[Sex difference in height growth and blood pressure change among Beijing school-age children and adolescents: a ten-year longitudinal study].

Objective: To explore sex difference in height growth and blood pressure (BP) change among Beijing school-age children and adolescents. Methods: Using physical examination data of 70 769 school-age children and adolescents from primary to high school during 2009-2018 in Shunyi District, a longitudinal dataset was formed with completed anthropometrical measurements of height and blood pressure (BP) after individual information linkage. Age-specific height, BP, growth rate of height and BP as well BP growth rate based on age at peak height velocity (PHA) were calculated. Linear mixed-effects model was used to identify sex disparity in the growth rates of height and BP. Results: Height and BP increased with age in both boys and girls, and the mean height and BP of boys were always higher than those of girls, except age group from 10 to 11 years. Sex disparity existed in growth rates of height and BP (P<0.001), which was demonstrated by the interaction item of"sex x age"in linear mixed-effects model. The PHA of boys was 12 years old, which was 2 years later than that of girls, about 10 years old. The curves of BP growth rate with age showed double peaks in both boys and girls. Boys reached the peak BP velocity at 13 years old, 3 years lagging behind that of girls who reached the peak at 10 years old. However, the peak of height and BP velocity of boys were higher than that of girls. The change of BP was highly synchronized in time with the increase of height, after adjusting for the growth rate of height by PHA. BP velocity increased with age before onset of puberty till PHA and then declined. Conclusion: Sex disparity in height growth and BP change among school-age children and adolescents is persistent and significant and the change of BP is highly synchronized in time with the increase of height.

[Association of blood pressure and left ventricular mass in children from the PROC cohort study].

Objective: To explore the association between blood pressure (BP) and the left ventricular mass (LVM) in children aged 6-8 years. Methods: The participants were from the community-based census-like design child cohort on sensitization, puberty, obesity and cardiovascular risk (PROC) conducted in six public non-boarding primary schools in Shunyi District, Beijing. Repeated three measurements on anthropometrical, M-mode and 2-dimensional (2D) echocardiographic imaging (2D/M ECHO) and blood biochemical assay, and BP measurements were carried out at baseline and follow-up from October 2018 to June 2019. A total of 1 659 children who had repeated BP measurements and cardiac structure information were included in this study. The average value of last two measurements of BP was determined as BP value for analysis. Formula recommended by Devereux was used to calculate the mass of left ventricle. Robust linear regression models were used to explore the association between BP and LVM in different groups. Results: The average age of all patients was (7.10±0.29) years old, including 832 boys (50.15%). Of all, 83.54% (1 386/1 659) were grouped as normal BP with average LVM (58.54±13.33) g, and 16.46% (273/1 659) as elevated BP group with LVM (63.84±15.78) g (P<0.001). The LVM of the normal BP group was lower than elevated BP group in overall participants, boys and girls (P<0.005). Univariate analysis showed that systolic BP was associated with LVM in overall, boys and girls (P<0.001) respectively. While diastolic BP was associated with LVM in overall and girls (P<0.03). Multivariable analysis indicated that the associations between systolic BP and LVM were observed in overall, boys and girls (P<0.05) with the ß (95%CI)=0.14 (0.08, 0.21), 0.18 (0.08, 0.27) and 0.12 (0.03, 0.22), respectively. However, the associations of diastolic BP and LVM were not significant. Conclusion: Systolic BP is highly associated with LVM and elevated BP could increase the LVM in children. Boys with elevated BP present a larger LVM and might indicate higher risk of left ventricular hypertrophy in adulthood.

[Association between trunk fat index and carotid intima-media thickness among children aged 6-8 years old in Beijing].

Objective: The study is to explore the association between trunk fat index (TFI) and carotid intima-media thickness (cIMT) among children aged 6-8 years old in Shunyi District, Beijing. Methods: The participants were enrolled from the child cohort on sensitization, puberty, obesity and cardiovascular risk (PROC) conducted in Shunyi District, Beijing from October 2018 to June 2019. The PROC used a community-based census-like design, and all eligible first-grade children from six public non-boarding primary schools in urban area were approached. Finally, a total of 1 503 children with written informed consent from parents and had complete data of TFI and cIMT were included for the present study. Sequential baseline surveys including anthropometric measurements, laboratory testing and ultrasonography measurement were conducted to collect the data on height, weight, body composition, blood pressure, serum lipids and cIMT. Linear regression was used to determine the predictors of cIMT, receiver operating characteristic (ROC) curve analysis was used to determine the cut-off value of TFI to identify children with high cIMT, and analysis of covariance was used to evaluate the post-consistency classification of cIMT by TFI. Results: The age of 1 503 participants was (6.7±0.3) years, and 752 boys accounted for 50.0%. The average cIMT was (0.358±0.024) and (0.355±0.023) mm, and the M (P25, P75) of TFI was 0.70 (0.22, 1.78) and 0.74 (0.23, 1.52) kg/m2 for boys and girls, respectively. The detection rates for boys and girls of high cIMT were 2.1% and 3.3%, respectively. Linear regression analysis showed that height, systolic blood pressure (SBP), diastolic blood pressure (DBP), TFI were positively correlated with cIMT in boys (P values<0.05). And height, SBP, triglyceride (TG), TFI were positively correlated with cIMT, and high-density lipoprotein cholesterol (HDL-C) was negatively correlated with cIMT in girls (P values<0.05). ROC curve analysis indicated that the best cut-off values for TFI to identify children with high cIMT were 1.78 and 1.14 kg/m2, at P75 and P66 for boys and girls, respectively. After grouped with the cut-off value of TFI and adjusted for age, height, SBP, DBP, TG, HDL-C, multivariable covariance analysis showed a consistent cut-off of inter-group cIMT mean by TFI groups (P values<0.005). Conclusion: TFI is associated with cIMT, which underscore its application potential in identifying early vascular structural damage.