Background：The diagnosis of true obesity was recommended to be based on body fat quantity and distribution by body composition measurement. However, the riskbased overfat cutoffs were scarce for pediatric population.
Objective：To develop cutoffs and the optimal combination for body fat indices for screening persistent hyperglycemia and dyslipidemia among the pediatric population.
Design：Prospective cohort study.
Methods：Subjects who participated in the 2017 baseline and 2019 followup survey of Schoolbased Cardiovascular and Bone Health (SCVBH) Promotion Program with complete data of body composition and blood test, were selected as the study population. The gold standard was persistent hyperglycemia and dyslipidemia in both baseline and followup surveys, including persistent impaired fasting glucose (IFG), persistent high total cholesterol (TC), persistent high TG, persistent high low density lipoprotein cholesterol (LDLC), persistent low high density lipoprotein cholesterol (HDLC) and persistent high NonHDLC. The predictors included body mass index (BMI) and body fat indices derived from bioelectrical impedance analysis, including fat mass index (FMI), fat mass percentage (FMP), trunk to leg fat ratio (TLR).The area under the receiver operating characteristic curve was used to determine the best combination and optimal cutoffs of body fat indices for detecting persistent hyperglycemia and dyslipidemia.
Main outcome measuresThe best combination and optimal cutoffs of body fat indices for detecting persistent hyperglycemia and dyslipidemia.
Results：A total of 10 603 (mean age at baseline: 10.9 ± 3.3 years, 49.4% males) children and adolescents aged 618years were included for analysis. Among, 371 (3.5%) were diagnosed as persistent lFG,131 (1.2%) as persistent high TC, 128 (1.2%) as persistent high TG, 118 (1.1%) as persistent high LDLC, 448 (4.2%) as persistent low HDLC, and 212 (2.0%) as persistent high nonHDLC. According to the results for ROC analyses and Delong tests, the capability of FMI+TLR combination for detecting persistent IFG, persistent high TC and persistent high LDLC were statistically higher than BMI in both sexes (All P<0.05). Moreover, the combined use of FMI+TLR presented higher capability for detecting persistent high NonHDLC ［AUCFMI+TLR：0.664 (0.6150.713) vs AUCBMI：0.617 (0.5570.677), P<0.001］ than BMI in girls. According to the ROC analysis, the optimal overfat cutoffs of FMI were determined at the range of 75th percentile to 95th percentile, and TLR were determined at the range of 75th percentile to 90th percentile, varied by indicators for persistent hyperglycemia and dyslipidemia.
Conclusion：The FMI + TLR combination presented higher predictability for discriminating persistent hyperglycemia and dyslipidemia among children and adolescents. We suggest the 75th percentile of FMI to be the cutoff for mild general overfat, the 90th percentile of FMI to be the cutoff for severe general overfat, the75th percentile of TLR to be the cutoff for mild central overfat, the 90th percentile of TLR to be the cutoff for severe central overfat.
Background：The accuracy of bioelectrical impedance analysis (BIA) in measuring body composition of children and adolescents is controversial, and there is a lack of correction formulas that do not rely on the brand and model of BIA instrument.
Objective：To evaluate the consistency of BIA and dualenergy Xray absorptiometry (DXA) in measuring body composition in children and adolescents aged 619 years.
Design：Crosssectional survey.
Methods：The subjects were selected from the 20132023 China Life Cycle Body Composition Study, and 1,841 schoolage children and adolescents were tested using the same BIA and DXA instruments. Intragroup correlation coefficient (ICC), relative error frequency (RE), and BlandAltman analysis were used to evaluate the consistency of measurements of fat mass (FM), nonfat tissue mass (FFM), and limb skeletal muscle mass (ASM). With DXA as the dependent variable and resistance index (RI) as the independent variable, a prediction model for BIA correction was established.
Main outcome measures：ICC, RE, and BlandAltman analysis.
Results：In different sexes, compared with DXA, BIA underestimated FM (RMSE=2.60, 2.27 kg, P<0.05), underestimated ASM (RMSE=1.02, 0.91 kg, P<0.05), and overestimated FFM (RMSE=3.07, 2.66 kg, P<0.05) for male and female students. The ICC of FM, FFM and ASM of male and female students were all >0.90 (P<0.05). With the increase of age, the proportion of ICC and RE with absolute value <15% in FM increased gradually, while the proportion of ICC and RE with absolute value <15% in ASM first increased and then decreased. With the increase of BMI, the proportion of ICC and RE with absolute value <15% of FM increased gradually. The BIA corrected prediction model is: FM= 2.336+0.871×RI50-1.739×RI500+0.517×SexM1F2-0.478×Age+0.753×Weight (R2=0.940)；FFM=2.795-1.406×RI50+2.177×RI500-0.329×SexM1F2+0.471×Age+0.243×Weight (R2=0.985); ASM=-1.937-0.697×RI50+1.132×RI500-0.389×SexM1F2+0.119×Age+0.095×Weight (R2=0.976).
Conclusion：BIA measured ASM, FFM and DXA in schoolage children and adolescents with good agreement, FM and DXA with poor agreement. The corrected model of FM, FFM and ASM measured by BIA has good fitting effect, and can be used to evaluate the body composition of schoolage children and adolescents with different types of multifrequency BIA instruments.
Background: Current research mostly explored the effect of single behavior on muscle development under traditional regression models, ignoring the temporal relationship between behavior changes. The iso-temporal substitution model can accurately quantify the comprehensive effect of all behavior changes on muscle development.
Objective: To explore the association between different physical behaviors and muscle development in children and adolescents in Guangzhou based on the iso-temporal substitution model.
Design: ross-sectional survey.
Methods: A total of 7,767 children and adolescents aged 6-17 years were enrolled in Guangzhou between November 2020 and June 2021. Questionnaire survey was conducted to collect information on physical activity, sleep, and sedentary behaviors. Body compositions were measured using bioelectrical impedance analysis. Based on linear regression model, iso-temporal substitution model was conducted to evaluate the effect estimates for substitution of sedentary behavior with moderate-vigorous physical activity(MVPA), light physical activity(LPA), or sleep on muscle development, with 30 min·d-1 as the substitution unit.
Main outcome measures: Fat-free mass index (FFMI), fat-free mass percentage (FFM%), and appendicular skeletal muscle mass percentage (ASMM%).
Results: Replacing 30min of sedentary behavior with MVPA per day significantly increased the Z-scores of FFMI, FFM%, and ASMM% by 0.08, 0.04, and 0.07 units (all P<0.05), respectively. Replacing sedentary behavior with 30 min·d-1 of sleep duration was significantly associated with decrease of FFMI Z score (β=0.04, P<0.05) and increase of FFM% Z score (β=0.03, P>0.05). The stratification analysis by gender and grade level showed similar results, with no significant heterogeneity between subgroups.
Conclusion: Replacing sedentary behavior with 30 min of MVPA per day is associated with the increase of FFM and ASMM. The iso-temporal substitution of sedentary behavior with sleep may also be positively associated with muscle development.
LIU Qin, PENG Zhilian, YUAN Shuanggui, LI Xinggui, MA Jun, AN Xizhou, CHEN Jingyu, LUO Shunqing, HE Xiangqian, CHEN Lanling, HUANG Daochao, LIANG Xiaohua
Background: Traditional indicators like BMI are insufficient for comprehensive assessment of children's nutritional status and health risks. Body composition analysis offers a more precise method to evaluate the distribution of fat, muscle, and water content in children's bodies, providing new avenues for health assessment.
Objective: To investigate the correlation between body composition and blood pressure levels among schoolage children in two southwestern provinces and one municipality (Sichuan, Guizhou, Chongqing) of China, providing scientific evidence for early prevention of childhood hypertension.
Design: Crosssectional survey.
MethodsUsing multistage stratified cluster sampling, students from primary and secondary schools in the three areas were recruited. Data on basic information, family circumstances, pubertal development, family medical history, nutritional status, and dietary habits were collected through questionnaires. Standardized physical measurements, blood pressure measurements, and body composition parameters (body fat percentage, muscle ratio, water content, protein, and mineral content) were obtained using bioelectrical impedance analysis. Univariate analysis was conducted for included variables, and restricted cubic splines (RCS) analysis was used to explore the doseresponse relationship between body composition and elevated blood pressure risk.
Main outcome measures: Association between body composition and blood pressure.
Results: The study analyzed 8,397 students from six schools across the three areas, including 5,722 primary school students and 2,675 secondary school students; 4,593 from urban areas and 3,804 from rural areas. The mean age was (10.9±2.4) years, with 4,445 boys (52.9%) and 3,952 girls. Elevated blood pressure was detected in 784 students (9.3%), with higher prevalence in boys compared to girls, overweight/obese children compared to nonoverweight/obese children, those who had entered puberty compared to those who had not, and those with high salt intake compared to those without (all P<0.05). All five body composition indicators showed significant correlations with blood pressure (all P<0.05). Genderspecific patterns emerged in the relationship between body composition indicators and elevated blood pressure risk. In girls, body fat percentage, water content, muscle ratio, and protein content showed linear correlations with elevated blood pressure risk, while mineral content showed a nonlinear correlation. In boys, body fat percentage and mineral content showed nearly linear correlations with elevated blood pressure, while muscle ratio, water content, and protein content showed nonlinear correlations. Using medium levels of each gender as reference, only low body fat percentage and high water and protein content in boys showed no statistically significant differences in systolic blood pressure, diastolic blood pressure, and mean arterial pressure, while other parameters showed significant increases or decreases.
Conclusion: Body composition is closely associated with elevated blood pressure in both male and female primary and secondary school students. Incorporating body composition analysis into cardiovascular health risk assessment may aid in early identification of elevated blood pressure in children.
Background: The influencing factors of obesity phenotype were not yet entirely clear. Most existing studies focused on the association between single lifestyle behavior and obesity phenotype but lacking comprehensive investigation of lifestyle behaviors on obesity phenotype.
Objective: To explore the association of the healthy lifestyle behavior index and its levels with obesity phenotypes in children and adolescents, and to provide a scientific basis for promoting healthy development of children and adolescents.
Design: Crosssectional study.
Methods: The questionnaire survey for lifestyle behavior was performed among a total of 8,222 children and adolescents in Guangzhou, and healthy lifestyle behavior index was constructed, and cardiovascular metabolic indexes were tested. The association of the healthy behavior index and its levels with obesity phenotype was analyzed using multivariate logistics regression.
Main outcome measures: Obesity phenotypes were classified by combining weight and metabolic status as Metabolically Healthy Normal Weight (MHNW), Metabolically Unhealthy Normal Weight (MUNW), Metabolically Healthy Overweight (MHOW), Metabolically Unhealthy Overweight (MUOW), Metabolically Healthy Obesity (MHO), and Metabolically Unhealthy Obesity (MUO).
Results: Each point increase in the lifestyle behavior index was associated with reduced risk of MUNW, MHOW, and MUO (ORs=0.95, 0.91, and 0.88, respectively, all P<0.05). Highlevel behavioral indices reduced the risk of MUNW, MHOW, and MUO by 18%, 29%, and 41%, respectively, compared to a lowlevel index (all P<0.05). Highlevel behavioral indices reduced the risk of MUO by 38% compared to MHO (P<0.05). Increase in healthy lifestyle behavior index was associated with lower risk of MUNW (OR=0.93, P<0.05) in boys and reduced risk of MHOW in girls (OR=0.88, P<0.05). When stratified by age, the highlevel behavioral indices reduced the risk of MUNW by 21% in the age group of 1218 years and MHOW by 41% in the age group of 611 years.
Conclusion: The increased healthy lifestyle behavior index is associated with lower risk of MUNW, MHOW, and MUO. Additionally, these associations differ in sex and age.
Objective: To explore the association between dietary patterns and body composition among children and adolescents in Guangzhou.
Design: Crosssectional survey.
Methods: Primary and middle school students aged 617 years were enrolled using the stratified cluster sampling method from March to December 2019. Information on dietary intake 13 types of food was collected by questionnaires. Body composition measurements were performed. Factor analysis was used to extract dietary patterns. Multivariate linear regression models were used to analyze the association between dietary patterns and body composition.
Main outcome measures: Zscores of body fat percentage (BF%), fatfree mass index (FFMI), and fat mass/fatfree mass ratio (FM/FFM).
Results: total of 7,590 children and adolescents were included in the analysis, with an average age of 11.7±2.9 years, and 4064 males (53.5%). Four dietary patterns were constructed, including balanced diet, refined grains and meat, fried and pickled food, and fruit and dairy diet patterns. After adjusting for demographic characteristics, the highest quartile of factor scores in the balanced diet pattern compared to the lowest quartile showed a decrease of 0.07 standard deviations in BF% Zscore (β=-0.07, 95%CI=-0.140.00) and FM/FFM Zscore (β=-0.07, 95%CI=-0.140.00). In the fruit and dairy diet pattern, the highest quartile of factor scores compared to the lowest quartile showed an increase of 0.10 standard deviations in FFMI Zscore (β=0.10, 95%CI=0.030.17). No statistically significant association was found between other dietary patterns and body composition (P>0.05).
Conclusion: The balanced diet pattern is associated with a reduction in body fat, and the fruit and dairy diet pattern is associated with an increase in fatfree tissue or muscle.
Background: Skeletal muscle is a vital component of body composition, playing a key role in maintaining normal growth, development, and overall health in children. However, the levels of skeletal muscle development in children and adolescents differ across various social environments and ethnic backgrounds.
Objective: To provide genderand agespecific reference standards for skeletal muscle development in children and adolescents, and to compare the patterns of appendicular skeletal muscle development between Chinese and U.S. children and adolescents.
Design: Crosssectional study.
Methods: A nationwide sample of 12,583 Chinese children and adolescents aged 318 years was drawn from the China Child and Adolescent Cardiovascular Health study (20132019). Data from the National Health and Nutrition Examination Survey (NHANES) for U.S. children and adolescents, aged 818 years from 2011 to 2018 (n=6,467), were also included. Wholebody and appendicular skeletal muscle mass were measured using dualenergy Xray absorptiometry (DXA). Generalized Additive Models for Location Scale and Shape (GAMLSS) method was utilized to estimate the genderand agespecific reference values.
Main outcome measures: Appendicular Skeletal Muscle Index (ASMI), Appendicular Skeletal Muscle Ratio (ASMR), Upper Limb Skeletal Muscle Index (ULSMI), and Lower Limb Skeletal Muscle Index (LLSMI).
Results: Overall, ASMI, ULSMI, and LLSMI increased with age in children and adolescents. Boys showed a gradual slowing trend of growth after 14 years of age, while girls exhibited a deceleration and even a decrease after 13 years of age. Additionally, for all age groups, U.S. children had higher values for the same Zscores compared to Chinese children, with this difference widening after 14 years of age. ASMR showed a slightly different developmental pattern, with an initial increase followed by a decrease, but the rate of increase was faster in the Chinese population between the ages of 1014 years. All indicators demonstrated significant gender differences, with boys having higher values in all measures.
Conclusion: Developmental patterns and disparities of skeletal muscle mass between Chinese and U. S. pediatric population should be assessed based on the sexand agespecific skeletal muscle reference standards of their respective countries.
Background: The prevalence of overweight and obesity among children and adolescents in China is increasing. Existing studies have mostly explored the effects of single lifestyle behaviors on body composition, lacking evidence about the association between integrated lifestyle behaviors and body composition.
Objective: To explore the association between healthy lifestyle behavior index and body composition in children and adolescents.
Design: Crosssectional survey.
Methods: This study enrolled 1,703 students aged 6 to 17 years in April 2019 in a middle school and an elementary school in Guangzhou. Body composition was measured by dualenergy Xray absorptiometry, and a questionnaire survey was performed to collect information about lifestyle behaviors. The healthy lifestyle behavior index was constructed based on seven items, including adequate sleep, moderate sedentary behavioral time, adequate moderate to vigorousintensity activity, daily breakfast, daily vegetables, daily fruits, and no intake of sugarsweetened beverages. For each item meeting, one point was assigned, and the healthy lifestyle behavior index is the total sum of all points achieved, which was further divided into three levels: low (02 points), medium (4 points), and high (7 points). Multiple linear regression models were performed to analyze the association of the healthy lifestyle behavior index and its levels with body composition (Zscores).
Main outcome measures: Total body and central adiposity, whole body and appendicular muscle mass.
Results: Of the 1,703 students aged 617 years, 924 (54.3%) were boys and 779 (45.7%) were girls. In the statistical analysis, adjustments were made for the age of children and adolescents, the highest educational level of their parents, and annual family income. In boys, the healthy lifestyle behavior index was positively associated with the muscle mass index (MMI) and the appendicular skeletal muscle mass index (ASMI) (all βs=0.07, both 95%CI=0.02 0.12). Compared to the lowlevel behavioral index, the medium and highlevel indices were associated with increased Zscores for MMI (βmedium=0.22; βhigh=0.30) and ASMI (βmedium=0.22; βhigh=0.29). In girls, the healthy lifestyle behavior index was negatively associated with Zscores for BF%, VFA, and FMR (all β=-0.07, all 95%CI=-0.12 -0.01). Compared to the lowlevel index, there was an association between the highlevel index and lower Zscores for BF%, VFA, and FMR, with β coefficients of -0.29, -0.29, and -0.28, respectively. When stratified by age groups, the associations between the healthy lifestyle behavior index and body composition remained statistically significant in pubertal boys (1217 years old) and girls (1017 years old).
Conclusion: Healthy lifestyle behavior index is associated with an increase in muscle mass in boys and decreases in total body and central adiposity in girls.
Background: Maternal separation anxiety is important for children's socialemotional development. However, the influence of postpartum separation anxiety on early childhood and the critical time points of its effect are still unclear.
Objective: To explore the impact of maternal separation anxiety at different time points within 2 years at 4 time points after delivery on socialemotional behavior problems of preschool children.
Design: Prospective cohort study.
Methods: In the Shanghai Sleep Birth Cohort, women during the third trimester, aged 18 to 45, gestational age ≥28 weeks, without any known deformity, longterm resident in Shanghai, delivery in the eastern division of the Renji Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, and single pregnancy were included as the cohort population. The offsprings were included if they were born at term and weighed 2500 to 4000g at birth, and excluded if they were admitted to the NICU after birth, or their Apgar score was ≤7 at 1 or 5 minutes with asphyxia at birth. Maternal education level, family annual income, maternal age at delivery, maternal depression, anxiety, and overall stress level were assessed during late pregnancy, and the offspring were evaluated for temperament type when they were 6 months old. Maternal separation anxiety was assessed by the Maternal Separation Anxiety Scale (MSAS) at 6, 12, 18, and 24 months postpartum, and the offspring's socialemotional development was assessed with the Strengths and Difficulties Questionnaire (SDQ) at age 6.
Main outcome measures: Total difficulties score, internalizing problems, and externalizing problems.
Results: From May 2012 to July 2013, 262 dyads of pregnant women and their offspring newborns were included according to the criteria for mothers and neonates. There was no statistical significance in the sensitivity analysis of baseline data between the withdrawn samples (n=80) and the final included samples in the current study (n=182). Maternal age at delivery was 29.7±3.3. Most of the mothers attained the highest education level of bachelor or college degree (73.1%). Maternal depression assessed by the Center for Epidemiological Studies Depression Scale, anxiety assessed by State-Trait Anxiety Inventory scale and stress level assessed by Life Events Scale for Pregnant Women represented good overall mental health. Family annual income of 140,000 to 290,000 RMB accounted for 48.6%, <140,000 RMB accounted for 38.1%. Among the temperament types of children aged 6 months, 44.3% were "easy", 39.2% were "intermediate low", and 16.5% were "intermediate high" or "difficult". Maternal separation anxiety gradually decreases at 6, 12, 18, 24 months postpartum. Specifically, maternal separation anxiety at 18 and 24 months postpartum was lower than that at 6 months postpartum, which was statistically significant. Higher family annual income predicted lower separation anxiety at 18 months postpartum, and mothers with higher education had lower levels of separation anxiety at 6 and 18 months postpartum. Maternal age at delivery was significantly negatively correlated with maternal separation anxiety at 18 months postpartum, maternal depression in late pregnancy was significantly positively correlated with maternal separation anxiety at 18 months and 24 months postpartum, and maternal trait anxiety in late pregnancy was significantly positively correlated with maternal separation anxiety at 24 months postpartum. Neither child gender nor temperament was significantly associated with maternal separation anxiety. After controlling for basic demographic information and maternal emotional state during late pregnancy, maternal separation anxiety at 12 and 18 months postpartum was significantly and positively associated with children's internalizing problems at 6 years of age. There was no significant association between maternal separation anxiety at 6 months postpartum and children's internalization problems at 6 years of age, and no significant association between maternal separation anxiety and children's externalization problems and difficulty scores at 6 years of age.
Conclusion: Maternal separation anxiety early in life is a unique risk factor for children's socioemotional development and is significantly associated with internalization problems in children at preschool age.
