First reference curves of waist and hip circumferences in an Asian population of youths: CASPIAN study

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.

The association of anthropometric indices in adolescence with the occurrence of the metabolic syndrome in early adulthood: Tehran Lipid and Glucose Study (TLGS)

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT

Little is known about the predictive ability of anthropometric indices in adolescence for prediction of early adulthood metabolic syndrome (MetS). There are controversies about the predictive power of body mass index (BMI) vs. waist circumference (WC) for prediction of MetS in late adolescence; some of the studies did not support the need to measure WC in mid-adolescence, in addition to BMI; on the other hand, some other studies proposed either similar predictability or superiority of WC to identify MetS in late adolescence.

WHAT THIS STUDY ADDS

This is the first study to evaluate the adolescent anthropometric indices in relation to early adulthood MetS incidence one decade later in the Middle East region. There is an important sex difference regarding the incidence of MetS in Tehranian adolescents. It is interesting to know that all anthropometric indices in the pubertal age group (11-14 years) had better predictive ability compared to late-pubertal (15-18 years) adolescents. In addition, adolescent abdominal obesity surrogates, including WC and waist-to-height ratio, predicted adulthood MetS better than BMI in boys. It seems that WC had an independent role beyond BMI in identification of adulthood MetS in Tehranian boys (11-18 years old).

BACKGROUND

Little is known about the predictive ability of anthropometric indices in adolescence for prediction of early adulthood metabolic syndrome (MetS).

OBJECTIVE

Our purpose was to explore incidence of MetS and the optimal anthropometric indicator to predict early adulthood MetS in Tehranian adolescents.

METHODS

Using data from the population-based, prospective, Tehran Lipid and Glucose Study, the utility of four anthropometric indices of adolescents in predicting early adulthood MetS (2009 Joint Scientific Statement definition) was examined among 1100 participants, aged 11-18 years, who were free of MetS at baseline, during a mean of 10.2 years of follow-up.

RESULTS

The cumulative incidence of MetS was 25.5% (95% confidence interval [CI]: 21.8-29.2%) for young men and 1.8% (95% CI: 0.6-3%) for young women. In boys, waist circumference (WC) had the highest odds ratio (OR) for the MetS risk, followed by waist-to-height ratio (WHtR). Adjusting body mass index (BMI) in addition to WC did not change the results in the 11-14-year age group (OR for WC: 2.28 [1.64-3.16] without BMI adjustment vs. 1.98 [1.05-3.73] with BMI adjustment), suggesting that WC may predict MetS risk beyond BMI. None of the anthropometric indices were found to have significant associations with subsequent MetS risk in girls.

CONCLUSIONS

Measures of abdominal obesity including WHtR and WC predicted early adulthood MetS better than BMI in Tehranian male adolescents (11-18 years old).

Heritability of the metabolic syndrome and its components in the Tehran Lipid and Glucose Study (TLGS)

Growing evidence suggests that metabolic syndrome (MetS) has both genetic and environmental bases. We estimated the heritability of the MetS and its components in the families from the Tehran Lipid and Glucose Study (TLGS). We investigated 904 nuclear families in TLGS with two biological parents and at least one offspring (1565 parents and 2448 children), aged 3–90 years, for whom MetS information was available and had at least two members of family with MetS. Variance component methods were used to estimate age and sex adjusted heritability of metabolic syndrome score (MSS) and MetS components using SOLAR software. The heritability of waist circumference (WC), HDL-cholesterol (HDL-C), triglycerides (TGs), fasting blood sugar (FBS), systolic blood pressure (SBP) and diastolic blood pressure (DBP) as continuous traits after adjusting for age and gender were 27, 46, 36, 29, 25, 26 and 15%, respectively, and MSS had a heritability of 15%. When MetS components were analysed as discrete traits, the estimates of age and gender adjusted heritability for MetS, abdominal obesity, low HDL-C, high TG, high FBS and high blood pressure (BP) were 22, 40, 34, 38 and 23%, respectively (P < 0·05). Three factors were extracted from the six continuous traits of the MetS including factor I (BP), factor II (lipids) and factor III (obesity and FBS). Heritability estimation for these three factors were 7, 13 (P < 0·05) and 2%, respectively. The highest heritability was for HDL-C and TG. The results strongly encourage efforts to identify the underlying susceptibility genes.

The structure of metabolic syndrome components across follow-up survey from childhood to adolescence

BACKGROUND

The choice of what parameters are needed for the diagnosis of Metabolic syndrome (MetS) has been criticized due to the lack of an actual "gold standard" diagnostic test even in adults. This problem seems to be greater in children and adolescents.

OBJECTIVES

Stability assessment of factor structure underlying metabolic syndrome (MetS) components from childhood to adolescence in a panel study.

PATIENTS AND METHODS

A total number of 643 (305 boys and 338 girls) children (from 1999 to 2001), aged 6-10 years, with a complete median follow-up of 6.7 years (from 2006 to 2008) were selected among participants of Tehran Lipid and Glucose Study. We proposed 6 measured variables based on risk factors defined in Adult Treatment Panel III guidelines to describe clustering of MetS components.

RESULTS

The Goodness of fit of the two-factor model, extracted from exploratory factor analysis, was appropriate for boys and girls in both stages of the study using confirmatory factor analysis. Systolic blood pressure (SBP) and triglycerides (TGs), with parameter estimates (PE) of 1 and 0.75, respectively, were the greatest risk factors at baseline in boys and girls. Waist circumference with PE of 0.88 and 0.62, and SBP with PE of 0.99 and 0.86 in adolescent boys and girls, respectively, were important risk factors.

CONCLUSIONS

Our panel study supports the stability of the two-factor six-variable model across two developmental stages from childhood to adolescence, among which adiposity, SBP, and TG were the predominant risk factors.

Gender Differences Time Trends for Metabolic Syndrome and Its Components among Tehranian Children and Adolescents

Aims. To investigate the trend of metabolic syndrome and its components in Tehran children and adolescents during a median followup of 6.6 years. Methods. Data from 1999-2001 (phase I), 2002-2005 (phase II), and 2006-2008 (phase III) of the Tehran, Lipid and Glucose Study were analyzed (n = 5439; age 6-18 years) for the trend of metabolic syndrome (MetS) and its components. General estimation equation (GEE) models were used to analyze this correlated data. Results. The crude prevalence of MetS for boys at baseline was 13.2%, which increased to 16.4% in the third phase. In girls, the prevalence of Mets decreased from 11.8% at baseline to 6% during followup. The odd ratios (OR) of obesity over the whole study period were raised in both sexes. The OR of abdominal obesity increased significantly in boys, but no change was observed in girls. No significant OR was observed in boys, while OR for MetS was shown to have a decreasing trend in girls during the followup. In the three time points, the ORs of MetS decreased significantly in girls but no significant difference was observed in boys. Conclusion. Inspite of increasing trend for obesity in both sexes, the trend of MetS decreased in girls and was relatively stable in boys, in Tehranian children, and adolescents.

Mother-Daughter Correlation of Central Obesity and Other Noncommunicable Disease Risk Factors

This study aimed to investigate the mother-daughter correlation for central obesity and other noncommunicable disease risk factors. The authors used metabolic and anthropometric data from the Tehran Lipid and Glucose Study, enrolling 1041 mother-daughter pairs for the current study. Three age strata were defined: 3 to 9 years for childhood (146 mother-daughter pairs), 10 to 17 years for adolescence (395 mother-daughter pairs), and 18 to 25 years for early adulthood (500 mother-daughter pairs). Familial associations for central obesity and other noncommunicable disease risk factors were assessed. The prevalence of central obesity was 44.7% in mothers and 11.2% in daughters (6.2% in the 3-9, 19.2% in the 10-17, and 6.4% in the 18-25 years groups). Mothers with central obesity were more likely than nonobese mothers to have daughters with central obesity (10.5% and 1.7%, respectively; P = .0001). Central obesity indices among daughters were positively correlated with those of their mothers in all 3 age strata. Correlations for other noncommunicable disease risk factors were analyzed before and after adjusting the risk factor levels for mothers’ and daughters’ waist circumferences (WCs) within each group to determine whether risk factor correlations were, in part, a result of the central obesity correlations. After the non-communicable disease risk factor levels of participants were adjusted for their WCs, the mother-daughter correlations remained significant. The consistent association of central obesity between mothers and daughters may indicate the key role that could be played by the mother in the primary prevention of central obesity, particularly in high-risk families.

Can a trial of motivational lifestyle counseling be effective for controlling childhood obesity and the associated cardiometabolic risk factors?

OBJECTIVES

This study was conducted to assess the effectiveness of a simple office-based program for encouraging healthy lifestyle on controlling childhood obesity and associated cardiometabolic risk factors.

METHODS

This non-randomized 24-week lifestyle modification trial was conducted among 457 obese children and adolescents, aged 2-18 years, who had at least one cardiometabolic risk factor in addition to obesity. This trial included three components of exercise, diet education and behavior modification, with all recommendations provided by a pediatrician, two general physicians and a nurse. Instead of strict inhibitory recommendations, healthier lifestyle was encouraged.

RESULTS

Overall 448 (98.04%) of enrolled children completed the trial with a mean age of 9.6 ± 2.9 years. After the trial, the mean of anthropometric measures and cardiometabolic risk factors decreased significantly, the mean high-density lipoprotein cholesterol (HDL-C) increased significantly, and the prevalence of the metabolic syndrome decreased from 20.8% to 1.8%. Triglycerides, LDL-C, diastolic blood pressure and WC had the highest decrease in all age groups, with the most prominent changes in the 14-18-year age group. By each -1SD decline in BMI and WC, risk factors had significant improvement.

CONCLUSION

Motivational office-based counseling can be effective in treatment of childhood obesity and its associated cardio-metabolic risk factors. Such approach can be implemented in the primary health care system; and can be of special concern in low- and middle-income countries with limited human and financial resources. We suggest that expanding the roles of non-physician clinicians such as nurse practitioners can help to increase the amount of time available for such services.

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, 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.

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.

Trends in risk factors for cardiovascular disease among Iranian adolescents: the Tehran Lipid and Glucose Study, 1999-2008

OBJECTIVES

Data on secular trends in adolescent obesity and dyslipidemia are limited. Data on obesity status collected during 3 surveys were used to evaluate these trends in obesity and dyslipidemia among Tehranian adolescents and to assess the likelihood of risk factors for cardiovascular disease.

METHODS

We analyzed data for adolescents (age 10 to 19 years) from 3 cross-sectional surveys of the Tehran Lipid and Glucose Study: 1999-2001 (n = 3010, 47.2% males), 2002-2005 (n = 1107, 48.4% males), and 2006-2008 (n = 1090, 46.6% males). Overweight and abdominal obesity were defined using Iranian body mass index (BMI) percentiles, International Obesity Task Force (IOTF) criteria, and Iranian waist circumference (WC) charts. Hypertension was defined by using the National Heart, Lung, and Blood Institute's recommended cut points, and dyslipidemia was defined according to the recent recommendations of the American Heart Association.

RESULTS

The overall adjusted prevalences of "at risk for overweight" and overweight changed from 13% and 8% (using Iranian cutoffs), respectively, and 14.8% and 4.7% (using IOTF criteria) in 1999-2001 to 19% and 15% (Iranian cutoffs) and 23.0% and 9.2% (IOTF criteria) in 2006-2008 (P < 0.01 for all comparisons). The prevalence of abdominal obesity increased in males from 14.5% in 1999-2001 to 33.3% in 2006-2008 (P < 0.001). Almost half the adolescents had low high-density lipoprotein cholesterol (HDL-C) in the 3 surveys. In all surveys, as BMI and WC increased, multivariate age- and sex-adjusted odds ratios of low HDL-C and high triglyceride levels significantly increased. Overweight was associated with a greater likelihood of these risk factors, as compared with increased WC.

CONCLUSIONS

Overweight and abdominal obesity are increasing in Tehranian adolescents, and these increases are accompanied by abnormalities in levels of serum triglyceride and HDL-C.

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.

Predictive value of body mass index and waist circumference for metabolic syndrome in 6-12-year-olds

AIM

To determine the predictive value of body mass index (BMI) and waist circumference (WC) and their optimal cut-off points for metabolic syndrome (MetS), and also the incidence of MetS.

METHODS

This study included 888 children, aged 6-12 years, who were followed for a mean of 6.6 years. BMI, WC and their optimal cut-off points to predict MetS were investigated.

RESULTS

The cumulative incidence of MetS was 10.7%. The adjusted ORs for age, sex and family history to predict MetS for BMI and WC z-scores were 2.6 (95% CI, 2.0-3.5) and 2.6 (95% CI, 1.9-3.5), respectively. In their correspondent models, area under the receiver operating characteristic (ROC) curve was 0.73 (95% CI, 0.68-0.79) for BMI z-scores and 0.72 (95% CI, 0.67-0.78) for WC z-scores with no statistically significant difference. The optimal cut-off values for BMI were 16.5 kg/m(2) for boys and 16.3 kg/m(2) for girls and those for WC were 57.5 cm for boys and 56.5 cm for girls.

CONCLUSIONS

Our findings suggest that both BMI and WC have the same power to predict MetS and also children with higher BMI or WC are more susceptible to MetS. Moreover, a high incidence of MetS in children highlights the importance of interventional strategies during early childhood.

Barriers to a healthy lifestyle among obese adolescents: a qualitative study from Iran

PURPOSE

Existing data show a rising prevalence of overweight and obesity among Iranian adolescents. The current study investigates adolescents' perceptions regarding overweight/obesity and explores barriers to a healthy life style among Iranian adolescents.

METHODS

A grounded theory approach was used for analyzing the participants' experiences, and their perceptions. To collect data, semi-structured focus group discussions and in-depth interviews were conducted with 51 adolescents (27 girls and 24 boys), aged 15-17 years, who were either overweight or obese. Qualitative content analysis of the data was conducted manually and differences in coding were resolved via discussion by four independent reviewers.

RESULTS

Two main barriers, personal and environmental emerged from data analysis. Positive perception of condition, priority of studying, lack of willingness, unsatisfactory results, low self-esteem, and perceived lack of control were the major personal barriers while lack of family and cultural support, inadequate education and scarcity of resources were the common environmental barriers to adolescents' healthy lifestyles.

CONCLUSIONS

Findings demonstrated the main personal and environmental barriers for a healthy life style as perceived by adolescents. Understanding these barriers might contribute to existing literature by providing evidence from a different culture, and help to design effective preventive strategies, and implement appropriate interventions.

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.

Effects of a lifestyle modification trial among phenotypically obese metabolically normal and phenotypically obese metabolically abnormal adolescents in comparison with phenotypically normal metabolically obese adolescents

This study aimed to assess the effects of a 2-month lifestyle modification trial on cardio-metabolic abnormalities and C-reactive protein (CRP) among obese adolescents with metabolic syndrome [phenotypically obese metabolically abnormal (POMA)] and obese adolescents without a cardio-metabolic disorder [phenotypically obese metabolically normal (POMN)], as well as in normal-weight adolescents with at least one cardio-metabolic disorder [phenotypically normal metabolically obese (PNMO)]. The study comprised 360 adolescents assigned in three groups of equal number of POMN, POMA and PNMO. They were enrolled in a trial consisting of aerobic activity classes, diet and behaviour modification, and were recalled after 6 months. Overall, 94.7% of participants completed the 2-month trial, and 87.3% of them returned after 6 months. The mean CRP was not significantly different between the POMA and PNMO groups, but was higher than in the POMN group. After the trial, body mass index (BMI) and waist circumference (WC) decreased in obese participants, and the mean body fat mass decreased in all groups. At 2 months, the mean total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), triglycerides (TG) and CRP decreased in the POMA and PNMO groups. After 2 and 6 months, the decrease in mean TC, LDL-C, TG, CRP and systolic blood pressure was greater in the POMA than in the POMN group. The magnitude of decrease in CRP correlated with that of BMI, WC, fat mass, TG, TC and LDL-C. Lifestyle modification programmes for primordial/primary prevention of chronic diseases would be beneficial at the population level and should not be limited to obese children.

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.

Association of the components of the metabolic syndrome with non-alcoholic fatty liver disease among normal-weight, overweight and obese children and adolescents

OBJECTIVES

This study aimed to determine the prevalence of the metabolic syndrome, abnormalities of liver enzymes and sonographic fatty liver, as well as the inter-related associations in normal weight, overweight and obese children and adolescents.

METHODS

This cross-sectional study was conducted among a sample of 1107 students (56.1% girls), aged 6-18 years in Isfahan, Iran. In addition to physical examination, fasting blood glucose, serum lipid profile and liver enzymes were determined. Liver sonography was performed among 931 participants. These variables were compared among participants with different body mass index (BMI) categories.

RESULTS

From lower to higher BMI category, alanine aminotransferase (ALT), total cholesterol, LDL-cholesterol, triglycerides and systolic blood pressure increased, and HDL-cholesterol decreased significantly. Elevated ALT, aspartate aminotransferase (AST) and alkaline phosphatase (ALP) were documented in respectively 4.1%, 6.6% and 9.8% of normal weight group. The corresponding figure was 9.5%, 9.8% and 9.1% in overweight group, and 16.9%, 14.9% and 10.8% in obese group, respectively. In all BMI categories, ALT increased significantly by increasing the number of the components of the metabolic syndrome. Odds ratio for elevated liver enzymes and sonographic fatty liver increased significantly with higher number of the components of the metabolic syndrome and higher BMI categories before and after adjustment for age.

CONCLUSIONS

Because of the interrelationship of biochemical and sonographic indexes of fatty liver with the components of the metabolic syndrome, and with increase in their number, it is suggested to determine the clinical impact of such association in future longitudinal studies.

First reference curves of waist circumference for German children in comparison to international values: the PEP Family Heart Study

BACKGROUND

Waist circumference (WC) is a sensitive marker for abdominal obesity in the pediatric age group. However, WC is influenced by age, sex, ethnicity and body mass index (BMI), causing difficulties in the selection of the most appropriate cut-off value. Considering the lack of reference values in Germany, we developed age- and gender-specific WC smoothed reference curves in German children, and compared them with reference curves obtained from different countries.

METHODS

A representative sample of 3531 German children (1788 boys, 1743 girls) aged 3-11 years participating in the Prevention Education Program (PEP) Family Heart Study was studied. WC was measured according to the recommendations of the World Health Organization, then age- and sex-specific WC reference curves were constructed and smoothed using the LMS method and SPSS 14.0 for statistical analysis.

RESULTS

WC increased with age in both boys and girls. Boys had higher values of WC than girls at every age and percentile level. 4.1% of the boys and 2.8% of the girls had WC values >97th percentile as compared to 6.3% of the boys and 4.9% of the girls with >97th percentile of BMI (severe obesity). 3.1% of the boys and 2% of the girls had both risk factors. Because 85.3% of the boys and 87.3% of the girls with WC<90th percentile had normal weight, this cut-off point might be appropriate for defining high WC.

CONCLUSIONS

These first WC reference curves of German children can be added to the existing international curves for children; comparison of different populations demonstrated that the German values are in the middle range of the curves obtained in different countries. Our findings about significant differences between the reference curves obtained in various regions emphasize the necessity of developing population-specific percentiles, and to use them in clinical and epidemiological studies among children.

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

BACKGROUND

Central body fat is a better predictor than overall body fat for cardiovascular (CV) risk factors in both adults and children. Waist circumference (WC) has been used as a proxy measure of central body fat. Children at high CV risk may be identified by WC measurements. Waist-to-height ratio (WHTR) has been proposed as an alternative, conveniently age-independent measure of CV risk although WHTR percentiles have not been reported. We aim to provide age- and sex-specific reference values for WC and WHTR in Hong Kong Chinese children.

METHODS

Cross sectional study in a large representative sample of 14,842 children aged 6 to 18 years in 2005/6. Sex-specific descriptive statistics for whole-year age groups and smoothed percentile curves of WC and WHTR were derived and presented.

RESULTS

WC increased with age, although less after age 14 years in girls. WHTR decreased with age (particularly up to age 14). WHTR correlated less closely than WC with BMI (r = 0.65, 0.59 cf. 0.93, 0.91, for boys and girls respectively).

CONCLUSION

Reference values and percentile curves for WC and WHRT of Chinese children and adolescents are provided. Both WC and WHTR are age dependent. Since the use of WHRT does not obviate the need for age-related reference standards, simple WC measurement is a more convenient method for central fat estimation than WHRT.