Ludwig-Maximilians University of Munich, Institute of Social Paediatrics and Adolescent Medicine, Division of Epidemiology, Munich, Germany.
Int J Obes (Lond). 2010 Apr;34(4):642-8. doi: 10.1038/ijo.2009.301. Epub 2010 Jan 19.
The worldwide increasing prevalence of childhood overweight seems to be due to an increasing proportion of extremely high body mass index (BMI) values rather than to a shift of the entire BMI distribution. These findings might be attributed to incremental exposure to risk factors particularly affecting overweight children.
To assess the possible differences in associations of several risk factors by subgroups of children's BMI distribution.
We applied quantile regression to cross-sectional data on 9698 German preschoolers (5-6 years) collected in 1999 and 2002. Sex- and age-specific BMI standard deviation scores (BMI-SDSs) were used as the outcome variable, and maternal BMI, maternal smoking during pregnancy, exclusive formula feeding, child's weight gain from birth to 2 years of life and low parental education as explanatory variables.
All risk factors except formula feeding contributed to a positive shift in mean BMI-SDS. The estimated effects of all risk factors on BMI-SDS were greatest for children with the highest BMI-SDS value. For example, high television (TV) viewing (>2 h day(-1)) had an effect of 0.46 (95% confidence interval (CI): 0.46, 0.46) SDS units on overweight children (90th percentile), but only a 0.22 (95% CI: 0.11, 0.33) SDS effect on normal-weight children (50th percentile).
For well-known risk factors of childhood overweight, stronger associations in children with higher BMI values were observed. These findings might possibly help to explain the secular shift in the upper BMI percentiles in children.
全球儿童超重的患病率不断上升，这似乎是由于极高的体重指数（BMI）值的比例不断增加，而不是整个 BMI 分布的转移。这些发现可能归因于对特别影响超重儿童的危险因素的增量暴露。
评估在儿童 BMI 分布的亚组中，几个危险因素的关联可能存在差异。
我们应用分位数回归分析了 1999 年和 2002 年收集的 9698 名德国学龄前儿童（5-6 岁）的横断面数据。性别和年龄特异性 BMI 标准差评分（BMI-SDS）被用作因变量，而母亲 BMI、母亲怀孕期间吸烟、纯配方奶喂养、儿童从出生到 2 岁的体重增加和低父母教育程度被用作解释变量。
除了配方奶喂养之外，所有的危险因素都导致了 BMI-SDS 的平均正向转移。所有危险因素对 BMI-SDS 的估计影响在 BMI-SDS 值最高的儿童中最大。例如，高电视（TV）观看时间（>2 小时/天）对超重儿童（第 90 百分位）的 BMI-SDS 有 0.46（95%置信区间（CI）：0.46，0.46）的影响，但对正常体重儿童（第 50 百分位）的 BMI-SDS 影响仅为 0.22（95%CI：0.11，0.33）。
对于儿童超重的已知危险因素，在 BMI 值较高的儿童中观察到更强的关联。这些发现可能有助于解释儿童 BMI 百分位数的长期转移。
