The R package mice imputes incomplete multivariate data by chained equations. The software mice 1.0 appeared in the year 2000 as an S-PLUS library, and in 2001 as an R package. mice 1.0 introduced predictor selection, passive imputation and automatic pooling. This article documents mice, which extends the functionality of mice 1.0 in several ways. In mice, the analysis of imputed data is made completely general, whereas the range of models under which pooling works is substantially extended. mice adds new functionality for imputing multilevel data, automatic predictor selection, data handling, post-processing imputed values, specialized pooling routines, model selection tools, and diagnostic graphs. Imputation of categorical data is improved in order to bypass problems caused by perfect prediction. Special attention is paid to transformations, sum scores, indices and interactions using passive imputation, and to the proper setup of the predictor matrix. mice can be downloaded from the Comprehensive R Archive Network. This article provides a hands-on, stepwise approach to solve applied incomplete data problems.

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mice: Multivariate Imputation by Chained Equations in R

Objective To construct growth curves for school-aged children and adolescents that accord with the WHO Child Growth Standards for preschool children and the body mass index (BMI) cut-offs for adults. Methods Data from the 1977 National Center for Health Statistics (NCHS)/WHO growth reference (1–24 years) were merged with data from the under-fives growth standards’ cross-sectional sample (18–71 months) to smooth the transition between the two samples. State-of-the-art statistical methods used to construct the WHO Child Growth Standards (0–5 years), i.e. the Box-Cox power exponential (BCPE) method with appropriate diagnostic tools for the selection of best models, were applied to this combined sample. Findings The merged data sets resulted in a smooth transition at 5 years for height-for-age, weight-for-age and BMI-for-age. For BMI-for-age across all centiles the magnitude of the difference between the two curves at age 5 years is mostly 0.0 kg/m² to 0.1 kg/m². At 19 years, the new BMI values at +1 standard deviation (SD) are 25.4 kg/m² for boys and 25.0 kg/m² for girls. These values are equivalent to the overweight cut-off for adults (> 25.0 kg/m²). Similarly, the +2 SD value (29.7 kg/m² for both sexes) compares closely with the cut-off for obesity (> 30.0 kg/m²). Conclusion The new curves are closely aligned with the WHO Child Growth Standards at 5 years, and the recommended adult cut-offs for overweight and obesity at 19 years. They fill the gap in growth curves and provide an appropriate reference for the 5 to 19 years age group. Bulletin of the World Health Organization 2007;85:660–667.

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Development of a WHO growth reference for school-aged children and adolescents

https://www.thelancet.com/pdfs/journals/lancet/PIIS0140-6736(12)60820-4.pdf

National regional and worldwide estimates of preterm birth rates in the year 2010 with time trends since 1990 for selected countries: a systematic analysis and implications.

Objectives. Obesity has become a global epidemic but our understanding of the problem in children is limited due to lack of comparable representative data from different countries, and varying criteria for defining obesity. This paper summarises the available information on recent trends in child overweight and obesity prevalence. Methods. PubMed was searched for data relating to trends over time, in papers published between January 1980 and October 2005. Additional studies identified by citations in retrieved papers and by consultation with experts were included. Data for trends over time were found for school-age populations in 25 countries and for pre-school populations in 42 countries. Using these reports, and data collected for the World Health Organization's Burden of Disease Program, we estimated the global prevalence of overweight and obesity among school-age children for 2006 and likely prevalence levels for 2010. Results. The prevalence of childhood overweight has increased in almost all countri...

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Worldwide trends in childhood overweight and obesity

Objective To determine cut offs to define thinness in children and adolescents, based on body mass index at age 18 years. Design International survey of six large nationally representative cross sectional studies on growth. Setting Brazil, Great Britain, Hong Kong, the Netherlands, Singapore, and the United States. Subjects 97 876 males and 94 851 females from birth to 25 years. Main outcome measure Body mass index (BMI, weight/height2). Results The World Health Organization defines grade 2 thinness in adults as BMI Conclusions The proposed cut-off points should help to provide internationally comparable prevalence rates of thinness in children and adolescents.

https://www.bmj.com/content/bmj/335/7612/194.full.pdf

Body mass index cut offs to define thinness in children and adolescents: international survey

Since 1858, an increase of mean stature has been observed in the Netherlands, reflecting the improving nutritional, hygienic, and health status of the population. In this study, stature, weight, and pubertal development of Dutch youth, derived from four consecutive nationwide cross- sectional growth studies during the past 42 y, are compared to assess the size and rate of the secular growth change. Data on length, height, weight, head circumference, sexual maturation, and demographics of 14500 boys and girls of Dutch origin in the age range 0-20 y were collected in 1996 and 1997. Growth references for height and weight were constructed with a method that summarizes the distribution by three smooth curves representing skewness (L curve), the median (M curve), and coefficient of variation (S curve). The relationship between height and demographic variables was assessed by multivariate analysis. Reference curves for menarche and secondary sex characteristics were estimated by a generalized additive model using a logit transformation. A positive secular growth change has been present in the past 42 y for children, adolescents, and young adults of Dutch origin, although at a slower rate in the last 17 y. Height differences according to region, educational level of child and parents, and family size have remained. In girls, median age at menarche has decreased by 6 mo during the past four decades to 13.15 y. Environmental conditions have been favorable for many decades in the Netherlands, and the positive secular change in height has not yet come to a halt, in contrast to Scandinavian countries. Main contributors to the increase in height may be improved nutrition, child health, and hygiene, and a reduction of family size.

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Continuing positive secular growth change in the Netherlands 1955-1997

This study evaluates the agreement between child and parent reports on children's health-related quality of life (HRQoL) in a representative sample of 1,105 Dutch children (age 8-11 years old). Both children and their parents completed a 56 item questionnaire (TACQOL). The questionnaire contains seven eight-item scales: physical complaints, motor functioning, autonomy, cognitive functioning, social functioning, positive emotions and negative emotions. The Pearson correlations between the child and parent reports were between 0.44 and 0.61 (p < 0.001). The intraclass correlations were between 0.39 and 0.62. On average, the children reported a significantly lower HRQoL than their parents on the physical complaints, motor functioning, autonomy, cognitive functioning and positive emotions scales (paired t-test: p < 0.05). Agreement on all of the scales was related to the magnitude of the HRQoL scores and to some background variables (gender, age, temporary illness and visiting a physician). According to multitrait-multimethod analyses, both the child and parent reports proved to be valid.

The proxy problem: Child report versus parent report in health-related quality of life research

Bullying victimization is associated with several health issues. Prevention of bullying is therefore an important goal for health and education professionals. In the present study, 2766 children from 32 Dutch elementary schools participated by completing a questionnaire on bullying behavior, and the involvement of teachers, parents and classmates in bullying incidents. The results of this study show that bullying is still prevalent in Dutch schools. More than 16% of the children aged 9-11 years reported being bullied on a regular basis and 5.5% reported regular active bullying during the current school term. Almost half of the bullied children did not tell their teacher that they were being bullied. When teachers knew about the bullying, they often tried to stop it, but in many cases the bullying stayed the same or even got worse. With regard to active bullying, neither the majority of the teachers nor parents talked to the bullies about their behavior. Our results stress the importance of regular communication between children, parents, teachers and health care professionals with regard to bullying incidents. In addition, teachers need to learn effective ways to deal with bullying incidents. Schools need to adopt a whole-school approach with their anti-bullying interventions.

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Bullying: who does what, when and where? Involvement of children, teachers and parents in bullying behavior

Objectives - To compare the distribution of body mass index (BMI) in a national representative study in The Netherlands in 1996-7 with that from a study in 1980. Methods - Cross sectional data on height, weight, and demographics of 14 500 boys and girls of Dutch origin, aged 0-21 years, were collected from 1996 to 1997. BMI references were derived using the LMS method. The 90th, 50th, and 10th BMI centiles of the 1980 study were used as baseline. Association of demographic variables with BMI-SDS was assessed by ANOVA. Results - BMI age reference charts were constructed. From 3 years of age onwards 14-22% of the children exceeded the 90th centile of 1980, 52-60% the 50th centile, and 92-95% the 10th centile. BMI was related to region, educational level of parents (negatively) and family size (negatively). The - 0.9, +1.1, and +2.3 SD lines in 1996-7 corresponded to the adult cut off points of 20, 25, and 30 kg/m2 recommended by the World Health Organisation/European childhood obesity group. Conclusion - BMI age references have increased in the past 17 years. Therefore, strategies to prevent obesity in childhood should be a priority in child public health.

https://adc.bmj.com/content/archdischild/82/2/107.full.pdf

Body index measurements in 1996–7 compared with 1980

Health-related quality of life (HRQoL), conceptualized as patients' own evaluations of their health status, is an important criterion in evaluating health and health care and in the treatment of individual patients. Until now, few systematic attempts have been made to develop instruments to assess the HRQoL of children using such a conceptualization. This article describes the conceptualization and results of a study aiming to develop such an instrument for children aged 6-15 years using their parents as a proxy. The feasibility and psychometric performance of the instrument were evaluated in a study of 77 patients of the paediatric out-patient clinic of Leiden University Hospital. For each of the a priori-defined domains, a parent form scale could be constructed with satisfactory reliability and moderate correlations with the other scales. Only some of the parents indicating health status problems also signalled negative reactions to these problems. This is, in our view, a strong argument for the distinction between health status and quality of life (QoL). The correlation coefficients between the parent form and a children's questionnaire were low. Overall, the psychometric performance of the TACQOL parent form looks promising, which suggests that this instrument - with some modifications - can indeed be used to assess group differences in HRQoL in children. The results, however, should be replicated in larger samples, currently under study. The relation between parents' proxy reports on the HRQoL of their children and children's self-reports needs further investigation.

S.P. Verloove-Vanhorick

Papers

Continuing positive secular growth change in the Netherlands 1955-1997

The proxy problem: Child report versus parent report in health-related quality of life research

Bullying: who does what, when and where? Involvement of children, teachers and parents in bullying behavior

Body index measurements in 1996–7 compared with 1980

Measuring health-related quality of life in children: the development of the TACQOL parent form.