T. J. Cole

Establishing a standard definition for child overweight and obesity worldwide: international survey.

Abstract Objective: To develop an internationally acceptable definition of child overweight and obesity, specifying the measurement, the reference population, and the age and sex specific cut off points. Design: International survey of six large nationally representative cross sectional growth studies. 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 of age Main outcome measure: Body mass index (weight/height2). Results: For each of the surveys, centile curves were drawn that at age 18 years passed through the widely used cut off points of 25 and 30 kg/m2 for adult overweight and obesity. The resulting curves were averaged to provide age and sex specific cut off points from 2-18 years. Conclusions: The proposed cut off points, which are less arbitrary and more internationally based than current alternatives, should help to provide internationally comparable prevalence rates of overweight and obesity in children.

Body mass index reference curves for the UK, 1990.

Reference curves for stature and weight in British children have been available for the past 30 years, and have recently been updated. However weight by itself is a poor indicator of fatness or obesity, and there has never been a corresponding set of reference curves to assess weight for height. Body mass index (BMI) or weight/height has been popular for assessing obesity in adults for many years, but its use in children has developed only recently. Here centile curves for BMI in British children are presented, from birth to 23 years, based on the same large representative sample as used to update the stature and weight references. The charts were derived using Coles LMS method, which adjusts the BMI distribution for skewness and allows BMI in individual subjects to be expressed as an exact centile or SD score. Use of the charts in clinical practice is aided by the provision of nine centiles, where the two extremes identify the fattest and thinnest four per 1000 of the population.

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

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 <17. This same cut off, applied to the six datasets at age 18 years, gave mean BMI close to a z score of −2 and 80% of the median. Thus it matches existing criteria for wasting in children based on weight for height. For each dataset, centile curves were drawn to pass through the cut off of BMI 17 at 18 years. The resulting curves were averaged to provide age and sex specific cut-off points from 2-18 years. Similar cut offs were derived based on BMI 16 and 18.5 at 18 years, together providing definitions of thinness grades 1, 2, and 3 in children and adolescents consistent with the WHO adult definitions. Conclusions The proposed cut-off points should help to provide internationally comparable prevalence rates of thinness in children and adolescents.

Multi-ethnic reference values for spirometry for the 3-95-yr age range: The global lung function 2012 equations

The aim of the Task Force was to derive continuous prediction equations and their lower limits of normal for spirometric indices, which are applicable globally. Over 160,000 data points from 72 centres in 33 countries were shared with the European Respiratory Society Global Lung Function Initiative. Eliminating data that could not be used (mostly missing ethnic group, some outliers) left 97,759 records of healthy nonsmokers (55.3% females) aged 2.5–95 yrs. Lung function data were collated and prediction equations derived using the LMS method, which allows simultaneous modelling of the mean (mu), the coefficient of variation (sigma) and skewness (lambda) of a distribution family. After discarding 23,572 records, mostly because they could not be combined with other ethnic or geographic groups, reference equations were derived for healthy individuals aged 3–95 yrs for Caucasians (n=57,395), African–Americans (n=3,545), and North (n=4,992) and South East Asians (n=8,255). Forced expiratory value in 1 s (FEV1) and forced vital capacity (FVC) between ethnic groups differed proportionally from that in Caucasians, such that FEV1/FVC remained virtually independent of ethnic group. For individuals not represented by these four groups, or of mixed ethnic origins, a composite equation taken as the average of the above equations is provided to facilitate interpretation until a more appropriate solution is developed. Spirometric prediction equations for the 3–95-age range are now available that include appropriate age-dependent lower limits of normal. They can be applied globally to different ethnic groups. Additional data from the Indian subcontinent and Arabic, Polynesian and Latin American countries, as well as Africa will further improve these equations in the future.

Cross sectional stature and weight reference curves for the UK, 1990.

The current reference curves of stature and weight for the UK were first published in 1966 and have been used ever since despite increasing concern that they may not adequately describe the growth of present day British children. Using current data from seven sources new reference curves have been estimated from birth to 20 years for children in 1990. The great majority of the data are nationally representative. The analysis used Coles LMS method and has produced efficient estimates of the conventional centiles and gives a good fit to the data. These curves differ from the currently used curves at key ages for both stature and weight. In view of the concerns expressed about the current curves and the differences between them and the new curves, it is proposed that the curves presented here should be adopted as the new UK reference curves.

British 1990 growth reference centiles for weight, height, body mass index and head circumference fitted by maximum penalized likelihood

To update the British growth reference, anthropometric data for weight, height, body mass index (weight/height2) and head circumference from 17 distinct surveys representative of England, Scotland and Wales (37,700 children, age range 23 weeks gestation to 23 years) were analysed by maximum penalized likelihood using the LMS method. This estimates the measurement centiles in terms of three age-sex-specific cubic spline curves: the L curve (Box-Cox power to remove skewness), M curve (median) and S curve (coefficient of variation). A two-stage fitting procedure was developed to model the age trends in median weight and height, and simulation was used to estimate confidence intervals for the fitted centiles. The reference converts measurements to standard deviation scores (SDS) that are very close to Normally distributed - the means, medians and skewness for the four measurements are effectively zero overall, with standard deviations very close to one and only slight evidence of positive kurtosis beyond+/-2 SDS. The ability to express anthropometry as SDS greatly simplifies growth assessment.

Extended international (IOTF) body mass index cut-offs for thinness, overweight and obesity

The international (International Obesity Task Force; IOTF) body mass index (BMI) cut‐offs are widely used to assess the prevalence of child overweight, obesity and thinness. Based on data from six countries fitted by the LMS method, they link BMI values at 18 years (16, 17, 18.5, 25 and 30 kg m−2) to child centiles, which are averaged across the countries. Unlike other BMI references, e.g. the World Health Organization (WHO) standard, these cut‐offs cannot be expressed as centiles (e.g. 85th).

Fetal origins of adult disease—the hypothesis revisited

The idea that stimuli or insults during critical or sensitive periods in early life can have lifetime consequences is well established in developmental biology and has been termed “programming.”1 The first evidence for programming, obtained over 100 years ago, confirmed the critical period for imprinting in birds.2 Programming stimuli may be generated endogenously (for instance, internal hormonal signals3) or they may be environmental. One important type of environmental programming is that induced by early nutrition. Since McCances studies in the 1960s on the long term effects of early nutrition in rats,4 numerous animal studies have shown that nutrition in infancy or fetal life can induce lifetime effects on metabolism, growth, and neurodevelopment and on major disease processes such as hypertension, diabetes, atherosclerosis, and obesity.5–8 If these phenomena applied in humans, it would be a matter of major public health and clinical importance. #### Summary points The hypothesis that adult disease has fetal origins is plausible, but much supportive evidence is flawed by incomplete and incorrect statistical interpretation When size in early life is related to later health outcomes only after adjustment for current size, it is probably the change in size between these points (postnatal centile crossing) rather than fetal biology that is implicated Even when birth size is directly related to later outcome, some studies fail to explore whether this is partly or wholly explained by postnatal rather that prenatal factors These considerations are critical to understanding the biology and timing of “programming,” the direction of future research, and future public health interventions The considerable research focused on early programming of adult outcomes in humans has taken two approaches: experimental, using early randomised nutritional interventions with prospective follow up (an approach that we have favoured9), and observational. Inferences from data based on observational approaches …

Measurement and long-term health risks of child and adolescent fatness.

This paper reviews child and adolescent adiposity measures and associated long-term health risks. The first section argues that anthropometric measures are practical for large scale epidemiological studies, particularly the body mass index. Limitations of this and other measures are presented. The second section summarises the evidence on the relationship between child and adolescent and adult adiposity. This is based on a search for relevant literature in the following computerised databases: Medline (1985–96), BIDS (EMBASE and Science Citation Index 1985–96). The literature search revealed that the child to adult adiposity relationship is now well‐documented, although methodological differences hinder comparisons. Nonetheless, consistently elevated risks of adult obesity are evident for fatter children, although the prediction of adult obesity from child and adolescent adiposity measures is only moderate. Fewer studies could be identified in relation to long-term health risks of child and adolescent adiposity. It is therefore difficult to specify categories of risk associated with childhood adiposity without more information from long-term studies. Further evidence is also required to confirm the suggestion from some studies that adult disease risks are associated with a change in adiposity from normal weight in childhood to obesity in adulthood. However, on the basis of the evidence available, it is argued that population‐based approaches to the prevention of obesity are likely to be more effective than approaches targeted at fat children. Population-based approaches are desirable, first because of the poor prediction of adult obesity from child and adolescent measures, and second, because risks of adult mortality and morbidity may be elevated for individuals who become overweight after adolescence.

Randomised trial of early diet in preterm babies and later intelligence quotient

abstract Objectives: To determine whether perinatal nutrition influences cognitive function at 7 1/2 - 8 years in children born preterm. Design: Randomised, blinded nutritional intervention trial. Blinded follow up at 7 1/2 - 8 years. Setting: Intervention phase in two neonatal units; follow up in a clinic or school setting. Subjects: 424 preterm infants who weighed under 1850 g at birth; 360 of those who survived were tested at 7 1/2 - 8 years. Interventions: Standard infant formula versus nutrient enriched preterm formula randomly assigned as sole diet (trial A) or supplements to maternal milk (trial B) fed for a mean of 1 month. Main outcome measures: Intelligence quotient (IQ) at 7 1/2 - 8 years with abbreviated Weschler intelligence scale for children (revised). Results: There was a major sex difference in the impact of diet. At 7 1/2 - 8 years boys previously fed standard versus preterm formula as sole diet had a 12.2 point disadvantage (95% confidence interval 3.7 to 20.6; P<0.01) in verbal IQ. In those with highest intakes of trial diets corresponding figures were 9.5 point disadvantage and 14.4 point disadvantage in overall IQ (1.2 to 17.7; P<0.05) and verbal IQ (5.7 to 23.2; P<0.01). Consequently, more infants fed term formula had low verbal IQ (<85): 31% versus 14% for both sexes (P=0.02) and 47% versus 13% in boys P=0.009). There was a higher incidence of cerebral palsy in those fed term formula; exclusion of such children did not alter the findings. Conclusions: Preterm infants are vulnerable to suboptimal early nutrition in terms of their cognitive performance—notably, language based skills—at 7 1/2 - 8 years, when cognitive scores are highly predictive of adult ones. Our data on cerebral palsy generate a new hypothesis that suboptimal nutritional management during a critical or plastic early period of rapid brain growth could impair functional compensation in those sustaining an earlier brain insult. Cognitive function, notably in males, may be permanently impaired by suboptimal neonatal nutrition.