Towards evidence based referral criteria for growth monitoring

Evaluating the sensitivity and specificity of the UK and Dutch growth referral criteria in predicting the diagnosis of pathological short stature

OBJECTIVE

The aim of this observational study was to evaluate the UK and Dutch referral criteria for short stature to determine their sensitivity and specificity in predicting pathological short stature. Adherence to the recommended panel of investigations was also assessed.

STUDY DESIGN

Retrospective review of medical records to examine the auxological parameters, investigations and diagnosis of subjects referred to two paediatric endocrine clinics at the Royal London Children's Hospital between 2016 and 2021. We analysed: height SD score (HtSDS), height SDS minus target height SDS (Ht-THSDS) and height deflection SDS (HtDefSDS). The UK referral criteria were HtSDS <-2.7, Ht-THSDS >2.0 and HtDefSDS >1.3. The Dutch referral criteria were HtSDS <-2.0, Ht-THSDS >1.6 and HtDefSDS >1.0.

RESULTS

Data were available for 143 subjects (72% males) with mean (range) age 8.7 years (0.5-19.9). HtSDS and Ht-THSDS were significantly lower in the pathological stature (n=66) versus the non-pathological stature (n=77) subjects (-2.67±0.82 vs -1.97±0.70; p<0.001 and -2.07±1.02 vs -1.06±0.99; p<0.001, respectively). The sensitivity and specificity to detect pathology was 41% and 83% for the UK criteria (HtSDS <-2.7) compared with 59% and 79% for the Dutch criteria (HtSDS <-2.0), 48% and 83% for UK criteria (Ht-THSDS <-2.0) compared with 74% and 72% for Dutch criteria (Ht-THSDS <-1.6) and 33% and 68% for UK criteria (HtDefSDS >1.3) compared with 44% and 63% for the Dutch criteria (HtDefSDS >1.0). On average, each patient had 88% of the recommended investigations, and 53% had all the recommended testing. New pathology was identified in 36% of subjects.

CONCLUSIONS

In isolation, the UK auxological referral thresholds have limited sensitivity and specificity for pathological short stature. The combination of HtSDS and Ht-THSDS improved the sensitivity of UK criteria to detect pathology from 41% to 68%. Attention to the child's genetic height potential prior to referral can prevent unnecessary assessments.

Development and validation of a mobile application for point of care evaluation of growth failure

OBJECTIVES

Lack of systematic evaluation of short stature results in unnecessary work-up on one hand while missing pathology on the other. We have developed a mobile application that guides work-up based on age, auxology (height, BMI, and corrected standard deviation score), and skeletal maturation with an aim of reducing the diagnostic errors. Aim of this study is to develop and validate a mobile application for point of care evaluation of short stature.

METHODS

The application was developed (n=400) and validated (n=412) on children and adolescents (2-18 years of age) presenting to our Pediatric Endocrinology Clinic with short stature. Height standard deviation score thresholds determining the need for workup were derived from Receiver Operating Characteristics (ROC) curve. Student's t-test and ROC curves were used to identify the most appropriate parameter differentiating constitutional delay of growth and puberty (CDGP) from pathological and nutritional from endocrine causes. The validation of the application involved comparing the application predicted and clinical diagnosis at each step of the algorithm.

RESULTS

The mobile application diagnosis was concordant with clinical diagnosis in 408 (99.0%) with discordance in four (two with CDGP labeled as growth hormone deficiency [GHD] and two with GHD labeled as CDGP).

CONCLUSIONS

Mobile application guided short stature assessment has a high concordance with the clinical diagnosis and is expected to help point of care short stature evaluation.

Evaluation of Short Stature in Children and Adolescents

Short stature is a common presentation to pediatricians with a significant overlap between physiology and pathology. Thus, while most short children have a physiological cause, growth failure may be the only manifestation of severe underlying disease. Growth failure evaluation aims to avoid unnecessary investigations in children with a physiological cause without missing pathology. Guidelines for the evaluation of short stature allow stepwise evaluation but are limited by their resource-intense nature. An objective application of anthropometric indices and careful clinical evaluation allows rational growth failure workup. The use of height standard deviation score (SDS) for determining the need for evaluation (no evaluation above -2, follow-up between -2 to -3, and immediate workup with height below -3), corrected height SDS to identify familial short stature (above -1.5), height SDS for bone age for constitutional delay of puberty and growth (above -2), and BMI SDS for nutritional pattern growth failure (below -1) helps reduce the burden of investigations. The present review provides a framework for comprehensive growth evaluation across resource levels and settings.

The value of a simple method to decrease diagnostic errors in Turner syndrome: a case report

Introduction

Turner syndrome is a genetic disorder in females and is the result of complete or partial loss of an X chromosome during fertilization. The missing X chromosome is originally either from the mother's ovum or the father's sperm cell. Approximately 45% of patients have the 45,X karyotype and the rest have other variants of Turner syndrome, which are either mosaicism patterns or structural abnormalities of the X chromosome. Here, we report a case of Turner syndrome that is the fifth case of Turner syndrome with balanced Robertsonian translocation of (13;14)(q10;q10), and the sixth case with 44,X chromosomes, reported in the literature thus far.

Case presentation

A 10.3-year-old Persian girl was brought to our clinic by her parents, with the complaint of failure to thrive and short height. She had been examined and investigated by endocrinologists since the age of 4 years, but no definite diagnosis was made. At the time of presentation, she had been through three provocative growth hormone tests and had been on no medications for about a year. Her physical examination revealed mild retrognathia and micrognathia. Initially, she was started on somatropin treatment which, after 12 months, did not appropriately improve her height velocity. Therefore, a more thorough physical examination was performed, in which high arched palate and low posterior hairline were observed. There was also a difference between target height and patient height standard deviation scores. Karyotype study was requested, and Turner syndrome was confirmed.

Conclusion

The diagnosis of this case was not straightforward, both because the somatic presentations were not obvious, and because the physicians had not looked for them when performing the physical examinations. This case report introduces a rare 44,X chromosome karyotype of Turner syndrome and highlights the value in using the difference between target height and patient height standard deviation scores as a simple and inexpensive tool for diagnosis of this syndrome.

Early Detection of Abnormal Growth Associated with Juvenile Acquired Hypothyroidism

CONTEXT

Development of the typical growth phenotype in juvenile acquired hypothyroidism (JHT), the faltering linear growth with increasing weight, has not been thoroughly characterized.

OBJECTIVE

To describe longitudinal growth pattern in children developing JHT and investigate how their growth differs from the general population in systematic growth monitoring.

DESIGN

Retrospective case-control study.

SETTING

JHT cases from 3 Finnish University Hospitals and healthy matched controls from primary health care.

PATIENTS

A total of 109 JHT patients aged 1.2 to 15.6 years (born 1983-2010) with 554 height and weight measurements obtained for 5 years preceding JHT diagnosis. Each patient was paired with 100 healthy controls (born 1983-2008) by sex and age. Longitudinal growth pattern was evaluated in mixed linear models. Growth monitoring parameters were evaluated using receiver operating characteristics analysis.

RESULTS

At diagnosis, JHT patients were heavier (mean adjusted body mass index-for-age [BMISDS] difference, 0.65 [95% CI, 0.46-0.84]) and shorter (mean adjusted height-for-age deviation from the target height [THDEVSDS] difference, -0.34 [95% CI, -0.57 to -0.10]) than healthy controls. However, 5 years before diagnosis, patients were heavier (mean BMISDS difference, 0.33 [95% CI, 0.12-0.54]) and taller (mean THDEVSDS difference, 0.29 [95% CI, 0.06-0.52]) than controls. JHT could be detected with good accuracy when several growth parameters were used simultaneously in screening (area under the curve, 0.83 [95% CI, 0.78-0.89]).

CONCLUSIONS

Abnormal growth pattern of patients with JHT evolves years before diagnosis. Systematic growth monitoring would detect abnormal growth at an early phase of JHT and facilitate timely diagnosis of JHT.

Towards a Rational and Efficient Diagnostic Approach in Children Referred for Growth Failure to the General Paediatrician

Based on a recent Dutch national guideline, we propose a structured stepwise diagnostic approach for children with growth failure (short stature and/or growth faltering), aiming at high sensitivity for pathologic causes at acceptable specificity. The first step is a detailed clinical assessment, aiming at obtaining relevant clinical clues from the medical history (including family history), physical examination (emphasising head circumference, body proportions and dysmorphic features) and assessment of the growth curve. The second step consists of screening: a radiograph of the hand and wrist (for bone age and assessment of anatomical abnormalities suggestive for a skeletal dysplasia) and laboratory tests aiming at detecting disorders that can present as isolated short stature (anaemia, growth hormone deficiency, hypothyroidism, coeliac disease, renal failure, metabolic bone diseases, renal tubular acidosis, inflammatory bowel disease, Turner syndrome [TS]). We advise molecular array analysis rather than conventional karyotyping for short girls because this detects not only TS but also copy number variants and uniparental isodisomy, increasing diagnostic yield at a lower cost. Third, in case of diagnostic clues for primary growth disorders, further specific testing for candidate genes or a hypothesis-free approach is indicated; suspicion of a secondary growth disorder warrants adequate further targeted testing.

Algorithm-Driven Electronic Health Record Notification Enhances the Detection of Turner Syndrome

Early diagnosis of Turner syndrome enhances care, but in routine practice, even within larger referral centers, diagnosis is delayed. Our study examines the utility of an electronic health record algorithm in identifying patients at high risk for Turner syndrome. Six percent of those identified had missed diagnoses of Turner syndrome.

Growth hormone therapy in children; research and practice - A review

Short stature remains the most common reason for referral to a pediatric Endocrinologist and its management remains a challenge. One of the main controversies is the diagnosis of idiopathic short stature and the role of new technologies for genetic investigation of children with inadequate growth. Complexities in management of children with short stature includes selection of who should receive interventions such as recombinant human growth hormone, and how should this agent dose be adjusted during treatment. Should anthropometrical data be the primary determinant or should biochemical and genetic data be used to improve growth response and safety? Furthermore, what is considered a suboptimal response to growth hormone therapy and how should this be managed? Treatment of children with short stature remains a "hot" topic and more data is needed in several areas. These issues are reviewed in this paper.

Worm plot to diagnose fit in quantile regression

The worm plot is a series of detrended Q-Q plots, split by covariate levels. The worm plot is a diagnostic tool for visualizing how well a statistical model fits the data, for finding locations at which the fit can be improved, and for comparing the fit of different models. This paper shows how the worm plot can be used in conjunction with quantile regression. No parametric distributional assumptions are needed to create the worm plot. We fitted both an LMS and a quantile regression model on Dutch height data. The worm plot shows that the quantile regression model is superior to the LMS model in terms of fit. At the same time, it also contains a warning that the particular quantile model used may actually overfit the data. The resulting quantile curves are wiggly at the extremes, and appear less well suited for drawing growth diagrams. The paper concludes that the worm plot is a natural diagnostic tool for quantile regression.

Growth and development after oesophageal atresia surgery: Need for long-term multidisciplinary follow-up

Survival rates in oesophageal atresia patients have reached over 90%. In long-term follow-up studies the focus has shifted from purely surgical or gastrointestinal evaluation to a multidisciplinary approach. We reviewed the literature on the long-term morbidity of these patients and discuss mainly issues of physical growth and neurodevelopment. We conclude that growth problems - both stunting and wasting - are frequently seen, but that sufficient longitudinal data are lacking. Therefore, it is unclear whether catch-up growth into adolescence and adulthood occurs. Data on determinants of growth retardation are also lacking in current literature. Studies on neurodevelopment beyond preschool age are scarce but oesophageal atresia patients seem at risk for academic problems and motor function delay. Many factors contribute to the susceptibility to growth and development problems and we propose a multidisciplinary follow-up schedule into adulthood future care which may help improve quality of life.

Growth monitoring: a survey of current practices of primary care paediatricians in Europe

OBJECTIVE

We aimed to study current practices in growth monitoring by European primary care paediatricians and to explore their perceived needs in this field.

METHODS

We developed a cross-sectional, anonymous on-line survey and contacted primary care paediatricians listed in national directories in the 18 European countries with a confederation of primary care paediatricians. Paediatricians participated in the survey between April and September 2011.

RESULTS

Of the 1,198 paediatricians from 11 European countries (response rate 13%) who participated, 29% used the 2006 World Health Organization Multicentre Growth Reference Study growth charts, 69% used national growth charts; 61% used software to draw growth charts and 79% did not use a formal algorithm to detect abnormal growth on growth charts. Among the 21% of paediatricians who used algorithms, many used non-algorithmic simple thresholds for height and weight and none used the algorithms published in the international literature. In all, 69% of paediatricians declared that a validated algorithm to monitor growth would be useful in daily practice. We found important between-country variations.

CONCLUSION

The varied growth-monitoring practices declared by primary care paediatricians reveals the need for standardization and evidence-based algorithms to define abnormal growth and the development of software that would use such algorithms.

Early recognition of growth abnormalities permitting early intervention

Normal growth is a sign of good health. Monitoring for growth disturbances is fundamental to children's health care. Early detection and diagnosis of the causes of short stature allows management of underlying medical conditions, optimizing attainment of good health and normal adult height.

CONCLUSION

This review summarizes currently available information on monitoring for short stature in children and conditions usually associated with short stature and summarizes the authors' conclusions on the early recognition of growth disorders.

Methods to obtain referral criteria in growth monitoring

An important goal of growth monitoring is to identify genetic disorders, diseases or other conditions that manifest themselves through an abnormal growth. The two main conditions that can be detected by height monitoring are Turner’s syndrome and growth hormone deficiency. Conditions or risk factors that can be detected by monitoring weight or body mass index include hypernatremic dehydration, celiac disease, cystic fibrosis and obesity. Monitoring infant head growth can be used to detect macrocephaly, developmental disorder and ill health in childhood. This paper describes statistical methods to obtain evidence-based referral criteria in growth monitoring. The referral criteria that we discuss are based on either anthropometric measurement(s) at a fixed age using (1) a Centile or a Standard Deviation Score, (2) a Standard Deviation corrected for parental height, (3) a Likelihood Ratio Statistic and (4) an ellipse, or on multiple measurements over time using (5) a growth rate and (6) a growth curve model. We review the potential uses of these methods, and outline their strengths and limitations.

A chart to predict adult height from a child's current height

BACKGROUND

A child's adult height is commonly predicted using their target height, based on mid-parent height. However, if no growth disorder is suspected, the child's current height is a far better predictor of their adult height.

AIM

To develop a chart to predict a child's adult height from their current height, adjusting for regression to the mean.

SUBJECTS AND METHODS

Data from the First Zurich Longitudinal Growth Study provided correlations between child height and adult height by age and sex, for use in a regression model predicting adult height centile from child height centile. The model was validated using data from the British 1946 and 1958 birth cohorts.

RESULTS

The chart is illustrated superimposed on the British 1990 boys height chart. The predicted height has a standard error of 4-5 cm for ages from 4 years to puberty in both sexes. The regression adjustment partially compensates for biased predictions in early and late developers in puberty. A simplified version of the chart for restricted age ranges is also shown, as used on the UK-WHO 0-4 years growth charts.

CONCLUSION

The height prediction chart should be of value for parents, and indirectly professionals, to predict adult height in their children.

Genetic evaluation of short stature

After a proper medical history, growth analysis and physical examination of a short child, followed by radiological and laboratory screening, the clinician may decide to perform genetic testing. We propose several clinical algorithms that can be used to establish the diagnosis. GH1 and GHRHR should be tested in children with severe isolated growth hormone deficiency and a positive family history. A multiple pituitary dysfunction can be caused by defects in several genes, of which PROP1 and POU1F1 are most common. GH resistance can be caused by genetic defects in GHR, STAT5B, IGF1, IGFALS, which all have their specific clinical and biochemical characteristics. IGF-I resistance is seen in heterozygous defects of the IGF1R. If besides short stature additional abnormalities are present, these should be matched with known dysmorphic syndromes. If no obvious candidate gene can be determined, a whole genome approach can be taken to check for deletions, duplications and/or uniparental disomies.

Pituitary stalk interruption syndrome: diagnostic delay and sensitivity of the auxological criteria of the growth hormone research society

OBJECTIVES

To study the diagnostic delay for pituitary stalk interruption syndrome (PSIS) with growth hormone deficiency (GHD) and the sensitivity of the auxological criteria of the Growth Hormone Research Society (GHRS) consensus guidelines.

METHODS

A single-center retrospective case-cohort study covering records from January 2000 through December 2007 evaluated the performance of each GHRS auxological criterion for patients with GHD and PSIS. Diagnostic delay was calculated as the difference between the age at which the earliest GHRS criterion could have been observed and the age at diagnosis of PSIS with GHD. A diagnostic delay exceeding one year was defined as late diagnosis.

RESULTS

The study included 21 patients, 16 (76%) of whom had isolated GHD and 5 (24%) multiple pituitary hormone deficiencies. The median age at diagnosis was 3.6 years (interquartile range, IQR, 2.6-5.5). The median diagnostic delay was 2.3 years (range 0-12.6; IQR 1.5-3.6), with late diagnosis for 17 patients (81%). Height more than 1.5 SDS below target height was the most effective criterion: 90% of the patients met the criterion before diagnosis at a median age of 1 year, and it was the first criterion to be fulfilled for 84%.

CONCLUSION

In our cohort, the delay for diagnosis of PSIS with GHD was long and could have been reduced by using the GHRS criteria, in particular, height more than 1.5 SDS below the target height. The specificity of such a strategy needs to be tested in healthy populations.

Evaluation of linear measurement and growth plotting in an inpatient pediatric setting

Routine growth monitoring is crucial for all children. American Academy of Pediatrics guidelines state that children should be measured annually, but some children may not routinely be evaluated by primary care providers. Inpatient admissions provide the opportunity to identify growth disorders. The purpose of this study was to obtain data on the linear measuring practices in an urban children's hospital. Charts were reviewed from a random sample of 200 children who were admitted; 57% were measured, 42% had measurements plotted on growth charts, and 24% had measurements plotted correctly. Ongoing education is necessary for nursing staff to accurately obtain and plot measurements.

Screening rules for growth to detect celiac disease: a case-control simulation study

Background

It is generally assumed that most patients with celiac disease (CD) have a slowed growth in terms of length (or height) and weight. However, the effectiveness of slowed growth as a tool for identifying children with CD is unknown. Our aim is to study the diagnostic efficiency of several growth criteria used to detect CD children.

Methods

A case-control simulation study was carried out. Longitudinal length and weight measurements from birth to 2.5 years of age were used from three groups of CD patients (n = 134) (one group diagnosed by screening, two groups with clinical manifestations), and a reference group obtained from the Social Medical Survey of Children Attending Child Health Clinics (SMOCC) cohort (n = 2,151) in The Netherlands. The main outcome measures were sensitivity, specificity and positive predictive value (PPV) for each criterion.

Results

Body mass index (BMI) performed best for the groups with clinical manifestations. Thirty percent of the CD children with clinical manifestations and two percent of the reference children had a BMI Standard Deviation Score (SDS) less than -1.5 and a decrease in BMI SDS of at least -2.5 (PPV = 0.85%). The growth criteria did not discriminate between the screened CD group and the reference group.

Conclusion

For the CD children with clinical manifestations, the most sensitive growth parameter is a decrease in BMI SDS. BMI is a better predictor than weight, and much better than length or height. Toddlers with CD detected by screening grow normally at this stage of the disease.

Selecting short-statured children needing growth hormone testing: derivation and validation of a clinical decision rule

Background

Numerous short-statured children are evaluated for growth hormone (GH) deficiency (GHD). In most patients, GH provocative tests are normal and are thus in retrospect unnecessary.

Methods

A retrospective cohort study was conducted to identify predictors of growth hormone (GH) deficiency (GHD) in children seen for short stature, and to construct a very sensitive and fairly specific predictive tool to avoid unnecessary GH provocative tests. GHD was defined by the presence of 2 GH concentration peaks < 10 ng/ml. Certain GHD was defined as GHD and viewing pituitary stalk interruption syndrome on magnetic resonance imaging. Independent predictors were identified with uni- and multi-variate analyses and then combined in a decision rule that was validated in another population.

Results

The initial study included 167 patients, 36 (22%) of whom had GHD, including 5 (3%) with certain GHD. Independent predictors of GHD were: growth rate < -1 DS (adjusted odds ratio: 3.2; 95% confidence interval [1.3–7.9]), IGF-I concentration < -2 DS (2.8 [1.1–7.3]) and BMI z-score ≥ 0 (2.8 [1.2–6.5]). A clinical decision rule suggesting that patients be tested only if they had a growth rate < -1 DS and a IGF-I concentration < -2 DS achieved 100% sensitivity [48–100] for certain GHD and 63% [47–79] for GHD, and a specificity of 68% [60–76]. Applying this rule to the validation population (n = 40, including 13 patients with certain GHD), the sensitivity for certain GHD was 92% [76–100] and the specificity 70% [53–88].

Conclusion

We have derived and performed an internal validation of a highly sensitive decision rule that could safely help to avoid more than 2/3 of the unnecessary GH tests. External validation of this rule is needed before any application.

The diagnostic work up of growth failure in secondary health care; an evaluation of consensus guidelines

Background

As abnormal growth might be the first manifestation of undetected diseases, it is important to have accurate referral criteria and a proper diagnostic work-up. In the present paper we evaluate the diagnostic work-up in secondary health care according to existing consensus guidelines and study the frequency of underlying medical disorders.

Methods

Data on growth and additional diagnostic procedures were collected from medical records of new patients referred for short stature to the outpatient clinics of the general paediatric departments of two hospitals (Erasmus MC – Sophia Children's Hospital, Rotterdam and Spaarne Hospital, Haarlem) between January 1998 and December 2002. As the Dutch Consensus Guideline (DCG) is the only guideline addressing referral criteria as well as diagnostic work-up, the analyses were based on its seven auxological referral criteria to determine the characteristics of children who are incorrectly referred and the adequacy of workup of those who are referred.

Results

Twenty four percent of children older than 3 years were inappropriately referred (NCR). Of the correctly referred children 74–88% were short corrected for parental height, 40–61% had a height SDS <-2.5 and 21% showed height deflection (Δ HSDS < -0.25/yr or Δ HSDS < -1). In none of the children a complete detailed routine diagnostic work up was performed and in more than 30% no routine laboratory examination was done at all. Pathologic causes of short stature were found in 27 children (5%).

Conclusion

Existing guidelines for workup of children with suspected growth failure are poorly implemented. Although poorly implemented the DCG detects at least 5% pathologic causes of growth failure in children referred for short stature. New guidelines for referral are required with a better sensitivity and specificity, wherein distance to target height should get more attention. The general diagnostic work up for short stature should include testing for celiac disease in all children and for Turner syndrome in girls.

Idiopathic short stature: definition, epidemiology, and diagnostic evaluation

Idiopathic short stature is a condition in which the height of the individual is more than 2 SD below the corresponding mean height for a given age, sex and population, in whom no identifiable disorder is present. It can be subcategorized into familial and non-familial ISS, and according to pubertal delay. It should be differentiated from dysmorphic syndromes, skeletal dysplasias, short stature secondary to a small birth size (small for gestational age, SGA), and systemic and endocrine diseases. ISS is the diagnostic group that remains after excluding known conditions in short children.

Improved accuracy when screening for human growth disorders by likelihood ratios

The standard deviation score (SDS) is a powerful tool for screening for growth-related problems. However, referral rules of the type 'if SDS(Y)<d, then refer' (for some constant d) are not optimal for answering the question: 'Does this child with measurement Y belong to the reference or to the diseased population?'. If the growth standard for the diseased population is known, then the likelihood ratio (LR) and the log-likelihood ratio (LLR) can be calculated for individual measurements. Rules of the type 'if LLR(Y)<e, then refer' are uniformly the most powerful test for any constant e, implying that their receiver operating characteristic curves are above those for all other possible tests based on Y. As an empirical demonstration, both types of rules are applied to longitudinal growth data comparing a group with diagnosed Turner syndrome and a reference group from birth to 10 years of age. Conforming with theory, the LR rules were found to be superior to the SDS rules in terms of sensitivity and specificity. We conclude that the LR is the natural measure for two-group studies that can be easily calculated for individual measurements. The LR is firmly rooted within both statistical and decision theory and can be used to estimate the absolute probability of disease.

Referral patterns of children with poor growth in primary health care

BACKGROUND

To promote early diagnosis and treatment of short stature, consensus meetings were held in the mid nineteen nineties in the Netherlands and the UK. This resulted in guidelines for referral. In this study we evaluate the referral pattern of short stature in primary health care using these guidelines, comparing it with cut-off values mentioned by the WHO.

METHODS

Three sets of referral rules were tested on the growth data of a random sample (n = 400) of all children born between 01-01-1985 and 31-12-1988, attending school doctors between 1998 and 2000 in Leiden and Alphen aan den Rijn (the Netherlands): the screening criteria mentioned in the Dutch Consensus Guideline (DCG), those of the UK Consensus Guideline (UKCG) and the cut-off values mentioned in the WHO Global Database on Child growth and Malnutrition.

RESULTS

Application of the DCG would lead to the referral of too many children (almost 80%). The largest part of the referrals is due to the deflection of height, followed by distance to target height and takes primarily place during the first 3 years. The deflection away from the parental height would also lead to too many referrals. In contrast, the UKCG only leads to 0.3% referrals and the WHO-criteria to approximately 10%.

CONCLUSION

The current Dutch consensus guideline leads to too many referrals, mainly due to the deflection of length during the first 3 years of life. The UKCG leads to far less referrals, but may be relatively insensitive to detect clinically relevant growth disorders like Turner syndrome. New guidelines for growth monitoring are needed, which combine a low percentage of false positive results with a good sensitivity.

Are age references for waist circumference, hip circumference and waist-hip ratio in Dutch children useful in clinical practice?

The aim of this study was to present age references for waist circumference (WC), hip circumference (HC), and waist/hip ratio (WHR) in Dutch children. Cross-sectional data were obtained from 14,500 children of Dutch origin in the age range 0-21 years. National references were constructed with the LMS method. This method summarises the distribution by three smooth curves representing skewness (L curve), the median (M curve), and coefficient of variation (S curve). The correlations between body mass index-standard deviation score (BMI-SDS), the circumferences and their ratio, and demographic variables were assessed by (multiple) regression analysis for three age groups: 0-<5 years (1), 5-<12.5 years (2), and 12.5-<21 years (3). A cut-off for clinical use was suggested based on the International Obesity Task Force criteria for BMI. Mean WC and HC values increased with age. Mean WC was slightly higher in boys than in girls, and this difference was statistically significant from 11 years of age onwards. In contrast, HC was significantly higher in girls than in boys from 9 years onwards. The correlation between WC-SDS and BMI-SDS ( r =0.73, P <0.01) and between HC and BMI-SDS ( r =0.67, P <0.01) increased with age. With regard to WHR-SDS, a low correlation was found for 12.5-20 years of age ( r =0.2, P <0.01). WC-SDS correlated positively with height SDS ( r =0.35, P <0.01).

CONCLUSION

Waist circumferences can be used to screen for increased abdominal fat mass in children, whereby a cut-off point of 1.3 standard deviation score seems most suitable.

Individual growth curve models for assessing evidence-based referral criteria in growth monitoring

The goal of this study is to assess whether a growth curve model approach will lead to a more precise detection of Turner sydnrome (TS) than conventional referral criteria for growth monitoring. The Jenss-Bayley growth curve model was used to describe the process of growth over time. A new screening rule is defined on the parameters of this growth curve model, parental height and gestational age. The rule is applied to longitudinal growth data of a group of children with TS (n=777) and a reference (n=487) group. The outcome measures are sensitivity, specificity and median referral age. Growth curve parameters for TS children were different from reference children and can therefore be used for screening. The Jenss-Bayley growth model, which uses all longitudinal measurements from birth to a maximum age of 5 years with at least one measurement after the age of 2, together with parental height and gestational age can achieve a sensitivity of 85.2 per cent with a specificity of 99.5 per cent and a median referral age of 4.2 (the last measurement between the age of 2 and 5 of each child is considered to be the moment of referral). Sensitivity increases by 2 percentage points when decreasing the specificity to 99 per cent. The Jenss-Bayley growth model from birth to a maximum age of 8 years with at least one measurement after the age of 2, together with parental height results in a sensitivity of 89.0 per cent with a specificity of 99.5 per cent and a median referral age of 6.1. For a specificity of 98 per cent, we obtain a sensitivity of 92.3 per cent. In comparison to conventional rules applied to the same data, sensitivity is about 11-30 percentage points higher at the same level of specificity for the Jenss-Bayley growth rule. We conclude that from the age of 4, growth curve models can improve the screening on TS to conventional screening rules.