Child development with the D-score: tuning instruments to unity

The chapter familiarises the reader with an intuitive yet powerful methodology to tune instruments to a common unit, presenting a fresh approach that expresses measurements made by different instruments on the D-score scale. As a result, the reader may compare D-scores between ages, children or cohorts. It shows how to exploit common developmental milestones to bridge instruments and cohorts; presents an analysis to obtain D-scores from 16 cohorts and 14 instruments; compares D-score age-distribution across populations from four continents; suggests an indicator for the United Nations Sustainable Development Goals; and defines developmentally-on-track.

Child development with the D-score: turning milestones into measurement

The chapter equips the reader with a basic understanding of robust psychometric methods that are needed to turn developmental milestones into measurements, introducing the fundamental issues in defining a unit for child development and demonstrates the relevant quantitative methodology. It reviews quantitative approaches to measuring child development;introduces the Rasch model in a non-technical way;shows how to estimate model parameters from real data;puts forth a set of principles for model evaluation and assessment of scale quality;analyses the relation between early D-scores and later intelligence;and compares the D-scores from three studies that all use the same instrument.

An Approach to the Patient With Delayed Puberty

Pediatric endocrinologists often evaluate and treat youth with delayed puberty. Stereotypically, these patients are 14-year-old young men who present due to lack of pubertal development. Concerns about stature are often present, arising from gradual shifts to lower height percentiles on the population-based, cross-sectional curves. Fathers and/or mothers may have also experienced later than average pubertal onset. In this review, we will discuss a practical clinical approach to the evaluation and management of youth with delayed puberty, including the differential diagnosis and key aspects of evaluation and management informed by recent review of the existing literature. We will also discuss scenarios that pose additional clinical challenges, including: (1) the young woman whose case poses questions regarding how presentation and approach differs for females vs males; (2) the 14-year-old female or 16-year-old young man who highlight the need to reconsider the most likely diagnoses, including whether idiopathic delayed puberty can still be considered constitutional delay of growth and puberty at such late ages; and finally (3) the 12- to 13-year-old whose presentation raises questions about whether age cutoffs for the diagnosis and treatment of delayed puberty should be adjusted downward to coincide with the earlier onset of puberty in the general population.

Delayed puberty in boys in central Sweden: an observational study on diagnosing and management in clinical practice

OBJECTIVES

To compare the usefulness of the classical definition of delayed puberty (DP) in boys with puberty nomograms and to describe the management of DP in boys in a hospital-based setting.

STUDY DESIGN

Observational retrospective multicentre study with a short-term follow-up.

SETTING AND PARTICIPANTS

Boys diagnosed with DP during 2013-2015 at paediatric departments in four counties in central Sweden. The medical records of 165 boys were reviewed.

PRIMARY AND SECONDARY OUTCOME MEASURES

Number of boys with DP after re-evaluation of the diagnosis according to the classical definition in comparison with puberty nomograms. Description of investigations performed and treatment provided to boys with DP.

RESULTS

In total, 45 and 58 boys were found to have DP according to the classical definition and the nomograms, respectively. Biochemical and/or radiological testing was performed in 91% of the 58 boys, but an underlying disease was only found in 9% of them. Approximately 79% of the boys received testosterone treatment, either as injections of testosterone enanthate or as testosterone undecanoate.

CONCLUSIONS

Puberty nomograms may be helpful instruments when diagnosing pubertal disorders in boys as they are not limited to an age close to 14 years and also identify boys with pubertal arrest. The majority of boys with DP undergo biochemical or radiological examinations, but underlying diseases are unusual emphasising the need for structural clinical practice guidelines for this patient group.

Child development with the D-score: tuning instruments to unity

The chapter familiarises the reader with an intuitive yet powerful methodology to tune instruments to a common unit, presenting a fresh approach that expresses measurements made by different instruments on the D-score scale. As a result, the reader may compare D-scores between ages, children or cohorts. It shows how to exploit common developmental milestones to bridge instruments and cohorts; presents an analysis to obtain D-scores from 16 cohorts and 14 instruments; compares D-score age-distribution across populations from four continents; suggests an indicator for the United Nations Sustainable Development Goals; and defines developmentally-on-track.

Child development with the D-score: turning milestones into measurement

The chapter equips the reader with a basic understanding of robust psychometric methods that are needed to turn developmental milestones into measurements, introducing the fundamental issues in defining a unit for child development and demonstrates the relevant quantitative methodology. It reviews quantitative approaches to measuring child development;introduces the Rasch model in a non-technical way;shows how to estimate model parameters from real data;puts forth a set of principles for model evaluation and assessment of scale quality;analyses the relation between early D-scores and later intelligence;and compares the D-scores from three studies that all use the same instrument.

Preschool Communication: Early Identification of Concerns About Preschool Language Development and Social Participation

Background: Adverse communication development in preschool children is a risk factor influencing child health and well-being with a negative impact on social participation. Language and social skills develop and maintain human adaptability over the life course. However, the accuracy of detecting language problems in asymptomatic children in primary care needs to be improved. Therefore, it is important to identify concerns about language development as a risk factor for child health. The association between parental and professional caregivers' concerns about language development and the level of preschool social participation was assessed, as well as the possible mediating/moderating effect of the perception of social competence. In addition, validity and predictive value of parental and professional caregivers' concerns about language development were tested. Methods: To identify emerging concerns about development and social participation, a community sample of 341 preschool children was systematically assessed with a comprehensive preventive child health care "toolkit" of instruments, including parent-completed tools like the Parents' Evaluation of Developmental Status (PEDS) and child competence Visual Analog Scales (VAS). At baseline, children were aged 3 years and at follow-up ~4 years. Results: There was a statistically significant association between parental and professional caregivers' concerns about language development and the level of preschool social participation, with a mediating effect of child social competence at the age of 3 years as well as 4 years. Negative predictive value of parental and professional caregiver language concerns at the age of 3 and 4 years were 99 and 97%, respectively. Furthermore, this article showed that while some preschool children grow out of language problems, others may develop them. Conclusion: Short but valid pediatric primary care tools like the PEDS and child competence VAS can support monitoring and early identification of concerns about language development and social competence as a risk factor for preschool social participation. Personalized health care requires continued communication between parents, professional caregivers and preventive child health care about parental and professional caregiver perceptions concerning preschool language development as well as the perception of a child's social competence.

Latent class distributional regression for the estimation of non-linear reference limits from contaminated data sources

BACKGROUND

Medical decision making based on quantitative test results depends on reliable reference intervals, which represent the range of physiological test results in a healthy population. Current methods for the estimation of reference limits focus either on modelling the age-dependent dynamics of different analytes directly in a prospective setting or the extraction of independent distributions from contaminated data sources, e.g. data with latent heterogeneity due to unlabeled pathologic cases. In this article, we propose a new method to estimate indirect reference limits with non-linear dependencies on covariates from contaminated datasets by combining the framework of mixture models and distributional regression.

RESULTS

Simulation results based on mixtures of Gaussian and gamma distributions suggest accurate approximation of the true quantiles that improves with increasing sample size and decreasing overlap between the mixture components. Due to the high flexibility of the framework, initialization of the algorithm requires careful considerations regarding appropriate starting weights. Estimated quantiles from the extracted distribution of healthy hemoglobin concentration in boys and girls provide clinically useful pediatric reference limits similar to solutions obtained using different approaches which require more samples and are computationally more expensive.

CONCLUSIONS

Latent class distributional regression models represent the first method to estimate indirect non-linear reference limits from a single model fit, but the general scope of applications can be extended to other scenarios with latent heterogeneity.

Innovative postnatal risk assessment in preventive child health Care: A study protocol

AIM

To introduce the rationale and design of a postnatal risk assessment study, which will be embedded in Preventive Child Health Care. This study will evaluate: (a) the predictive value of an innovative postnatal risk assessment, meant to assess the risk of growth and developmental problems in young children; and (b) its effectiveness in combination with tailored care pathways.

DESIGN

This study concerns a historically controlled study design and is designed as part of the Healthy Pregnancy 4 All-2 program. We hypothesize that child growth and developmental problems will be reduced in the intervention cohort due to the postnatal risk assessment and corresponding care pathways.

METHODS

The study was approved in August 2016. Children and their parents, visiting well-baby clinics during regular visits, will participate in the intervention (N = 2,650). Additional data of a historical control group (N = 2,650) in the same neighbourhoods will be collected. The intervention, consisting of the risk assessment and its corresponding care pathways, will be executed in the period between birth and 2 months of (corrected) age. The predictive value of the risk assessment and its effectiveness in combination with its corresponding care pathways will be assessed by Preventive Child Health Care nurses and physicians in four Preventive Child Health Care organisations in three municipalities with adverse perinatal outcomes. A total risk score above a predefined threshold, which is based on a weighted risk score, determines structured multidisciplinary consultation.

DISCUSSION

The successful implementation of this innovative postnatal risk assessment including corresponding care pathways has potential for further integration of risk assessment and a family-centred approach in the work process of Preventive Child Health Care nurses and physicians.

IMPACT

This study introduces a systematic approach in postnatal health care which may improve growth and developmental outcomes of children and even future generations.

Towards a Rational and Efficient Diagnostic Approach in Children Referred for Tall Stature and/or Accelerated Growth to the General Paediatrician

Tall stature and/or accelerated growth (TS/AG) in a child can be the result of a primary or secondary growth disorder, but more frequently no cause can be found (idiopathic TS). The conditions with the most important therapeutic implications are Klinefelter syndrome, Marfan syndrome and secondary growth disorders such as precocious puberty, hyperthyroidism and growth hormone excess. We propose a diagnostic flow chart offering a systematic approach to evaluate children referred for TS/AG to the general paediatrician. Based on the incidence, prevalence and clinical features of medical conditions associated with TS/AG, we identified relevant clues for primary and secondary growth disorders that may be obtained from the medical history, physical evaluation, growth analysis and additional laboratory and genetic testing. In addition to obtaining a diagnosis, a further goal is to predict adult height based on growth pattern, pubertal development and skeletal maturation. We speculate that an improved diagnostic approach in addition to expanding use of genetic testing may increase the diagnostic yield and lower the age at diagnosis of children with a pathologic cause of TS/AG.

Age at Pubertal Development in a Hispanic-Latina Female Population: Should the Definitions Be Revisited?

STUDY OBJECTIVE

To assess pubertal events in a Hispanic female population and to create normograms of puberty.

DESIGN

Longitudinal.

SETTING

University facility.

PARTICIPANTS

Five hundred forty-nine girls from the Growth and Obesity Chilean Cohort study.

INTERVENTIONS

Follow-up twice a year beginning at age 6 years.

MAIN OUTCOME MEASURES

Breast development, pubic hair development, and age. Breast development (B2, B3, and B4) and pubarche (P2) were determined. Age at menarche was obtained from the adolescents and their mothers. Age and growth velocity at peak height velocity were calculated.

RESULTS

In girls, B2, B3, and B4 occur at median ages of 9.2, 10.2, and 10.9 years, respectively. The median age at P2 was 9.7 years. The mean age at peak height velocity and the growth velocity were 10.6 years (SD = 1.1) and 8 cm/y, respectively. The mean age at menarche was 11.9 years (SD = 1.1); only 2.8% (15 /530) of girls experienced menarche after 14 years and 1.9% before 10 years. The mean interval time between B2 and menarche was 2.5 ± 1.0 years. Transient thelarche occurred in 8.6% of girls.

CONCLUSION

This longitudinal cohort shows that thelarche occurred 1.2 months later than previously reported in cross-sectional studies. Conversely, we found that pubic hair appeared 12 months earlier and menarche occurred 9 months earlier than previously reported. These findings are important in setting normalcy data and avoiding unnecessary clinical consultations.

The D-score: a metric for interpreting the early development of infants and toddlers across global settings

INTRODUCTION

Early childhood development can be described by an underlying latent construct. Global comparisons of children's development are hindered by the lack of a validated metric that is comparable across cultures and contexts, especially for children under age 3 years. We constructed and validated a new metric, the Developmental Score (D-score), using existing data from 16 longitudinal studies.

METHODS

Studies had item-level developmental assessment data for children 0-48 months and longitudinal outcomes at ages >4-18 years, including measures of IQ and receptive vocabulary. Existing data from 11 low-income, middle-income and high-income countries were merged for >36 000 children. Item mapping produced 95 'equate groups' of same-skill items across 12 different assessment instruments. A statistical model was built using the Rasch model with item difficulties constrained to be equal in a subset of equate groups, linking instruments to a common scale, the D-score, a continuous metric with interval-scale properties. D-score-for-age z-scores (DAZ) were evaluated for discriminant, concurrent and predictive validity to outcomes in middle childhood to adolescence.

RESULTS

Concurrent validity of DAZ with original instruments was strong (average r=0.71), with few exceptions. In approximately 70% of data rounds collected across studies, DAZ discriminated between children above/below cut-points for low birth weight (<2500 g) and stunting (-2 SD below median height-for-age). DAZ increased significantly with maternal education in 55% of data rounds. Predictive correlations of DAZ with outcomes obtained 2-16 years later were generally between 0.20 and 0.40. Correlations equalled or exceeded those obtained with original instruments despite using an average of 55% fewer items to estimate the D-score.

CONCLUSION

The D-score metric enables quantitative comparisons of early childhood development across ages and sets the stage for creating simple, low-cost, global-use instruments to facilitate valid cross-national comparisons of early childhood development.

Early childhood development: an imperative for action and measurement at scale

Experiences during early childhood shape biological and psychological structures and functions in ways that affect health, well-being and productivity throughout the life course. The science of early childhood and its long-term consequences have generated political momentum to improve early childhood development and elevated action to country, regional and global levels. These advances have made it urgent that a framework, measurement tools and indicators to monitor progress globally and in countries are developed and sustained. We review progress in three areas of measurement contributing to these goals: the development of an index to allow country comparisons of young children’s development that can easily be incorporated into ongoing national surveys; improvements in population-level assessments of young children at risk of poor early development; and the production of country profiles of determinants, drivers and coverage for early childhood development and services using currently available data in 91 countries. While advances in these three areas are encouraging, more investment is needed to standardise measurement tools, regularly collect country data at the population level, and improve country capacity to collect, interpret and use data relevant to monitoring progress in early childhood development.

Counting outcomes, coverage and quality for early child development programmes

Improved measurement in early child development (ECD) is a strategic focus of the WHO, UNICEF and World Bank Nurturing Care Framework. However, evidence-based approaches to monitoring and evaluation (M&E) of ECD projects in low-income and middle-income countries (LMIC) are lacking. The Grand Challenges Canada®-funded Saving Brains® ECD portfolio provides a unique opportunity to explore approaches to M&E of ECD programmes across diverse settings. Focused literature review and participatory mixed-method evaluation of the Saving Brains portfolio was undertaken using an adapted impact framework. Findings related to measurement of quality, coverage and outcomes for scaling ECD were considered. Thirty-nine ECD projects implemented in 23 LMIC were evaluated. Projects used a 'theory of change' based M&E approach to measure a range of inputs, outputs and outcomes. Over 29 projects measured cognitive, language, motor and socioemotional outcomes. 18 projects used developmental screening tools to measure outcomes, with a trade-off between feasibility and preferred practice. Environmental inputs such as the home environment were measured in 15 projects. Qualitative data reflected the importance of measurement of project quality and coverage, despite challenges measuring these constructs across contexts. Improved measurement of intervention quality and measurement of coverage, which requires definition of the numerator (ie, intervention) and denominator (ie, population in need/at risk), are needed for scaling ECD programmes. Innovation in outcome measurement, including intermediary outcome measures that are feasible and practical to measure in routine services, is also required, with disaggregation to better target interventions to those most in need and ensure that no child is left behind.

Management of hypogonadism from birth to adolescence

Management of patients with hypogonadism is dependent on the underlying cause. Whilst functional hypogonadism presenting as delayed puberty in adolescence is relatively common, permanent hypogonadism presenting in infancy or adolescence is unusual. The main differential diagnoses of delayed puberty include self-limited delayed puberty (DP), idiopathic hypogonadotropic hypogonadism (IHH) and hypergonadotropic hypogonadism. Treatment of self-limited DP involves expectant observation or short courses of low dose sex steroid supplementation. More complex and involved management is required in permanent hypogonadism to achieve both development of secondary sexual characteristics and to maximize the potential for fertility. This review will cover the options for management involving sex steroid or gonadotropin therapy, with discussion of benefits, limitations and specific considerations of the different treatment options.

Growth throughout childhood of children born growth restricted

OBJECTIVE

Many studies that examine growth in growth-restricted children at birth do not discriminate between fetal growth restriction (FGR) and small for gestational age (SGA). These terms however are not synonymous. In SGA, stunting and increased weight gain have been reported. We do not know if this holds true for FGR. Our aim was to study postnatal growth until age 12.5 years in a cohort of children born FGR due to early onset placental insufficiency, and its relation to FGR severity.

DESIGN

Prospective cohort study, follow-up of an antenatal randomised controlled trial in two tertiary centres.

PATIENTS

Children aged 12.5 years born after FGR, with mothers who had severe early onset hypertensive pregnancy disorders (N=96).

MAIN OUTCOME MEASURES

Anthropometry at age 12.5 years in SD scores (SDS).

RESULTS

Mean height SDS (SD) corrected for target height was -0.09 (0.94), mean body mass index (BMI) SDS was 0.00 (1.16) and mean head circumference SDS was -0.37 (1.11). Catch-up growth was at fastest rate between term age and 3 months and similar for height (0.55 SDS/months) and weight (0.49 SDS/months). Neither FGR severity nor gestational age was related to height and BMI at age 12.5 years.

CONCLUSIONS

Children born growth restricted due to early onset placental insufficiency have height and BMI scores comparable to their age-matched peers at age 12.5 years. FGR severity was not related to height and BMI at age 12.5 years. These reassuring results differ from most studies that examine SGA children.

Pubertal Progression and Reproductive Hormones in Healthy Girls With Transient Thelarche

CONTEXT

Detailed evaluation of pubertal progression in girls from longitudinal studies is sparse, and the phenomenon of transient thelarche (TT), defined as the appearance, regression, and subsequent reappearance of breast buds, in healthy girls remains undescribed.

OBJECTIVE

To describe TT in terms of pubertal progression, growth, genotypes, and reproductive hormones and to apply new puberty nomograms for breast stages, pubic hair, and menarche.

DESIGN

A prospective, longitudinal population-based study.

PATIENTS OR OTHER PARTICIPANTS

Ninety-eight healthy Danish schoolchildren (Caucasian girls) followed longitudinally as part of the COPENHAGEN Puberty Study were included in the evaluation of TT. A total of 1466 girls from 2 cross-sectional studies were included in the creation of the puberty nomograms.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Pubertal progression, specifically thelarche, reproductive hormones, genotype, and growth.

RESULTS

Twelve of 98 (12%) girls experienced TT. A larger proportion of girls with TT entered puberty by the pubarche pathway (50%) compared with girls with normal progression (15.4%), P = 0.014. Girls with TT progressed through puberty normally when evaluated using puberty nomograms. Reproductive hormones and growth velocity were lower at the first (transient) thelarche than the second (permanent) thelarche.

CONCLUSION

TT is a frequent phenomenon that appears to be a peripheral occurrence independent of central puberty. It does not appear to affect subsequent pubertal progression as evaluated by our new puberty nomograms.

New reference charts for testicular volume in Dutch children and adolescents allow the calculation of standard deviation scores

AIM

Accurate calculations of testicular volume standard deviation (SD) scores are not currently available. We constructed LMS-smoothed age-reference charts for testicular volume in healthy boys.

METHODS

The LMS method was used to calculate reference data, based on testicular volumes from ultrasonography and Prader orchidometer of 769 healthy Dutch boys aged 6 months to 19 years. We also explored the association between testicular growth and pubic hair development, and data were compared to orchidometric testicular volumes from the 1997 Dutch nationwide growth study.

RESULTS

The LMS-smoothed reference charts showed that no revision of the definition of normal onset of male puberty - from nine to 14 years of age - was warranted. In healthy boys, the pubic hair stage SD scores corresponded with testicular volume SD scores (r = 0.394). However, testes were relatively small for pubic hair stage in Klinefelter's syndrome and relatively large in immunoglobulin superfamily member 1 deficiency syndrome.

CONCLUSION

The age-corrected SD scores for testicular volume will aid in the diagnosis and follow-up of abnormalities in the timing and progression of male puberty and in research evaluations. The SD scores can be compared with pubic hair SD scores to identify discrepancies between cell functions that result in relative microorchidism or macroorchidism.

A permutation test to analyse systematic bias and random measurement errors of medical devices via boosting location and scale models

Measurement errors of medico-technical devices can be separated into systematic bias and random error. We propose a new method to address both simultaneously via generalized additive models for location, scale and shape (GAMLSS) in combination with permutation tests. More precisely, we extend a recently proposed boosting algorithm for GAMLSS to provide a test procedure to analyse potential device effects on the measurements. We carried out a large-scale simulation study to provide empirical evidence that our method is able to identify possible sources of systematic bias as well as random error under different conditions. Finally, we apply our approach to compare measurements of skin pigmentation from two different devices in an epidemiological study.