Growth charts for children aged 6-17 years in Shanxi, China: comparison with other cities of China and WHO.

BACKGROUND: Growth charts are an important method for evaluating a child's health, growth, and nutritional status. It is essential to monitor the growth of children and adolescents using growth charts. OBJECTIVES: To present body mass index (BMI)-for-age references reflecting children's growth in Shanxi. We also compare our new data with growth references of other cities of China and World Health Organization (WHO) growth standards. METHODS: A stratified cluster random sampling method was used to recruit 5461 children and adolescents aged 6-17 years. Height and weight were measured and BMI was calculated. The LMS method was used to calculate the percentile values of body mass index by sex and age. Smoothed BMI-for-age growth curves were presented for both sexes and compared with reference data from other cities of China and WHO. RESULTS: BMI centiles increased with age but with different patterns in both boys and girls. The centile curves from the 3rd to the 50th had a slight increase, while a sharp increase was seen from 11 to 17 years in boys and from 6 to 14 years in girls in the higher centiles. In comparison with other cities of China, the values for the 50th percentile are higher than those reported for children from China 2009, Shanghai, Changsha and China 2010 in both sexes. In comparison with WHO growth references, Chinese girls and boys had higher values in all percentiles, whereas curves of girls look roughly the same. The medians for BMI in Shanxi increase linearly from 6 to 17 years in boys. CONCLUSIONS: The BMI percentiles of children aged 6-17 years in Shanxi differed significantly from the growth reference curves of other cities of China and WHO. Recommending the provision of BMI reference curves for local children and adolescents to assess their growth and development and monitor their nutritional status. Early detection of overweight and obesity in children provides a scientific basis for the prevention and control of overweight and obesity in children.

Normative reference data for intracranial volume in children: The results of CT volumetry.

BACKGROUND: Intracranial volume (ICV) is an important indicator of the development of the brain and skull in children. At present, there is a lack of ICV growth standards based on large infant and children samples. Our aim was to assess the normal range of the ICV variation in Russian children using a modern automatic system for constructing the endocranial cavity (Endex) and to provide growth standards of the ICV for clinical practice. METHODS: High-resolution head CT scans were obtained from 673 apparently healthy children (380 boys and 293 girls) aged 0-17 years and transformed into the ICV estimates using the Endex software. The open-source software RefCurv utilizing R and the GAMLSS add-on package with the LMS method was then used for the construction of smooth centile growth references for ICV according to age and sex. RESULTS: We demonstrated that the ICVs estimates calculated using the Endex software are perfectly comparable with those obtained by a conventional technique (i.e. seed feeling). Sex-specific pediatric growth charts for ICV were constructed. CONCLUSIONS: This study makes available for use in clinical practice ICV growth charts for the age from 0 to 17 based on a sample of 673 high-resolution CT images.

Development of specific growth charts for children with Fanconi anemia.

Patients with Fanconi anemia (FA) are often perceived to have poor growth when general population growth curves are utilized. We hypothesize that FA patients have unique growth and aimed to create FA-specific growth charts. Height and weight data from ages 0 to 20 years were extracted from medical records of patients treated at the Fanconi Anemia Comprehensive Care Clinic at the University of Minnesota. Height, weight, and BMI growth curves were generated and fitted to reference percentiles using the Lambda-Mu-Sigma method. FA-specific percentiles were compared to WHO standards for ages 0-2 and CDC references for ages 2-20. In FA males, the 50th height- and weight-for-age percentiles overlap with the 3rd reference percentile. In FA females, only the 50th height-for-age percentile overlaps with the 3rd reference percentile. For weight, FA females show progressive growth failure between 6 and 24 months followed by stabilization around the 50th percentile. The FA BMI-for-age percentiles show similar patterns to the weight-for-age percentiles but have different timing of onset of adiposity rebound and broader variability in females. Growth in FA patients follows a different trajectory than available normative curves. FA-specific growth charts may be useful to better guide accurate growth expectations, evaluations, and treatment.

LMS-based continuous pediatric reference values for soluble receptor activator of nuclear factor kappa B ligand (sRANKL) and osteoprotegerin (OPG) in the HARP cohort.

Soluble RANKL (sRANKL) and osteoprotegerin (OPG) are regulators of osteoclast differentiation and activation, but adequate pediatric reference values are lacking. Here we provide LMS (Lambda-Mu-Sigma)-based continuous pediatric reference percentiles for sRANKL, OPG and sRANKL/OPG ratio that will allow calculation of standardized patient z-scores to assess bone modeling in children. PURPOSE: Soluble receptor activator of nuclear factor kappa B ligand (sRANKL) and osteoprotegerin (OPG) are regulators of osteoclast differentiation and activation and thus bone metabolic turnover in children. Adequate pediatric reference values for their serum/plasma concentrations are lacking. The development of Lambda-Mu-Sigma (LMS)-based continuous reference percentiles for laboratory parameters allow improved data interpretation in clinical practice. METHODS: A total of 300 children aged 0.1-18 years (166 boys) were enrolled in the HAnnover Reference values for Pediatrics (HARP) study. sRANKL and OPG were assessed by ELISA. LMS-based continuous reference percentiles were generated using RefCurv software. RESULTS: LMS-based percentiles were established for sRANKL, OPG and sRANKL/OPG ratio, which were all found to be age-dependent. sRANKL and sRANKL/OPG associated with sex. In boys, sRANKL percentiles were highest during infancy, followed by a continuous decline until the age of 7 years and a second peak around age 12-13 years. In girls, a continuous, slow decline of sRANKL percentiles was noticed from infancy onwards until the age of 13 years, followed by a rapid decline until adulthood. OPG percentiles continuously declined from infancy to adulthood. The percentiles for sRANKL/OPG ratio paralleled those of sRANKL. Serum concentrations of sRANKL correlated with OPG and serum phosphate z-scores, while OPG concentrations inversely associated with standardized body weight, BMI, and urinary phosphate to creatinine ratio (each p < 0.05). CONCLUSION: This is the first report of LMS-based continuous pediatric reference percentiles for sRANKL, OPG and sRANKL/OPG ratio that allows calculation of standardized patient z-scores to assess bone metabolic turnover in children.

The multiple reference range of mean uterine artery pulsatility index for natural and in vitro fertilization singletons during 11-14 gestational weeks.

Background: Ultrasonography of the uterine artery (UtA) in the first and second trimesters of pregnancy can assess uterine-placental blood perfusion and guide early clinical prevention. Establishing normal ranges of the UtA pulsatility index (UtA-PI) at 11-14 weeks of pregnancy is helpful for the early identification of high-risk pregnant women and improving the prognosis. This study aimed to establish a reference range of UtA-PI based on crown-rump length (CRL) for spontaneous and in vitro fertilization (IVF) singleton pregnancy during 11-14 weeks, respectively. Methods: A prospective study was performed at Peking Union Medical College Hospital. Healthy, low-risk women with a singleton pregnancy at 11-14 gestational weeks were consecutively recruited for this study from December 2017 to December 2020. All participants underwent routine prenatal ultrasound examination. The CRL of the fetus and the UtA-PI were measured in both uterine arteries, and average values were calculated. The LMS method was used to fit the percentile (P)5, P10, P25, P50, P75, P90, and P95 curves of the UtA-PI value of spontaneous and IVF singleton pregnancy with CRL changes, respectively. Results: A total of 1,962 pregnant women with normal fetuses were included in this study, including 1,792 pregnancies conceived naturally and 170 IVF fetuses. The UtA-PI reference range in the spontaneous pregnancy group was consistently higher than that in the IVF group during 11-14 weeks, and showed a statistically significant difference in UtA-PI for spontaneous and IVF pregnancies (P<0.001). According to the LMS method, each percentile curve of UtA-PI decreased with the increase of CRL in both the natural pregnancy group and the IVF group. The P95 range of UtA-PI for pregnant women with naturally conceived and IVF pregnancy was 2.74 to 2.11 and 2.50 to 1.94, respectively. The overall change of UtA-PI differentials of the two groups showed a downward trend and decreased slightly with the increase of CRL. Conclusions: This study provided a single-center, large sample of data and constructed a CRL-based reference value of UtA-PI for spontaneous and IVF singleton pregnancy, which provides a reliable basis for early UtA evaluation and early clinical decision-making during 11-14 gestational weeks.

Reference blood pressure values obtained using the auscultation method for 2-year-old Japanese children: from the Japan Environment and Children's Study.

BACKGROUND: Reference blood pressure (BP) values for Japanese children based on a large number of measurements by auscultation have not yet been established. METHODS: This was a cross-sectional analysis of data from a birth-cohort study. The data from the sub-cohort study conducted for children at the age of 2 years in the Japan Environment and Children's Study from April 2015 to January 2017 were analyzed. BP was measured via auscultation using an aneroid sphygmomanometer. Each participant was measured in triplicate, and the average value of two consecutive measurements with a difference of less than 5 mmHg was recorded. The reference BP values were estimated using the lambda-mu-sigma (LMS) method and compared with those obtained via the polynomial regression model. RESULTS: Data from 3361 participants were analyzed. Although the difference between the estimated BP values by the LMS and the polynomial regression model was small, the LMS model was more valid based on the results of the fit curve of the observed values and regression models for each model. For 2-year-old children with heights in the 50th percentile, the 50th, 90th, 95th, and 99th percentile reference values of systolic BP (mmHg) for boys were 91, 102, 106, and 112, and that for girls were 90, 101, 103, and 109, respectively, and those of diastolic BP for boys were 52, 62, 65, and 71, and that for girls were 52, 62, 65, and 71, respectively. CONCLUSION: The reference BP values for 2-year-old Japanese children were determined based on auscultation and were made available.

Methods for Constructing Normalised Reference Scores: An Application for Assessing Child Development at 24 Months of Age.

The use of the lambda-mu-sigma (LMS) method for estimating centiles and producing reference ranges has received much interest in clinical practice, especially for assessing growth in childhood. However, this method may not be directly applicable where measures are based on a score calculated from question response categories that is bounded within finite intervals, for example, in psychometrics. In such cases, the main assumption of normality of the conditional distribution of the transformed response measurement is violated due to the presence of ceiling (and floor) effects, leading to biased fitted centiles when derived using the common LMS method. This paper describes the methodology for constructing reference intervals when the response variable is bounded and explores different distribution families for the centile estimation, using a score derived from a parent-completed assessment of cognitive and language development in 24 month-old children. Results indicated that the z-scores, and thus the extracted centiles, improved when kurtosis was also modeled and that the ceiling effect was addressed with the use of the inflated binomial distribution. Therefore, the selection of the appropriate distribution when constructing centile curves is crucial.

Development of a Zimbabwean child growth curve and its comparison with the World Health Organization child growth standards.

BACKGROUND: There is limited research that describes the growth trajectories of African children. The development of World Health Organization (WHO) growth standards considered a sample of children who lived in environments optimum for human growth. AIM: This study aimed to develop weight-for-age and height-for-age growth curves from the Zimbabwean 2018 National Nutrition Survey and compare them with the WHO growth standards. SETTING: Study participants were recruited from all districts in Zimbabwe. METHODS: Height-for-age and weight-for-age data collected from 32 248 children were used to develop the Zimbabwean references. Smooth growth curves (height, weight and body mass index [BMI]-for-age) were estimated with the Lambda Mu Sigma (LMS) method and compared with the WHO growth standards. RESULTS: Zimbabwean children were shorter and weighed less in comparison with the WHO growth standards. The -2 standard deviation (s.d.) Z-score curves (height-for-age) for Zimbabwean children (boys and girls) were below the -1 s.d. Z-score curves of the WHO growth standards. The Zimbabwean Z-scores (BMI-for-age) values above -1 s.d. were significantly higher in comparison with the corresponding WHO growth standards. CONCLUSION: Utilising the WHO growth standards would diagnose a higher proportion of Zimbabwean children as stunted whilst underestimating the proportion at risk of obesity. The WHO growth standards lack a consideration of the geographical, economic, political and environmental constraints existing between countries.

Establishing Height-for-Age Z-Score Growth Reference Curves and Stunting Prevalence in Children and Adolescents in Pakistan.

Height-for-age Z-score (HAZ) curves are widely used for detecting children with stunting. The aim of this study was to provide smoothed HAZ growth reference values and their curves for Pakistani children and adolescents aged 2-18 years. The prevalence of stunting in Pakistani children was determined. A total of 10,668 healthy Pakistani participants were included. Information related to age, sex, city of residence and height (cm) was used. Age- and sex-specific smoothed HAZ growth reference values and associated graphs were obtained using the lambda-mu-sigma (LMS) method. The prevalence of stunting was calculated by applying WHO 2007 and USCDC 2000 height-for-age references and local reference of the study population. In both sexes, the smoothed HAZ curves increased with age. For 2 and 3 years of age, the height values of the girls were greater than those of the boys. The boys were then taller than the girls. Comparing our median height (z = 0) growth reference data from WHO, USCDC and corresponding data from other countries, Pakistani children and adolescents have significantly different reference values than their counterparts in the reference group. A marked overestimation of the prevalence of stunting was observed (10.8% and 17.9% according to WHO and USCDC, respectively) compared to the local reference (3.0%). It is recommended that the prevalence of stunting in children and adolescents is determined by applying local height growth references to plan health strategies and treatments in the local population.

Reference values of inside leg length and inside leg length to stature ratio for Japanese children, 0-12 years of age.

BACKGROUND: Large datasets of detailed anthropometric measurements are scarce in children. The Japanese Standard Association 1978-1981 survey provides a rare opportunity to use high quality data from Japanese children. AIM: To construct inside leg length (ILL) and inside leg length to stature ratio (ILL/S) reference centile curves for Japanese children. SUBJECTS AND METHODS: The study sample consisted of 14,825 boys and 14,577 girls age 0-18 years for stature and weight measurements, and 9064 boys and 8796 girls age 0-12 years for ILL measurements, who participated in the 1978-1981 national survey on body sizes. LMS method was used to construct the reference centile curves. The reference centile curves for stature, weight, ILL, and ILL/S were compared to those of British children. RESULTS: The L, M, and S reference values for Japanese children are presented for stature, weight, ILL, and ILL/S. Compared with British children of 0-12 years of age, Japanese children of 0-12 years of age had shorter median stature, shorter median ILL, and shorter median ILL/S. CONCLUSION: We present the first reference values for ILL and ILL/S in Japanese children. Japanese children had relatively shorter legs compared to British children from infancy.

Nutritional status and growth centiles using anthropometric measures of school-aged children and adolescents from Multan district.

BACKGROUND: Nutritional status among children and adolescents is assessed using growth rates. The aim of this study was to assess age- and gender-specific height, weight, and body mass index (BMI) centiles among children and adolescents relative to World Health Organization (WHO) references. METHODS: A sample of 1040 school-aged children and adolescents aged 3-18 years from Multan District in Pakistan were selected for the study between January and March 2020. Multistage stratified random sampling was used for sample selection. Centile curves of height, weight, and BMI for age and gender were obtained using the lambda-mu-sigma (LMS) method, and results were compared with WHO 2007 references. RESULTS: For boys and girls, the average height was 137.37 ± 8.24 and 135.62 ± 9.64 cm, average weight was 36.32 ± 6.84 and 35.21 ± 7.27 kg, and average BMI was 18.44 ± 2.67 and 18.36 ± 2.91, respectively. The height centiles of boys were higher than the WHO reference, and during the prepubertal period (age 8 years or older) the centiles were lower than the WHO reference. The height centiles of girls were higher than the WHO reference, and during the pubertal period (age 10 years or older) the centiles were lower than the WHO reference. The gender-wise BMI centiles were higher compared to the WHO reference. CONCLUSION: The prevalence of thinness, overweight, and obesity in boys and girls was significantly higher than the WHO reference. The results of this study on centiles are up-to-date and will be used as a standard for comparison.

New Growth Curves for Spanish Children (0-10 Years) in the Region of Extremadura.

The anthropometric reference data used to examine the growth pattern of children in Spain are obtained from studies carried out several years ago. In the region of Extremadura, the tables obtained by the Faustino Obergozo Foundation, which date back to 2004, are used. The first objective of this work is to develop growth tables and graphs that accurately reflect the somatometric variables of children in Extremadura. Secondly, the averages of these variables by sex will be compared to determine if there are significant differences between them. A database provided by the General Directorate of Planning, Training, and Health and Social Quality of the Regional Government of Extremadura was used, which contains the measurements of height, weight, and body mass index (BMI) of boys and girls in Extremadura between the years 2006-2016. The database was analyzed using the Statistical Package for the Social Sciences (SPSS) version 23 and the R software version 3.5.1, considering a cross-sectional study. As a result, the tables and growth graphs of Extremadura's population base for weight and height are presented, from birth to 10 years, as well as comparisons of the average values of the analyzed variables between boys and girls. We found that there are significant differences in the mean values, according to sex, of the height and weight. On the other hand, BMI progressed normally when comparing the results of the Extremadura population with those reflected by the World Health Organization (WHO). Differences were found when comparing the results with those obtained by the Faustino Orbegozo Foundation.

Developing neck circumference growth reference charts for Pakistani children and adolescents using the lambda-mu-sigma and quantile regression method.

OBJECTIVE: Neck circumference (NC) is currently used as an embryonic marker of obesity and its associated risks. But its use in clinical evaluations and other epidemiological purposes requires sex and age-specific standardised cut-offs which are still scarce for the Pakistani paediatric population. We therefore developed sex and age-specific growth reference charts for NC for Pakistani children and adolescents aged 2-18 years. DESIGN: Cross-sectional multi-ethnic anthropometric survey (MEAS) study. SETTING: Multan, Lahore, Rawalpindi and Islamabad. PARTICIPANTS: The dataset of 10 668 healthy Pakistani children and adolescents aged 2-18 years collected in MEAS were used. Information related to age, sex and NC were taken as study variables. The lambda-mu-sigma (LMS) and quantile regression (QR) methods were applied to develop growth reference charts for NC. RESULTS: The 5th, 10th, 25th, 50th, 75th, 90th and 95th smoothed percentile values of NC were presented. The centile values showed that neck size increased with age in both boys and girls. During 8 and 14 years of age, girls were found to have larger NC than boys. A comparison of NC median (50th) percentile values with references from Iranian and Turkish populations reveals substantially lower NC percentiles in Pakistani children and adolescents compared to their peers in the reference population. CONCLUSION: The comparative results suggest that the uses of NC references of developed countries are inadequate for Pakistani children. A small variability between empirical centiles and centiles obtained by QR procedure recommends that growth charts should be constructed by QR as an alternative method.

First growth reference curves for Tunisian children and adolescents.

A growth chart is a powerful graphical tool displaying children's growth patterns. The aim of this study was to develop growth reference curves appropriate for Tunisian children. The collection of data from this cross-sectional study was conducted on 4358 healthy subjects (2182 girls and 2176 boys) in three pediatric centers and 15 schools. Smoothed growth curves were estimated using the LMS method. The smoothed percentile curves for height, weight, sitting height (SH), and leg length (LL) increase rapidly during the 1st years of life and then progress slowly until 18 years. However, the sitting height-to-height ratio (SHTHR) curves decrease sharply before the age of 4 and then stabilize in both sexes. In addition, the comparison between boys and girls indicated that the values are very similar at most ages. Except during puberty, the values in boys increase (P<0.0001) for the weight, height, SH, and LL parameters and decline (P<0.0001) in the SHTHR compared to the values in girls. The growth rate curves presented two remarkable velocity peaks: the first appears during the 1st years of life and the second at puberty. Height gains at the last stage of growth (puberty) are around 15.45% of final height for boys and 15.52% for girls. This study showed a number of discrepancies for certain age groups when comparing the median weight and height values with those of the World Health Organization, the National Center for Health Statistics, and Algerian references in both sexes. Conclusion: The smoothed percentile curves for weight and height will be useful to access the general growth of Tunisian children. Furthermore, the SH, LL, and SHTHR curves can be used to monitor body proportions during childhood.

Population-based waist circumference reference values in Japanese children (0-6 years): comparisons with Dutch, Swedish and Turkish preschool children.

BACKGROUND: During 1978-1981 the Japanese Standards Association conducted a national survey to collect 64 distinct body measurements for Japanese children and adults. During 1978-1981, the prevalence of childhood obesity was relatively low yet the population was well nourished in Japanese children. The aim of this study is to construct waist circumference and waist circumference to stature ratio reference centile curves for Japanese preschool children. METHODS: We utilized 1978-1981 national survey data on body sizes. There are 4937 boys and 4758 girls age 0-6 years for waist circumference measurements. Waist circumference was measured at the level of the umbilicus. Using LMS method, centile curves were constructed for waist circumference and waist circumference to stature ratio. These reference values were compared with those of Dutch, Swedish and Turkish children. RESULTS: Centile reference curves were made for clinical and epidemiological use. Japanese children had smaller waist circumference centile values as compared to waist circumference measured at the midpoint of the lowest rib cage and the iliac crest of Dutch, Swedish and Turkish children. However, Japanese children had comparable waist circumference to stature ratio centile values to those of Dutch and Turkish children. CONCLUSIONS: This study presents the first age-, sex-, and ethnicity-specific reference values for waist circumference and waist circumference to stature ratio in Japanese preschool children.

Real-Time Implementation of EEG Oscillatory Phase-Informed Visual Stimulation Using a Least Mean Square-Based AR Model.

It is a technically challenging problem to assess the instantaneous brain state using electroencephalography (EEG) in a real-time closed-loop setup because the prediction of future signals is required to define the current state, such as the instantaneous phase and amplitude. To accomplish this in real-time, a conventional Yule-Walker (YW)-based autoregressive (AR) model has been used. However, the brain state-dependent real-time implementation of a closed-loop system employing an adaptive method has not yet been explored. Our primary purpose was to investigate whether time-series forward prediction using an adaptive least mean square (LMS)-based AR model would be implementable in a real-time closed-loop system or not. EEG state-dependent triggers synchronized with the EEG peaks and troughs of alpha oscillations in both an open-eyes resting state and a visual task. For the resting and visual conditions, statistical results showed that the proposed method succeeded in giving triggers at a specific phase of EEG oscillations for all participants. These individual results showed that the LMS-based AR model was successfully implemented in a real-time closed-loop system targeting specific phases of alpha oscillations and can be used as an adaptive alternative to the conventional and machine-learning approaches with a low computational load.

Sample size and sample composition for constructing growth reference centiles.

Growth reference centile charts are widely used in child health to assess weight, height and other age-varying measurements. The centiles are easy to construct from reference data, using the LMS method or GAMLSS (Generalised Additive Models for Location Scale and Shape). However, there is as yet no clear guidance on how to design such studies, and in particular how many reference data to collect, and this has led to study sizes varying widely. The paper aims to provide a theoretical framework for optimally designing growth reference studies based on cross-sectional data. Centiles for weight, height, body mass index and head circumference, in 6878 boys aged 0-21 years from the Fourth Dutch Growth Study, were fitted using GAMLSS. The effect on precision of varying the sample size and the distribution of measurement ages (sample composition) was explored by fitting a series of GAMLSS models to simulated data. Sample composition was defined as uniform on the ageλ scale, where λ was chosen to give constant precision across the age range. Precision was measured on the z-score scale, and was the same for all four measurements, with a standard error of 0.041 z-score units for the median and 0.066 for the 2nd and 98th centiles. Compared to a naïve calculation, the process of smoothing the centiles increased the notional sample size two- to threefold by 'borrowing strength'. The sample composition for estimating the median curve was optimal for λ=0.4, reflecting considerable over-sampling of infants compared to children. However, for the 2nd and 98th centiles, λ=0.75 was optimal, with less infant over-sampling. The conclusion is that both sample size and sample composition need to be optimised. The paper provides practical advice on design, and concludes that optimally designed studies need 7000-25,000 subjects per sex.

Application of the LMS method of constructing fetal reference charts: comparison with the original method.

Objectives: In view of the concern expressed about the current references, new references for fetal biparietal diameter and head circumference should be constructed for contemporary local populations.Methods: We conducted a retrospective cross-sectional study in two hospitals in Guangdong, Southern China. Fetal biparietal diameter and head circumference percentiles regression were fitted using Cole's LMS method. The BPD and HC data were then transformed into Z-scores that were calculated using two series of reference equations obtained from two methods: Cole's LMS method and the original "mean and SD method." Each Z-score distribution was presented as the mean and standard deviation. Finally, the sensitivity and specificity of each reference for identifying fetuses <2.5th or >97.5th percentile (based on the observed distribution of Z-scores) were calculated. The misclassified number and Youden's index were listed.Results: A total of 17,974 biparietal diameter and 18,269 head circumference measurements were chosen to establish a reference chart. The LMS method could fit the local population better than the "mean and SD method" as it had a lower number of misclassified fetuses and a higher Youden's index.Conclusion: The Cole's LMS method was able to construct a satisfied reference range of fetal head sizes in Southern China.

Developing waist circumference, waist-to-height ratio percentile curves for Pakistani children and adolescents aged 2-18 years using Lambda-Mu-Sigma (LMS) method.

Objectives Children from different countries and with different ethnic backgrounds have a distinct pattern of central fat deposition. Therefore, it is essential to develop population-specific percentiles of waist circumference (WC), waist-to-height ratio (WHtR) and waist-to-height ratio exponent (WHtR (exp)) for the evaluation of central obesity. The objective of this study was to develop age-and-gender-specific smoothed WC and WHtR percentile curves for the Pakistani children and adolescents aged 2-18 years. Methods A cross-sectional data-set from a multi-ethnic anthropometric survey was considered. A sample of 10,668 healthy subjects (boys = 51.92%; and girls = 48.08%), aged 2-18 years was studied. Height (cm) and WC (cm) of each subject was measured under standard procedure and WHtR & WHtR (exp) were calculated. Age-and-gender-specific smoothed curves were obtained using the lambda-mu-sigma (LMS) method and compared with percentile curves obtained from different countries. Results Except few early ages, the WC values increased with age in both sexes. Both boys and girls had approximately similar WC during 6-11 years of age and after age of 11, the boys had larger WC than the girls had. For WHtR, the centile curves showed a continuous decrease by 16 years of age and then increased gradually. WHtR of the girls in various ages were having similar or higher than those of the boys. In comparison of WC 50th and 90th percentiles with other countries, it was found that except few ages, the Pakistani children had larger WC than the other reference populations and the results of WHtR were also comparable to the other nations. Conclusions We present new reference data of WC, WHtR and WHtR (exp) using a representative sample of the Pakistani children aged 2-18 years. These reference values can be used provisionally for early detection of central obesity and its associated risks in the Pakistani children.

Diagnostic Performance of Neck Circumference and Cut-off Values for Identifying Overweight and Obese Pakistani Children: A Receiver Operating Characteristic Analysis

Objective: Neck circumference (NC) is considered to be an alternative screening method for obesity. The aims were: (1) to examine the correlation between body mass index (BMI) and NC; and (2) to determine diagnostic performance including the best cut-off values of NC for identification of overweight and obese Pakistani children. Methods: The study sample was 7,921 children, aged 5-14 years, by cross-sectional survey carried-out in four major cities of Pakistan. Receiver operating characteristic analysis was used to investigate the diagnostics performance of NC and to determine the optimal cut-off points for identifying children with overweight and obesity. Results: The mean of each anthropometric variable (i.e., height, weight, BMI and NC) increased with age in both sexes. In the whole sample, NC had a strong positive correlation (r=0.61, p<0.01) with BMI. NC optimal cut-off points for identifying overweight and obesity in Pakistani boys ranged between 25.00 to 30.35 cm and the corresponding values for the girls were 24.00 to 31.62 cm. In the prepubertal period, NC cut-off points indicative overweight, in both boys and girls were 26.36 cm and 25.27 cm, respectively; the corresponding values for obesity were 26.78 cm and 25.02 cm. During puberty, the cut-off values for overweight and obesity respectively were 28.32 cm and 28.57 cm in boys and 28.70 cm and 28.82 cm in girls. Conclusion: NC may be used as a simple and widely applicable measure for identification of overweight and obesity with reasonable accuracy in Pakistani children.