Growth Percentiles Research Articles

The effects of radiation therapy on height and spine MRI characteristics in children with neuroblastoma

PurposeTo investigate the effect of radiotherapy (RT) on height and spine using magnetic resonance imaging (MRI) analysis in children with neuroblastoma and to identify parameters related to patient height. Methods and materialsWe performed a retrospective cohort study of neuroblastoma patients treated between January 1997 and December 2007. Twenty-seven children were enrolled. Whole spine MRI was completed and height percentiles were compared with national growth charts. ResultsThe median ages were 28, 43, and 126months at diagnosis, RT, and analysis, respectively. All of the enrolled children received local RT, and 15 patients received total body irradiation (TBI). Median growth percentiles were 67.0, 54.0, and 4.9 at diagnosis, RT, and analysis, respectively. The number of irradiated vertebrae (P=0.009) and having undergone TBI (P=0.03) were significantly associated with shorter stature. Among the MRI parameters for irradiated vertebrae, signal intensity was higher (P=0.05) and more heterogeneous (P=0.02) in T1-weighted images and roundness was lower (P=0.03) in T2-weighted images. ConclusionsHeight of children with neuroblastoma was significantly affected by RT. The number of irradiated vertebrae and having undergone TBI were significantly associated with lower height. Irradiated spine showed changes in both signal and shape on MRI.

Use of WHO growth curves for patients with cystic fibrosis may provide a false sense of security.

Use of WHO growth curves for patients with cystic fibrosis may provide a false sense of security.

The Impact of Measurement Error on the Accuracy of Individual and Aggregate SGP

Student growth percentiles (SGPs) express students' current observed scores as percentile ranks in the distribution of scores among students with the same prior‐year scores. A common concern about SGPs at the student level, and mean or median SGPs (MGPs) at the aggregate level, is potential bias due to test measurement error (ME). Shang, vanIwaarden, and Betebenner (SVB; this issue) develop a simulation‐extrapolation (SIMEX) approach to adjust SGPs for test ME. In this paper, we use a tractable example in which different SGP estimators, including SVB's SIMEX estimator, can be computed analytically to explain why ME is detrimental to both student‐level and aggregate‐level SGP estimation. A comparison of the alternative SGP estimators to the standard approach demonstrates the common bias‐variance tradeoff problem: estimators that decrease the bias relative to the standard SGP estimator increase variance, and vice versa. Even the most accurate estimator for individual student SGP has large errors of roughly 19 percentile points on average for realistic settings. Those estimators that reduce bias may suffice at the aggregate level but no single estimator is optimal for meeting the dual goals of student‐ and aggregate level inferences.

How Does Value Added Compare to Student Growth Percentiles?

We compare teacher evaluation scores from a typical value-added model to results from the Colorado Growth Model (CGM), which 16 states currently use or plan to use as a component of their teacher performance evaluations. The CGM assigns a growth percentile to each student by comparing each student's achievement to that of other students with similar past test scores. The median (or average) growth percentile of a teacher's students provides the measure of teacher effectiveness. The CGM does not account for other student background characteristics and excludes other features included in many value-added models used by states and school districts. Using data from the District of Columbia Public Schools (DCPS), we examine changes in evaluation scores across the two methods for all teachers and for teacher subgroups. We find that use of growth percentiles in place of value added would have altered evaluation consequences for 14% of DCPS teachers. Most differences in evaluation scores based on the two methods are not related to the characteristics of students’ teachers.

A Comparison of Student Growth Percentile and Value-Added Models of Teacher Performance

School districts and state departments of education frequently must choose among a variety of methods to estimate teacher quality. This article investigates the consequences of some of these choices. We examine estimates derived from student growth percentile and commonly used value-added models. Using simulated data, we examine how well the estimators can rank teachers and avoid misclassification errors under a variety of assignment scenarios of teachers to students. We find that growth percentile measures perform worse than value-added measures that control for prior year student test scores and include teacher fixed effects when assignment of students to teachers is nonrandom. In addition, using actual data from a large diverse anonymous state, we find evidence that growth percentile measures are less correlated with value-added measures that include teacher fixed effects when there is evidence of nonrandom grouping of students in schools. This evidence suggests that the choice between estimators is most consequential under nonrandom assignment of teachers to students and that value-added measures controlling for teacher fixed effects may be better suited to estimating teacher quality in this case.

Pregnancy in an NTBC‐Treated Patient With Hereditary Tyrosinemia Type I

Pregnancy in an NTBC‐Treated Patient With Hereditary Tyrosinemia Type I

Population Structure and Dynamics of Northern Pike and Smallmouth Bass in Coeur d'Alene Lake, Idaho

Abstract Numerous species have been introduced to Coeur d'Alene Lake, Idaho over the last century, but minimal research has been completed to understand their population dynamics. The objective of this study was to describe the population demographics and dynamics of northern pike (Esox lucius) and smallmouth bass (Micropterus dolomieu), two important nonnative sport fishes in the system to provide information that will assist with guiding management decisions. The oldest northern pike was age 7 and the oldest smallmouth bass was age 11. Populations of both species exhibited very stable recruitment with a recruitment coefficient of determination of 0.99 for northern pike and 0.98 for smallmouth bass. Total annual mortality was estimated as 66% for northern pike and 42% for smallmouth bass. Growth of northern pike in Coeur d'Alene Lake was comparable to the 50–75th percentiles of growth exhibited by lentic northern pike populations across North America. Northern pike in Coeur d'Alene Lake were most similar...

Meconium-related ileus in very low birth weight and extremely low birth weight infants: immediate and one-year postoperative outcomes.

PurposeOne of the major causes of bowel obstruction in extremely premature infants is a meconium obstruction. However, there are many challenges not only in the recognition and diagnosis, but also in the management of meconium obstruction. This study aimed to find perioperative clinical features and determine the postoperative course of meconium-related ileus in very low birth weight (VLBW) and extremely low birth weight (ELBW) infants.MethodsWe retrospectively reviewed the clinical data of premature infants (n = 11, VLBW infnats; n = 16, ELBW infants) with a meconium-related ileus who underwent operation for intractable ileus between January 2009 and May 2013.ResultsThe average duration of conservative management was longer and postnatal age was older in ELBW infants than VLBW infants: 19.9 days vs. 11.5 days and 34.9 days vs. 19.2 days. The immediate postoperative course (day that beginning feeding and full feeding) was not significantly different based on birth weight, but the ELBW infants had slightly higher mortality. At 12 months of corrected age after operation, both average body weight and average height was below 10th percentile for growth in most infants (61.1%).ConclusionThere was a slightly high mortality in the ELBW infants, but two groups did not experience significant differences in the immediate postoperative course of meconium-related ileus. Nevertheless, considering their growth patterns, it is necessary to do a close follow-up and more aggressive nutritional management to achieve optimal growth and development in both patient groups.

Alternative Statistical Frameworks for Student Growth Percentile Estimation

This article suggests two alternative statistical approaches for estimating student growth percentiles (SGP). The first is to estimate percentile ranks of current test scores conditional on past test scores directly, by modeling the conditional cumulative distribution functions, rather than indirectly through quantile regressions. This would remove the need for post hoc procedures required to ensure monotonicity of the estimated quantile functions, and for inversion of those functions to obtain SGP. We provide a brief empirical example demonstrating this approach and its potential benefits for handling discreteness of the observed test scores. The second suggestion is to estimate SGP directly from longitudinal item-level data, using multidimensional item response theory models, rather than from test scale scores. This leads to an isomorphism between using item-level data from one test to make inferences about latent student achievement, and using item-level data from multiple tests administered over time to make inferences about latent SGP. This framework can be used to solve the bias problems for current SGP methods caused by measurement error in both the current and past test scores, and provides straightforward assessments of uncertainty in SGP. We note practical problems that need to be addressed to implement our suggestions.

National growth charts for United Arab Emirates children with Down syndrome from birth to 15 years of age.

BackgroundSpecific centile growth charts for children with Down syndrome (DS) have been produced in many countries and are known to differ from those of normal children. Since growth assessment depends on the growth pattern characteristic for these conditions, disorder-specific charts are desirable for various ethnic groups.AimsTo provide cross-sectional weight, height, and head circumference (HC) references for healthy United Arab Emirates (UAE) children with DS.MethodsA retrospective and cross-sectional growth study of Emirati children with DS, aged 0 to 18 years old, was conducted. Height, weight, and HC were measured in each child. Cole’s LMS statistical method was applied to estimate age-specific percentiles, and measurements were compared to UAE reference values for normal children.ResultsIncidence of DS in the UAE population is 1 in 374 live births (267 in 10 000 live births). We analyzed 1263 growth examinations of 182 children with DS born between 1994 and 2012. The male-to-female ratio was 1.6:1. Height, weight, and HC centile charts were constructed for ages 0 to 13 years. The prevalence of overweight and obesity in DS children aged 10 to 13 years of age was 32% and 19%, respectively. The DS children were significantly shorter and heavier than normal children in the UAE.ConclusionsWeight, height, and HC growth charts were created for children with DS. These can be used as a reference standard for the UAE children with DS. Overweight and obesity are quite common in DS children ≥10 years of age, as DS children tend to be shorter and heavier than non-DS children.

Development and validation of weight, height and age bands to guide the prescription of fixed-dose dispersible tablet formulations.

Conversion of pediatric essential drugs from syrup to dispersible tablet formulations would require fixed dose options guided by the weight band in which a child falls or a proxy for weight, such as height or age. The purpose of this study was to determine whether weight, height, or age bands can be created that would lead to greater than 95% of children receiving a therapeutic dose of 6 commonly prescribed essential drugs, including paracetamol, iron sulfate, amoxicillin, co-trimoxazole (i.e., trimethoprim/sulfamethoxazole), ciprofloxacin, and co-artemether (i.e., artemether/lumefantrine). Using World Health Organization growth standards, we created 4 weight bands and then matched them to height and age 50th percentile growth curves. The resulting weight, height, and age bands were then applied to Ugandan and Bangladeshi anthropometric data sets, and the percentage of children who would have received a correct therapeutic dose based upon weight, height, or age was determined. This percentage was interpreted as acceptable if >95%, marginal if 90% to 95% and unacceptable if <90%. Applying the 4 weight bands to the 6 selected drugs, greater than 95% of children would have received an acceptable therapeutic dose across the 4 weight bands for each of the 6 drugs tested. None of the drugs tested would deliver an acceptable therapeutic dose across all bands based upon height or age among Ugandan children, and only co-trimoxazole would have been delivered at acceptable therapeutic levels based upon these bands in Bangladeshi children. For the 6 drugs tested, dispersible tablets prescribed on the basis of a 4-dose regimen determined by weight bands would deliver an acceptable therapeutic dose greater than 95% of the time. Substituting weight for age or height bands would result in unacceptable levels of under- or overdosing.

Covariate Measurement Error Correction for Student Growth Percentiles Using the SIMEX Method

In this study, we examined the impact of covariate measurement error (ME) on the estimation of quantile regression and student growth percentiles (SGPs), and find that SGPs tend to be overestimated among students with higher prior achievement and underestimated among those with lower prior achievement, a problem we describe as ME endogeneity in this article. We proceeded to assess the effect of covariate ME correction on SGP estimation at two levels—the individual (student) and the aggregate (classroom). Our ME correction approach was limited to the simulation‐extrapolation method known as SIMEX. For both the individual and aggregate SGP, we find SIMEX effective in bias reduction. Further, because SIMEX is especially effective in reducing SGP bias for students with very high or very low prior achievement, it significantly weakens the ME endogeneity. SIMEX is also effective in reducing the MSE of aggregate SGP, provided that the students are sorted to some extent on their latent prior achievement. Our empirical study confirms the pattern of the simulation results: SIMEX mainly affects the mean SGP of classes in the highest and lowest quintiles of the prior score distribution, and significantly lowers the correlation between class SGP and prior achievement.

Personalized third-trimester fetal growth evaluation: comparisons of individualized growth assessment, percentile line and conditional probability methods

Objective: To compare third-trimester size trajectory prediction errors (average transformed percent deviations) for three individualized fetal growth assessment methods.Methods: This study utilized longitudinal measurements of nine directly measured size parameters in 118 fetuses with normal neonatal growth outcomes. Expected value (EV) function coefficients and variance components were obtained using two-level random coefficient modeling. Growth models (IGA) or EV coefficients and variance components (PLM and CPM) were used to calculate predicted values at ∼400 third-trimester time points. Percent deviations (%Dev) calculated at these time points using all three methods were expressed as percentages of IGA MA-specific reference ranges [transformed percent deviations (T%Dev)]. Third-trimester T%Dev values were averaged (aT%Dev) for each parameter. Mean ± standard deviation’s for sets of aT%Dev values derived from each method (IGA, PLM and CPM) were calculated and compared.Results: Mean aT%Dev values for nine parameters were: (i) IGA: −4.3 to 5.2% (9/9 not different from zero); (ii) PLM: −32.7 to 25.6% (4/9 not different from zero) and (iii) CPM: −20.4 to 17.4% (5/9 not different from zero). Seven of nine systematic deviations from zero were statistically significant when IGA values were compared to either PLM or CPM values. Variabilities were smaller for IGA when compared to those for PLM or CPM, with (i) 5/9 being statistically significant (IGA versus PLM), (ii) 2/9 being statistically significant (IGA versus CPM) and (iii) 5/9 being statistically significant (PLM versus CPM).Conclusions: Significant differences in the agreement between predicted third-trimester size parameters and their measured values were found for the three methods tested. With most parameters, IGA gave smaller mean aT%Dev values and smaller variabilities. The CPM method was better than the PLM approach for most but not all parameters. These results suggest that third-trimester size trajectories are best characterized by IGA in fetuses with normal growth outcomes.

295: Unexpected consequences: impact of a conservative fetal growth curve on near term delivery for growth restriction

In 2011, our institution moved from a birthweight (BW)-based fetal growth curve to an ultrasound (US) weight-based curve. BW based curves overestimate growth centile in preterm fetuses, potentially underdiagnosing fetal growth restriction (FGR). We aimed to determine whether rates of near-term delivery (37-38+6 weeks) for the indication of FGR changed as a result of the change in growth curve.

Selecting Growth Measures for Use in School Evaluation Systems

The specifics of how growth models should be constructed and used for educational evaluation is a topic of lively policy debate in states and school districts nationwide. In this article, we take up the question of model choice—framed within a policy context—and examine three competing approaches. The first approach, reflected in the popular student growth percentiles (SGPs) framework, eschews all controls for student covariates and schooling environments. The second approach, typically associated with value-added models (VAMs), controls for student-background characteristics and under some conditions can be used to identify the causal effects of educational units (i.e., districts, schools, and teachers). The third approach, also VAM-based, fully levels the playing field so that the correlation between the growth measures and student demographics is essentially zero. We argue that the third approach is the most desirable for use in school evaluation systems. Our case rests on personnel economics, incentive-design theory, and the potential role that growth measures can play in improving instruction in K-12 schools.

Identification of pathologically small fetuses using customized, ultrasound and population‐based growth norms

Fetal growth restriction is a strong risk factor for stillbirth. We compared the performance of three fetal growth curves - customized, ultrasound (Hadlock) and population - in identifying abnormally grown fetuses at risk of stillbirth. We performed a case-control study of singleton stillbirths (delivered between 2000 and 2010) at one center. Four liveborn controls were randomly identified for each stillbirth. Ultrasound-estimated fetal weight within 1 month prior to delivery was used to calculate growth percentiles for each fetus using three fetal growth norms. Sensitivities and odds ratios for stillbirth, as well as odds of abnormal growth according to formula, were calculated. There were 49 stillbirths and 197 live births. Using the customized norms, growth of the fetuses destined to be stillborn was bimodal, with both more small-for-gestational-age (SGA; < 10(th) percentile) and large-for-gestational-age (LGA; ≥ 90(th) percentile) fetuses. Odds of being abnormally grown were significantly higher using ultrasound compared with population norms (P = 0.02) but were not statistically different using ultrasound and customized norms (P = 0.21). Sensitivity for identification of SGA on ultrasound as a predictor of stillbirth was higher using customized (39%; 95% CI, 24-54%) or ultrasound (33%; 95% CI, 19-47%), rather than population (14%; 95% CI, 4-25%), norms. Among fetuses destined to be stillborn, customized and ultrasound norms identified a greater proportion of both SGA and LGA estimated fetal weights. The customized norms performed best in identifying death among SGA fetuses. These results should be interpreted within the limitations of the study design.

Factors associated with growth and blood pressure patterns in children with sickle cell anemia: Silent Cerebral Infarct Multi-Center Clinical Trial cohort.

Individuals with sickle cell anemia (SCA) exhibit delayed growth trajectories and lower blood pressure (BP) measurements than individuals without SCA. We evaluated factors associated with height, weight, and BP and established reference growth curves and BP tables using data from the Silent Cerebral Infarct Multi-Center Clinical (SIT) Trial (NCT00072761). Quantile regression models were used to determine the percentiles of growth and BP measurements. Multivariable quantile regression was used to test associations of baseline variables with height, weight, and BP measurements. Height and weight measurements were collected from a total of 949 participants with median age of 10.5 years [Interquartile range (IQR) 8.2-12.9] and median follow-up time of 3.2 years (IQR 1.8-4.7, range 0-12.9). Serial BP measurements were collected from a total of 944 and 943 participants, respectively, with median age of 10.6 years (IQR = 8.3-12.9 years), and median follow-up time of 3.3 years (IQR = 1.7-4.8). Multivariable quantile regression analysis revealed that higher hemoglobin measurements at baseline were associated with greater height (P < 0.001), weight (P = 0.000), systolic BP (P < 0.001), and diastolic BP (P = 0.003) measurements. We now provide new reference values for height, weight, and BP measurements that are now readily available for medical management.

PO-0587 Nutritional Modification To Decrease The Extrauterine Growth Restriction In Very Low Birth Weight Infants

Background and aims Extrauterine growth restriction (EUGR; ≤10th percentile of intrauterine growth expected in accordance with the estimated gestational age) is a common problem in preterm infants. After birth, nutrition in preterm infant is dependent on externally administered nutrition and many preterm infants experience significant energy and nutrition deficits. We modified our nutrition protocol and evaluated the incidence of EUGR and growth status. Methods A prospective observational cohort study compared infants ≤1,500 g before (n = 37) and after (n = 50) modification of nutrition protocol. Modification included early starts of macronutrients with higher goal, earlier adding of human milk fortifier and higher goal of daily administered calorie. We evaluated demographics, enteral feeding, growth parameters, laboratory data and discharge outcomes. Differences in subgroups of infants ≤1,000 g and 1,000–1,500 g were also assessed. Results Modified nutrition protocol reduced the incidence of EUGR at 36 weeks gestational age (GA) (91.8% vs. 66.0%, p = 0.005) and at discharge from NICU (89.1% vs. 56.0%, p = 0.001). EUGR was significantly reduced in infants 1,000–1,500 g and trended toward reduction in infants Conclusions Modified nutritional protocol based on supplying the early aggressive macronutrients and higher calorie, can significantly reduce the incidence of EUGR in infants ≤1,500 g without any complications. We need further investigation to improve growth in infants

Management implications of long-term tree growth and mortality rates: A modeling study of big-leaf mahogany (Swietenia macrophylla) in the Brazilian Amazon

Knowledge of tree age-size relationships is essential towards evaluating the sustainability of harvest regulations that include minimum diameter cutting limits and fixed-length cutting cycles. Although many tropical trees form annual growth rings and can be aged from discs or cores, destructive sampling is not always an option for valuable or threatened species. We used an individual-based population model developed for big-leaf mahogany (Swietenia macrophylla, Meliaceae) in southeast Amazonia, Brazil to simulate stem age-size relationships and examine forest management implications of mortality and diameter increment growth. Growth trajectories of 10,000 simulated mahogany trees were consistent with growth trajectories reconstructed from 32 mahogany discs with annual rings. Trajectories were highly variable and strongly autocorrelated; diameter was a poor predictor of tree age even when accounting for up to 10years of previous growth history. Commercial-sized trees (60cm diameter) ranged in age from 33 to 180years (74yr median). Only 12.5% of seedlings survived to this size, but survival and time to reach commercial size depended strongly on early growth history (first 10years of life). A tree grown at the 75th percentile growth rate throughout its lifetime requires 70years to attain commercial size, but Brazilian forest management regulations imply a rotation length of 60years. These results demonstrate that individual-based models parameterized with typical census data can incorporate individual variation and growth autocorrelation and realistically simulate tree growth and mortality. In the absence of tree ring data, such models can be used to evaluate the consequences of long-term growth and mortality for sustainable management. In the case of mahogany, our results suggest that non-detrimental harvests cannot be achieved without lengthening cutting cycles, increasing commercial tree retention rates, and regularly applying silvicultural treatments designed to increase stem diameter growth rates. Forest managers can have the greatest effect on the rate of commercial recruitment in the first 10years after a harvest by implementing treatments ensuring that adequate numbers of new stems establish and recruit to dominant positions in recovering canopy gaps. Regrettably, sustainable mahogany management systems developed based on understanding of the species’ ecology will not be as simple as current harvest regulations in Brazil imply.

Iron Deficiency Anemia in Predominantly Breastfed Young Children

Due to the increase of breastfeeding in infants, iron deficiency anemia (IDA) related to prolonged, predominant breastfeeding should be of concern. Mostly, the manifestation of IDA is indistinguishable and the enthusiastic advocacy of breastfeeding without concomitant education of complementary food may lead to ignorance of breast milk-related IDA, which may result in impaired psychomotor development of the baby. This retrospective study was conducted to re-emphasize this easily ignored but still prevalent illness. This retrospective study involved 15 breastfeeding babies who were diagnosed with IDA between January 2007 and December 2010 at age 6-18 months. The clinical presentation, age at diagnosis, initial hemoglobin level and mean corpuscular volume, growth percentile, and duration of treatment were recorded and analyzed. None of the babies was suspected to have anemia by caregivers. Pallor was noticed by physicians in nine patients; one patient had seizure, one patient had pica, and, for the remaining four patients, IDA was diagnosed incidentally due to other medical events. Oral iron supplementation for an average of 3.6 months improved both hemoglobin level (from 8.0 g/dL to 11.5 g/dL) and mean corpuscular volume (from 57.5 fL to 73.9 fL). Most babies had appropriate growth and normal neurological development; two babies had both IDA and thalassemia. Although the association of IDA with prolonged, predominant breastfeeding is well known, its presentation is so subtle that its detection relies mainly on alert medical personnel.