目的 评价生物电阻抗法(BIA)与双能X线吸收法(DXA)测量儿童青少年的骨矿物含量(BMC)的一致性,为BIA准确测量儿童青少年BMC提供依据.方法 采用方便抽样法,于2019年4-5月在广州市某区招募1469名7～17岁儿童青少年,采用DXA和BIA技术分别测量BMC.采用组内相关系数(ICC)、Bland-Altman分析评价一致性.Bland-Alt-man分析在对数转换的数据中进行.将BMC按性别年龄别三分位数分类,计算Kappa值评价一致性.以DXA测量值为因变量,建立BIA校正预测模型.结果 男、女生的ICC分别为0.93和0.94.在Bland-Altman分析中,男、女生的BIA与DXA比值的一致性限范围均较宽,分别为0.27～0.76和0.17～0.72.男、女生中两方法判断BMC三分类水平的Kappa值分别为0.57和0.45,呈中高度一致.按BMI分组,各体重状态男生及超重女生的Kappa值均在0.75以上,一致性程度极好.构建的男、女生BIA校正预测模型分别为:BMCDXA=-0.51 +0.44×BMCBIA+ 0.06×Age+0.02×BMI;BMCDXA=-0.55 +0.43×BMCBIA +0.06×Age+0.02×BMI.模型的R2值分别为0.87和0.87.结论 BIA与DXA所测BMC值一致性较差,但在判断分类BMC水平方面一致性尚可,研究建立的BIA测量BMC校正模型拟合效果好,提示BIA可能适用于评估儿童群体的BMC发育水平.

Objective An ongoing debate surrounds the relationship between body composition and pubertal timing, in particular for boys. This cross-sectional study aimed to investigate the association of body composition with pubertal timing among children and adolescents. Methods A total of 1,493 boys and 1,261 girls who entered puberty were enrolled in Guangzhou, China. Tanner stages were evaluated by examination of breast development for girls and testicular volume for boys. Fat mass (FM) and fat-free mass (FFM) were determined by bioelectrical impedance analysis. Parameters for body composition were transformed into age-and gender-specific Z-scores. The association of body composition with pubertal timing was examined using multinomial logistic regression with inverse probability weighting (IPW) based on the propensity score. Results For boys, IPW analysis showed Z-scores of body fat percentage (BF%) and FM index (FMI) were negatively associated with early puberty (OR = 0.75, 95% CI = 0.64–0.87; OR = 0.74, 95% CI = 0.63–0.88). As for girls, in contrast to boys, positive associations were seen between BF% and FMI with early puberty (OR = 1.39, 95% CI = 1.19–1.64; OR = 1.59, 95% CI = 1.33–1.90). With respect to appendicular skeletal muscle mass index (ASMI), there was a positive association with early puberty and a negative one with late puberty in boys (OR = 1.26, 95% CI = 1.07–1.49; OR = 0.82, 95% CI = 0.69–0.99). Conclusion There is a positive association of FM with early puberty for girls while negative for boys. FFM yields a positive association with early puberty and a negative one with late puberty in boys, but not in girls. Our findings highlight the gender differences in the connection between body composition and pubertal onset.

This study aimed to assess the associations of total body fat and fat distribution with bone mineral density (BMD) among children and adolescents in this cross-sectional study. A total of 1032 boys and 897 girls aged 6–17 years were enrolled between May 2019 and June 2019 in Guangzhou, China. BMD, total body fat (fat mass index [FMI] and body fat percentage [BF

Objective:To analyze the current status of body composition and development patterns of children and adolescents aged 6-17 years in Guangzhou.Methods:This was a cross-sectional study involving 8 169 school students from 3 elementary schools and 3 middle schools in Guangzhou from March to December 2019.The fat-free mass (FFM) and fat mass (FM) were measured by the bioelectrical impedance analysis.The fat-free mass index (FFMI) and fat mass index (FMI) were calculated via the height standardization. T test was used to compare quantitative variables between groups.The growth pattern of body composition was described using the Hattori chart. Results:A total of 4 431 boys (54.24%) and 3 738 girls (45.76%) were involved in this study.FFM and FM both increased with age between boys and girls.Except for boys aged 11 years, FFM in boys were significantly higher than that in girls with the same age (all P<0.05). In the age of 7-10 years, FM in boys were significantly higher than that in girls with the same age, while it was significantly higher in girls aged 12 years and older than that of boys at the same age (all P<0.05). The Hattori chart showed that the difference in body composition between genders occurred after 11 years old.In contrast to girls, increases in the weight and body mass index (BMI) in boys were mainly attributed to the FFM development. Conclusions:The development of FFM and FM in children and adolescents varies with age, accompanied with the gender-specific features.FFM in boys is higher than that of girls at the same age.The weight gain in boys is mainly attributed to the development of fat-free tissues, and thus the utility of BMI may lead to the overestimation of obesity.