Lambda-mu-sigma Research Articles

Development of LMS and Z Score Growth References for Egyptian Children From Birth Up to 5 Years.

Background: The Lambda-Mu-Sigma (LMS) and Z score methods are important for assessment of growth and nutritional status. In Egypt, there is a lack of this tool for monitoring growth in preschool children.Objective: To develop LMS and Z score growth references for assessment of growth and nutritional status for Egyptian children from birth up to 5 years.Methods: A total of 27,537 children [13,888 boys (50.4%) and 13,649 girls (49.6%)] from birth up to 5 years were included in a multistage cross sectional randomized study from different Egyptian geographic districts to create LMS and Z score references for weight, length/height, and body mass index corresponding to age in addition to weight for length/height. Healthy term infants and children, exclusive breast feeding for at least 4 months and not suffering from any chronic diseases were included in this study. Children with dysmorphic features, preterm infants, admitted in neonatal or pediatric intensive care units and having any chronic diseases (hematological, cardiac, hepatic, and renal) were excluded. In addition any health condition that affects child growth including nutritional disorders was also excluded. Un-paired t-test was calculated to compare the means of weight for age, length/height for age, weight for length/height, and BMI for-age z scores of the Egyptian and WHO reference values.Results: Through detailed tables and graphs, LMS and Z scores for weight for age, length/height for age, weight for length/height, and BMI for age of both sexes were represented. Our findings showed no statistically significant difference between reference charts of WHO and Egyptian Z score charts (P > 0.05).Conclusion: This study provides the first reference for Egyptian children from birth up to 5 years based on Z score tool for assessment the growth and nutritional status in various clinical conditions and research, also allows comparison with references of other countries.

Reference value of Forced Oscillation Technique for healthy preschool children.

The reference values of Forced Oscillation Technique (FOT) parameters of the inspiratory and expiratory phase for preschool children have not yet been established. To evaluate FOT measures in Thai healthy preschool children. Preschool children, aged 3-6 years, were screened. Children who were positive for the International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire for asthma, positive family history of allergic diseases, recent lower respiratory tract infections, and environmental tobacco smoke were excluded. FOT parameters, including resistance (Rrs), reactance (Xrs), frequency of resonance (Fres) and area of reactance (ALX), were measured. A total of 390 healthy children with the mean age of 5.1 ± 0.9 years were enrolled. FOT was successfully performed in 378 children (96.9%). The mean (SD) for the whole breath (WB) resistance at 5Hz (R5), 20 Hz (R20) and R5-20 were 11.49 (2.69) cmH2O/L/s, 9.46 (2.19) cmH2O/L/s and 2.02 (0.82) cmH2O/L/s, respectively. The median (IQR) for WB reactance at 5Hx (X5), Fres and ALX were -1.51 (-2.37 to -0.96) cmH2O/L/s, 11.17 (8.50-15.65) Hz, and 7.53 (3.72-14.32) cmH2O/L/s, respectively. Significantly difference in WB R5, R20, X5, Fres and ALX between male and female children were demonstrated. The expiratory phase R5, R20, R5-20 were significantly higher than those of the inspiratory phase (p < 0.001). There are significant correlations between the height and FOT parameters. Reference curve for the FOT parameters was generated based on height using the lambda-mu-sigma (LMS) method. Reference curve of FOT parameters measured in healthy preschool children were demonstrated. Majority of preschool children could perform FOT method.

Fat and fat-free mass index references in children and young adults: assessments along racial and ethnic lines

Fat-free mass index (FFMI) and fat mass index (FMI) are superior to BMI and fat percentage in evaluating nutritional status. However, existing references fail to account for racial/ethnic differences in body composition among children. Our goal was to produce age-based normative references for FFMI and FMI in children for specific racial/ethnic groups. Body composition, weight, and height were measured in 1122 normal healthy children aged 2-21 y. Bone mineral content measured by DXA, total body water by deuterium dilution, and total body potassium by whole-body γ counting were combined to calculate fat-free mass (FFM) and fat mass (FM) using equations based on the Reference Child and Adolescent models. FFMI and FMI were calculated by dividing FFM and FM by height squared, respectively. After outlier removal, the LMS (Lambda-Mu-Sigma) function within R's GAMLSS package was used to produce age-based FFMI and FMI growth curves for black (B), white (W), and Hispanic (H) children for each sex. Combined models were produced in cases where outcomes did not differ by race/ethnicity. Resulting models were compared with previously published FFMI and FMI models. FFMI and FMI models based on 1079 children, aged 2-21 y, were created for both sexes. FFMI models for B children showed higher values throughout. W and H children were combined to produce FFMI models for each sex. H boys were modeled individually for FMI, whereas W and B boys were combined. FMI models for girls were created for each race/ethnicity. Models agreed well with those based on children from the United Kingdom of comparable race/ethnicity. Race/ethnicity-specific references for FFMI and FMI will increase the accuracy of health and nutrition status assessment in children over race/ethnicity-generic references. The models allow the calculation of SD scores to assess health and nutrition status in children.

Age- and Sex-Specific Pediatric Reference Intervals of Serum Electrolytes in Jilin Province of China Using the A Priori Approach.

ObjectivesThe purpose of this study was to establish age- and sex-specific pediatric reference intervals of serum potassium (K), sodium (Na), chlorine (Cl), calcium (Ca), magnesium (Mg), and phosphorus (P) using a direct sampling technique.MethodsIn accordance with the a priori approach, healthy individuals (n = 6,466, aged 1 month to <18 years) were enrolled from five regions in Jilin Province, China, and all analytes were performed in the center laboratory. Reference intervals were divided according to the regression tree and Harris and Boyd’s method, and then they were calculated by the nonparametric rank method. The dynamic changes of reference intervals were evaluated by the lambda-mu-sigma (LMS) method.ResultsReference intervals of serum Na and Ca were divided into three age-specific partitions. The concentrations of K, Cl, and Mg remained stable with age. However, only dramatic sex-specific changes of P were shown in those 11 to less than 13 years old and 13 to less than 15 years old, with an earlier peak time in females than in males. The correlation between Na and Cl was the strongest among all serum electrolytes (r = 0.31).ConclusionsSerum electrolyte reference intervals for children and adolescents were established by regression tree, z test, and the LMS method, which provide a more accurate interpretation for diagnosis and prognosis evaluation of clinical pediatric diseases.

Percentile reference value of waist circumference for Chinese children aged 3-7 years

Objective: To study and establish the percentile reference values of waist circumference (WC) for Chinese children aged 3-7 years. Methods: A total of 26 480 children aged 3-7 years were collected as part of the National Survey on Physical Growth and Development of Children in nine cities (Beijing, Harbin, Xi'an, Shanghai, Nanjing, Wuhan, Guangzhou, Fuzhou and Kunming) in China from June to November 2015. Sex- and age-specific smoothed percentile reference values of WC were established using the Lambda Mu Sigma method. The P(75) and P(90) curves of WC for children aged 3-7 years in this study were linked with the published P(75) and P(90) cut-off points for Chinese children and adolescents aged 7-18 years. The P(50) percentile of WC in this study was compared with the corresponding percentiles of several foreign studies. Results: The P(5), P(10), P(15), P(20), P(25), P(50), P(75), P(80), P(85), P(90) and P(95) reference values of WC were obtained for boys and girls aged 3-7 years biannually, at the interval of every six months. Results showed that WC at the P(50) had significantly increased from 47.5 cm at the age of 3 to 54.2 cm at the age of 7 for boys and from 47.0 cm at the age of 3 to 52.2 cm for girls at the age of 7. The corresponding WC percentile values appeared a bit higher in boys than those in girls at the same age, with the differences from 0.4 to 3.6 cm. The differences between measured and fitted WC at each empirical percentile ranged from -0.3 to 0.5 cm for both boys and girls aged 3-7 years. The P(75) and P(90) values of WC for boys and girls aged 3-7 years in this study presented a consistent, continuous tendency on age with the published WC cut-off points (P(75) and P(90)) for Chinese children and adolescent aged 7-18. The increasing trend of WC by age in Chinese children aged 3-7 years was consistent with those of foreign studies, at the middle level for boys and lower middle level for girls. Conclusions: Through this study, we established the WC percentile values for Chinese children aged 3-7 years and achieved the continuity in age with the published WC cut-off points for Chinese children and adolescents aged 7-18. These established WC percentile values can be used as reference for clinical practice, health care and scientific research.

Normative Values for Muscular Fitness for Chinese Children and Adolescents Aged 7–18 Years

The primary aim of this study was to establish sex and age-specific muscular fitness (MF) norms for Chinese children and adolescents aged 7–18 years old. The secondary aim was to compare their MF values with those of children and adolescents in other countries and regions. The MF of 93,755 participants from China was evaluated by handgrip strength (upper limbs strength), sit-ups (trunk strength) and a standing broad jump (lower limbs strength), with a total of 90,424, 90,281 and 90,663 data values, respectively. The Lambda-Mu-Sigma (LMS) method was used to calculate smooth curves and table data. The MF of Chinese boys was higher than that of girls in all age groups. After the age of 11, the growth rate of boys accelerated while that of girls slowed down. Age-related changes were larger for boys than for girls. In the international comparison, all the MF indicators of Chinese children and adolescents were lower than those of their Japanese peers but were higher than those of their European peers, with the exception of handgrip strength. The results of this study can be used to evaluate, monitor and apply interventions that improve MF. They can also be used to compare trends across countries and regions.

Establishment of Z Score Reference of Growth Parameters for Egyptian School Children and Adolescents Aged From 5 to 19 Years: A Cross Sectional Study.

Background: Growth charts are an important method for evaluating a child's health, growth, and nutritional status.Objective: To establish Lambda—Mu- Sigma (LMS) and Z score references for assessment of growth and nutritional status in Egyptian school children and adolescents.Methods: A total of 34,822 Egyptian school children and adolescents from 5 to 19 years were enrolled in a cross sectional randomized study from December 2017 to November 2019 to create LMS and Z score references for weight, height and body mass index (BMI) corresponding to ages. They were selected from different districts in Egypt. Apparent Healthy children with good nutritional history and not suffering from any chronic diseases were included in the study.Results: Egyptian children of both sexes (54.3% boys and 45.7 % girls) from 5 to 19 years old were studied. Then LMS and Z scores for weight for age, height for age, BMI for age of both sexes were represented in detailed tables and graphs. There was no statistically significant difference between the Egyptian Z score charts and the reference values of WHO for weight, height and BMI corresponding to age (P > 0.05).Conclusion: This is the first national reference for growth and nutritional assessment using LMS and Z score charts in Egyptian school children and adolescents, this tool is essential for healthcare and research.

Respiratory events in sleeping infants of the first year of life and their reference values

The authors present the reference values of the major respiratory events based on polysomnographic evaluation of 2,073 sleeping infants of the first year of life. These reference values were developed in accordance with the adopted LMS (lambda-mu-sigma) algorithm aimed at smoothing and maximal approximation of the calculated values to the real ones. The article describes the centile curves and centile tables of the respiratory events indices, maximal lengths and densities of the different types of apneas, periodic breathing, oxygen saturation and de-saturation indices at different sleep stages of the 1-to-52-week-old infants. The reference values are compared with available literature data.

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.

Reference Centiles to Monitor the 6-minute-walk Test in Ambulant Children with Cerebral Palsy and Identification of Effects after Rehabilitation Utilizing Whole-body Vibration

ABSTRACT Background: Children with cerebral palsy present age-driven development in gross motor skills and walking capacity. Aims: To precisely monitor the 6-minute walk test (6MWT) in children with CP, GMFCS levels 1 and 2 over 6 months and to assess the effect of a 6-month rehabilitation program including whole-body vibration. Methods: Retrospective analysis of data of 157 children with CP who received standardized rehabilitation (DRKS00011331). 6MWT was assessed at the start (M0) and end of the training (M6), as well as at a 6-month follow-up (M12). Centiles were created using the lambda-mu-sigma (LMS) method. Results: We created 6MWT percentiles using data of all 157 children (M0 data). A medium treatment effect size (Cohen’s d = 0.69) was found (M6 and M12 data). Conclusions: The generated centiles may help monitor 6MWT changes over 6 months. Combining WBV and conventional physiotherapy can significantly improve 6MWT in children with CP. Abbreviations: 6MWT: 6-Minute Walk Test; CP: Cerebral palsy; ES: effect size; GMFCS: Gross Motor Function Classification System; GMFM-66: Gross Motor Function Measure 66; LOESS: locally weighted scatterplot smoothing; LMS: lambda-mu-sigma; MCID: minimal clinical important difference; SD: standard deviation; SRM: standardized response mean; WBV: whole-body vibration.

Establishing body mass index growth charts for Pakistani children and adolescents using the Lambda-Mu-Sigma (LMS) and quantile regression method.

Assessment of growth and nutritional status is an essential part of clinical evaluation and care in pediatrics. We therefore, aimed to establish age and gender specific smoothed BMI growth reference charts of Pakistani children and adolescents aged 2-18 years and to compare our LMS median percentile values with WHO 2007 international references and with references from other foreign studies. A representative cross-sectional sample of 10,668 healthy Pakistani subjects aged 2 to 18 years was studied. For calculation of BMI (kg/m2), height (cm) and weight (kg) were measured using standard procedures. Age and gender specific smoothed BMI growth reference values and associated charts were obtained using lambda-mu-sigma (LMS) as well as quantile regression (QR) statistical methods. In the sample studied, the mean (± SD) BMI of all subjects was 16.50 (± 2.83 kg/m2). Smoothed BMI percentile curves (5th, 10th, 25th, 50th, 75th, 90th and 95th) obtained by using LMS and QR methods, showed that BMI increased with age in both sexes. During pubertal age, girls had larger percentiles than boys. Centile values estimated by the LMS and QR procedure had small variability from the empirical centiles. Comparison of LMS BMI 50th percentile with references from WHO 2007 and data from other countries demonstrated that Pakistani children had substantially lower BMI percentiles than their counterparts in the reference population. This comprehensive study suggests that WHO 2007 references are not suitable for Pakistani children. The QR method should be considered as an alternative method to develop growth charts.

Anthropometric measurements of school-going-girls of the Punjab, Pakistan

BackgroundChild’s growth has been considered an important indicator to evaluate health trends in a population and to devise strategies accordingly. The purpose of the present study was to determine most commonly occurring weight abnormalities among school-going girls from Punjab and to compare with international growth references devised by World Health Organization (WHO) and Centre for Disease Control and Prevention (CDC).MethodsIn this cross-sectional study a sample of 10,050 child and adolescent girls from 12 districts, 35 public/private sector schools, located in rural, semi-urban and urban areas of northern, central and southern Punjab were included. Parameters were measured according to standardised techniques and centile curves obtained by Lambda, Mu, Sigma (LMS) method.ResultsThe results showed an increase in weight, height and BMI of the Punjabi girls until 15 years. When compared with international growth references, weight and BMI in our population were significantly lowered; however, height was lower during 12–16 years of age and the differences observed were more pronounced with CDC as compared to WHO. When 3rd, 50th and 90th percentiles of weight, height and BMI in our population were compared with international standards, the values were lower in our paediatric population.ConclusionThe Punjabi schoolgirls significantly differed from CDC and WHO references, and this difference should be taken into consideration for evaluation of growth abnormalities in our paediatric population. However, in the absence of national reference data, WHO standards have been considered more appropriate for comparison.

Assessment of Global Lung Function Initiative (GLI) reference equations for diffusing capacity in relation to respiratory burden in the Swedish CArdioPulmonary bioImage Study (SCAPIS).

The Global Lung Function Initiative (GLI) has recently published international reference values for diffusing capacity of the lung for carbon monoxide (D LCO). Lower limit of normal (LLN), i.e. the 5th percentile, usually defines impaired D LCO We examined if the GLI LLN for D LCO differs from the LLN in a Swedish population of healthy, never-smoking individuals and how any such differences affect identification of subjects with respiratory burden.Spirometry, D LCO, chest high-resolution computed tomography (HRCT) and questionnaires were obtained from the first 15 040 participants, aged 50-64 years, of the Swedish CArdioPulmonary bioImage Study (SCAPIS). Both GLI reference values and the lambda-mu-sigma (LMS) method were used to define the LLN in asymptomatic never-smokers without respiratory disease (n=4903, of which 2329 were women).Both the median and LLN for D LCO from SCAPIS were above the median and LLN from the GLI (p<0.05). The prevalence of D LCO <GLI LLN (and also <SCAPIS LLN) was 3.9%, while the prevalence of D LCO >GLI LLN but <SCAPIS LLN was 5.7%. Subjects with D LCO >GLI LLN but <SCAPIS LLN (n=860) had more emphysema (14.3% versus 4.5%, p<0.001), chronic airflow limitation (8.5% versus 3.9%, p<0.001) and chronic bronchitis (8.3% versus 4.4%, p<0.01) than subjects (n=13 600) with normal D LCO (>GLI LLN and >SCAPIS LLN). No differences were found with regard to physician-diagnosed asthma.The GLI LLN for D LCO is lower than the estimated LLN in healthy, never-smoking, middle-aged Swedish adults. Individuals with D LCO above the GLI LLN but below the SCAPIS LLN had, to a larger extent, an increased respiratory burden. This suggests clinical implications for choosing an adequate LLN for studied populations.

A need for an update of Polish birth weight reference norms

The indicators of perinatal outcome are birth weight and gestational age. The standard method of assessing the outcome is comparing the newborn’s birth weight with the reference system, presented in the form of percentile charts. Acceleration or delay in prenatal development, which are associated with environmental changes, stress the need to validate the developmental norms. The goal of this study is to evaluate the need to construct new and accurate reference standards. The study includes data of newborns from singleton pregnancies: 4919 born in 2000 and 3683 born in 2015. Study variables included gestational age, sex, and birth weight. Percentile values estimated for two groups of infants born in years separated by a 15-year period, born in 2000 and in 2015, were compared. Birth weight percentiles, from the 28th to the 42nd week of gestation, were calculated using the Lambda Mu Sigma method. Estimated values revealed the birth weight standards in different weeks of gestational age for both years: 2000 and 2015. Comparison among medians estimated for infants born in these years showed the existence of significant differences among boys in the 28th, 36th, and 39th weeks and among girls in the 34th and 41st weeks of gestational age. As the period between the two measurements involves several years, environmental changes during this time period might have significantly affected the course of pregnancy and thus the birth weight. Hence, there is a need to validate the developmental norms. The reference standards should be renewed, and must be done on a periodical basis.

PediTools Electronic Growth Chart Calculators: Applications in Clinical Care, Research, and Quality Improvement.

BackgroundParameterization of pediatric growth charts allows precise quantitation of growth metrics that would be difficult or impossible with traditional paper charts. However, limited availability of growth chart calculators for use by clinicians and clinical researchers currently restricts broader application.ObjectiveThe aim of this study was to assess the deployment of electronic calculators for growth charts using the lambda-mu-sigma (LMS) parameterization method, with examples of their utilization for patient care delivery, clinical research, and quality improvement projects.MethodsThe publicly accessible PediTools website of clinical calculators was developed to allow LMS-based calculations on anthropometric measurements of individual patients. Similar calculations were applied in a retrospective study of a population of patients from 7 Massachusetts neonatal intensive care units (NICUs) to compare interhospital growth outcomes (change in weight Z-score from birth to discharge [∆Z weight]) and their association with gestational age at birth. At 1 hospital, a bundle of quality improvement interventions targeting improved growth was implemented, and the outcomes were assessed prospectively via monitoring of ∆Z weight pre- and postintervention.ResultsThe PediTools website was launched in January 2012, and as of June 2019, it received over 500,000 page views per month, with users from over 21 countries. A retrospective analysis of 7975 patients at 7 Massachusetts NICUs, born between 2006 and 2011, at 23 to 34 completed weeks gestation identified an overall ∆Z weight from birth to discharge of –0.81 (P<.001). However, the degree of ∆Z weight differed significantly by hospital, ranging from –0.56 to –1.05 (P<.001). Also identified was the association between inferior growth outcomes and lower gestational age at birth, as well as that the degree of association between ∆Z weight and gestation at birth also differed by hospital. At 1 hospital, implementing a bundle of interventions targeting growth resulted in a significant and sustained reduction in loss of weight Z-score from birth to discharge.ConclusionsLMS-based anthropometric measurement calculation tools on a public website have been widely utilized. Application in a retrospective clinical study on a large dataset demonstrated inferior growth at lower gestational age and interhospital variation in growth outcomes. Change in weight Z-score has potential utility as an outcome measure for monitoring clinical quality improvement. We also announce the release of open-source computer code written in R to allow other clinicians and clinical researchers to easily perform similar analyses.

Growth Charts for Tribal, School-Going Children in Jharkhand Using Anthropometry and Lambda-Mu-Sigma Methods to Create Growth Charts.

BackgroundThis study intends to find the growth patterns of selected school children. Globally accepted statistical methods were used to evaluate the data and prepare a growth chart.MethodsThis cross-sectional study was conducted with school-going children from 16 selected schools of a tribal district in Jharkhand using multistage cluster random sampling. In each selected school, 60 students, 30 boys and 30 girls, were chosen randomly, totaling 960 children (full data was for 935 children only). Growth charts were created using Lambda-Mu-Sigma (LMS) chart maker version 2.5 for height, weight and body mass index (BMI). In the charts, the LMS values with Z scores for each age and respective height and weight for boys and girls were recorded.ResultsThe 468 boys and 467 girls were in the range of 6–14 years of age. Percentile values obtained for the measured heights in centimetres were evaluated and compared with Indian Academy of Pediatrics reference charts for boys and girls for the same age group, and our values were found to be on the lower side. We were able to plot a growth chart of the data set; as the tribal children’s ethnicity is different, this growth chart might be used to assess nutritional status.ConclusionWe concluded that growth curves for height, weight, and BMI may be used for evaluating children of age 6–14 years in the tribal population. The measures can be a good indicator of their nourishment status and overall growth patterns, which might be indigenous to their ethnicity. A larger sample size of similar tribal populations may give a clearer picture.

Aligning Lung Function Equipment and Reference Values in Adults

Background: When introducing new equipment or reference equations into the lung function laboratory, systematic z-score deviations could arise due to local differences in population or equipment. Objective: To propose a workable method for aligning reference equations with lung function equipment. Method: Using two cases of equipment transition in our laboratory as a test case, we first performed lung function testing after the transition, on a control group of 40 normal young adults (20 male/20 female; 20–30 years old). For those indices with an average z-score in excess of ±0.5, adapted reference values were obtained by an offset or scaling factor on the M coefficient with the so-called lambda-mu-sigma (LMS) method recommended by the Global Lung Function Initiative, and the z-scores were computed again. Results: Following a transition involving instrumental dead space reduction, the lung clearance index was predictably reduced, resulting in a mean (±SD) z-score of –1.9 (±1.1) in the control group; by adapting the reference values with an offset on M, the z-score became –0.1 (±1.1). Applying the same method to a transition of standard lung function equipment, the z-scores became centered around zero in the control group, but also became properly aligned in a test group of 81 other subjects spanning a wider age range (20–80 years). Conclusions: We proposed and verified a method for aligning local equipment with reference values obtained elsewhere, or following a local change in equipment. The key is to measure a relatively small young adult group, identifying those lung function indices that need adaptation based on z-scores, in order to then obtain laboratory-specific reference values that can be applied over the entire age range.

Multicentre reference values for cardiac magnetic resonance imaging derived ventricular size and function for children aged 0-18 years.

AimsCardiovascular magnetic resonance (CMR) imaging is an important tool in the assessment of paediatric cardiac disease. Reported reference values of ventricular volumes and masses in the paediatric population are based on small cohorts and several methodologic differences between studies exist. We sought to create steady-state free precession (SSFP) CMR reference values for biventricular volumes and mass by combining data of previously published studies and re-analysing these data in a standardized manner.Methods and resultsA total of 141 healthy children (68 boys) from three European centres underwent cine-SSFP CMR imaging. Cardiac structures were manually contoured for end-diastolic and end-systolic phases in the short-axis orientation according to current standardized CMR post-processing guidelines. Volumes and masses were derived from these contours. Age-related reference curves were constructed using the lambda mu sigma method. Median age was 12.7 years (range 0.6–18.5). We report biventricular volumes and masses, unindexed and indexed for body surface area, stratified by age groups. In general, boys had approximately 15% higher biventricular volumes and masses compared with girls. Only in children aged <6 years old no gender differences could be observed. Left ventricle ejection fraction was slightly higher in boys in this study population (median 67% vs. 65%, P = 0.016). Age-related reference curves showed non-linear relations between age and cardiac parameters.ConclusionWe report volumetric SSFP CMR imaging reference values for children aged 0–18 years old in a relatively large multi-centre cohort. These references can be used in the follow-up of paediatric cardiac disease and for research purposes.

Establishing Growth Reference Charts for Head Circumference of the Pakistani Children, Using the Lambda-Mu-Sigma (LMS) Statistical Method

Background: For growth monitoring of brain, head circumference (HdC) reference data are needed. Rapid increase in the HdC is usually seen within first few years of life which marks histological changes in the brain. However, in Pakistan, there is a dearth of research on the potential use of HdC measurements. Objectives: We aimed to develop the age and gender specific smoothed HdC growth reference charts for the Pakistani children, aged 2 to 5 years. Methods: A representative cross-sectional sample of 1474 Pakistani children, aged 2 - 5 years, was studied. Age and gender specific smoothed HdC growth reference values and their charts were obtained using the lambda-mu-sigma (LMS) statistical method. The smoothed HdC percentiles (3rd, 5th, 10th, 25th, 50th, 75th, 90th, 95th and 97th) were calculated and their charts were drawn. Results: The percentile values of HdC increased with age in both sexes. The boys had more increase in HdC percentiles than the girls had, except for the 95th and 97th percentiles. Comparison of 50th percentiles of HdC with those of the other countries demonstrated that the Pakistani children had substantially lower HdC percentiles than their counterparts in the other populations. Conclusions: The results showed that reference values for the HdC were smaller than the corresponding reference values provided by the World Health Organization. Therefore, it is suggested that each country should produce its own HdC growth charts because the use of the charts of other countries as standards may provide misleading information of the children population under study.

The prevalence of malnutrition and growth percentiles for urban South African children

BackgroundLow- and middle-income countries (LMIC) are experiencing a double-burden of malnutrition characterised by high prevalence of both under- and over-nutrition. We set out using data from the mixed-longitudinal Birth-to-Twenty Plus (Bt20+) birth cohort, to evaluate the patterns of malnutrition and growth in a large South African (SA) city by; (i) assessing the prevalence of undernutrition from birth to 5 years of age and overweight and obesity from ages 2 to 21 years in black and white, male and female children, and (ii) determining percentiles for height, weight, BMI, waist and hip circumferences and comparing the centiles to American and Dutch references.MethodsHeight, weight, waist and hip circumferences were measured on urban black and white SA children from the Bt20+. A total of 3273 children born between April and June 1990 in the Greater Johannesburg Metropolitan area were included in the cohort. Z-scores were derived using the WHO 2006 child growth standards (0–5 years), for defining stunting, underweight and wasting. The International Obesity Task Force (IOTF) references were used to define overweight and obesity. Percentiles were developed using the lambda mu sigma (LMS) method and compared to American and Dutch references.ResultsBlack children were consistently shorter and black males lighter than white children and American references. The prevalence of stunting peaked at 2 years and was significantly higher in males than females and in black than white children. Black females had a greater prevalence of overweight and obesity than black males from 10 to 17 years. The percentiles for black females for weight and BMI were similar to those of South African white and American references but both black and white South African females had lower waist circumferences than American references.ConclusionThe growth percentiles show that young South African urban black females are experiencing general but not central obesity due to a secular change which is faster in weight than height. High levels of undernutrition persist alongside high levels of over-nutrition with adolescence being a critical period for the upsurge in obesity in females. Early intervention is needed to combat the rise in obesity.