青少年（7-18岁）的纵向数据，我们使用随机效应模型，根据社会经济地位（SEP）和性别，对1981-85年、1986-90年、1991-95年、1996-2000年出生的队列的平均身高和BMI轨迹进行了估计。我们估计了高（城市化指数≥中位数，人均家庭收入≥中位数，父母教育程度≥高中，或职业等级I-IV）与低SEP群体之间的差异。

发现：平均身高和BMI轨迹在各个队列中均有所上升。在所有队列中，高SEP群体的生长轨迹均高于低SEP群体，这在SEP指标中均有体现。对于身高，社会经济差异在各个队列中持续存在（例如，男孩在10岁时，城市化指数最早队列与最晚队列的身高差异分别为3.8厘米和2.9厘米，家庭收入分别为3.6厘米和3.1厘米）。对于BMI，高SEP群体的趋势大于低SEP群体，因此社会经济差异在各个队列中有所增加（例如，男孩在10岁时，城市化指数导致的差异从0.5至0.8kg/m2，家庭收入导致的差异从0.4至1.1kg/m2）。按SEP划分，生长迟缓和超重/肥胖的趋势也呈现出相似的趋势。SEP指标与消瘦之间没有关联。

解释：中国青少年的身体成长中的社会经济差异持续存在。矮小与低SEP相关，但高BMI与高SEP相关。公共卫生干预措施应针对SEP进行定制，以提高儿童的生长，同时减少超重/肥胖。” }