Optimal waist-to-height ratio values for cardiometabolic risk screening in an ethnically diverse sample of South African urban and rural school boys and girls

The association between waist-to-height ratio and cognitive function in older adults

OBJECTIVES

The waist-to-height ratio (WHtR) is a simple, practical, and effective tool used to assess central obesity. Despite its usefulness, few studies have investigated the association between WHtR and cognitive function among older adults in the United States. This study aims to investigate the associations between WHtR and cognitive function.

METHODS

The study sample comprised adults who participated in the National Health and Nutrition Examination Survey (NHANES) between 2011 and 2014. WHtR was calculated from measured waist circumference and height. Cognitive function was assessed using the digit symbol substitution test. A weighted multiple linear regression analysis was performed to evaluate the association between WHtR and cognitive function, with smooth curve fitting applied to detect non-linearities.

RESULTS

Our analysis included 1709 participants over the age of 65. After adjusting for potential confounders, WHtR was found to have a negative association with cognitive function (β = -36.91, 95% CI: -54.54 to -19.29, P < 0.001). Subgroup analyzes stratified by sex and race showed that the negative correlation of WHtR with cognitive function remained in both men and women, as well as in non-Hispanic white and other races. Among women, the association between WHtR and cognitive function followed an inverted U-shaped curve, with an inflection point of 0.68.

CONCLUSION

This study provides evidence of a negative association between WHtR and cognitive function in older adults. These findings suggest that in advanced age, central obesity may have negative implications for cognitive function.

Waist-based anthropometric measures and central adiposity-related comorbidities in children

BACKGROUND

Waist-related measures are commonly used to classify central adiposity and related comorbidities. This classification may be essential among children, as it may identify the risk of future non-communicable diseases.

METHODS

A cross-sectional study was conducted in the Eastern Cape province, South Africa, among 459 primary school learners aged 9-14 years. Height, weight and waist circumference (WC) were measured using standardised techniques recommended by World Health Organization (WHO). The anthropometric measurements, including body mass index (BMI), WC, waist-to-hip ratio (WHR) and waist-to-height ratio (WHtR) were computed and evaluated.

RESULTS

Most participants were girls (57.70%) with an average age of 11.20 ± 1.60 years. The average weight was 38.81 kg ± 10.49 kg with an average height of 144.16 (standard deviation [s.d.] = 10.37) cm. The sample had a BMI of 18.41 kg/m2 (s.d. = 3.19). The results showed, on average, WC of 62.10 cm ± 8.12 cm, WHR of 0.82 ± 0.15 and WHtR of 0.44 ± 0.05. Girls reported significantly higher BMI, WC and WHtR. Based on WHtR, the results showed the acceptable ability to classify children according to abdominal obesity, thus identifying their risk for comorbidities.

CONCLUSION

Overall body fat indicated by BMI and central obesity shown by waist-related anthropometric measures can play a significant role in classifying children in terms of their risk of comorbidities.Contribution: To prevent the risks of metabolic diseases in childhood, it is necessary to detect abdominal obesity early using WC-based anthropometric measurements, especially WHtR, to identify those at risk.

Utility of waist-to-height ratio, waist circumference and body mass index in predicting clustered cardiometabolic risk factors and subclinical vascular phenotypes in children and adolescents: A pooled analysis of individual data from 14 countries

AIMS

The clinical utility of waist-to-height ratio (WHtR) in predicting cardiometabolic risk factors (CMRFs) and subclinical markers of cardiovascular disease remains controversial. We aimed to compare the utility of WHtR with waist circumference (WC) and body mass index (BMI) in identifying children and adolescents (youths) at risk for cardiometabolic outcomes, including clustered CMRFs, high carotid intima-media thickness (cIMT), and arterial stiffness (assessed as high pulse wave velocity, PWV).

METHODS

We analyzed data from 34,224 youths (51.0 % boys, aged 6-18 years) with CMRFs, 5004 (49.5 % boys, aged 6-18 years) with cIMT measurement, and 3100 (56.4 % boys, aged 6-17 years) with PWV measurement from 20 pediatric samples across 14 countries.

RESULTS

WHtR, WC, and BMI z-scores had similar performance in discriminating youths with ≥3 CMRFs, with the area under the curve (AUC) (95 % confidence interval, CI)) ranging from 0.77 (0.75-0.78) to 0.78 (0.76-0.80) using the modified National Cholesterol Education Program (NCEP) definition, and from 0.77 (0.74-0.79) to 0.77 (0.74-0.80) using the International Diabetes Federation (IDF) definition. Similarly, all three measures showed similar performance in discriminating youths with subclinical vascular outcomes, with AUC (95 % CI) ranging from 0.67 (0.64-0.71) to 0.70 (0.66-0.73) for high cIMT (≥P95 values) and from 0.60 (0.58-0.66) to 0.62 (0.58-0.66) for high PWV (≥P95 values).

CONCLUSIONS

Our findings suggest that WHtR, WC, and BMI are equally effective in identifying at-risk youths across diverse pediatric populations worldwide. Given its simplicity and ease of use, WHtR could be a preferable option for quickly screening youths with increased cardiometabolic risk in clinical settings.

Prevalence of modifiable risk factors for cardiovascular disease among school-going children and adolescents in Eldoret, Kenya

Introduction

Cardiovascular disease (CVD) prevalence in Kenya is rising. Overweight, pre-hypertension and physical inactivity at younger ages is contributory. These risk factors are inadequately documented among Kenyan children and adolescents, hampering CVD prevention.

Methods

this cross-sectional study randomly sampled 384 participants from Eldoret, Kenya. After ethical considerations, physical activity was assessed. Body mass index (BMI), Waist-Hip-Ratio (WHR) and Waist-Height-Ratio (WHtR) were determined, and blood pressure (BP) was measured.

Results

participants were 14.6±2.7 years, and 62.6% were female. Eight percent had BMI ≥25.0 kg/m2. Of these, 87% were in secondary schools. Using SBP, 27.9% had CVD risk (42.5% and 20% for males and females ≥13 years and 26.5% and 27% for those <13 years, respectively). For DBP, 12.8% had elevated-to-hypertensive BP (13.2% and 8.3% for males and females ≥13 years and 11.8% and 25.4% for those <13 years, respectively). Combining SBP and DBP, 8.1%, mostly males, had elevated-to-hypertensive BP. Using respective WHR cutoffs of 0.90 and 0.85, 31% (boys) and 15.6% (girls) were at CVD risk. For WHtR, 39.6% of boys were >0.463 cut-off (0.493±0.02) against 32.4% for girls >0.469 cut-off (0.517±0.05). Of these, 52.6% (boys) and 69.7% (girls) were in secondary schools. Overall, 45% of participants were sports-inactive and 77.2% did minimal physical activities.

Conclusion

among school-going children and adolescents in Eldoret, Kenya, the prevalence of CVD risk factors was high, especially among boys and in high schools. Large proportions had elevated BP, BMI, WHR and WHtR, and, further, were sedentary, posing a high CVD risk. Lifestyle interventions to mitigate this are urgently needed.

Independent effects of posttraumatic stress disorder diagnosis and metabolic syndrome status on prefrontal cortical thickness and subcortical gray matter volumes

INTRODUCTION

Posttraumatic stress disorder (PTSD) and metabolic syndrome (MetS) are associated with overlapping brain structural differences. These often involve brain structures involved in the regulation of appetite, food intake, satiety, and reward processing. We examined the individual and interactive effects of PTSD diagnosis and MetS on cortical thickness and subcortical gray matter volumes in patients with PTSD (n = 104) compared to trauma-exposed controls (n = 97).

METHODS

Multivariate models were constructed for FreeSurfer-generated prefrontal cortical thickness and subcortical gray matter regions-of-interest (ROIs) to explore the effects of PTSD diagnosis and MetS as predictors, adjusting for relevant socio-demographic and clinical covariates. Individual prefrontal cortical and subcortical limbic ROIs were also selected based on a priori evidence of their involvement in both PTSD and MetS.

RESULTS

The mean age of the sample (n = 201; 78% female) was 41.6 (SD, 13.1) years. PTSD and MetS status showed independent associations with prefrontal cortical thickness and subcortical gray matter volumes across multiple ROIs, adjusting for age, sex, scanner sequence, alcohol, and tobacco use.

CONCLUSIONS

PTSD and MetS are independently associated with brain structural differences, including thinner prefrontal cortical thickness and smaller subcortical gray matter volumes, across multiple ROIs implicated in the hedonic and homeostatic regulation of food intake.

Establishing international optimal cut-offs of waist-to-height ratio for predicting cardiometabolic risk in children and adolescents aged 6-18 years

BACKGROUND

Waist-to-height ratio (WHtR) has been proposed as a simple and effective screening tool for assessing central obesity and cardiometabolic risk in both adult and pediatric populations. However, evidence suggests that the use of a uniform WHtR cut-off of 0.50 may not be universally optimal for pediatric populations globally. We aimed to determine the optimal cut-offs of WHtR in children and adolescents with increased cardiometabolic risk across different countries worldwide.

METHODS

We used ten population-based cross-sectional data on 24,605 children and adolescents aged 6-18 years from Brazil, China, Greece, Iran, Italy, Korea, South Africa, Spain, the UK, and the USA for establishing optimal WHtR cut-offs. We performed an external independent test (9,619 children and adolescents aged 6-18 years who came from other six countries) to validate the optimal WHtR cut-offs based on the predicting performance for at least two or three cardiometabolic risk factors.

RESULTS

Based on receiver operator characteristic curve analyses of various WHtR cut-offs to discriminate those with ≥ 2 cardiometabolic risk factors, the relatively optimal percentile cut-offs of WHtR in the normal weight subsample population in each country did not always coincide with a single fixed percentile, but varied from the 75th to 95th percentiles across the ten countries. However, these relatively optimal percentile values tended to cluster irrespective of sex, metabolic syndrome (MetS) criteria used, and WC measurement position. In general, using ≥ 2 cardiometabolic risk factors as the predictive outcome, the relatively optimal WHtR cut-off was around 0.50 in European and the US youths but was lower, around 0.46, in Asian, African, and South American youths. Secondary analyses that directly tested WHtR values ranging from 0.42 to 0.56 at 0.01 increments largely confirmed the results of the main analyses. In addition, the proposed cut-offs of 0.50 and 0.46 for two specific pediatric populations, respectively, showed a good performance in predicting ≥ 2 or ≥ 3 cardiometabolic risk factors in external independent test populations from six countries (Brazil, China, Germany, Italy, Korea, and the USA).

CONCLUSIONS

The proposed international WHtR cut-offs are easy and useful to identify central obesity and cardiometabolic risk in children and adolescents globally, thus allowing international comparison across populations.

Optimal cut-off value of waist circumference-to-height ratio to predict central obesity in children and adolescents: A systematic review and meta-analysis of diagnostic studies

Introduction

Waist circumference-to-height ratio (WHtR) is a simple anthropometric index with good screening power and fast interpretation for early detection of childhood abdominal obesity. This systematic review and meta-analysis aims to determine the best cut-off value of WHtR to use in clinical setting.

Methods

Comprehensive searches were conducted in PubMed, Scopus, and Web of Science by the end of March 2021. Observational studies investigated the best WHtR cut-off to detect abdominal obesity in children and adolescents were included. Thirteen articles (n = 180,119) were included in this systematic review and eight documents were included in the meta-analysis.

Results

The overall optimal cut-off was 0.49 with pooled sensitivity, specificity and diagnostic odds ratio (DOR) of 0.93 (95% confidence interval (CI): 0.93-0.96), 0.88 (95% CI: 0.85-0.91) and 102.6 (95% CI: 50.7-207.5), respectively. The optimal WHtR cut-off to predict abdominal obesity in girls and boys were both 0.49.

Discussion

The current study shows that we could use this cut-off as a simple index for predicting abdominal obesity in children and adolescents without the need for any charts in practice.

Correlation of body mass index and waist to height ratio with cardiovascular risk factors in Colombian preschool and school children

Objective

To analyze the agreement between body mass index (BMI) and waist-to-height Ratio (WHtR) to identify preschool and school children with cardiovascular risk factors (CRFs).

Methods

Three-hundred-twenty-one kids were divided into preschool (3-5 years) and school children (6-10 years). BMI was used to classify children as overweight or obese. Abdominal obesity was defined with a WHtR ≥0.50. Fasting blood lipids, glucose and insulin were measured, and the homeostasis model assessment of insulin resistance (HOMA-IR) was calculated. The presence of CRFs and multiple non-waist circumference (non-WC) metabolic syndrome factors (MetS-Factors) [high HOMA-IR, high triglycerides and low high-density lipoprotein cholesterol (HDL-C)] were analyzed.

Results

One-hundred-twelve preschool and 209 school children were evaluated. WHtR ≥0.50 classified abdominal obesity in more than half of the preschool children, exceeding those classified with overweight+obesity by BMI (59.5% vs. 9.8%; p<0.001). There was no agreement between WHtR and BMI to identify preschool kids with CRFs and multiple non-WC MetS-Factors (kappa: 0.0 to 0.23, p>0.05). There were similar proportions of school children classified with abdominal obesity by the WHtR and overweight+obesity by the BMI (18.7% vs. 24.9%; p>0.05). There was substantial agreement between WHtR and BMI to identify school children with high total cholesterol values, low-density lipoprotein cholesterol (LDL-C), triglycerides, non-HDL-C, insulin, HOMA-IR, low HDL-C values, and the presence of multiple non-WC MetS-Factors (kappa: 0.616 to 0.857, p<0.001).

Conclusion

In preschool children WHtR ≥0.5 disagree with BMI results, but in school kids, it has good agreement with the BMI to classify the children´s nutritional status and to identify those with CRFs.

Association between anthropometric indices and non-anthropometric components of the metabolic syndrome in Saudi adults

Context

Waist circumference (WC) is used in screening for metabolic syndrome (MetS) based on its association with cardiometabolic risk. This might apply differently in ethnically different populations. Associations with other measures are also unclear.

Objective

This work aimed to investigate the association between neck circumference (NC), WC, WC:hip circumference, WC:height (WC:Ht), NC:Ht, fat percentage, body mass index (BMI), conicity index, abdominal volume index, and weight-adjusted waist index with nonanthropometric components of MetS in nondiabetic Saudi adults.

Methods

This cross-sectional study took place in public health centers in Jeddah, comprising 1365 Saudi adults (772 men and 593 women) aged 18 years or older not previously diagnosed with diabetes.

Main outcome measures included

the presence of 2 or more nonanthropometric components of the MetS were used to define clinical metabolic abnormality (CMA). The predictive ability of studied anthropometric indices for CMA was determined using the area under receiver operating characteristics (AUC) curve and binary logistic regression.

Results

A total of 157 men and 83 women had CMA. NC and NC:Ht had the highest predictive ability for CMA in men (odds ratio [OR]_NC = 1.79, P < .001 and OR_NC:Ht = 1.68, P < .001; AUC_NC = 0.69 [95% CI, 0.64-0.74] and AUC_NC:Ht = 0.69 [95% CI, 0.64-0.73]). In women, WC had the highest predictive ability OR_WC = 1.81, P < .001; AUC_WC = 0.75 [95% CI, 0.69-0.80]).

Conclusion

Upper-body anthropometric indicators that were associated with subcutaneous fat had the highest predictive ability for CMA in men whereas abdominal obesity indictors had the best predictive ability in women, suggesting that fat distribution might contribute to CMA in a sex-specific manner.

Accuracy of different cutoffs of the waist-to-height ratio as a screening tool for cardiometabolic risk in children and adolescents: A systematic review and meta-analysis of diagnostic test accuracy studies

The present systematic review with meta-analysis sought to estimate the accuracy of different waist-to-height ratio (WHtR) cutoff ranges as risk indicators for cardiometabolic health in different populations of children and adolescents. Systematic searches were undertaken to identify studies in apparently healthy participants aged 3-18 years that conducted receiver operating characteristic curve analysis and reported area under the receiver operating characteristic curves for WHtR with any cardiometabolic biomarker. Forty-one cross-sectional studies were included in the meta-analysis, including 138,561 young individuals (50% girls). Higher area under summary receiver operating characteristic (AUSROC) values were observed in cutoffs between 0.46 and 0.50 (AUSROC = 0.83, 95%CI: 0.80-0.86) and ≥0.51 (AUSROC = 0.87, 95%CI: 0.84-0.90) (p < 0.001 in comparison with cutoffs 0.41 to 0.45), with similar results in both sexes. The AUSROC value increased in the East and Southeast Asian regions using a WHtR cutoff of ≥0.46 (AUSROC = 0.90, 95%CI: 0.87 to 0.92). A cutoff of ≥0.54 was optimal for the Latin American region (AUSROC = 0.96, 95%CI: 0.94-0.97). Our meta-analysis identified optimal cutoff values of WHtR for use in children and adolescents from different regions. Despite the widely accepted WHtR cutoff of 0.50, the present study indicated that a single cutoff value of WHtR may be inappropriate.

Assessment of Anthropometric Indices for Optimal Cut-Offs for Obesity Screening in a South African Adolescent Population

Simple Summary

The diagnosis of obesity in sub-Saharan African children relies on cut-off values for body mass index percentile (pBMI) and waist-to-height ratio (WtHR) established in western populations. Hence, this study assessed anthropometric indices to determine optimal cut-off values for obesity screening in the South African adolescent population. Findings from this study showed that the cut-off value for pBMI was p85.2th, which improved the sensitivity of the test by approximately 30% compared to the CDC recommended BMI percentile of p95.0th. Moreover, the optimal cut-off for WHtR was 0.481, which was close to the recommended cut-off value of 0.5. This study reveals a lower pBMI cut-off value, different from the CDC recommended cut-off, for screening obesity in a South African adolescent population and suggests that the optimal pBMI cut-off for obesity screening may be ethnic-specific.

Abstract

The assessment of obesity in sub-Saharan Africa relies on cut-offs established from western populations. This study assessed anthropometric indices to determine optimal cut-off values for obesity screening in the South African adolescent population. A cross-sectional study involving 1144 (796 females and 348 males) adolescents aged 11–17 years from the Eastern Cape Province of South African was conducted. Anthropometric parameters were measured. Receiver operating characteristic (ROC) analysis was performed to assess the sensitivity and specificity of obesity screening tools and establish cut-offs. The optimal cut-offs for obesity in the cohort using waist-to-height ratio (WHtR) as reference were: neck circumference (NC) = 30.6 cm, mid-upper arm circumference (MUAC) = 25.9 cm, waist circumference (WC) = 75.1 cm, hip circumference (HC) = 92.15 cm and body mass index percentile (pBMI) = p85.2th. The new pBMI cut-off value at p85.2th improved the sensitivity of the test by approximately 30% compared to the CDC recommended BMI percentile (pBMIr) of p95.0th. When pBMI was used as reference, the optimal cut-offs in the cohort were: WHtR = 0.481, NC = 30.95 cm, MUAC = 27.95 cm, WC = 76.1 cm and HC = 95.75 cm. The WHtR optimal cut-off of 0.481 was close to the recommended cut-off value of 0.5. The predicted prevalence of obesity obtained using cut-offs from ROC analysis was higher than those from recommended references. All cut-off values for the various anthropometric measures generally increased with age for all percentile ranges. This study reveals a lower pBMI cut-off value, different from the CDC recommended cut-off, for screening obesity in a South African adolescent population. The study has established that the optimal pBMI cut-off for obesity screening may be ethnic-specific.

Performance of waist-to-height ratio as a screening tool for identifying cardiometabolic risk in children: a meta-analysis

OBJECTIVE

To provide the latest evidence of performance and robustness of waist-to-height ratio (WHtR) in discriminating clusters of cardiometabolic risk factors (CMRs) and promote WHtR in routine primary health care practice in children, a meta-analysis was used.

METHODS

Searches was performed in eight databases from inception to July 03, 2020. Inclusion criteria were: (1) observational study, (2) children and adolescents, (3) provided WHtR measurements, (4) had CMRs as outcomes, and (5) diagnostic studies. Exclusion criteria were: (1) non-original articles, (2) unable to extract 2 × 2 contingency tables, (3) not in English or Chinese language, (4) populations comprising clinical patients, or (5) duplicate articles. WHtR cutoff points, 2 × 2 contingency tables were extracted from published reports. Outcomes included: CMR clusters of at least three CMRs (CMR₃), two (CMR₂), one (CMR₁), and CMR components. Bivariate mixed-effects models were performed to estimate the summarised area under the curves (AUSROC) with 95% CIs and related indexes. We conducted subgroup analyses by sex and East Asian ethnicity.

RESULTS

Fifty-three observational studies were included. The AUSROC reached 0.91 (95% CI: 0.88-0.93), 0.85 (95% CI: 0.81, 0.88) and 0.75 (95% CI: 0.71, 0.79) for CMR₃, CMR₂, and CMR₁, respectively. The pooled sensitivity and specificity for CMR₃ reached 0.84 and exceeded 0.75 for CMR₂. For CMR₁, the sensitivity achieved 0.55 with 0.84 for specificity. We had similar findings for our subgroup and sensitivity analyses.

CONCLUSIONS

WHtR shows good and robust performance in identifying CMRs clustering across racial populations, suggesting its promising utility in public health practice globally.

The prevalence of pediatric metabolic syndrome-a critical look on the discrepancies between definitions and its clinical importance

Introduction

The Metabolic Syndrome (MetS) describes the clustering of cardio-metabolic risk factors—including abdominal obesity, insulin resistance, elevated blood pressure, high levels of triglycerides, and low levels of high-density lipoproteins—that increase the risk for developing cardiovascular diseases and type 2 diabetes mellitus. However, a generally accepted definition of MetS in pediatric patients is still lacking.

Objectives

The aim was to summarize current prevalence data of childhood MetS as well as to discuss the continuing disagreement between different pediatric definitions and the clinical importance of such diagnosis.

Methodology

A systematic literature search on the prevalence of pediatric MetS was conducted. Articles that were published during the past 5 years (2014–2019), using at least one of four predetermined classifications (International Diabetes Federation, Cook et al., Ford et al., and de Ferranti et al.), were included.

Results

The search resulted in 1167 articles, of which 31 publications met all inclusion criteria.

Discussion

The prevalence of MetS ranged between 0.3 and 26.4%, whereby the rising number of children and adolescents with MetS partly depended on the definition used. The IDF definition generally provided the lowest prevalences (0.3–9.5%), whereas the classification of de Ferranti et al. yielded the highest (4.0–26.4%). In order to develop a more valid definition, further research on long-term consequences of childhood risk factors such as abdominal obesity, insulin resistance, hypertension, and dyslipidemia is needed. There is also a temptation to suggest one valid, globally accepted definition of metabolic syndrome for pediatric populations but we believe that it is more appropriate to suggest definitions of MetS that are specific to males vs. females, as well as being specific to race/ethnicity or geographic region. Finally, while this notion of definitions of MetS specific to certain subgroups is important, it still needs to be tested in future research.

Comparisons of body mass index, waist circumference, waist-to-height ratio and a body shape index (ABSI) in predicting high blood pressure among Malaysian adolescents: a cross-sectional study

OBJECTIVE

To compare the performance of different anthropometric indices including body mass index (BMI), waist circumference (WC), waist-to-height ratio (WHtR) and a body shape index to predict high blood pressure (BP) in adolescents using the 90th and 95th percentiles as two different thresholds.

DESIGN

Cross-sectional study.

SETTING

Probability proportionate to size was used to randomly select two schools in Selangor state, Malaysia.

PARTICIPANTS

A total of 513 adolescents (58.9% women and 41.1% men) aged 12-16 years were recruited.

PRIMARY AND SECONDARY OUTCOME MEASURES

Weight, height, WC and BP of the adolescents were measured. The predictive power of anthropometric indices was analysed by sex using the receiver operating characteristic curve.

RESULTS

BMI and WHtR were the indices with higher areas under the curve (AUCs), yet the optimal cut-offs to predict high BP using the 95th percentile were higher than the threshold for overweight/obesity. Most indices showed poor sensitivity under the suggested cut-offs. In contrast, the optimal BMI and WHtR cut-offs to predict high BP using the 90th percentile were lower (men: BMI-for-age=0.79, WHtR=0.46; women: BMI-for-age=0.92, WHtR=0.45). BMI showed the highest AUC in both sexes but had poor sensitivity among women. WHtR presented good sensitivity and specificity in both sexes.

CONCLUSIONS

These findings suggested that WHtR might be a useful indicator for screening high blood pressure risk in the routine primary-level health services for adolescents. Future studies are warranted to involve a larger sample size to confirm these findings.

Utility of waist circumference-to-height ratio as a screening tool for generalized and central obesity among Iranian children and adolescents: The CASPIAN-V study

BACKGROUND

Waist-to-height ratio (WHtR) is regarded as a simple anthropometric index for evaluating central adiposity because of its independence of age, gender, and ethnicity.

OBJECTIVE

The purpose of this study was to determine the optimal WHtR cutoff value in screening obesity and to compare it with other obesity indicators including body mass index (BMI) and waist circumference (WC) in Iranian children and adolescents.

METHODS

This large survey was conducted on 14 274 Iranian children and adolescents as a national school-based surveillance study (CASPIAN) in 2015. The receiver operating characteristic curve analysis was performed to estimate the optimal cut-off points of WHtR for the prediction of general and central obesity. The area under curve (AUC) was used to compare the ability of WHtR cut-off points, BMI and WC percentiles to discriminate students with and without obesity according to age and sex.

RESULTS

The optimal WHtR cutoff value for predicting general obesity was 0.49 and 0.48 for boys and girls, respectively and for central obesity according to WC ≥ 90th percentile was 0.50 for both genders. AUC values of WHtR for predicting general and central obesity were 87% and 96%, which indicates its strong predictive ability. For central obesity, the AUCs of WHtR were superior to those of WC percentiles. The kappa agreement coefficient was 0.55 between WC ≥ 90th percentile and WHtR ≥ 0.5.

CONCLUSIONS

The WHtR ≥ 0.5 as a simple and useful screening tool is better than WC, for predicting general and central obesity in different age and sex groups of Iranian children and adolescents.

Waist-to-height ratio as a risk marker for metabolic syndrome in childhood. A meta-analysis

BACKGROUND

Individuals with abdominal obesity have a higher cardiovascular risk, regardless of the degree of global overweight.

OBJECTIVE

To estimate the accuracy of the Waist/height ratio (WtHR) as a risk marker for metabolic syndrome (MS) in children or adolescents.

METHODS

Published cohort or cross-sectional studies (Pubmed, Embase-SCOPUS and CINAHL) were searched, with no limits of time. Studies providing Waist/height ratio and clustered criteria of metabolic syndrome were included.

RESULTS

Thirty-one studies (66,912 subjects) were selected. Overall, a high WtHR (≥0.5) was associated with a four-fold increased risk of clustered criteria of MS (odds ratio [OR] 4.15, 95% confidence interval [95% CI]: 2.69 to 6.42) and two-fold increased risk when adjusted by general obesity (adjusted OR 2.26, 95% CI: 1.29 to 3.98). The WtHR, as a quantitative measure, showed a pooled area under the curve of 0.76 (95% CI: 0.71 to 0.80) and, as a dichotomous measure, with a cut-off point close to 0.5, a sensitivity of 60% (95% CI: 50% to 68.8%) and a specificity of 79% (95% CI: 71.6% to 83.9%).

CONCLUSIONS

Measuring WtHR may be considered in regular health checks of children and adolescents, as it can measure cardiovascular risk regardless of the degree of general obesity.

Anthropometrics, Metabolic Syndrome, and Mortality Hazard

Independent indices (height, body mass index, a body shape index, and hip index) derived from basic anthropometrics have been found to be powerful predictors of mortality hazard, especially when the attributable risks are summed over these indices to give an anthropometric risk index (ARI). The metabolic syndrome (MS) is defined based on the co-occurrence of anthropometric, clinical, and laboratory criteria and is also widely employed for evaluating disease risk. Here, we investigate correlations between ARI and MS in a general population sample, the United States Third National Health and Nutrition Examination Survey. Baseline values of ARI and MS were also evaluated for their association with mortality over approximately 20 years of follow-up. ARI was found to be positively correlated with each component of MS, suggesting connections between the two entities as measures of cardiometabolic risk. ARI and MS were both significant predictors of mortality hazard. Although the association of ARI with mortality hazard was stronger than that of MS, a combined model with both ARI and MS score as predictors improved predictive ability over either construct in isolation. We conclude that the combination of anthropometrics and clinical and laboratory measurements holds the potential to increase the effectiveness of risk assessment compared to using either anthropometrics or the current components of MS alone.

Validation of surrogate markers for metabolic syndrome and cardiometabolic risk factor clustering in children and adolescents: A nationwide population-based study

Prevalence of metabolic syndrome (MetS) in children is increasing and identifying the risk factors for MetS during childhood is an important first step to prevent chronic diseases later in life. The aim of the present study was to evaluate the prevalence of MetS and cardiometabolic risk factor (CMRF) clustering among Korean children and adolescents and to validate the associated anthropometric and laboratory surrogate markers. We used data from the 2011–2014 Korean National Health and Nutrition Examination Survey. In total, data for 2,935 subjects (1539 boys, 52.6%) aged 10–19 years were assessed. MetS was defined by central obesity plus any two or more of CMRFs such as abdominal obesity, hypertension, hyperglycemia, hypertriglyceridemia, and decreased high density lipoprotein cholesterol (HDL-C) using the International Diabetes Federation criteria for children and adolescents. The presence of two or more CMRFs was classified as CMRF clustering. The prevalence of MetS and CMRF clustering in this group was found to be 1.8% and 8.9%, respectively. The receiver operating characteristic analysis of MetS and CMRF clustering, and the area under the curve (95% confidence interval) of surrogate markers revealed that the waist circumference to height ratio [0.960 (95% CI 0.959–0.960), cut-off 0.491] showed the highest predictability for MetS whereas triglyceride to HDL-C ratio [0.891 (95% CI 0.891–0.892), cut-off 2.63] showed the highest predictability for CMRF clustering. Long-term follow-up is needed for further validation.

ANTHROPOMETRY AND CLUSTERED CARDIOMETABOLIC RISK FACTORS IN YOUNG PEOPLE: A SYSTEMATIC REVIEW

OBJECTIVE

To conduct a systematic review of the literature on the ability of anthropometric indicators to predict clustered cardiometabolic risk factors (CMRF) in children and adolescents.

DATA SOURCE

Studies published from June 1st, 2011 to May 31st, 2016 in the PubMed, SciELO and LILACS databases were analyzed. The research was based on keywords derived from the terms "anthropometric indicators" AND "cardiometabolic risk factors". Observational studies on the ability of anthropometric indicators as predictors of clustered CMRF in children and adolescents in Portuguese, English and Spanish languages were included. Studies with a specific group of obese patients or with other diseases were not included.

DATA SYNTHESIS

Of the 2,755 articles retrieved, 31 were selected for systematic review. Twenty-eight studies analyzed body mass index (BMI) as a predictor of clustered CMRF. Only 3 of the 25 cross-sectional studies found no association between anthropometric indicators and clustered CMRF. The results of six studies that compared the predictive ability of different anthropometric measures for clustered CMRF were divergent, and it was not possible to define a single indicator as the best predictor of clustered CMRF. Only six articles were cohort studies, and the findings suggested that changes in adiposity during childhood predict alterations in the clustered CMRF in adolescence.

CONCLUSIONS

BMI, waist circumference and waist-to-height ratio were predictors of clustered CMRF in childhood and adolescence and exhibited a similar predictive ability for these outcomes. These findings suggest anthropometric indicators as an interesting screening tool of clustered CMRF at early ages.

Optimal waist circumference threshold for diagnosing metabolic syndrome in African people living with HIV infection

Background

The applicability of the internationally advocated cut-off points of waist circumference (WC) derived from Caucasians to diagnose metabolic syndrome (MS) in HIV-infected Africans is unknown. This study aimed to determine the optimal WC cutoffs for MS diagnosis in HIV-infected people receiving care at public healthcare facilities in the Western Cape Province in South Africa.

Methods

Data from 748 randomly selected participants (591 women), with a median age of 38 years, were analysed. The Youden’s index and the top-left-point approaches were used to determine the optimal cutoffs of WC for predicting ≥2 non-adipose MS components.

Results

The two approaches generated the same WC cut-off point in women, 92 cm (sensitivity 64%, specificity 64%) but different cut-off points in men: 87 cm (sensitivity 48%, specificity 85%) based on the Younden’s index and 83 cm (sensitivity 59%, specificity 74%) by the top-left-point method. The advocated thresholds of 94 cm in men had low sensitivity (30%) but high specificity (92%) whereas 80 cm in women showed low specificity (32%) but high sensitivity (85%) for diagnosing MS in this sample. Most African-specific cut-off points performed well, with 90 cm providing acceptable performance in both men (sensitivity 43%, specificity 88%) and women (sensitivity 66%, specificity 59%).

Conclusions

This study underlines the sub-optimal performance of internationally recommended WC thresholds for MS diagnosis in HIV-infected Africans, and supports the need to revisit the guidelines on WC criterion in African population across the board. A single threshold of 90 cm for both genders would be a practical suggestion.

Differential prevalence and associations of overweight and obesity by gender and population group among school learners in South Africa: a cross-sectional study

BACKGROUND

Factors influencing the increasing prevalence of overweight/obesity among children and adolescents in sub-Saharan Africa remain unclear. We assessed the prevalence and determinants of overweight and obesity and effects on cardio-metabolic profile in school learners in the Western Cape, South Africa.

METHODS

Cross-sectional data were collected from 7 to 18-year-old South African school learners attending 14 schools, randomly selected from 107 government schools in the areas. The learners were selected through stratified random sampling techniques. Logistic regressions were used to assess the determinants of overweight/obesity and its association with cardio-metabolic profile.

RESULTS

Among the 1559 participants, the overall prevalence of overweight/obesity was 22.9%. Being a girl (Odds ratio 2.51, 95% CI: 1.92-3.29), or Black African (1.35, 1.04-.75) was associated with increased odds of being overweight/obese. The identified health consequences among the overweight/obese learners differed between the ethnic groups. Overweight/obese coloured (mixed ancestry) learners were more likely to have hypertension (3.27, 1.18-9.08), hypertriglyceridemia (1.94, 0.99-3.78) and low high-density lipoprotein cholesterol (HDL-C) (3.65, 2.33-5.72), overweight/obese Black African learners had higher odds for hypertension (3.62, 1.31-10.04) and low HDL-C (1.56, 1.01-2.40) and overweight/obese White learners were prone to low HDL-C (5.04, 1.35-18.80).

CONCLUSIONS

Overweight/obesity is highly prevalent among school learners in Western Cape (South Africa), with being female or Black African increasing the odds. That overweight/obesity is also associated with adverse cardio-metabolic risk profile aggravates the problem and suggests worse cardiovascular outcomes in South African young adults in the future.

Usefulness of the Waist Circumference-to-Height Ratio in Screening for Obesity and Metabolic Syndrome among Korean Children and Adolescents: Korea National Health and Nutrition Examination Survey, 2010-2014

The aims of this study were to assess the diagnostic value of the weight-to-height ratio (WHtR) for the detection of obesity and metabolic syndrome (MS) in Korean children and adolescents, and to determine the advantages of WHtR as a population-based screening tool in comparison with other obesity indicators, such as body mass index (BMI) and waist circumference (WC). We performed a cross-sectional analysis of data from 3057 children and adolescents (1625 boys, 1332 girls) aged 10-19 years who were included in the fifth Korean National Health and Nutrition Examination Survey (KNHANES, 2010-2012) up to the second year of the sixth KNHANES (2013-2014). Receiver operation characteristic (ROC) curves were generated to determine the optimal cutoff value and accuracy of WHtR for predicting individual obesity indicators or more than two non-WC components of MS. The area under the ROC curve (AUC) is a measure of the diagnostic power of a test. A perfect test will have an AUC of 1.0, and an AUC equal to 0.5 means that the test performs no better than chance. The optimal WHtR cutoff for the evaluation of general obesity and central obesity was 0.50 in boys and 0.47-0.48 in girls, and the AUC was 0.9. Regarding the assessment of each MS risk factor, the optimal WHtR cutoff was 0.43-0.50 in boys and 0.43-0.49 in girls, and these cutoffs were statistically significant only for the detection of high triglyceride and low High-density lipoprotein (HDL) cholesterol levels. When a pairwise comparison of the AUCs was conducted between WHtR and BMI/WC percentiles to quantify the differences in power for MS screening, the WHtR AUC values (boys, 0.691; girls, 0.684) were higher than those of other indices; however, these differences were not statistically significant (boys, p = 0.467; girls, p = 0.51). The WHtR cutoff value was 0.44 (sensitivity, 67.7%; specificity, 64.6%) for boys and 0.43 (sensitivity, 66.4%; specificity, 66.9%) for girls. There was no significant difference between the diagnostic power of WHtR and that of BMI/WC when screening for MS. Although the use of WHtR was not superior, WHtR is still useful as a screening tool for metabolic problems related to obesity because of its convenience.

Performance of different adiposity measures for predicting cardiovascular risk in adolescents

This study aims to compare the performance of body mass index (BMI), waist circumference (WC), and waist-to-height-ratio (WHtR) to predict the presence of at least 3 main CV risk factors in US adolescents. A total of 3621 adolescents (boys: 49.9%) aged 12–17 years from the US National Health and Nutrition Examination Survey (1999–2012) were included in this study. Measured CV risk factors included systolic/diastolic blood pressure, triglycerides, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, and fasting plasma glucose. The AUC of BMI-z score, WC-z score and WHtR-z score to predict at least three CV risk factors were similar (~0.85), irrespective of criteria used to define abnormal levels of CV risk factors. A 1-SD increase in any of three indices to predict CV risk was also similar for the three adiposity scores. For instance, a 1-SD increase risk in BMI-z score, WC-z score and WHtR-z score was 3.32 (95%CI 2.53–4.36), 3.43 (95%CI 2.64–4.46), and 3.45 (95%CI 2.64–4.52), respectively, in the total population using the International Diabetes Federation definition. In addition, the most efficient WHtR cut-off for screening CV risk was ~0.50 in US adolescents. In summary, BMI, WC and WHtR performed similarly well to predict the presence of at least 3 main CV risk factors among US adolescents.

Waist-to-height ratio, body mass index and waist circumference for screening paediatric cardio-metabolic risk factors: a meta-analysis

Waist-to-height ratio (WHtR) is superior to body mass index and waist circumference for measuring adult cardio-metabolic risk factors. However, there is no meta-analysis to evaluate its discriminatory power in children and adolescents. A meta-analysis was conducted using multiple databases, including Embase and Medline. Studies were included that utilized receiver-operating characteristics curve analysis and published area under the receiver-operating characteristics curves (AUC) for adiposity indicators with hyperglycaemia, elevated blood pressure, dyslipidemia, metabolic syndrome and other cardio-metabolic outcomes. Thirty-four studies met the inclusion criteria. AUC values were extracted and pooled using a random-effects model and were weighted using the inverse variance method. The mean AUC values for each index were greater than 0.6 for most outcomes including hypertension. The values were the highest when screening for metabolic syndrome (AUC > 0.8). WHtR did not have significantly better screening power than other two indexes in most outcomes, except for elevated triglycerides when compared with body mass index and high metabolic risk score when compared with waist circumference. Although not being superior in discriminatory power, WHtR is convenient in terms of measurement and interpretation, which is advantageous in practice and allows for the quick identification of children with cardio-metabolic risk factors at an early age.

An Anthropometric Risk Index Based on Combining Height, Weight, Waist, and Hip Measurements

Body mass index (BMI) can be considered an application of a power law model to express body weight independently of height. Based on the same power law principle, we previously introduced a body shape index (ABSI) to be independent of BMI and height. Here, we develop a new hip index (HI) whose normalized value is independent of height, BMI, and ABSI. Similar to BMI, HI demonstrates a U-shaped relationship to mortality in the Third National Health and Nutrition Examination Survey (NHANES III) population. We further develop a new anthropometric risk index (ARI) by adding log hazard ratios from separate nonlinear regressions of the four indicators, height, BMI, ABSI, and HI, against NHANES III mortality hazard. ARI far outperforms any of the individual indicators as a linear mortality predictor in NHANES III. The superior performance of ARI also holds for predicting mortality hazard in the independent Atherosclerosis Risk in Communities (ARIC) cohort. Thus, HI, along with BMI and ABSI, can capture the risk profile associated with body size and shape. These can be combined in a risk indicator that utilizes complementary information from height, weight, and waist and hip circumference. The combined ARI is promising for further research and clinical applications.

Establishing Waist-to-Height Ratio Standards from Criterion-Referenced BMI Using ROC Curves in Low-Income Children

The purpose of this study was to establish health-related waist-to-height ratio (WHtR) cut-points associating with FITNESSGRAM's body mass index (BMI) criterion-referenced standards in low-income children. A secondary aim was to examine the classification agreement between the derived WHtR cut-points and various cardiometabolic blood markers using current recommendations. Participants were 219 children from low-income schools (mean age = 10.5 ± 0.6 years). Waist circumference, height, weight, and cardiometabolic blood markers were collected in a fasting state before school hours. Receiver operating characteristic (ROC) curves were used to determine WHtR cut-points that associated with a child meeting FITNESSGRAM's age- and sex-specific criterion-referenced standards for BMI. The derived WHtR cut-point was 0.50 (AUC = 0.89, p < 0.001; sensitivity = 0.86, specificity = 0.82, and accuracy = 84.3%). Classification agreement using the derived WHtR cut-point with various blood marker standards was statistically significant but considered weak to fair (kappa 0.14-0.34, agreement = 59%-67%, and p < 0.01). The WHtR cut-point of 0.50 can be used with strong accuracy to distinguish low-income children who met FITNESSGRAM's criterion-referenced standards for body composition; however, the evidence was weaker for its use in distinguishing low-income children meeting specific cardiometabolic blood marker recommendations.

Predictive capacity of anthropometric indicators for dyslipidemia screening in children and adolescents

OBJECTIVE

To analyze the predictive capacity of anthropometric indicators and their cut-off values for dyslipidemia screening in children and adolescents.

METHODS

This was a cross-sectional study involving 1139 children and adolescents, of both sexes, aged 6-18 years. Body weight, height, waist circumference, subscapular, and triceps skinfold thickness were measured. The body mass index and waist-to-height ratio were calculated. Children and adolescents exhibiting at least one of the following lipid alterations were defined as having dyslipidemia: elevated total cholesterol, low high-density lipoprotein, elevated low-density lipoprotein, and high triglyceride concentration. A receiver operating characteristic curve was constructed and the area under the curve, sensitivity, and specificity was calculated for the parameters analyzed.

RESULTS

The prevalence of dyslipidemia was 62.1%. The waist-to-height ratio, waist circumference, subscapular, body mass index, and triceps skinfold thickness, in this order, presented the largest number of significant accuracies, ranging from 0.59 to 0.78. The associations of the anthropometric indicators with dyslipidemia were stronger among adolescents than among children. Significant differences between accuracies of the anthropometric indicators were only observed by the end of adolescence; the accuracy of waist-to-height ratio was higher than that of subscapular (p=0.048) for females, and the accuracy of waist circumference was higher than that of subscapular (p=0.029) and body mass index (p=0.012) for males. In general, the cut-off values of the anthropometric predictors of dyslipidemia increased with age, except for waist-to-height ratio. Sensitivity and specificity varied substantially between anthropometric indicators, ranging from 75.6 to 53.5 and from 75.0 to 50.0, respectively.

CONCLUSIONS

The anthropometric indicators studied had little utility as screening tools for dyslipidemia, especially in children.

Waist circumference to height ratio in children and adolescents

BACKGROUND

Waist circumference (WC) to height ratio (WC/HT) is used as a measure of central obesity. However, the optimum ratio that will separate populations with high from low cardiovascular risk remains controversial. This investigation evaluates an optimum WC/HT value to define central obesity in children.

METHODS

The sensitivity and specificity of WC/HT in 649 children (age 2-18 years) without evidence of heart disease were analyzed for WC and for body mass index (BMI).

RESULTS

A WC/HT ≥0.5 resulted in sensitivity:specificity of 99%:72% for detecting central obesity and 83%:77% for detecting overweight (BMI ≥85th percentile) subjects. A value of WC/HT ≥0.55 yielded sensitivity:specificity of 80%:96% for detecting central obesity and 75%:94% for detecting subjects with obesity (BMI ≥95th percentile).

CONCLUSIONS

The use of WC/HT between ≥0.5 and <0.55 identified subjects at-risk for central obesity and WC/HT ≥0.55 identified central obesity with a high probability.