Sensitivity and specificity of body mass index and skinfold thicknesses in detecting excess adiposity in children aged 8-12 years

Inequalities in adiposity trends between 1979 and 1999 in Guatemalan children

BACKGROUND

Guatemala suffered from civil war and high levels of inequality and childhood stunting in the second half of the 20th century, but little is known about inequalities in secular trends in adiposity.

OBJECTIVES

To investigate differences in childhood body mass index (BMI) and skinfold thickness trajectories from 1979 to 1999 between three groups of children: High socioeconomic position (SEP) Ladino, Low SEP Ladino, and Low SEP Indigenous Maya.

METHODS

The sample comprised 19 346 children aged 7-17 years with 54 638 observations. The outcomes were height, BMI, triceps skinfold thickness (TST), and subscapular skinfold thickness (SST) Z-scores according to the Centers for Disease Control and Prevention (CDC) references. Sex-specific multilevel models were used to estimate and compare mean trajectories from 1979 to 1999 between the three groups.

RESULTS

Mean Z-scores were always highest for High SEP Ladino children and lowest for Low SEP Maya children. Despite their very short stature, the Low SEP groups had SST trajectories that were above the 50th centile. The BMI trajectories were relatively flat and within one major centile band of the CDC median, with differences between the three groups that were small (0.2-0.3 Z-scores) and did not attenuate over time. Conversely, the TST Z-score trajectories demonstrated larger positive secular trends (e.g., from -1.25 in 1979 to -0.06 in 1999 for Low SEP Maya boys), with differences between the three groups that were large (0.5-1.2 Z-scores) and did attenuate over time (in boys). Secular trends and between-group difference in the SST Z-score trajectories were less pronounced, but again we found stronger evidence in boys that the estimated inequalities attenuated over time.

CONCLUSIONS

Secular trends and inequalities in skinfolds differ from those for BMI in Guatemalan children. Differences between groups in skinfolds attenuated over time, at least in boys, but whether this is good news is questionable given the very short stature yet relatively large subscapular skinfolds of the Low SEP groups.

Integrative multiomics analysis of infant gut microbiome and serum metabolome reveals key molecular biomarkers of early onset childhood obesity

Evidence supports a complex interplay of gut microbiome and host metabolism as regulators of obesity. The metabolic phenotype and microbial metabolism of host diet may also contribute to greater obesity risk in children early in life. This study aimed to identify features that discriminated overweight/obese from normal weight infants by integrating gut microbiome and serum metabolome profiles. This prospective analysis included 50 South Asian children living in Canada, selected from the SouTh Asian biRth cohorT (START). Serum metabolites were measured by multisegment injection-capillary electrophoresis-mass spectrometry and the relative abundance of bacterial 16S rRNA gene amplicon sequence variant was evaluated at 1 year. Cumulative body mass index (BMI_AUC) and skinfold thickness (SSF_AUC) scores were calculated from birth to 3 years as the total area under the growth curve (AUC). BMI_AUC and/or SSF_AUC >85th percentile was used to define overweight/obesity. Data Integration Analysis for Biomarker discovery using Latent cOmponent (DIABLO) was used to identify discriminant features associated with childhood overweight/obesity. The associations between identified features and anthropometric measures were examined using logistic regression. Circulating metabolites including glutamic acid, acetylcarnitine, carnitine, and threonine were positively, whereas γ-aminobutyric acid (GABA), symmetric dimethylarginine (SDMA), and asymmetric dimethylarginine (ADMA) were negatively associated with childhood overweight/obesity. The abundance of the Pseudobutyrivibrio and Lactobacillus genera were positively, and Clostridium sensu stricto 1 and Akkermansia were negatively associated with childhood overweight/obesity. Integrative analysis revealed that Akkermansia was positively whereas Lactobacillus was inversely correlated with GABA and SDMA, and Pseudobutyrivibrio was inversely correlated with GABA. This study provides insights into metabolic and microbial signatures which may regulate satiety, energy metabolism, inflammatory processes, and/or gut barrier function, and therefore, obesity trajectories in childhood. Understanding the functional capacity of these molecular features and potentially modifiable risk factors such as dietary exposures early in life may offer a novel approach for preventing childhood obesity.

Differences in nutritional status between rural and urban Yucatec Maya children: The importance of early life conditions

Early‐life conditions shape childhood growth and are affected by urbanization and the nutritional transition. To investigate how early‐life conditions (across the “first” and “second” 1000 days) are associated with rural and urban children's nutritional status, we analyzed anthropometric data from Maya children in Yucatan, Mexico. We collected weight, height and triceps skinfold measures, then computed body mass and fat mass indices (BMI/FMI), in a cross‐sectional sample of 6‐year‐olds (urban n = 72, rural n = 66). Demographic, socioeconomic and early‐life variables (birthweight/mode, rural/urban residence, household crowding) were collected by maternal interview. We statistically analyzed rural‐urban differences in demographic, socioeconomic, early‐life, and anthropometric variables, then created linear mixed models to evaluate associations between early‐life variables and child anthropometric outcomes. Two‐way interactions were tested between early‐life variables and child sex, and between early‐life variables and rural‐urban residence. Results showed that rural children were shorter‐statured, with lower overweight/obesity and cesarean delivery rates, compared to urban children. Household crowding was a negative predictor of anthropometric outcomes; the strongest effect was in boys and in urban children. Birthweight positively predicted anthropometric outcomes, especially weight/BMI. Birth mode was positively (not statistically) associated with any anthropometric outcome. Cesarean delivery was more common in boys than in girls, and predicted increased height in urban boys. In conclusion, urbanization and household crowding were the most powerful predictors of Maya 6‐year‐old anthropometry. The negative effects of crowding may disproportionately affect Maya boys versus girls and urban versus rural children. Early‐life conditions shape Maya children's nutritional status both in the “first” and “second” 1000 days.

Four-site skinfolds thickness percentiles of schoolchildren and adolescents in Turkey

OBJECTIVE

The primary purpose of the current study was to establish Turkish smoothed centile charts and Lambda, Mu, Sigma (LMS) tables for four-site skinfold thickness based on a population-based sample, and secondary purpose was to elaborate a reference for the percentage of body fat.

DESIGN

A cross-sectional and descriptive study was conducted between January and May 2017. Triceps, biceps and subscapular, suprailiac skinfold thicknesses were measured using Holtain skinfold caliper. Age- and gender-specific percentile values were determined with the LMS method, and body fat percentage was calculated using the Westrate and Deurenberg equation.

SETTING

Afyonkarahisar province in Turkey.

PARTICIPANTS

The current study was conducted on 4565, 6-18-year-old students.

RESULTS

The triceps, biceps and subscapular skinfolds of the girls were higher than the boys. From the age of seven, the sum of four skinfold thicknesses of the girls was more than those of the boys. This difference became more evident after the age of 12. Although fat percentages of girls showed a fluctuating change, it decreased with the age in boys. Westrate and Deurenberg equation fat percentages of girls until adolescence were lower than boys, but increased after 12 years of age and exceeded that of boys.

CONCLUSIONS

The current study has provided sex- and age-specific reference values for skinfold thickness and has shown that obesity in girls is higher than in boys in schoolchildren in Afyonkarahisar. The current study has also shown that skinfold thickness measurements are a valuable tool for screening obesity in children.

Impact of promoting healthy infant feeding practices on energy intake and anthropometric measures of children up to 6 years of age: A randomised controlled trial

BACKGROUND

The first 2 years of life are the window of opportunity to promote healthy feeding practices. Thus, the present study aimed to assess the impact of a health workers training in infant dietary guidelines on energy intake and anthropometric measurement into childhood.

METHODS

Cluster randomised field trial (NCT00635453) was conducted in Porto Alegre, Brazil. Healthcare centres were randomised into intervention (n = 9) and control (n = 11) groups. In intervention sites, health workers were trained to promote healthy feeding practices based on the Brazilian guideline for children's nutrition. Pregnant women who were in the last trimester of pregnancy were registered as potential mothers who would receive dietary counselling from the health workers. Energy and macronutrient intake and anthropometric measurements were obtained from children at ages 6 months, 12 months, 3 years and 6 years from low-income families.

RESULTS

At age 3 years, intervention group had lower consumption of energy [-92.5 kcal; 95% confidence interval (CI) = -153.5 to -31.5], carbohydrates (-11.9 g; 95% CI = -19.9 to -2.3), and total fat (-3.9 g; 95% CI = -6.2 to -1.2), compared to the control group. At 6 years of age, children in the intervention group had lower waist circumference (-1.3 cm; 95% CI = -2.7 to -0.0), triceps (-1.3 mm; 95% CI = -2.5 to -0.0) and subscapular skinfolds (-1.3 mm; 16 95% CI = -2.6 to -0.0) thickness measurements compared to those in the control group.

CONCLUSIONS

The health workers training to promote infant healthy feeding practices resulted in lower energy, carbohydrates and fat intake at 3 years and lower waist circumference, triceps and subscapular skinfolds measurements at 6 years.

The Influence of Maturity Status on Anthropometric Profile and Body Composition of Youth Goalkeepers

The anthropometric profile assessment is an important aspect to consider during the growth stages of youth sport practitioners due to its usefulness in controlling maturity status and overall health. We performed an anthropometric profile evaluation in a sample of youth goalkeepers (n = 42) during a training camp, dividing them into three categories based on their years from peak height velocity (YPHV). We also checked if the selection of goalkeepers was associated with the birth quartile. The results showed that most of the participants' anthropometric parameters followed the normal trend according to the maturation stages. However, several subjects showed an overweight/obese condition and/or high waist circumference. Non-optimal values were found, mostly in the group of goalkeepers around the PHV. In addition, no selection based on birth quartile was seen. Therefore, the anthropometric profile and body composition of youth goalkeepers are physiologically affected by maturity status. However, several subjects were found to be overweight/obese and at cardiometabolic risk, suggesting that children and adolescents, although practicing sport, should pay attention to potentially contributing factors such as the attainment of the recommended levels of physical activity, lowering sedentary time, and adopt a healthy lifestyle.

Diagnostic Accuracy of Body Mass Index in Defining Childhood Obesity: Analysis of Cross-Sectional Data from Ghanaian Children

Background: Screening methods for childhood obesity are based largely on the published body mass index (BMI) criteria. Nonetheless, their accuracy in African children is largely unknown. The diagnostic accuracies of the World Health Organization (WHO), the Centers for Disease Control and Prevention (CDC), and the International Obesity Taskforce (IOTF) BMI-based criteria in defining obesity using deuterium dilution as a criterion method in a sample of Ghanaian children are presented. Methods: Data on anthropometric indices and percent body fat were collected from 183 children aged 8–11 years. The sensitivity, specificity, and predictive values were calculated. The overall performance of the BMI criteria was evaluated using the receiver operating characteristics area under the curve (AUC). Results: Overall sensitivity of WHO, CDC, and IOTF were 59.4% (40.6–76.3), 53.1% (34.7–70.9), and 46.9% (29.1–65.3) respectively. The overall specificity was high, ranging from 98.7% by WHO to 100.0% by IOTF. The AUC were 0.936 (0.865–1.000), 0.924 (0.852–0.995), and 0.945 (0.879–1.000) by the WHO, CDC, and IOTF criteria respectively for the overall sample. Prevalence of obesity by the WHO, CDC, IOTF, and deuterium oxide-derived percent body fat were 11.5%, 10.4%, 8.2%, and 17.5% respectively, with significant positive correlations between the BMI z-scores and percent body fat. Conclusions: The BMI-based criteria were largely specific but with moderate sensitivity in detecting excess body fat in Ghanaian children. To improve diagnostic accuracy, direct measurement of body fat and other health risk factors should be considered in addition to BMI.

Developing an Impedance Based Equation for Fat-Free Mass of Black Preadolescent South African Children

Bioelectrical impedance analysis (BIA) is a practical alternative to dual-energy X-ray absorptiometry (DXA) for determining body composition in children. Currently, there are no population specific equations available for predicting fat-free mass (FFM) in South African populations. We determined agreement between fat-free mass measured by DXA (FFM_DXA) and FFM calculated from published multi-frequency bioelectrical impedance prediction equations (FFM_BIA); and developed a new equation for predicting FFM for preadolescent black South African children. Cross-sectional data on a convenience sample of 84 children (mean age 8.5 ± 1.4 years; 44 {52%} girls) included body composition assessed using Dual X-ray Absorptiometry (FFM_DXA) and impedance values obtained from the Seca mBCA 514 Medical Body Composition analyzer used to calculate FFM using 17 published prediction equations (FFM_BIA). Only two equations yielded FFM estimates that were similar to the DXA readings (p > 0.05). According to the Bland–Altman analysis, the mean differences in FFM (kg) were 0.15 (LOA: −2.68; 2.37) and 0.01 (LOA: −2.68; 2.66). Our new prediction equation, FFM=105.20+0.807×Sex+0.174×Weight+0.01×Reactance+15.71×log(RI), yielded an adjusted R² = 0.9544. No statistical shrinkage was observed during cross-validation. A new equation enables the BIA-based prediction of FFM in the assessment of preadolescent black South African children.

Vitamin D receptor gene polymorphisms are associated with triceps skin fold thickness and body fat percentage but not with body mass index or waist circumference in Han Chinese

Background

Evidence shows that low serum vitamin D concentrations account for an increased risk of obesity by inducing vitamin D receptor (VDR) hypofunction. Although the correlation between single nucleotide polymorphisms (SNPs) of VDR gene and obesity-related anthropometric measures (such as body mass index [BMI] and waist circumference[WC]) has already been tested, there are only few studies on the association between direct measures of body fat percentage (BFP) and triceps skinfold thickness and the SNPs of VDR. The aim of the present study was to evaluate the effect of VDR gene polymorphism on multiple obesity indexes in Han Chinese, including BMI, WC, BFP and triceps skinfold thickness.

Methods

In this cross-sectional study, five hundred and seventeen healthy Chinese adults were enrolled in the trial. Four loci in VDR gene (rs2228570 [FokI], rs2189480, rs2239179 and rs7975232[ApaI]) were genotyped by TaqMan probe assays. Obesity indexes including BMI, WC, BFP and triceps skinfold thickness were used to evaluate the relationship to the VDR SNPs. Multiple logistic regression, linear regression and general multifactor dimensionality reduction (GMDR) were performed to analyze the correlation of VDR gene and obesity indexes.

Results

None of the VDR SNPs were associated with BMI and WC, the C allele of FokI and the T allele of ApaI were associated with an increase in BFP (β = 0.069,P = 0.007; β = 0.087, P = 0.022 respectively); the G allele of rs2239179 and the T allele of ApaI were associated with an increase in triceps skin fold thickness (β = 0.074, P = 0.001; β = 0.122, P < 0.001 respectively). In regards to adiposity-related metabolic parameters, we found that the GT genotype of ApaI was associated with higher level of total cholesterol (TC) (P = 0.013) and Low-density lipoprotein cholesterol (LDL-C) (P = 0.001).

Conclusions

Though we failed to prove that VDR SNPs were in correlation with BMI and WC, we did establish the association between VDR variants and BFP, as well as triceps skinfold thickness. Data obtained suggested that the VDR variants play an important role in regulating adipose tissue activity and adiposity among Han Chinese.

Electronic supplementary material

The online version of this article (10.1186/s12944-019-1027-2) contains supplementary material, which is available to authorized users.

Ultra-processed food consumption and its effects on anthropometric and glucose profile: A longitudinal study during childhood

BACKGROUND AND AIMS

Obesity and insulin resistance development are related to known risk factors (such as diet) that begin in childhood. Among dietary factors, the consumption of ultra-processed foods has received attention. The present study investigated the association between ultra-processed foods consumption at preschool age and changes in anthropometric measurements from preschool to school age and glucose profile at school age.

METHODS AND RESULTS

The present study was a follow-up of a randomized controlled trial, conducted with 307 children of low socioeconomic status from São Leopoldo, Brazil. At ages 4 and 8 years, children's anthropometric assessments were collected from preschool to school age including body-mass index (BMI) for-age, waist circumference (WC), waist-to-height ratio (WHtR) and skinfold. At the age 8 years, blood tests were performed to measure glucose profile. Dietary data were collected through 24-h recalls and the children's ultra-processed food intake was assessed. Linear regression analysis was used to assess the relationship between ultra-processed food consumption and the outcomes. The percentage of daily energy provided by ultra-processed foods was 41.8 ± 8.7 (753.8 ± 191.0 kcal) at preschool age and 47.8 ± 8.9 (753.8 ± 191.0 kcal) at school age, on average. The adjusted linear regression analyses showed that ultra-processed food consumption at preschool age was a predictor of an increase in delta WC from preschool to school age (β = 0.07; 95%CI 0.01-0.14; P = 0.030), but not for glucose metabolism.

CONCLUSION

Our data suggest that early ultra-processed food consumption played a role in increasing abdominal obesity in children. These results reinforce the importance of effective strategies to prevent the excessive consumption of ultra-processed foods, especially in early ages.

Triponderal mass index rather than body mass index: An indicator of high adiposity in Italian children and adolescents

OBJECTIVE

The aims of this study were to compare body mass index (BMI) and triponderal mass index (TMI) as predictors of fat mass percentage (FM%) and to develop TMI cutoffs for screening high adiposity. Therefore, TMI- and BMI-based references against FM% criterion for indicating adiposity in Italian children and adolescents were compared.

METHODS

This was a cross-sectional study conducted at the University of Rome Tor Vergata, Human Nutrition Unit, from 2008 to 2015. The sample included 485 children and adolescents from 8 to 17 y of age from central-southern Italy. Body weight (kg) and height (m) were assessed to calculate BMI and TMI. FM% was assessed by dual-energy x-ray absorptiometry. The prevalence of high adiposity was based on the 75th percentile of FM%, according to Ogden et al. curves. Statistical tests such as Mann-Whitney, Kruskal-Wallis, polynomial regression, receiver operating characteristics curve, and Cohen's κ, were performed using SPSS version 24 and MedCalc version 18.

RESULTS

Prevalence of high adiposity according to FM% was 50.2% (95% confidence interval [CI], 43.2-57.2) in boys and 43.2% (95% CI, 37.3-49.2) in girls. TMI rather than BMI could better predict FM% for both sexes (boys R² = 0.67 and girls R² = 0.79 versus boys R² = 0.44 and girls R² = 0.74, respectively). TMI was found to present a significantly higher area under the curve than BMI for indicating high adiposity in children and adolescents. TMI sex- and age-specific cutoffs were responsible by better classification of adiposity, followed by the International Obesity Task Force, World Health Organization, and Cacciari reference curves.

CONCLUSION

TMI is a useful screening tool in pediatric clinical practice and epidemiologic studies concerning childhood obesity.

Association of Body Fat Mass and Fat Distribution With the Incidence of Hypertension in a Population-Based Chinese Cohort: A 22-Year Follow-Up

BACKGROUND

There have been few studies on the association between the incidence of hypertension and the presence and distribution of body fat. The aim of this article was to evaluate this association.

METHODS AND RESULTS

Data were obtained from the China Health Nutrition Survey, a 22-year cohort study of 12 907 participants. Body mass index and triceps skinfold thickness were used as markers of body fat, whereas waist circumference (WC) was used as a marker of fat distribution. Cox regression was used to examine the association of body mass index, WC, and skinfold thickness with the incidence of hypertension. The interval between the baseline and hypertension diagnosis was the time variable, and hypertension was the end event. The mean age and proportion of men and women were 38.29 and 38.03 years and 45.63% and 54.37%, respectively. Compared with normal WC, abdominal obesity was associated with hypertension (P<0.001; crude hazard ratio, 2.11; 95% confidence interval, 1.89-2.37). Similarly, overweight (crude hazard ratio, 1.75; 95% confidence interval, 1.64-1.87) and obesity (crude hazard ratio, 3.19; 95% confidence interval, 2.80-3.63) were risk factors for hypertension (all P<0.001). When stratified by sex, the results confirmed that WC and body mass index predicted the development of hypertension in both men and women but not skinfold thickness in women.

CONCLUSIONS

Body mass index and WC were independent risk factors for hypertension, but skinfold thickness was a poor marker of body fat and could not be used to predict hypertension.

Prevalence and Perception of Childhood Obesity in California's Farmworker Communities

In California's central valley, childhood obesity rates are above the national average. The majority of families living in the rural, agricultural communities of this region are immigrant of Mexican heritage, and face numerous social and environmental challenges. Demographic and anthropometric data were collected from a population of Mexican-heritage children 3-8 years (N = 609) and families (N = 466) living in two central valley communities. Overall, 45 % of children and 82 % of mothers were classified as overweight or obese. Multivariable analyses indicated that mother's BMI and acculturation level were positively associated with child BMI z-score. Most children classified as overweight or obese (92 % and 53 %, respectively) were perceived as having 'normal' weight by their mothers. Childhood obesity remains a major public health issue in Mexican-heritage, central valley communities. Our model indicates that mother's BMI is predictor of child obesity, and parents tend to underestimate their child's weight status. These findings highlight a need for family-targeted and culturally-tailored approaches to address relevant perceptions of obesity and risk factors in these communities.

Waist-to-height ratio and sedentary lifestyle as predictors of metabolic syndrome in children in Ecuador

OBJECTIVE

To determine the predictors and prevalence of metabolic syndrome (MS) and the presence of vascular inflammation in apparently-normal children (10-15 years) of both sexes in Guayaquil, Ecuador.

STUDY DESIGN AND METHODS

We included 395 apparently-healthy students from a middle-income school in a cross-sectional survey. Informed consent was obtained from students and parents. Anthropometric measurements including blood pressure (BP), body mass index (BMI) and waist-to-height ratio (WHtR), and blood tests were recorded. Vascular inflammation parameters were assessed. Percentiles of the different parameters were used, and MS was defined according to National Cholesterol Education Program Adult Treatment Panel III criteria (NCEP-ATPIII). Waist circumference>P 75, blood pressure>P 90, glucose>100mg/dl, triglycerides>100mg/dl, HDL<45mg/dl. If 3 of the 5 criteria were present, this was considered MS.

RESULTS

The mean age was 12 years (186 boys, 209 girls). The overall prevalence of MS was 9.37% (6.33% in girls, 3.04% in boys). Sustained hypertension was detected in 6.6% of children and pre-hypertension in 7.1%. Obesity was found in 1.8% of subjects, and overweight in 15.2%. Triglycerides has a RR 2.34 (1.97-2.76); HOMA index has a RR 1.97(1.62-2.40); HDL cholesterol has a RR 1.84(1.58-2.13); Insulin level has a RR 1.53(1.40-1.67) and interleukin 6 has RR 1.83(1.20-2.79). Serum glucose, total cholesterol and LDL-Cholesterol had no association with the metabolic syndrome. HDL-Cholesterol<45mg/dl and triglyceride>100mg/dl were present in 70% of subjects with MS. The WHtR threshold≥0.5 was 100% sensitive in both sexes (67% specificity in boys and 69% in girls). There were significant associations between the WHtR and pre-hypertension and sedentary lifestyle (P<0.001 and P<0.003 respectively). A WHtR value of ≥0.50 indicated a 2.2-fold increased risk of MS compared with normal WHtR, and normal weight.

CONCLUSIONS

A WHtR≥0.5 was 100% sensitive in detecting MS in 10-15 year-old boys and girls in the normal or overweight range of the BMI. This assessment is a simple and practical tool for use in population-based studies of cardiovascular risk. When combined with pre-hypertension and a sedentary lifestyle, the WHtR is highly sensitive in predicting MS.

Skinfold reference curves and their use in predicting metabolic syndrome risk in children

OBJECTIVES

To draw skinfold (SF) reference curves (subscapular, suprailiac, biceps, triceps) and to determine SF cutoff points for predicting the risk of metabolic syndrome (MetS) in children aged 6-10 years old.

METHODS

This was a cross-sectional study with a random sample of 1480 children aged 6-10 years old, 52.2% females, from public and private schools located in the urban and rural areas of the municipality of Uberaba (MG). Anthropometry, blood pressure, and fasting blood samples were taken at school, following specific protocols. The LMS method was used to draw the reference curves and ROC curve analysis to determine the accuracy and cutoff points for the evaluated skinfolds.

RESULTS

The four SF evaluated (subscapular, suprailiac, biceps, and triceps) and their sum (∑4SF) were accurate in predicting MetS for both girls and boys. Additionally, cutoffs have been proposed and percentile curves (p5, p10, p25, p50, p75, p90, and p95) were outlined for the four SF and ∑4SF, for both genders.

CONCLUSION

SF measurements were accurate in predicting metabolic syndrome in children aged 6-10 years old. Age- and gender-specific smoothed percentiles curves of SF provide a reference for the detection of risk for MetS in children.

Validity of segmental bioelectrical impedance analysis for estimating fat-free mass in children including overweight individuals

This study examined the validity of segmental bioelectrical impedance (BI) analysis for predicting the fat-free masses (FFMs) of whole-body and body segments in children including overweight individuals. The FFM and impedance (Z) values of arms, trunk, legs, and whole body were determined using a dual-energy X-ray absorptiometry and segmental BI analyses, respectively, in 149 boys and girls aged 6 to 12 years, who were divided into model-development (n = 74), cross-validation (n = 35), and overweight (n = 40) groups. Simple regression analysis was applied to (length)²/Z (BI index) for each of the whole-body and 3 segments to develop the prediction equations of the measured FFM of the related body part. In the model-development group, the BI index of each of the 3 segments and whole body was significantly correlated to the measured FFM (R² = 0.867-0.932, standard error of estimation = 0.18-1.44 kg (5.9%-8.7%)). There was no significant difference between the measured and predicted FFM values without systematic error. The application of each equation derived in the model-development group to the cross-validation and overweight groups did not produce significant differences between the measured and predicted FFM values and systematic errors, with an exception that the arm FFM in the overweight group was overestimated. Segmental bioelectrical impedance analysis is useful for predicting the FFM of each of whole-body and body segments in children including overweight individuals, although the application for estimating arm FFM in overweight individuals requires a certain modification.

Triceps and Subscapular Skinfold Thickness Percentiles and Cut-Offs for Overweight and Obesity in a Population-Based Sample of Schoolchildren and Adolescents in Bogota, Colombia

The assessment of skinfold thickness is an objective measure of adiposity. The aims of this study were to establish Colombian smoothed centile charts and LMS L (Box-Cox transformation), M (median), and S (coefficient of variation) tables for triceps, subscapular, and triceps + subscapular skinfolds; appropriate cut-offs were selected using receiver operating characteristic (ROC) analysis based on a population-based sample of children and adolescents in Bogotá, Colombia. A cross-sectional study was conducted in 9618 children and adolescents (55.7% girls; age range of 9-17.9 years). Triceps and subscapular skinfold measurements were obtained using standardized methods. We calculated the triceps + subscapular skinfold (T + SS) sum. Smoothed percentile curves for triceps and subscapular skinfold thickness were derived using the LMS method. ROC curve analyses were used to evaluate the optimal cut-off point of skinfold thickness for overweight and obesity, based on the International Obesity Task Force definitions. Subscapular and triceps skinfolds and T + SS were significantly higher in girls than in boys (p < 0.001). The ROC analysis showed that subscapular and triceps skinfolds and T + SS have a high discriminatory power in the identification of overweight and obesity in the sample population in this study. Our results provide sex- and age-specific normative reference standards for skinfold thickness values from a population from Bogotá, Colombia.

Association between Body Mass Index, Waist-to-Height Ratio and Adiposity in Children: A Systematic Review and Meta-Analysis

Obesity is defined as an abnormal or excessive fat accumulation that may impair health. Dual-energy X-ray absorptiometry (DEXA) has been suggested as the gold standard to define obesity, but because its use is complex and expensive, anthropometric measures such as body mass index (BMI) or the waist-to-height ratio (WtHr) have been used as alternatives. The aim of this study was to review the published literature and investigate the correlation of BMI and WtHr with body fat (BF) measured by DEXA in pediatric populations. References were sought in PubMed/Medline and Embase datasets. Five original articles, published between 2013 and 2015, were finally included in this review. Their sample size ranged from 83 to 5355, and the age of participants ranged from 4.9 to 19 years old. The most frequently reported association measurements were the coefficients of determination (R²), followed by correlation coefficients and least-squares regression coefficients. BF measured by DEXA was strongly correlated with both BMI (R² ranging from 0.32 to 0.91) and WtHr (R² ranging from 0.49 to 0.73). Thus, either BMI or WtHr may be useful to define obesity when more sophisticated techniques are not available. Our systematic review of the available literature found that neither index demonstrated superiority in assessing obesity in children.

Percentile curves for skinfold thickness for Canadian children and youth

Background. Skinfold thickness (SFT) measurements are a reliable and feasible method for assessing body fat in children but their use and interpretation is hindered by the scarcity of reference values in representative populations of children. The objective of the present study was to develop age- and sex-specific percentile curves for five SFT measures (biceps, triceps, subscapular, suprailiac, medial calf) in a representative population of Canadian children and youth.

Methods. We analyzed data from 3,938 children and adolescents between 6 and 19 years of age who participated in the Canadian Health Measures Survey cycles 1 (2007/2009) and 2 (2009/2011). Standardized procedures were used to measure SFT. Age- and sex-specific centiles for SFT were calculated using the GAMLSS method.

Results. Percentile curves were materially different in absolute value and shape for boys and girls. Percentile girls in girls steadily increased with age whereas percentile curves in boys were characterized by a pubertal centered peak.

Conclusions. The current study has presented for the first time percentile curves for five SFT measures in a representative sample of Canadian children and youth.

Auxological perspectives on 'growth' in DOHaD

David Barker established growth as a seminal link between early development and later health attainment and disease risk. This was nothing less than a paradigm shift in health and medicine, turning the focus of disease causality away from contemporary environmental influences to earliest growth as a time when functional anatomy and physiology sets in place critical structures and function for a lifetime. Barker's prodigious work investigated time- and place-specific interactions between maternal condition and exogenous environmental influences, focusing on how growth unfolds across development to function as a mechanistic link to ensuing health. Subsequent applications do not always attend to the specificity and sensitivity issues included in his original work, and commonly overlook the long-standing methods and knowledge base of auxology. Methodological areas in need of refinement include enhanced precision in how growth is represented and assessed. For example, multiple variables have been used as a referent for 'growth,' which is problematic because different body dimensions grow by different biological clocks with unique functional physiologies. In addition, categorical clinical variables obscure the spectrum of variability in growth experienced at the individual level. Finally, size alone is a limited measure as it does not capture how individuals change across age, or actually grow. The ground-breaking notion that prenatal influences are important for future health gave rise to robust interest in studying the fetus. Identifying the many pathways by which size is realized permits targeted interventions addressing meaningful mechanistic links between growth and disease risk to promote health across the lifespan.

Diagnostic performance of body mass index to identify obesity as defined by body adiposity in children and adolescents: a systematic review and meta-analysis

BACKGROUND

The ideal means of identifying obesity in children and adolescents has not been determined although body mass index (BMI) is the most widely used screening tool.

OBJECTIVE

We performed a systematic review and meta-analysis of studies assessing the diagnostic performance of BMI to detect adiposity in children up to 18 years.

METHODS

Data sources were EMBASE, MEDLINE, Cochrane, Database of Systematic Reviews Cochrane CENTRAL, Web of Science and SCOPUS up to March 2013. Studies providing measures of diagnostic performance of BMI and using body composition technique for body fat percentage measurement were included.

RESULTS

Thirty-seven eligible studies that evaluated 53 521 patients, with mean age ranging from 4 to 18 years were included in the meta-analysis. Commonly used BMI cut-offs for obesity showed pooled sensitivity to detect high adiposity of 0.73 (confidence interval [CI] 0.67-0.79), specificity of 0.93 (CI 0.88-0.96) and diagnostic odds ratio of 36.93 (CI 20.75-65.71). Males had lower sensitivity. Moderate heterogeneity was observed (I(2) = 48%) explained in meta-regression by differences across studies in race, BMI cut-off, BMI reference criteria (Center for Disease Control vs. International Obesity Task Force) and reference standard method assessing adiposity.

CONCLUSION

BMI has high specificity but low sensitivity to detect excess adiposity and fails to identify over a quarter of children with excess body fat percentage.

Body fat indices for identifying risk of hypertension in Indian children

BACKGROUND

High adiposity is major risk factor for hypertension. Various anthropometric indices are used to assess excess fatness.

OBJECTIVES

(1) To examine relationship of body mass index (BMI), waist circumference (WC), waist to height ratio (WHtR), triceps skin fold thickness (TSFT) and wrist measurements with blood pressure in children and adolescents 2) to suggest age- and gender-specific cutoffs for these indices in Indian children.

METHODS

Cross-sectional school-based study on a random sample of 6380 children (6-18 yr old, 3501 boys) from five major cities in India. Height, weight, waist and wrist circumference, TSFT, and blood pressure were recorded. Children with systolic blood pressure (BP) and/or Diastolic BP >95th percentile were classified as hypertensive.

RESULTS

Prevalence of overweight and obesity was 23.5% and 9.7%, respectively. Hypertension was observed in 5.6%. Multiple logistic regression (adjustments: age, gender) indicated double risk of hypertension for overweight and 7 times higher odds for obese than normal-weight children. Children with TSFT >95th centile for US children showed three times risk and with TSFT from 85th to 95th double risk of hypertension. Higher WC and WHtR exhibited 1.5 times risk and larger Wrist 1.3 times higher risk of hypertension (P<0.001). Receiver operating curve (ROC) analysis provided age-gender specific cut offs for the five indices to detect the risk of high BP. Area under ROC curves (AUC) for five indices were similar and greater in older age groups indicating equal sensitivity and specificity. Conclusion: Using age- and gender-specific cutoffs for BMI, TSFT, WC or WHtR may offer putative markers for early detection of hypertension.

CONCLUSION

Using age- and gender-specific cutoffs for BMI, TSFT, WC or WHtR may offer putative markers for early detection of hypertension.

Concordance of obesity classification between body mass index and percent body fat among school children in Saudi Arabia

Background

In Saudi Arabia, where childhood obesity is a major public health issue, it is important to identify the best tool for obesity classification. Hence, we compared two field methods for their usefulness in epidemiological studies.

Methods

The sample consisted of 874 primary school (grade I-IV) children, aged 6–10 years, and was obtained through a multi-stage random sampling procedure. Weight and height were measured, and BMI (kg/m²) was calculated. Percent body fat was determined with a Futrex analyzer that uses near infrared reactance (NIR) technology. Method specific cut-off values were used for obesity classification. Sensitivity, specificity, positive and negative predictive values were determined for BMI, and the agreement between BMI and percent body fat was calculated.

Results

Compared to boys, the mean BMI was higher in girls whereas the mean percent body fat was lower (p-values <0.0001). According to BMI, the prevalence of overweight or obesity was significantly higher in girls (34.3% vs. 17.3%); as oppose to percent body fat, which was similar between the sexes (6.6% vs. 7.0%). The sensitivity of BMI to classify overweight or obesity was high (boys =93%, girls = 100%); and its false-positive detection rate was also high (boys = 63%, girls = 81%). The agreement rate was low between these two methods (boys = 0.48, girls =0.24).

Conclusions

There is poor agreement in obesity classification between BMI and percent body fat, using NIR method, among Saudi school children.

A bedside measure of body composition in Duchenne muscular dystrophy

BACKGROUND

In clinical practice, monitoring body composition is a critical component of nutritional assessment and weight management in boys with Duchenne muscular dystrophy. We aimed to evaluate the accuracy of a simple bedside measurement tool for body composition, namely bioelectrical impedance analysis, in boys with Duchenne muscular dystrophy.

METHODS

Measures of fat-free mass were determined using a bioelectrical impedance analysis machine and compared against estimations obtained from a reference body composition model. Additionally, the use of raw impedance values was analyzed using three existing predictive equations for the estimation of fat-free mass. Accuracy of bioelectrical impedance analysis was assessed by comparison against the reference model by calculation of biases and limits of agreement.

RESULTS

Body composition was measured in 10 boys with Duchenne muscular dystrophy, mean age 9.01 ± 2.34 years. The bioelectrical impedance analysis machine values of fat-free mass were on average 2.3 ± 14.1 kg higher than reference values. Limits of agreement (based on 95% confidence interval of the mean) were -7.4 to 2.9 kg. There was a significant correlation between the mean fat-free mass and difference in fat-free mass between the bioelectrical impedance analysis machine and the reference model (r = -0.86; P = 0.02) suggesting that the bias was not consistent across the range of measurements. The most accurate predictive equation for the estimation of fat-free mass using raw impedance values was the equation by Pietrobelli et al. (mean difference, -0.7 kg; 95% limits of agreement, -3.5 to 2.0 kg).

CONCLUSIONS

In a clinical setting, where a rapid assessment of body composition is advantageous, the use of raw impedance values, combined with the equation by Pietrobelli et al., is recommended for the accurate estimation of fat-free mass, in boys with Duchenne muscular dystrophy.

Assessment of fat-free mass from bioelectrical impedance analysis in obese women with Prader-Willi syndrome

BACKGROUND

Fat-free mass (FFM) is lower in obese subjects with Prader-Willi syndrome (PWS) than in obese subjects without PWS. FFM prediction equations developed in non-PWS subjects may, thus, not work in PWS subjects.

AIM

To test whether the estimation of FFM from bioelectrical impedance analysis (BIA) in PWS subjects requires population-specific equations.

METHODS

Using dual-energy X-ray absorptiometry, this study measured FFM in 27 PWS and 56 non-PWS obese women and evaluated its association with the impedance index at 50 kHz (ZI50), i.e. the ratio between squared height and whole-body impedance at 50 kHz.

RESULTS

At the same level of ZI50, PWS women had a lower FFM than non-PWS women. However, when PWS-specific equations were used, FFM was accurately estimated at the population level. An equation employing a dummy variable coding for PWS status was able to explain 85% of the variance of FFM with a root mean squared error of 3.3 kg in the pooled sample (n = 83).

CONCLUSION

Population-specific equations are needed to estimate FFM from BIA in obese PWS women.

Validity of bioelectrical impedance measurement in predicting fat-free mass of Chinese children and adolescents

Background

The current study aimed to examine the validity of various published bioelectrical impedance analysis (BIA) equations in estimating FFM among Chinese children and adolescents and to develop BIA equations for the estimation of fat-free mass (FFM) appropriate for Chinese children and adolescents.

Material/Methods

A total of 255 healthy Chinese children and adolescents aged 9 to 19 years old (127 males and 128 females) from Tianjin, China, participated in the BIA measurement at 50 kHz between the hand and the foot. The criterion measure of FFM was also employed using dual-energy X-ray absorptiometry (DEXA). FFM estimated from 24 published BIA equations was cross-validated against the criterion measure from DEXA. Multiple linear regression was conducted to examine alternative BIA equation for the studied population.

Results

FFM estimated from the 24 published BIA equations yielded high correlations with the directly measured FFM from DEXA. However, none of the 24 equations was statistically equivalent with the DEXA-measured FFM. Using multiple linear regression and cross-validation against DEXA measurement, an alternative prediction equation was determined as follows: FFM (kg)=1.613+0.742×height (cm)2/impedance (Ω)+0.151×body weight (kg); R²=0.95; SEE=2.45kg; CV=6.5, 93.7% of the residuals of all the participants fell within the 95% limits of agreement.

Conclusions

BIA was highly correlated with FFM in Chinese children and adolescents. When the new developed BIA equations are applied, BIA can provide a practical and valid measurement of body composition in Chinese children and adolescents.

Anthropometry and physical activity level in the prediction of metabolic syndrome in children

OBJECTIVE

To evaluate the effectiveness of anthropometric measures and physical activity level in the prediction of metabolic syndrome (MetS) in children.

DESIGN

Cross-sectional study with children from public and private schools. Children underwent an anthropometric assessment, blood pressure measurement and biochemical evaluation of serum for determination of TAG, HDL-cholesterol and glucose. Physical activity level was calculated and number of steps per day obtained using a pedometer for seven consecutive days.

SETTING

Viçosa, south-eastern Brazil.

SUBJECTS

Boys and girls (n 187), mean age 9·90 (SD 0·7) years.

RESULTS

Conicity index, sum of four skinfolds, physical activity level and number of steps per day were accurate in predicting MetS in boys. Anthropometric indicators were accurate in predicting MetS for girls, specifically BMI, waist circumference measured at the narrowest point and at the level of the umbilicus, four skinfold thickness measures evaluated separately, the sum of subscapular and triceps skinfold thickness, the sum of four skinfolds and body fat percentage.

CONCLUSIONS

The sum of four skinfolds was the most accurate method in predicting MetS in both genders.

Effects of BMI, fat mass, and lean mass on asthma in childhood: a Mendelian randomization study

BACKGROUND

Observational studies have reported associations between body mass index (BMI) and asthma, but confounding and reverse causality remain plausible explanations. We aim to investigate evidence for a causal effect of BMI on asthma using a Mendelian randomization approach.

METHODS AND FINDINGS

We used Mendelian randomization to investigate causal effects of BMI, fat mass, and lean mass on current asthma at age 7½ y in the Avon Longitudinal Study of Parents and Children (ALSPAC). A weighted allele score based on 32 independent BMI-related single nucleotide polymorphisms (SNPs) was derived from external data, and associations with BMI, fat mass, lean mass, and asthma were estimated. We derived instrumental variable (IV) estimates of causal risk ratios (RRs). 4,835 children had available data on BMI-associated SNPs, asthma, and BMI. The weighted allele score was strongly associated with BMI, fat mass, and lean mass (all p-values<0.001) and with childhood asthma (RR 2.56, 95% CI 1.38-4.76 per unit score, p = 0.003). The estimated causal RR for the effect of BMI on asthma was 1.55 (95% CI 1.16-2.07) per kg/m2, p = 0.003. This effect appeared stronger for non-atopic (1.90, 95% CI 1.19-3.03) than for atopic asthma (1.37, 95% CI 0.89-2.11) though there was little evidence of heterogeneity (p = 0.31). The estimated causal RRs for the effects of fat mass and lean mass on asthma were 1.41 (95% CI 1.11-1.79) per 0.5 kg and 2.25 (95% CI 1.23-4.11) per kg, respectively. The possibility of genetic pleiotropy could not be discounted completely; however, additional IV analyses using FTO variant rs1558902 and the other BMI-related SNPs separately provided similar causal effects with wider confidence intervals. Loss of follow-up was unlikely to bias the estimated effects.

CONCLUSIONS

Higher BMI increases the risk of asthma in mid-childhood. Higher BMI may have contributed to the increase in asthma risk toward the end of the 20th century. Please see later in the article for the Editors' Summary.

Physical fitness and exercise training on individuals with spina bifida: a systematic review

Spina Bifida (SB) is characterized by several physical impairments; however, data on physical fitness and on the benefits of exercise training in individuals with SB are dispersed in the literature. Thus, this systematic review aimed to describe (i) physical fitness components (cardiorespiratory endurance, muscle strength, body composition, flexibility and neuromotor) and (ii) exercise training effects on the physical fitness of individuals with SB. CINAHL, MEDLINE and EMBASE were searched from January to March 2013 and updated in December 2013. Twenty-three studies were included. A summary of the results was performed using a best-evidence synthesis. Participants with SB had lower cardiorespiratory endurance (-32 to 54% in VO2 peak) and muscle strength (-58 to 90%) and higher body fat (159%) than their healthy peers. Mobility restrictions were present in 26.3-61% of participants. No data on neuromotor fitness were found. Aerobic and strength training improved participants' cardiorespiratory endurance (effect sizes 0.78-1.4) and muscle strength (effect sizes 0-0.59). Individuals with SB have impaired cardiorespiratory endurance, muscle strength, body composition and flexibility when compared to healthy peers. Exercise training seems to improve two of these fitness components (cardiorespiratory endurance and muscle strength). Nevertheless, the heterogeneity of the studies' designs, methods and instruments used limits the establishment of firm conclusions and highlights the need for further research.

Is Physical Fitness Associated with Health in Overweight and Obese Youth? A Systematic Review

A systematic review of literature was conducted to examine the association between changes in health-related fitness (e.g. aerobic capacity and muscular strength /endurance) and chronic disease risk factors in overweight and/or obese youth. Studies published from 2000-2010 were included if the physical activity intervention was a randomized controlled trial and reported changes in fitness and health outcomes by direction and significance (p< 0.05) of the effect. Aerobic capacity improved in 91% and muscular fitness improved in 82% of measures reported. Nearly all studies (32 of 33) reported improvement in at least one fitness test. Changes in outcomes related to adiposity, cardiovascular, musculoskeletal, metabolic, and mental/emotional health improved in 60%, 32%, 53%, 41%, and 33% of comparisons studied, respectively. In conclusion, overweight and obese youth can improve physical fitness across a variety of test measures. When fitness improves, beneficial health effects are observed in some, but not all chronic disease risk factors.

Bioelectrical impedance analysis to estimate body composition in children and adolescents: a systematic review and evidence appraisal of validity, responsiveness, reliability and measurement error

Bioelectrical impedance analysis (BIA) is a practical method to estimate percentage body fat (%BF). In this systematic review, we aimed to assess validity, responsiveness, reliability and measurement error of BIA methods in estimating %BF in children and adolescents.We searched for relevant studies in Pubmed, Embase and Cochrane through November 2012. Two reviewers independently screened titles and abstracts for inclusion, extracted data and rated methodological quality of the included studies. We performed a best evidence synthesis to synthesize the results, thereby excluding studies of poor quality. We included 50 published studies. Mean differences between BIA and reference methods (gold standard [criterion validity] and convergent measures of body composition [convergent validity]) were considerable and ranged from negative to positive values, resulting in conflicting evidence for criterion validity. We found strong evidence for a good reliability, i.e. (intra-class) correlations ≥0.82. However, test-retest mean differences ranged from 7.5% to 13.4% of total %BF in the included study samples, indicating considerable measurement error. Our systematic review suggests that BIA is a practical method to estimate %BF in children and adolescents. However, validity and measurement error are not satisfactory.

Distribuição da gordura corporal em escolares: um estudo usando o método LMS

INTRODUÇÃO: A avaliação do sobrepeso e obesidade em populações ainda tem sido baseada predominantemente no índice de massa corporal, o qual tem sido considerado o indicador universal da adiposidade. OBJETIVO: Analisar a distribuição da gordura corporal de escolares de sete a 10 anos, por meio da construção de referenciais percentílicos das dobras cutâneas, utilizando os parâmetros LMS. MÉTODO: Os dados são relativos a uma amostra representativa de escolares de sete a 10 anos frequentando escolas públicas e privadas, que participaram de pesquisa mais ampla de prevalência do sobrepeso e obesidade, realizada em 2002, em Florianópolis (Santa Catarina, Brasil), e composta por 2.918 crianças. Para este estudo utilizaram-se os dados antropométricos de estatura, dobras cutâneas subescapular, suprailíaca, tricipital e panturrilha medial. O método LMS, que visa normalizar os dados que apresentam assimetria em sua distribuição, foi utilizado para analisar e comparar a distribuição das dobras por faixa etária e sexo. RESULTADOS: Ambos os sexos apresentaram valores maiores de gordura subcutânea na região do tríceps e da panturrilha, porém, no sexo masculino estes foram inferiores aos das meninas e com pouco incremento ao longo da faixa etária investigada. A dobra que apresentou maior incremento nos valores medianos foi a suprailíaca, para o sexo feminino, a qual alcançou valores próximos aos da dobra tricipital aos 10 anos de idade. CONCLUSÕES: O método LMS propicia a análise da distribuição dos valores das dobras cutâneas, as quais são importantes para avaliar a evolução da gordura corporal e o estado nutricional de crianças.

A reduction in body mass index lowers risk for bilateral slipped capital femoral epiphysis

BACKGROUND

Slipped capital femoral epiphysis (SCFE) is occurring in greater numbers, at increasingly younger ages, and more frequently bilaterally (BL-SCFE). Obesity is one risk factor for SCFE. However, it is unclear whether postoperative decreases or increases in body mass index (BMI) alter the risk of subsequent contralateral SCFE.

QUESTIONS/PURPOSES

We therefore determined whether (1) BMI percentile was a risk factor for BL-SCFE; and (2) postoperative increases and/or decreases in BMI percentile influenced the risk for BL-SCFE.

METHODS

We retrospectively reviewed the records of 502 patients surgically treated for SCFE and identified 138 (27%) with BL-SCFE and 364 (73%) with unilateral SCFE (UL-SCFE); 173 patients, 60 (35%) with BL-SCFE and 113 (65%) with UL-SCFE met our inclusion criteria. Risk factors included sex, age, slip stability, slip chronicity, slip angle, and obesity. Percentile BMI was recorded at the time of first SCFE surgery, at the time of last followup for patients undergoing UL-SCFE, and at the time of second SCFE surgery for patients undergoing BL-SCFE.

RESULTS

Sex, age, slip stability, and slip angle were not associated with BL-SCFE. Postoperative obesity (odds ratio [OR], 3.5; 95% confidence interval [CI], 1.2-9.7) and acute slip chronicity (OR, 2.9; 95% CI, 1.3-6.7) had higher risks for sequential BL-SCFE. Obese patients who became nonobese postoperatively had a decreased risk of sequential BL-SCFE compared with those who remained obese (OR, 0.16; 95% CI, 1.2-116.5).

CONCLUSIONS

Only postoperative obesity and an acute slip were risk factors for sequential BL-SCFE. BMI reduction to lower than the 95% percentile after SCFE surgery was associated with lower risk for BL-SCFE development. The data suggest early supervised therapeutic weight management programs for patients treated for UL-SCFE are important to reduce risk of subsequent SCFE.

LEVEL OF EVIDENCE

Level III, prognostic study. See Guidelines for Authors for a complete description of levels of evidence.

Waist circumference-to-height ratio predicts adiposity better than body mass index in children and adolescents

OBJECTIVE

Body mass index (BMI) is the surrogate measure of adiposity most commonly employed in children and adults. Waist circumference (WC) and the waist circumference-to-height ratio (WCHt) have been proposed as markers of adiposity-related morbidity in children. However, no study to date has compared WCHt, WC, BMI and skinfolds thickness for their ability to detect body adiposity.

AIM

To compare WCHt, WC, BMI and skinfolds for their accuracy in predicting percent body fat (PBF), percent trunk fat (PTF) and fat mass index (FMI) in a large sample of children and adolescents.

DESIGN, SETTING AND PARTICIPANTS

We studied 2339 children and adolescents aged 8-18 years from the US National Health and Nutrition Examination Survey 2003/2004. Body fat was measured using dual-energy X-ray absorptiometry. Multivariable regression splines were used to model the association between PBF, PTF, FMI and the predictors of interest.

RESULTS

WCHt alone explained 64% of PBF variance as compared with 31% for WC, 32% for BMI and 72% for the sum of triceps and subscapular skinfolds (SF2) (P<0.001 for all). When age and gender were added to the predictors, the explained variance increased to 80% for the WCHt model, 72% for the WC model, 68% for the BMI model and 84% for the SF2 model. There was no practical advantage to add the ethnic group as further predictor. Similar relationships were observed with PTF and FMI.

CONCLUSIONS

WCHt is better than WC and BMI at predicting adiposity in children and adolescents. It can be a useful surrogate of body adiposity when skinfold measurements are not available.

Percentiles of percentage body fat in german children and adolescents: an international comparison

Background:

Age- and gender-specific percentiles of body mass index in children and adolescents are a cornerstone categorizing overweight and obesity in youths worldwide. Since corresponding worldwide growth curves of percent body fat (% BF) are missing, the purpose was to contribute smoothed percentiles of percentage body fat from a large urban sample of German youths and to include them in actual national and international percentile curves.

Methods:

We estimated % BF in 22 113 German youths aged 3 to 18 years participating in yearly cross-sectional surveys of the PEP Family Heart Study Nuremberg between 1993 and 2007. Percentage body fat was calculated from skinfold thickness using Slaughter equations. Ten smoothed percentile curves were constructed for % BF using the LMS method significant.

Results:

The age- and gender-specific reference curves demonstrate a continuous age-dependent increase of percentage body fat from age 3 to 18 years in girls; whereas in boys, the percentile curves steeply increase from 5 to 11 years and thereafter slightly decrease. The shape of the percentile curves, the maxima among boys at puberty and the median % BF at age 18 years are consistent with most of the current growth curves. % BF in urban studies seems to be lower than in national surveys .

Conclusions:

More than these nine studies should contribute to worldwide-standardized growth charts for % BF to better define overweight and obesity in youth.

Neto CS. Excesso de peso em crianças: comparação entre o critério internacional e nacional de classificação do índice de massa corpórea

OBJETIVO: Avaliar o desempenho dos pontos de corte para o índice de massa corpórea recomendados por Cole et al e Conde e Monteiro para diagnosticar o excesso de peso em crianças. MÉTODOS: A amostra foi composta por 585 escolares com idades entre seis e nove anos, do município de Ponta Grossa, no estado do Paraná. Foram realizadas medidas de peso, estatura e da dobra cutânea subescapular, a qual foi considerada como padrão-ouro para a caracterização do excesso de adiposidade, utilizando como ponto de corte o percentil 85 da curva de referência do National Center for Health Statistics. Foram calculados a sensibilidade, a especificidade e os valores preditivos positivo e negativo dos critérios de classificação do índice de massa corpórea desenvolvidos por Cole et al e Conde e Monteiro. RESULTADOS: A prevalência do excesso de peso foi de 20,7 e 28,9%, de acordo com os critérios de Cole et al e de Conde e Monteiro, respectivamente. Independentemente da idade analisada, a sensibilidade do critério nacional foi superior ao internacional para o sexo masculino, com extensão de 53,3 a 100,0% versus 33,3 a 92,3%, e semelhante para o feminino, variando de 68,4 a 100,0% para ambos os critérios. Em contrapartida, os pontos de corte de Cole et al apresentaram especificidade superior aos de Conde e Monteiro em ambos os sexos, variando de 87,3 a 98,4% versus 74,6 a 93,5%. CONCLUSÕES: Tanto o critério internacional quanto o nacional apresentaram resultados satisfatórios para o diagnóstico do excesso de peso em crianças brasileiras. Entretanto, o critério de Conde e Monteiro mostrou-se mais sensível, acarretando menor número de falsos-negativos.

Body mass index and percentage of body fat as indicators for obesity in an adolescent athletic population

Background:

Body mass index (BMI) is widely accepted in determining obesity. Skinfold thickness measurements have been commonly used to determine percentage of body fat.

Hypothesis:

The authors hypothesize that because BMI does not measure fat directly but relies on body weight alone, a large percentage of athletic adolescents will be misclassified as obese by BMI.

Design:

Cross-sectional study.

Methods:

To compare BMI and skinfold measurements as indicators for obesity in the adolescent athletic population, anthropometric data (height, weight, percentage body fat, age, and sex) were recorded from 33 896 student athletes (average age, 15 years; range, 11-19 years) during preparticipation physical examinations from 1985 to 2003. BMI was calculated from height and weight. Percentage of body fat was determined by measuring skinfold thickness.

Results:

According to their BMI percentile, 13.31% of adolescent athletes were obese. Using the skinfold method, only 5.95% were obese. Of those classified as obese by the BMI, 62% were considered false positives by the skinfold method. In contrast, there was a 99% probability that the nonobese by BMI would not be obese by the skinfold method (negative predictive value = 0.99).

Conclusions:

BMI is a measurement of relative body weight, not body composition. Because lean mass weighs far more than fat, many adolescent athletes are incorrectly classified as obese based on BMI. Skinfold testing provides a more accurate body assessment than BMI in adolescent athletes.

Clinical Relevance:

Correct body composition data can help to provide better diet and activity guidelines and prevent the psychological problems associated with being labeled as obese.

Components of the diet associated with child adiposity: a cross-sectional study

OBJECTIVE

This study sought to determine which components of youths' diets were related to adiposity while controlling for potential often-neglected confounders such as moderate to vigorous physical activity (MVPA) and dietary reporting error. Secondary goals of this study were to determine the extent to which MVPA confounded the associations between diet and adiposity and whether associations between diet and adiposity would differ depending on reporting error.

METHODS

An ethnically diverse urban sample of 342 children aged 9-10 years and 323 adolescents aged 17-18 years were recruited for this cross-sectional study. Body mass index (BMI) and waist circumference (WC) were measured in the school; dietary assessment included three 24-hour recalls via telephone in the evenings, and MVPA assessment included 5 days of accelerometry. Over (n = 68), under (n = 250), or plausible (n = 347) dietary intake reporters were identified with the Huang calculation method. Linear regression assessed the relationship between adiposity indicators (BMI z-score and WC) and components of the diet (energy intake, food groups, macronutrients) after controlling for reporting error, demographic variables, and MVPA.

RESULTS

When dietary reporting error and potential confounders such as MVPA and demographic variables were controlled, energy intake (EI), vegetables, refined grains, total fat, total protein, and total carbohydrate were positively related to BMI z-score and WC and artificially sweetened beverages to WC. MVPA was a significant confounder. For BMI z-score, but not WC, relationships and strength of these relationships differed depending on dietary reporting error group (plausible, underreporter, overreporter).

CONCLUSIONS

Among plausible reporters, as expected, EI, refined grains, and all macronutrients were positively related to adiposity; however, artificially sweetened beverages and vegetables, which are low-energy-dense foods, were also positively related to adiposity. Reporting error interfered with associations between diet and BMI z-score but not WC, suggesting WC is a more robust measure of adiposity in relation to diet.

Comparison of body mass index and triceps skinfold at 5 years and young adult body mass index, waist circumference and blood pressure

AIM

To examine which measure of obesity at 5 years, body mass index (BMI) or triceps skinfold thickness, is most strongly associated with 21-year risk factors for cardiovascular disease (CVD), including BMI, waist circumference (WC), systolic blood pressure (SBP) and diastolic blood pressure (DBP).

METHODS

Longitudinal birth cohort study with BMI and triceps skinfold measurements at age 5, and BMI, WC and blood pressure at 21 years. Overweight and obesity at 5 years were determined according to Cole-International Obesity Task Force standards, at 21, by World Health Organization definitions. Triceps skinfold thickness measurements were converted to a z-score, and cut-offs for overweight and obesity were chosen to reflect similar proportions to the BMI subgroups. BMI, WC, SBP and DBP were also measured at 21 years.

RESULTS

Five-year BMI and triceps skinfold thickness were both significantly associated with the CVD risk measures at 21 years. For overweight/obesity at 5 years, the adjusted odds ratio (95% confidence interval) for 21-year overweight/obesity was 5.6 (4.2, 7.4), for 21-year WC was 1.5 (1.2, 2.0). Mean difference (95% CI) in BMI was 4.4 (3.9, 5.0), in WC 8.3 cm (6.8, 9.8), in SBP 2.4 mm Hg (0.5, 4.3), in DBP 1.1 mm Hg (0.1, 2.2). For skinfold, the similar findings were odds ratio 2.6 (2.0, 3.4) and 1.2 (0.9, 1.6) for 21-year BMI and WC, and mean differences of 2.6 (2.0, 3.2), WC 4.8 cm (3.3, 6.3), SBP 2.3 mm Hg (0.5, 4.2) and DBP 0.7 mm Hg (-0.4, 1.8).

CONCLUSIONS

In children with overweight/obesity, BMI rather than triceps skinfold is the preferred epidemiological measure for identifying young adult CVD risk markers of BMI, WC and blood pressure.

Distribution of skinfold thickness and blood pressure among children and adolescents in Shandong, China

This article reported the distribution of skinfold thickness (SFT) and blood pressure (BP) among children and adolescents in Shandong, China. A total of 8568 students (4333 boys and 4235 girls) aged 7-18 years participated in this study. Triceps and subscapular SFT and BP of all subjects were measured, the sum of Triceps and subscapular SFT (SSFT) was used as an indicator of the overall SFT. The overall prevalence of relative high BP was 24.07% for boys and 22.36% for girls. The prevalence of relative high BP was increasing with SSFT percentiles, this trend was obvious especially in upper percentiles of SSFT. The prevalence of relative high BP increased from 13.27% (boys) and 13.33% (girls) in <5th SSFT percentile group to 55.50% (boys) and 48.17% (girls) in ≥95th SSFT percentile group, which increased by 3.2 and 2.6 times. There is a higher level of SSFT and higher prevalence of relative high BP among children and adolescents in Shandong, China.

Randomized controlled study of home-based treadmill training for ambulatory children with spina bifida

BACKGROUND

Many ambulatory children with spina bifida (SB) decline in their walking despite stable or even improved motor function.

OBJECTIVE

The authors evaluated the effects of a home-based treadmill training program on both ambulatory function and aerobic fitness.

METHODS

This randomized clinical trial of 34 ambulatory children with SB allocated 18 to supervised treadmill training for 12 weeks at home and 14 to usual care. Patients in home training exercised twice a week at an intensity of 66% of HR(peak) (peak heart rate) and gradually progressed from 70% to 140% of their individual walking speed. Main outcome measures were obtained at baseline, after intervention, and 3 months postintervention. Ambulation was measured using the 6-minute walk test (6MWT), during which gross energy consumption (ECS(gross)) and energy cost were calculated. Maximal exercise capacity was measured using an incremental treadmill test. Both VO(2peak) and speed(peak) were recorded as outcome parameters.

RESULTS

After training, significant changes were seen between the groups for 6MWT (P = .002; d = 1.08), speed(peak) (P = .001; d = 1.14), VO(2peak) (P = .034; d = 0.78), and ECS(gross) (P = .004; d = 1.01). Long-term effects were recorded for 6MWT (P = .003; η = 0.34), speed(peak) (P = .003; η = 0.35), and ECS(gross) (P = .014; η = 0.29) but not for VO(2peak).

CONCLUSION

A home-based, progressive treadmill training program for ambulatory children with SB has a large long-term effect on ambulation, with a moderate short-term effect on VO(2peak).

Overeating styles and adiposity among multiethnic youth

Reasons for inconsistent associations between overeating styles and adiposity among youth may include differences in effects by age, gender, or ethnicity; failure to control for social desirability of response; or adiposity measurement limitations. This study examined the relationship between overeating styles and multiple measures of adiposity, after controlling for social desirability and testing for moderation by ethnicity, age, and gender. Data from 304 9-10 year old children and 264 17-18 year old adolescents equally representing African American, Hispanic, and White ethnic groups were extracted from a larger cross-sectional study. Measures included the Dutch Eating Behavior Questionnaire (restrained, external, and emotional overeating subscales), the "Lie Scale" from the Revised Children's Manifest Anxiety Scale, and measured weight, height, waist circumference, and triceps skinfold. BMI z-score and a global adiposity index were calculated. Mixed model linear regression showed restraint was positively and external eating was negatively related to measures of adiposity. African American youth had a stronger inverse association between emotional eating and adiposity than White or Hispanic youth. Relationships were not influenced by social desirability nor moderated by age or gender. Overeating styles are related to adiposity in nearly all youth but the nature of these associations are moderated by ethnicity.

Dairy and milk consumption and child growth: Is BMI involved? An analysis of NHANES 1999-2004

Humans are unique among mammals in that many consume cow's milk or other dairy products well beyond the traditional age of weaning. Milk provides various nutrients and bioactive molecules to support growth and development, and the question arises as to whether this dietary behavior influences growth parameters. There is evidence that milk makes positive contributions to growth in height, but its associations with other aspects of body size, such as body mass index (BMI), are not well-established. National Health and Nutrition Examination Survey (NHANES) data from 1999 to 2004 and multivariate regression analysis were used to test the hypothesis that milk (g) or total dairy product consumption (kJ) is associated with higher BMI percentile among US White, Black, and Mexican-American children of age 2-4 years (n = 1,493) and 5-10 years (n = 2,526). Younger children in the highest quartile of dairy intake had higher BMIs (beta = 7.5-8.0; P < 0.01) than those in the lowest two quartiles. Controlling for energy intake eliminated differences between QIV and QI. Among children of 5-10 years of age dairy intake had no relationship to BMI. Young children in the highest quartile of milk intake had higher BMIs than all lower quartiles (beta = 7.1-12.8; beta = 6.3-11.8 in energy-controlled models; P < 0.05). Among children of 5-10 years of age, those in QIV for milk intake had higher BMIs than those in QII (beta = 8.3; beta = 7.1 in energy-controlled model; P < 0.01). Controlling for total protein or calcium did not change the results. Milk had more consistent positive associations with BMI than did dairy products, and these were strongest among children of 2-4 years of age.

Accuracy of simple clinical and epidemiological definitions of childhood obesity: systematic review and evidence appraisal

The optimum means of defining obesity in children is unclear, creating variation in practice, and hindering obesity surveillance, prevention and treatment. This study aimed to review evidence on the use of body mass index (BMI) and waist circumference for diagnosis of high body fat content and adverse cardiometabolic risk factors in children and adolescents. A systematic literature review was carried out and evidence appraised using the Quality Assessment of Studies of Diagnostic Accuracy in Systematic Reviews method. Literature searching began following the last systematic review of this topic (end 2001) and collected evidence in MEDLINE and EMBASE in 0- to 18-year-olds that compared the accuracy of BMI vs. waist circumference and compared BMI interpreted relative to national reference data vs. BMI interpreted relative to Cole/International Obesity Task Force international reference data. Ten studies compared diagnostic accuracy of BMI vs. waist circumference: they reported no improved identification of adverse cardiometabolic risk profiles from waist circumference over that provided by high BMI. Eight studies compared BMI with national reference data vs. the international approach: 5/8 found significantly poorer accuracy (lower sensitivity) using BMI with the international approach; 3/8 found similar sensitivity; in 7/7 studies that compared specificity this was similar. In conclusion, the present review provides no compelling evidence for use of either high waist circumference or BMI interpreted using the International Obesity Task Force approach in preference to the use of national BMI percentiles for the identification of children and adolescents with excess fatness and adverse cardiometabolic risk profile.

Estimation of percentage body fat in 6- to 13-year-old children by skinfold thickness, body mass index and waist circumference

We evaluated the accuracy of skinfold thicknesses, BMI and waist circumference for the prediction of percentage body fat (PBF) in a representative sample of 372 Swiss children aged 6-13 years. PBF was measured using dual-energy X-ray absorptiometry. On the basis of a preliminary bootstrap selection of predictors, seven regression models were evaluated. All models included sex, age and pubertal stage plus one of the following predictors: (1) log-transformed triceps skinfold (logTSF); (2) logTSF and waist circumference; (3) log-transformed sum of triceps and subscapular skinfolds (logSF2); (4) log-transformed sum of triceps, biceps, subscapular and supra-iliac skinfolds (logSF4); (5) BMI; (6) waist circumference; (7) BMI and waist circumference. The adjusted determination coefficient (R² adj) and the root mean squared error (RMSE; kg) were calculated for each model. LogSF4 (R² adj 0.85; RMSE 2.35) and logSF2 (R² adj 0.82; RMSE 2.54) were similarly accurate at predicting PBF and superior to logTSF (R² adj 0.75; RMSE 3.02), logTSF combined with waist circumference (R² adj 0.78; RMSE 2.85), BMI (R² adj 0.62; RMSE 3.73), waist circumference (R² adj 0.58; RMSE 3.89), and BMI combined with waist circumference (R² adj 0.63; RMSE 3.66) (P < 0.001 for all values of R² adj). The finding that logSF4 was only modestly superior to logSF2 and that logTSF was better than BMI and waist circumference at predicting PBF has important implications for paediatric epidemiological studies aimed at disentangling the effect of body fat on health outcomes.

Anthropometric correlates of lipoprotein profile and blood pressure in high BMI African American children

OBJECTIVE

To explore the association of anthropometric indices with lipoprotein profile and blood pressure as risk factors of cardiovascular disease, in African American (AA) children.

METHODS

A cross-sectional analysis was carried out on children aged 9-13 years with BMI >85th percentile. Height, weight, waist and hip circumferences, % body fat and blood pressure [systolic (sBP) and diastolic (dBP)] were measured. Fasting plasma levels of triglycerides (TG), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), intermediate density lipoprotein cholesterol (IDL-C) and very low-density lipoprotein cholesterol (VLDL-C) were analysed.

RESULTS

After accounting for age, gender and pubertal status of the child, multiple linear regression models showed that waist circumference and BMIz were strong predictors for lipoprotein variables. In independent analysis, waist circumference and BMI z-scores were found to be interdependently associated with TG, LDL-C:HDL-C ratio, VLDL-C and sBPz. However, for HDL-C, TG:HDL-C ratio and dBPz, waist circumference was independently and more strongly associated with these risk factors than BMI.

CONCLUSION

Waist circumference was a stronger predictor for lipoprotein variables and blood pressure in high BMI AA children than other anthropometric indices, and may be adequate as a screening test to identify children who are at increased risk for cardiovascular disease.