Waist circumference and waist-to-height ratio of Hong Kong Chinese children

Changing epidemiology of metabolic syndrome and type 2 diabetes in Chinese youth

China is gradually taking its place as one of the world's economic giants and concurrently learning to understand how to bear the burdens of diseases that are more common in the fully developed world, such as pediatric obesity, metabolic syndrome, and type 2 diabetes mellitus. The purpose of this review is to consolidate the available information regarding these and draw the focus toward their sequential progression and increasing prevalence in Chinese children. Studies were collected in both English and Chinese, and the data were reviewed on the basis of disease prevalence and risk factors that are known from scientific literature that has been published to date. The majority of studies with appropriate content for inclusion here have been conducted within the last 15 years and up to date information from recent local and international research has also been included. Several factors have been implicated for the rise in obesity, most notably, the progressing economic expansion and exposure of local Chinese populations to Western influences. With this, metabolic syndrome has become a growing concern, as it is a precursor to cardiovascular disease and type 2 diabetes, leading to the alarmingly rapid development of deleterious consequences in children. The International Diabetes Federation proposed a definition for metabolic syndrome in 2007 (MS-IDF2007) worldwide, but whether it is also suitable for the Chinese population remains uncertain, so we have created the Chinese definition of metabolic syndrome upon the IDF framework. This MS-CHN2012 definition is based on multicenter studies to simplify and standardize primary care screening methods and is the first of its kind in China. Juvenile type 2 diabetes is the most worrisome result of obesity and metabolic syndrome, and studies have shown that the prevalence has doubled within 5 years-surpassing the prevalence of juvenile type 1 diabetes. Because of the extremely low number of studies currently published on these topics in China, emphasis needs to be placed on the assessment of the health status of the population. Screening methods are imperative because lifestyle interventions can reduce and even reverse the pathologic consequences of this disease, if detected early.

Different waist circumference measurements and prediction of cardiovascular risk factors and metabolic syndrome in children

SUMMARY

OBJECTIVE

To compare the effectiveness of three waist circumference (WC) measurement sites to predict cardiovascular risk factors and metabolic syndrome (MS) in Brazilian children.

METHODS

187 children (mean age = 9.9 ± 0.7 years) were evaluated for weight, height, WC at three different sites: midpoint between the lower rib and iliac crest (WC1), umbilicus (WC2), and narrowest waist (WC3). Skinfolds (triceps and subscapular) and blood pressure were also measured. Analyses for triglycerides, HDL-C and glucose were carried out in 141 children.

RESULTS

For boys, the most accurate predictor of overweight and obesity (from body mass index, BMI) and low HDL-C levels was WC3, and for high percentage of body fat (from skinfolds) was WC1. For girls, WC2 was the most accurate predictor of MS, and hypertriglyceridemia, and for overweight and obesity, high body fat percentage, and low HDL-C levels, WC3 was the best predictor. WC1 was the most accurate in the prediction of high blood pressure.

CONCLUSIONS

Each WC measurement site was accurate in predicting cardiovascular risk factors and MS. However, our results indicate that WC3 was the best predictor of cardiovascular risk factors and MS in boys and girls.

Is waist-to-height ratio a useful indicator of cardio-metabolic risk in 6-10-year-old children?

BACKGROUND

Childhood obesity is a public health problem worldwide. Visceral obesity, particularly associated with cardio-metabolic risk, has been assessed by body mass index (BMI) and waist circumference, but both methods use sex-and age-specific percentile tables and are influenced by sexual maturity. Waist-to-height ratio (WHtR) is easier to obtain, does not involve tables and can be used to diagnose visceral obesity, even in normal-weight individuals. This study aims to compare the WHtR to the 2007 World Health Organization (WHO) reference for BMI in screening for the presence of cardio-metabolic and inflammatory risk factors in 6-10-year-old children.

METHODS

A cross-sectional study was undertaken with 175 subjects selected from the Reference Center for the Treatment of Children and Adolescents in Campos, Rio de Janeiro, Brazil. The subjects were classified according to the 2007 WHO standard as normal-weight (BMI z score>-1 and<1) or overweight/obese (BMI z score≥1). Systolic blood pressure (SBP), diastolic blood pressure (DBP), fasting glycemia, low-density lipoprotein (LDL), high-density lipoprotein (HDL), triglyceride (TG), Homeostatic Model Assessment--Insulin Resistance (HOMA-IR), leukocyte count and ultrasensitive C-reactive protein (CRP) were also analyzed.

RESULTS

There were significant correlations between WHtR and BMI z score (r=0.88, p<0.0001), SBP (r=0.51, p<0.0001), DBP (r=0.49, p<0.0001), LDL (r=0.25, p<0.0008, HDL (r=-0.28, p<0.0002), TG (r=0.26, p<0.0006), HOMA-IR (r=0.83, p<0.0001) and CRP (r=0.51, p<0.0001). WHtR and BMI areas under the curve were similar for all the cardio-metabolic parameters. A WHtR cut-off value of >0.47 was sensitive for screening insulin resistance and any one of the cardio-metabolic parameters.

CONCLUSIONS

The WHtR was as sensitive as the 2007 WHO BMI in screening for metabolic risk factors in 6-10-year-old children. The public health message "keep your waist to less than half your height" can be effective in reducing cardio-metabolic risk because most of these risk factors are already present at a cut point of WHtR≥0.5. However, as this is the first study to correlate the WHtR with inflammatory markers, we recommend further exploration of the use of WHtR in this age group and other population-based samples.

Distributions of waist circumference and waist-to-height ratio for children and adolescents in Shandong, China

Waist circumference (WC) and waist-to-height ratio (WHtR) are useful tools which can help to identify abdominal obesity among the childhood and adolescent populations. This study assessed the distributions of WC and WHtR for Shandong children and adolescents and compared them with those from other countries and regions. Data for this study were obtained from a large cross-sectional survey of schoolchildren carried out in 2010. A total of 42,296 students (21,218 boys and 21,078 girls) aged 7-18 years participated in this study. Height and WC of all subjects were measured and WHtR was calculated. Central obesity was defined as WC ≥ 90th percentile and a WHtR ≥ 0.5, respectively. Shandong children and adolescents had a high WC level, with the 50th percentiles of WC for children and adolescents aged 7 to 18 years in Shandong is above the reference values for Chinese children and adolescents by 1.3-3.1 cm for boys and 1.2-2.0 cm for girls, respectively. The WC levels in Shandong boys and girls were higher than those from Hong Kong, Malaysian, and Turkish. Overall, 20.20 and 16.57 % of boys and girls had a WC ≥90th percentile, 15.73 and 7.38 % of boys and girls had a WHtR ≥0.5.

CONCLUSION

The prevalence of central obesity among children and adolescents has become a serious public health problem, which would arouse special attention.

Lipid profiles in children with and without asthma: interaction of asthma and obesity on hyperlipidemia

AIMS

The joint effect of obesity and asthma on hyperlipidemia has never been explored. We aim to examine (1) the association of dyslipidemia and asthma, (2) the interaction effect of asthma and obesity on hyperlipidemia, and (3) whether a gender difference existed in the above relationships.

METHODS

Between 2009 and 2010, 10- to 15-year-old children were recruited from 7 schools and 2 hospitals in Northern Taiwan. The population consisted of 237 asthmatic children and 225 non-asthmatic controls, and was further divided into four groups: non-obese controls, obese controls, non-obese asthmatics, and obese asthmatics. Measurements included anthropometric measures and blood samples for analysis of metabolic factors. The Cook's criteria were used to define childhood metabolic syndrome. General linear models were used to analyze how lipid profiles were associated with obesity and asthma.

RESULTS

Total cholesterol and low density lipoprotein cholesterol levels increased progressively in the group order obese asthmatics>non-obese asthmatics>obese controls>non-obese controls. In boys, low density lipoprotein cholesterol levels were significantly higher in obese asthmatics compared to obese non-asthmatics, with a mean difference of 6.2 mmol/L in the general linear model. We also discovered a significant interactive effect of obesity and asthma on hyperlipidemia in boys (p for interaction=0.03).

CONCLUSIONS

Asthma was associated with higher low density lipoprotein cholesterol levels and this association was amplified in overweight and obese subjects. A gender difference was observed in the joint effect of obesity and asthma on hyperlipidemia.

Ability of different adiposity indicators to identify children with elevated blood pressure

OBJECTIVE

Body composition measured by dual-energy X-ray absorptiometry (DXA) is believed to be superior to crude measures such as BMI or waist circumference (WC) to assess health risks associated with adiposity in adults. We compared the ability of BMI, WC, waist-to-height ratio (WHtR), percentage body fat from skinfold thickness, and measures of total and central fat assessed by DXA to identify children with elevated blood pressure (BP).

STUDY DESIGN

The QUALITY Study follows 630 Caucasian families (father, mother, and child originally aged 8-10 years). BP, height, weight, WC, and skinfold thickness were measured according to standardized protocols. Elevated BP was defined as systolic or diastolic BP at least 90th age, sex, and height-specific percentile. Total and central fat were determined with DXA. The area under the receiver operating characteristic (ROC) curve (AUC) statistic was computed from logistic models that adjusted for age, sex, height, Tanner stage, and physical activity.

RESULTS

All adiposity indicators were highly correlated. WC and WHtR did not show superior ability over BMI to identify children with elevated SBP (P = 0.421 and 0.473). Measures of total and central fat from DXA did not show an improved ability over BMI or WC to identify children with elevated SBP (P = 0.325-0.662).

CONCLUSION

Results support the use of BMI in clinical and public health settings, at least in this age group. As all indicators had a limited ability to identify children with elevated BP, results also support measurement of BP in all children of this age independent of a weight status.

Waist circumference percentiles for Portuguese children and adolescents aged 10 to 18 years

The purposes of this study were to develop age- and sex-specific waist circumference reference data for Portuguese children and adolescents aged 10-18 years and to compare them with those from other countries. This was a school-based study performed in Portugal. A total of 22,003 children and adolescents aged 10-18 years were included in the study. Smoothed sex- and age-specific 5th, 10th, 25th, 50th, 75th, 90th, and 95th percentile curves of waist circumference were estimated using Cole's lambda-mu-sigma method. Waist circumference values increased with age in both boys and girls, and boys had higher values than girls at every age and percentile. In both sexes, the Portuguese values in the 90th percentile were closer to the Bolivian values and considerably lower than those of the American children for all age groups.

CONCLUSION

The data presented provide information for abdominal risk assessment and clinical and lifestyle intervention; our results also provide useful baseline data information for the implementation of a surveillance system required to monitor trends and factors associated with abdominal obesity in children and adolescents.

Waist circumference and waist-to-height ratio in Norwegian children 4-18 years of age: reference values and cut-off levels

AIM

To establish reference values for waist circumference and waist-to-height ratio of Norwegian children.

MATERIAL

Data were collected in 2003-2006 as part of a cross-sectional study, including 5725 children 4-18 years of age. Reference curves were fitted with the LMS method; appropriate cut-offs were selected using receiver operating characteristic analysis.

RESULTS

Reference values for waist circumference and waist-to-height ratio are presented. Mean waist circumference increased with age for both genders. Boys had a higher waist circumference at almost all ages. Mean waist-to-height ratio decreased until early adolescence and thereafter increased slightly towards adult age. There was a strong positive correlation between waist circumference and BMI (r = 0.907, p < 0.01) and a moderate positive correlation between waist-to-height ratio and BMI (r = 0.397 p < 0.01). A waist circumference cut-off value of 1.0 SDS (85th percentile) gave a sensitivity of 79% and a specificity of 94% to detect overweight. A cut-off value of 1.6 SDS (95th percentile) gave a sensitivity of 94% and a specificity of 96% to detect obesity.

CONCLUSION

This study presents the first reference values of waist circumference and waist-to-height ratio for Norwegian children 4-18 years, which also represent the first reference in Scandinavian schoolchildren. The 85th and 95th percentiles of waist circumference are proposed as appropriate cut-offs for central overweight and obesity.

Composição corporal inadequada em adolescentes: associação com fatores sociodemográficos

OBJETIVO: Verificar a associação da composição corporal inadequada com fatores sociodemográficos em adolescentes. MÉTODOS: Estudo transversal realizado em 627 adolescentes, com idades de 14 a 17 anos, de ambos os sexos, de uma cidade de Índice de Desenvolvimento Humano (IDH) médio/baixo. Foram coletadas informações sociodemográficas (sexo, idade, nível econômico e área de domicílio) e antropométricas (peso corporal, estatura, perímetro da cintura e espessura de cinco dobras cutâneas). Para análise da composição corporal inadequada, utilizou-se a proposta do Plano Canadense de Atividade Física, Aptidão e Estilo de vida. RESULTADOS: A prevalência de composição corporal inadequada foi de 24,1%. Adolescentes do sexo masculino (RP 3,16; IC95% 1,72-5,82) e dos estratos econômicos alto e intermediário (RP 2,44; IC95% 1,55-3,85) tiveram maior prevalência de índices inadequados de adiposidade, enquanto a faixa etária de 14-15 anos representou fator de proteção para composição corporal inadequada (RP 0,58; IC95% 0,37-0,90), comparada à faixa de 16-17 anos. CONCLUSÕES: A composição corporal inadequada esteve associada ao sexo, à idade e ao nível econômico. Intervenções devem levar em consideração as diferenças em função das características sociodemográficas.

Waist circumference, waist-hip ratio and waist-height ratio percentiles and central obesity among Pakistani children aged five to twelve years

Background

Central obesity has been associated with the risk of cardiovascular and metabolic disease in children and anthropometric indices predictive of central obesity include waist circumference (WC), waist-hip ratio (WHR) and waist-height ratio (WHtR). South Asian children have higher body fat distribution in the trunk region but the literature regarding WC and related indices is scarce in this region. The study was aimed to provide age- and gender-specific WC, WHR and WHtR smoothed percentiles, and to explore prevalence and correlates of central obesity, among Pakistani children aged five to twelve years.

Methods

A population-based cross-sectional study was conducted with a representative multistage random cluster sample of 1860 primary school children aged five to twelve years in Lahore, Pakistan. Smoothed percentile curves were constructed for WC, WHR and WHtR by the LMS method. Central obesity was defined as having both age- and gender-specific WC percentile ≥90^th and WHtR ≥0.5. Chi-square test was used as the test of trend. Multivariate logistic regression was used to quantify the independent predictors of central obesity and adjusted odds ratios (aOR) with 95% CI were obtained. Linear regression was used to explore the independent determinants of WC and WHtR. Statistical significance was considered at P < 0.05.

Results

First ever age- and gender-specific smoothed WC, WHR and WHtR reference curves for Pakistani children aged five to twelve years are presented. WC increased with age among both boys and girls. Fiftieth WC percentile curves for Pakistani children were higher as compared to those for Hong Kong and British children, and were lower as compared to those for Iranian, German and Swiss children. WHR showed a plateau pattern among boys while plateau among girls until nine years of age and decreased afterwards. WHtR was age-independent among both boys and girls, and WHtR cut-off of ≥0.5 for defining central obesity corresponded to 85^th WHtR percentile irrespective of age and gender. Twelve percent children (95% CI 10.1-13.0) had a WC ≥90^th percentile and 16.5% children (95% CI 14.7-18.1) had a WHtR ≥0.5 while 11% children (95% CI 8.9-11.6) had both WC ≥90^th percentile and WHtR ≥0.5. Significant predictors of central obesity included higher grade, urban area with high socioeconomic status (SES), high-income neighborhood and higher parental education. Children studying in higher grade (aOR 5.11, 95% CI 1.76-14.85) and those living in urban area with high SES (aOR 82.34, 95% CI 15.76-430.31) showed a significant independent association. Urban area with high SES and higher parental education showed a significant independent association with higher WC and higher WHtR while higher grade showed a significant independent association with higher WC.

Conclusions

Comprehensive worldwide reference values are needed to define central obesity and the present study is the first one to report anthropometric indices predictive of central obesity for Pakistani school-aged children. Eleven percent children were centrally obese and strong predictors included higher grade, urban area with high SES and higher parental education. These findings support the need for developing a National strategy for childhood obesity and implementing targeted interventions, prioritizing the higher social class and involving communities.

Waist circumference values according to height percentiles: a proposal to evaluate abdominal obesity in Mexican children and adolescents between 6 and 16 years of age

BACKGROUND AND AIMS

Waist circumference (WC) is a good anthropometric indicator for diagnosing abdominal obesity across different age groups, including children and adolescents. It is unknown whether height may modify this indicator independent of other variables such as age, gender and ethnicity. We undertook this study to determine whether WC of children and adolescents shows variations in size according to height percentiles and propose these values as reference to assess abdominal obesity in children.

METHODS

We carried out a cross-sectional analytical study in which weight, height and WC were measured in children and adolescents attending elementary schools in Mexico City. Included in the study were 3378 individuals between 6 and 16 years of age. Using quantile regression, estimated values of WC were obtained according to age and gender for the following percentiles of height: 10(th), 25(th), 50(th), 75(th) and 90(th). Likewise, for each of these height percentiles, the following percentiles of WC were calculated: 50(th), 75(th) and 90(th).

RESULTS

Among males, WC values increased 2.0 cm for ten units of height percentiles and 2.5 cm for each year of age. Among females, WC increased 1.0 cm and 2.8 cm, respectively. WC values of individuals of the same age and gender in the lower height percentiles were less than those of individuals in the upper height percentiles.

CONCLUSIONS

WC demonstrates variations directly associated with height percentiles.

Reference curves for BMI, waist circumference and waist-to-height ratio for Azorean adolescents (Portugal)

Objective

There are no percentile curves for BMI, waist circumference (WC) or waist-to-height ratio (WHtR) available for Portuguese children and adolescents. The purpose of the present study was to develop age- and sex-specific BMI, WC and WHtR percentile curves for a representative sample of adolescents living in the Portuguese islands of Azores, one of the poorest regions of Europe, and to compare them with those from other countries.

Design

Cross-sectional school-based study. Weight, height and WC were objectively measured according to standard procedures. Smoothed percentile curves were estimated using Cole's LMS method.

Setting

Azores, Portugal.

Subjects

Proportionate stratified random sample of 1500 adolescents, aged 15–18 years.

Results

Results showed some sex differences in the shape of the BMI curves: in girls, the upper percentile values tend to decrease by the age of 16 and 17 years; whereas in boys, the upper percentiles tend to be flat between 15 and 16 years and then increase until the age of 18 years. In both sexes, the upper percentile values of both WC and WHtR decreased slightly by the age of 16 years and then increased steeply. In both sexes, the Azorean values for the 50th and 90th WC percentiles were higher than those reported for adolescents from the majority of other countries.

Conclusions

The reference curves presented herein provide baseline data for the long-term surveillance of Azorean adolescents, as well as for national and international comparisons.

Sex differences in the cross-sectional areas of psoas major and thigh muscles in high school track and field athletes and nonathletes

The present study aimed to examine the sex differences in the cross-sectional areas of the psoas major, quadriceps femoris, hamstrings, and adductors in high school track and field athletes and nonathletes. The cross-sectional areas of the psoas major at L4-L5 and three thigh muscles at the mid-thigh were determined in the right side of the body using magnetic resonance imaging in 61 sprinters (29 boys and 32 girls), 50 jumpers (28 boys and 22 girls), 33 throwers (18 boys and 15 girls), and 40 nonathletes (20 boys and 20 girls), aged from 16 to 18 yrs. On the whole, the cross-sectional area for every muscle group was greater in the athletes than in the nonathletes and in the boys than in the girls. The average value of the cross-sectional area for the girls as a percentage of that for the boys in every subject group was lower in the psoas major (57.6-64.7%) than in the thigh muscles (67.8-82.9%). Among the thigh muscles, the muscle group which showed significant sex differences in the ratio of cross-sectional area to the two-third power of lean body mass was limited to the quadriceps femoris in the sprinters and nonathletes and hamstrings in the throwers. However, the ratio for the psoas major was significantly higher in the boys than in the girls in all subject groups. The current results indicate that, although regular participation in sports training during adolescence promotes hypertrophy in the psoas major and thigh muscles in not only boys but also girls, a greater sex difference exists in the muscularity of the psoas major than of the thigh muscles, in athletes and nonathletes.

Ethnic differences in body fat distribution among Asian pre-pubertal children: a cross-sectional multicenter study

Background

Ethnic differences in body fat distribution contribute to ethnic differences in cardiovascular morbidities and diabetes. However few data are available on differences in fat distribution in Asian children from various backgrounds. Therefore, the current study aimed to explore ethnic differences in body fat distribution among Asian children from four countries.

Methods

A total of 758 children aged 8-10 y from China, Lebanon, Malaysia and Thailand were recruited using a non-random purposive sampling approach to enrol children encompassing a wide BMI range. Height, weight, waist circumference (WC), fat mass (FM, derived from total body water [TBW] estimation using the deuterium dilution technique) and skinfold thickness (SFT) at biceps, triceps, subscapular, supraspinale and medial calf were collected.

Results

After controlling for height and weight, Chinese and Thai children had a significantly higher WC than their Lebanese and Malay counterparts. Chinese and Thais tended to have higher trunk fat deposits than Lebanese and Malays reflected in trunk SFT, trunk/upper extremity ratio or supraspinale/upper extremity ratio after adjustment for age and total body fat. The subscapular/supraspinale skinfold ratio was lower in Chinese and Thais compared with Lebanese and Malays after correcting for trunk SFT.

Conclusions

Asian pre-pubertal children from different origins vary in body fat distribution. These results indicate the importance of population-specific WC cut-off points or other fat distribution indices to identify the population at risk of obesity-related health problems.

Risk of metabolic syndrome among children living in metropolitan Kuala Lumpur: a case control study

Background

With the increasing prevalence of childhood obesity, the metabolic syndrome has been studied among children in many countries but not in Malaysia. Hence, this study aimed to compare metabolic risk factors between overweight/obese and normal weight children and to determine the influence of gender and ethnicity on the metabolic syndrome among school children aged 9-12 years in Kuala Lumpur and its metropolitan suburbs.

Methods

A case control study was conducted among 402 children, comprising 193 normal-weight and 209 overweight/obese. Weight, height, waist circumference (WC) and body composition were measured, and WHO (2007) growth reference was used to categorise children into the two weight groups. Blood pressure (BP) was taken, and blood was drawn after an overnight fast to determine fasting blood glucose (FBG) and full lipid profile, including triglycerides (TG), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C) and total cholesterol (TC). International Diabetes Federation (2007) criteria for children were used to identify metabolic syndrome.

Results

Participants comprised 60.9% (n = 245) Malay, 30.9% (n = 124) Chinese and 8.2% (n = 33) Indian. Overweight/obese children showed significantly poorer biochemical profile, higher body fat percentage and anthropometric characteristics compared to the normal-weight group. Among the metabolic risk factors, WC ≥90^th percentile was found to have the highest odds (OR = 189.0; 95%CI 70.8, 504.8), followed by HDL-C≤1.03 mmol/L (OR = 5.0; 95%CI 2.4, 11.1) and high BP (OR = 4.2; 95%CI 1.3, 18.7). Metabolic syndrome was found in 5.3% of the overweight/obese children but none of the normal-weight children (p < 0.01). Overweight/obese children had higher odds (OR = 16.3; 95%CI 2.2, 461.1) of developing the metabolic syndrome compared to normal-weight children. Binary logistic regression showed no significant association between age, gender and family history of communicable diseases with the metabolic syndrome. However, for ethnicity, Indians were found to have higher odds (OR = 5.5; 95%CI 1.5, 20.5) compared to Malays, with Chinese children (OR = 0.3; 95%CI 0.0, 2.7) having the lowest odds.

Conclusions

We conclude that being overweight or obese poses a greater risk of developing the metabolic syndrome among children. Indian ethnicity is at higher risk compared to their counterparts of the same age. Hence, primary intervention strategies are required to prevent this problem from escalating.

Evaluation of anthropometric indices for metabolic syndrome in Chinese adults aged 40 years and over

BACKGROUND

The prevalence of metabolic syndrome (MetS) is increasing worldwide with a marked impact in cardiovascular disease (CVD) and diabetes risk.

AIM OF THE STUDY

To evaluate the anthropometric indices for metabolic syndrome (MetS) and determine the optimal cut-off values of waist circumference (WC), body mass index (BMI), and waist height ratio (WHtR) for MetS in Chinese adults aged 40 years and over.

METHODS

A sample of Chinese adults aged 40 years and over including 430 men and 638 women was investigated. Blood pressure, weight, height, and WC were measured; HDL-cholesterol (HDL-C), Triglyceride (TG), and plasma glucose were examined. Receiver operating characteristics (ROC) curve analyses were used to evaluate the optimal cut-off point of WC, BMI, and WHtR for MetS.

RESULTS

According to the ROC curve analysis, the optimal cut-off point for WC was found to be 84.0 cm in men and 80.0 cm in women; for BMI, it was 26.0 in men and 25.0 in women; and for WHtR, it was 0.5 in both men and women. WHtR has the highest predictive value for fast plasma glucose in women, while BMI has the better prediction of dyslipidemia in men.

CONCLUSIONS

Anthropometric indices (WC, BMI, and WHtR) are useful screening tools for obesity, MetS, and CVD risk factors. BMI may be a better indicator than the others for screening obesity, dyslipidemia, and other risk components in Chinese men aged 40 years and over, while WHtR may be better for Chinese women, especially among those aged 70 years and over.

Percentile curves for fat patterning in German adolescents

BACKGROUND

because the body composition of adolescents varies more than that of adults and anthropometric parameters are regularly used for pediatric body fat measurements, we developed age-, gender-, and ethnicity-specific reference values for waist circumference (WC), hip circumference (HC), waist-to-height ratio (WHtR), waist-to-hip ratio (WHR), and skinfold thickness (SFT) in German adolescents.

METHODS

a representative sample of 1633 boys and 1391 girls aged 12-18 years participated in this cross-sectional study. Weight, height, body mass index (BMI), WC, HC, WHR, WHtR, and SFT were measured and smoothed; age-, gender-, and ethnicity-specific reference curves were developed using the LMS method.

RESULTS

females were significantly heavier than males at 12 years. Beyond age 14 males were significantly heavier and taller than females. The SFT sum increased continuously (+20%) in females and was significantly higher (7.4 mm) than in males. At the 90th percentile, SFTtriceps decreased (-12%) in males but increased (+11%) in females; SFT(subscapular) increased in both genders. From 12 to 18 years, WHtR and WHR remained constant, whereas WC and HC increased in both genders. WHtR was the best predictor for abdominal obesity in males (area under the curve [AUC] 0.974 ± 0.004) and females (AUC 0.986 ± 0.003), followed by body fat percentage (AUC 0.937 ± 0.008) in males and WHR (AUC 0.935 ± 0.009) in females.

CONCLUSION

these age- and gender-specific percentile curves for SFT, WC, HC, WHR, and WHtR, derived from a large national sample of German adolescents, may be useful for developing international reference values for waist circumference and other predictors of adult obesity.

Waist-to-height ratio, an optimal predictor for obesity and metabolic syndrome in Chinese adults

OBJECTIVE

Anthropometric indices to obesity were evaluated as predictors of metabolic syndrome risk factors. Our purpose was to explore an optimal or more reliable anthropometric indicator and optimal cut-off points for obesity on metabolic syndrome in Chinese adults.

PARTICIPANTS AND METHODS

The survey was conducted involving 2947 participants, aged 20 or above with cross-sectional study of population. The predictive validity and optimal cut-off values were analyzed by receiver operating characteristic (ROC) curves, area under curve (AUC) and the largest Youden's index (sensitivity + specificity - 1) by gender group, respectively. Kappa value showed diagnostic consistency.

RESULTS

According to the criteria of CDS 2004, IDF 2005 and AHA/NHLBI 2005, the prevalence of metabolic syndrome was 10.32%, 9.64% and 16.12% respectively, which indicated that the prevalence was higher in men than in women and increased with age (P < 0.05). The BMI, WC, WHR and WHtR in metabolic syndrome patients were greater than those in healthy volunteers and the indices in men were higher than those in women. With adjusted age and gender, the partial correlation coefficient for BMI-WC, BMI-WHR and BMI-WHtR was 0.7991, 0.5278 and 0.8196, respectively (P < 0.05). The area under curves (AUCs) of receiver operating characteristic (ROC) curves for WHtR was larger (P < 0.05) than that for WC and WHR. The cut-point of WHtR was approximately 0.5 in both genders with a satisfactory balance between sensitivity and specificity, where the Kappa (k) value for WHtR-BMI was higher than that for WHtR-WHR, and WHtR-WC.

CONCLUSIONS

The results indicated that WHtR might be an optimal anthropometric predictor of metabolic syndrome risk factors and the cut-point of WHtR was approximately 0.50 in both genders of Chinese adults.

Relationship of body mass index to percent body fat and waist circumference among schoolchildren in Japan--the influence of gender and obesity: a population-based cross-sectional study

Background

Although the correlation coefficient between body mass index (BMI) and percent body fat (%BF) or waist circumference (WC) has been reported, studies conducted among population-based schoolchildren to date have been limited in Japan, where %BF and WC are not usually measured in annual health examinations at elementary schools or junior high schools. The aim of the present study was to investigate the relationship of BMI to %BF and WC and to examine the influence of gender and obesity on these relationships among Japanese schoolchildren.

Methods

Subjects included 3,750 schoolchildren from the fourth and seventh grade in Ina-town, Saitama Prefecture, Japan between 2004 and 2008. Information about subject's age, sex, height, weight, %BF, and WC was collected from annual physical examinations. %BF was measured with a bipedal biometrical impedance analysis device. Obesity was defined by the following two criteria: the obese definition of the Centers for Disease Control and Prevention, and the definition of obesity for Japanese children. Pearson's correlation coefficients between BMI and %BF or WC were calculated separately for sex.

Results

Among fourth graders, the correlation coefficients between BMI and %BF were 0.74 for boys and 0.97 for girls, whereas those between BMI and WC were 0.94 for boys and 0.90 for girls. Similar results were observed in the analysis of seventh graders. The correlation coefficient between BMI and %BF varied by physique (obese or non-obese), with weaker correlations among the obese regardless of the definition of obesity; most correlation coefficients among obese boys were less than 0.5, whereas most correlations among obese girls were more than 0.7. On the other hand, the correlation coefficients between BMI and WC were more than 0.8 among boys and almost all coefficients were more than 0.7 among girls, regardless of physique.

Conclusions

BMI was positively correlated with %BF and WC among Japanese schoolchildren. The correlations could be influenced by obesity as well as by gender. Accordingly, it is essential to consider gender and obesity when using BMI as a surrogate for %BF and WC for epidemiological use.

Glucose intolerance and cardiometabolic risk in adolescents exposed to maternal gestational diabetes: a 15-year follow-up study

OBJECTIVE

Adolescent offspring of women with a history of gestational diabetes (GD) were evaluated for their cardiometabolic risks at a mean age of 15 years.

RESEARCH DESIGN AND METHODS

One hundred and twenty-nine adolescents who were assessed for their cardiometabolic risks at 8 years of age were reassessed at 15 years of age.

RESULTS

Adolescent offspring of mothers with GD had similar blood pressure, plasma lipid profile, and a rate of abnormal glucose tolerance as control subjects. In utero hyperinsulinemia was associated with a 17-fold increase in metabolic syndrome and a 10-fold increase in overweight at adolescence, independent of birth weight, Tanner stage, maternal GD status, and mother's BMI.

CONCLUSIONS

In utero environment of hyperinsulinemia, irrespective of the degree of maternal GD, was associated with increased risk of overweight and metabolic syndrome during early adolescence in the offspring.

Waist circumference and waist-to-height ratio in Han Chinese children living in Chongqing, south-west China

OBJECTIVE

To derive age- and sex-specific reference values for waist circumference (WC) and waist-to-height ratio (WHtR) for Han Chinese children and adolescents and to establish the prevalence of excess central adiposity in our study population.

DESIGN

Cross-sectional study of schoolchildren attending randomly selected primary and secondary schools in south-west China in October 2003 and April 2004. Anthropometry was measured using standard procedures. The LMS method was used to construct smoothed WC and WHtR percentile curves. Overweight and obesity were defined by the International Obesity Task Force (IOTF) criteria and the Working Group on Obesity in Children. Excess central adiposity fat was defined by previously published WC cut-points and a WHtR ≥ 0.5.

SETTING

Primary and secondary schools in Chongqing, south-west China.

SUBJECTS

A total of 7326 (49.2 % boys) Han Chinese students at 5-17 years old.

RESULTS

On the basis of the IOTF criteria, 26.4 % of boys were overweight or obese compared with 16.4 % of girls (P < 0.001). WC cut-points identified 31 % of boys and 28 % of girls as having excess central adiposity, whereas using the WHtR criterion, 14.8 % of boys and 5.6 % of girls were identified. Young boys (5-12 years) had a significantly (P < 0.001) higher WHtR than girls.

CONCLUSIONS

We have constructed WC and WHtR percentile curves for Han Chinese children and adolescents living in Chongqing. Our measurements were based on a student population with a relatively high rate of overweight and obesity. These data will provide a point of reference for future studies measuring the prevalence of overweight and obesity in China.

Umbilical waist-to-height ratio and trunk fat mass index (DXA) as markers of central adiposity and insulin resistance in Argentinean children with a family history of metabolic syndrome

Central adiposity is increasing in childhood. To find a simple index of central fatness that accurately predicts insulin resistance we studied 55 obese children and 53 siblings, aged 6-16 years. We recorded the family metabolic score, calculated clinical and DXA-derived fat distribution indexes and HOMA-IR. Umbilical waist-to-height ratio (W-to-Ht) had the best combination of ROC area (0.99, IC95: 0.93 to 1.0), Youden's index (0.976), coefficient of variation (4.9) and correlation with HOMA-IR (r = 0.58, p < 0.0001); it also correlated (p < 0.001) with BMI (r = 0.95) and DXA-trunk fat mass index (r = 0.93). It was the best predictor of insulin resistance in a multiple regression model (p < 0.0001). Odds ratios for insulin resistance were 9.33 when the family score was >10 (p < 0.01) and 14.35 when umbilical W-to-Ht was >0.54 (p < 0.0001). Umbilical W-to-Ht, a simple marker of central adiposity, strongly relates to children's DXA-trunk fat mass index and insulin resistance.

Waist circumference reference values for screening cardiovascular risk factors in Chinese children and adolescents

OBJECTIVES

To explore the optimal threshold values of waist circumference (WC) for detecting cardiovascular (CV) risk factors among Chinese children and adolescents.

METHODS

Association of WC with CV risk factors was studied among 65,898 children aged 7-18 years whose data were pooled from nine previous studies in China. CV risk factors in this study included hypertension (blood pressure above 95 percentile levels), dyslipidemia (with one or more of the following three indexes: TG > or = 1.7 mmol/L, TC > or = 5.18 mmol/L, and HDL-C < or = 1.04 mmol/L) and elevated glucose level (fasting plasma glucose > or = 5.6 mmol/L). Receive-operating characteristic analysis (ROC) and logistic regression were employed to derive optimal age- and sex-specific waist circumference references for predicting CV risk factors.

RESULTS

A slight increasing trend of CV risk factors was observed starting from the 75th percentile of waist circumference in the study population, while a remarkable increasing trend occurred from the 90th percentile. The optimal waist circumference thresholds for predicting high blood pressures were at the 75th percentile for both boys and girls, which was at the 90th percentiles for detecting at least two of the above three CV risk factors. In comparison with children with waist circumference below the 75th percentile, the odds ratio of two CV risk factors doubled among children with waist circumference between the 75th and the 90th percentile, and increased by 6 times among children with waist circumference above the 90th percentile. The trend of high blood pressure increasing with waist circumference remained significant after having been stratified by BMI category.

CONCLUSION

The 75th and the 90th percentiles of WC are the optimal cut-off points for predicting an increased and a substantially increased risk of CV factors in Chinese children and adolescents, respectively.

Waist circumference distribution of Chinese school-age children and adolescents

BACKGROUND

Waist circumference (WC), a proxy measure of central body fat, is a better predictor than overall body fat for cardiovascular risk factors in both adults and children. WC cutoffs have been established in many countries, but the national WC reference has not been developed in China.

OBJECTIVE

To study the distribution of WC in a representative group of Chinese children for establishing Chinese WC cutoff points.

METHODS

Cross-sectional data obtained from 15 mainland provinces and Hong Kong were collected. There were 160,225 children and adolescents aged 7-18 years old in total. The subjects were divided into five regional groups namely costal city, other city, north rural, south rural, and Hong Kong, for analyzing the distribution of WC.

RESULTS

A large variation in WC distribution was found among the five groups for both sexes. Coastal city group had the highest P85 WC values consistently from the early school ages to 18-year-old compared with other groups. In contrast, south rural group had P85 values consistently lagged behind not only the city groups but also the north rural group. Hong Kong group had a high P85 WC at early ages, but because of the smaller increments of WC during adolescence, the P85 curve was gradually exceeded by the north rural groups. Catch-up trend was found in the two rural groups since the peak of puberty. These disparities were caused by not only socioeconomic and urban-rural factors but also north-south differences. Because of the regional variation of WC, a "gradient" prevalence of central obesity was prospected among these groups. Comparisons of WC distributions between the Chinese and the U.S.A. or Netherlands demonstrated the necessary of setting up China's own WC cutoffs. Sex and age-specific percentiles were obtained and smoothed by using LMS method.

CONCLUSION

The data obtained from this study could be used to develop national WC cutoff points for Chinese children and adolescents.

Scaling of human body mass with height: the body mass index revisited

We adapt a biomechanical argument of Rashevsky, which places limits on the stress experienced by a torso supported by the legs, to deduce that body mass m of growing children should scale as the p th power of height h with 7/3 < p < 8/3. Further arguments based on stability and heat loss suggest that p should be close to 8/3. The arguments are extended to suggest that waist circumference w should scale as hq with q near the lower end of 2/3 < or = q < or = 1. Data from Hong Kong and British children are consistent with these hypotheses.

Population-based waist circumference and waist-to-height ratio reference values in preschool children

AIM

To establish new reference values for measurements of waist circumference and waist-to-height ratio in preschool children.

METHODS

A population-based, cross-sectional study of 4502 children aged 0-5 years derived from child health care in a Swedish county. Measurements of weight, height and waist circumference were recorded using a standardized procedure.

RESULTS

New reference values for waist circumference and waist-to-height ratio for preschool children are presented. Reference charts were constructed and are presented. Waist circumference increased with age (r = 0.80, p < 0.001). After adjustment to the individual height, expressed as waist-to-height ratio, there was an inverse correlation to age during the first 5 years of age (r = -0.87, p < 0.001).

CONCLUSION

The new reference values for waist circumference and waist-to-height ratio for Swedish preschool children enable future identification of new risk populations for childhood obesity. For clinicians, new reference charts for these two variables are provided for practical use.

Prevalência de sobrepeso e obesidade e indicadores de adiposidade central em escolares de Santa Catarina, Brasil

OBJETIVO: Estimar a prevalência de sobrepeso e obesidade entre escolares e sua associação com região, sexo, faixa etária e rede de ensino, e a correlação entre os índices antropométricos. MÉTODO: Estudo transversal com 4.964 escolares entre 6 a 10 anos de idade matriculados em 345 escolas do ensino fundamental do Estado de Santa Catarina. Foi utilizado o índice de massa corporal para diagnosticar sobrepeso e obesidade. Como indicadores de distribuição de gordura foram utilizadas circunferência de cintura, relação cintura-quadril, relação cintura-altura, dobras cutâneas triciptal e subescapular e razão subescapular-triciptal. Foram estimadas as razões de chance com IC 95% e calculada correlação de Pearson para avaliar a relação entre índice de massa corporal e índices antropométricos. RESULTADO: Do total dos escolares, 52,2% eram do sexo feminino. A prevalência de sobrepeso foi de 15,4% e de obesidade 6,0%. Não foi encontrada associação entre sobrepeso ou obesidade com regiões, sexo e faixa etária, somente entre sobrepeso e rede particular. Os escolares da rede particular apresentaram 1,46 (1,22-1,74) vezes mais chance de desenvolverem sobrepeso. Foi encontrada correlação forte entre o índice de massa corporal e a circunferência de cintura (r = 0,90). CONCLUSÃO: Os escolares da rede particular estão mais expostos ao sobrepeso e à obesidade, sugerindo que a condição socioeconômica dos escolares possa ser a explicação. A circunferência de cintura, além de indicador de adiposidade central, poderá ser utilizada como indicador de adiposidade total.