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SE Asian Growth Standards

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Aisling

Normal user

29 May 2015, 03:54

Hi, Does anyone have information on growth standards for SE Asia, specifically for Vietnam. The WHO growth standards are great reference points for assessing growth, and I know they did take in a wide variety of countries and body types during their formulation. However, it is no secret that Asian children (and adults) are shorter and smaller than most other races globally, and it was I remember noting during my studies that even when provided the optimal growth conditions, Asians did not reach the same height as Europeans, Africans etc. This raises my concern that by using the standard global WHO growth standards, we might be overestimating prevalence of stunting in many Asian countries. Is there anywhere that specific Asian growth standards can be accessed, or even the data from Asian countries which were used in the setting of the WHO growth standards? Many thanks.

Mark Myatt

Consultant Epideomiologist

Frequent user

16 Jun 2015, 08:23

I will try to field this one.

The WHO Growth Standards (WGS) are based on a false assumption that children's growth outcomes must be the same when their health and nutrition needs are met no matter who or where they are. This is a statement of human exceptionalism that stands against all we know from biology.

I think that there may be some value in the WGS to give shape to growth curves (i.e. so we can see roughly when children grow and with what expected velocity) and, maybe, for longitudinal assessment (i.e. the bias is admitted but remains constant over time). I think they may have very little use in terms of the absolute values of indicators. They are pretty much useless when it comes to making comparisons between populations.

The WGS was created using a lot of already available data from Europe and the USA. This was "topped up" by data from a handful of countries in an attempt to internationalise the reference population.

WGS is criteria rather than norm referenced and this has resulted in systematic exclusion of children from non-affluent households (i.e. we have a growth reference that reifies the bourgeoisie as the ideal that we should all aspire to). South Asia is represented in the WGS reference population ("selected affluent neighbourhoods of ... South Delhi, India" WHO 2006). Even then between 69% and 83% of the sample was rejected for a variety of environmental, behavioural, and socio-economic characteristics strongly associated with affluence.

WGS presents a reference that purposely excludes the vast majority of humankind and, consequently, relegates the vast majority of humanity to the status of non-productive subhumans - just listen to the way short people are described by many in the international nutrition community to see the truth of this.

BTW ... I am not "normalising" malnutrition here. It is that I do not see an automatic equality between bourgeoise affluence and the good life.

South-East Asia was not represented in the WGS reference data even though it is a highly populous area.

Having got that off my chest ...

When questions like this arise I reach for Evelyth and Tanner ("Worldwide Variation in Human Growth"). This is a thorough review of the subject area and provides an extensive bibliography. Looking at the data they present there is some overlap between height and weight growth for (e.g.) Indonesian-Malay children and European children but many populations have systematically lower height and weight growth. A similar pattern can be seen for sitting heights, shoulder widths, hip widths, and MUAC. This, as you suggest, makes the WGS a poor fit to the South-East Asian population.

I know of no specifically Asian growth standards. I think the "quick and dirty" solution could be that you use the WGS but "shift" the medians down based on a review of available data (Evelyth and Tanner is a good starting point). This is a low cost option. I think a local reference would be useful. Perhaps ASEAN might fund the development.

Sorry not to be of more help.

Anonymous 730

Nutrition and Food Security Officer

Normal user

16 Jun 2015, 08:37

Intriguing perspectives!I was in India ast year and,at a certain conference,an official said "We do not trust WHO"..."India is different"...and other interesting statements linked to Mark's sentiments.There are clear specifics that need further research,refining and agreement.

Aisling

Normal user

16 Jun 2015, 08:56

Hi Mark,

Thank you for your very information response. In fact, that was what I was afraid on hearing, but at least you have confirmed that there is not much out there in terms of reference points for this region (and I haven't just missed them!). I will take a look at the Evelyth and Tanner book you mentioned to try and come up with something useful. The rates of stunting noted in SE Asia in particular are quite shocking, particularly when you look at provincial data in some countries, but perhaps all is not lost for these children if they are in fact "normal" for their population.

I am also very interested in learning more about outcomes in short/stunted children if they are exposed to a proper ECD learning environment, but that is a different question altogether.

Thanks again for your comments and suggestions.

Anonymous 81

Public Health Nutritionist

Normal user

16 Jun 2015, 12:58


Is it because of such difference that the definition of overweight and Obesity is re-defined for India. In India, overweight is defined as a BMI of 23 or higher, and obesity, a BMI of 27 or higher.

Mark Myatt

Consultant Epideomiologist

Frequent user

16 Jun 2015, 13:14

Yes. BMI is a variant of W/H and is know to be severely affected by body shape and frame size. Some more on local BMI thresholds can be found here. the discussion on that page is also interesting.

Mark Myatt

Consultant Epideomiologist

Frequent user

17 Jun 2015, 08:37

As you may have noticed ... I am not a fan of the WGS approach. I remain unconvinced that the absence of the (bourgeois) ideal equates to a pathology. This may be how a bourgeois may see it.

The WGS does have some value as a yardstick. We may never see the population median H/A reach the reference median but we should, if we have avoidable stunting and effective programming, see it approach the reference median. Used this way the WGS does allow us to see progress.

I think we need to be clear about what we mean by "normal". It we were (e.g.) to build a reference from a population in which avoidable stuntedness were common then we risk seeing avoidable stuntedness as something unavoidable. A good reference probably needs to be criteria-referenced but, I think, less strictly so than the WGS. The older NCHS reference was useful in the sense that it was not a censorious "standard" but a representative sample of children living in a country with conditions predominantly favourable to growth.

WRT educational perfomance of stunted children. A lot of work has been done showing performance deficits. Much of this work suffers from a class bias (i.e. children from poorer background, regardless of anthropometry, tend to do poorly in curricula designed for children from wealthier backgrounds and stunted children are usually from poorer backgrounds) and inadequate control for confounding (e.g. as above with socio-economic status as a "grand confounder" but with more specificity so that (e.g.) poverty is associated with lack of electric light which reduces the ability of the child to study at home and poverty and stunting are associated as are parental education, access to pre-school education, disposable income to spend on toys and books, leisure time for study, dietary diversity, meal frequency, school absenteeism due to illness or lack of money to pay fees ... and so-on). Must studies appear to be both shallow and narrow. I think we can and should, in the short to medium term, concentrate on broader universal programming such as deworming and school-feeding as well as (of course) universal provision of quality education.

Melaku Begashaw

Normal user

17 Jun 2015, 08:59

Hello!
Thanks for having this discussion ones more. I was in similar location conducting 3 SMART nutrition surveys. Guess what?! In a properly done, well supervised and meeting all the plausibility test criteria survey;- significant number of 6-59 months children fall below 65cm, all of the acutely malnourished children fall in these group and almost all were labeled 'stunted' (around 50% stunting). It was a curious case and I did a re-measurement of all these children to avoid measurement error and similar result persists. Interestingly, one of the surveys was in an ethnically different population. The results for this survey was revealing. It did not have the observed stunting level as the other surveys. Additionally, a review of OTP admitted children revealed that all children that are being treated have their age <12 months.

What makes this stunting level surprising is the fact that the location is comparatively better off compared to many places I have been in Africa. I have hard time believing the results.

It is long overdue. This thing really needs a closure.

Anonymous 81

Public Health Nutritionist

Normal user

17 Jun 2015, 11:01

Asia is also different in low birth weight. In some countries, the prevalence of LBW is more than one-third of the newborn babies. so, the discussion/study requires beyond the growth reference for under five children.

Tamsin Walters

en-net moderator

Forum moderator

18 Jun 2015, 16:18

Dear all,

This question has generated some lively discussion so we've contacted WHO to input on the WHO Growth Standards and their use in populations in South East Asia. They will be posting a comment shortly.

Best wishes,
Tamsin

Bradley A. Woodruff

Self-employed

Technical expert

18 Jun 2015, 16:19

Although I am not as familiar with the old anthropometry literature as I wish I were, I believe studies have shown that there is little inherent genetic difference in length, weight, or other anthropometric measurements or indices in children less than 5 years of age. In fact, whatever genetic differences exist between different populations are probably not expressed until the puberty growth spurt. Therefore, a single growth standard should apply equally well to all the world's pre-school age children.

The theory that there are genetic differences in maximum attained adult height between difference populations is also in question. Adoption studies show that East Asians adopted as young children to European or North American households reach a much greater adult height that their cohorts in the country of origin. Moreover, the average adult height in many East Asian populations has increased substantially in recent decades with economic advancement and all the attendant cultural changes.

That said, there were no East Asian populations included in the development of the WHO Child Growth Standard which included the United States, Brazil, Norway, Ghana, India, and Oman. It might be useful in answering your questions to measure some children in East Asia who fit the inclusion criteria for the WHO Child Growth Standard, including optimal breastfeeding, up-to-date immunization, etc. to measure differences between them and the WHO standard. Although I do not know exactly how it was constructed, it may also be interesting to compare the Chinese national growth reference to the WHO standard.

Mark Myatt

Consultant Epideomiologist

Frequent user

19 Jun 2015, 08:00

All the world? What about children living at higher altitudes? They are smaller because of the low oxygen environment limits growth in the limbs (the brain being privileged). This may (in part) be genetic but is likely to be predominantly environmental.

I have done a little work on this topic (see this article and see elements of "adult" body shape established in children due to combinations of genetic and environmental effects.

Mercedes de Onis

Coordinator, Nutrition Dept, WHO

Normal user

26 Jun 2015, 17:09

I am not aware on the availability of growth standards specifically for Vietnam nor do I think they are under construction as the WHO growth standards were reviewed and adopted for use in Vietnam some years ago. The WHO standards are based on data collected in six countries (Brazil, Ghana, India, Norway, Oman, USA) following a prescriptive approach that excluded children with growth constraints due to environmental factors (as opposed to selecting elite segments of the population). There are a number of publications describing how the growth standards were constructed that go into great detail on how study populations from sites with high rates of stunting like India were selected. Linear growth among children in the six sites was strikingly similar confirming previous evidence from Martorell, Habicht and other researchers showing that, on average, children from different world regions have similar growth potential when raised in environments that minimized constraints to growth such as poor diets and infection. After the standards were released, countries like China or India conducted thorough evaluations of them prior to their adoption and there are documents reporting these processes as well as numerous peer reviewed papers evaluating the implications of shifting to the use of the WHO standards. More recently the Intergrowth21st consortium conducted a study in 8 countries using a methodology similar to that used to construct the WHO standards. The results of this multicountry study, conducted several years after the WHO study, and which includes China as a study site, are in strong agreement with the WHO results. You can find a full description in: (Villar J, et al. The likeness of fetal growth and newborn size across non-isolated populations in the INTERGROWTH-21st Project. Lancet Diabetes Endocrinol 2014).

Jane Hirst

University of Oxford

Normal user

29 Jun 2015, 08:59

This discussion is interesting, although I worry that Mark's comments about Standards having relevance for only a small minority of the world's population are misinformed and misleading.

International standards based on the WHO MGRS and INTERGROWTH-21st studies compare the longitudinal skeletal growth in diverse populations around the world free from overtly adverse influences. This allows us to determine how much of the variation in human size is due to differences between countries. The answer has been shown consistently to be only around 3%; hence the vast majority of the differences in human size and early growth observed around the world are due to factors independent of ethnicity.

The purpose of a standard is not to label a large proportion of the world's population as 'subhuman', rather to set a benchmark against which growth can be compared in individuals and populations around the world.

As the anonymous post above states, the problems of poor growth commonly begin in utero and the need for fetal standards is urgent. However, in fetal medicine the idea of 'customisation' for ethnicity has become popular in some countries (such as the UK), however we believe this makes no biological sense given the very small influence ethnicity plays on fetal growth when all other factors are equal. As Mercedes De Onis alludes to in her post, at one year of age the distribution of size of the babies in the INTERGROWTH-21st study was identical to the WHO Standard, despite the study being conducted over a decade later in different countries.

By measuring all children in the womb, at birth and in childhood against a common set of international standards, populations deviating from this growth can be readily identified and the causes and consequences sought. These questions are the topic of another debate.

Use of growth references specific to the local population risks normalising abnormal growth, perpetuating a cycle of low growth expectations in many parts of the world.

Carlos Grijalva-Eternod

UCL Institute for Global Health

Normal user

29 Jun 2015, 13:15

I am not the person to be in agreement with Mark’s remarks about growth, but I think he has very valuable comments that remain unaddressed by Mercedes or Jane’s replies.

Mark’s consistent comment, to which Mercedes and Jane partially agree and partially disagree, remains that given that the majority of the growth variation is environmentally mediated (the agreed part), and by environment we mean the social, economic and natural environment, why should we aim to have every child growing the same way (here is the disagreement)? Mercedes and Jane name all those environmental factors “growth constrainers” and Jane takes it further by suggesting that we risk normalising “abnormal growth” if we aim to use local growth references.

Past studies, all referenced in the 2006 WGS documentation have shown that in any given location, if environmental conditions were to be standardised, children will be expect to have similar growth patterns. Hence the 2006 WGS sought to answer the question “How children should grow?” but failed to add to that question “if their living conditions are similar”. Mark and others are more interested in this second and unacknowledged part of the question, given that the majority of children do not live in similar conditions.

Given that environmental conditions are not similar, growth patter will be expected to differ. That is, children who by one growth reference, developed in an environmentally different setting, are categorised as having “abnormal growth”, might be categorised as having “normal growth” by another growth reference developed in a different environmental setting. The 2006 WGS were obtained from affluent communities from six countries, and most come from urban settings, and most following very specific breastfeeding and feeding patterns. I think this narrow environmental variability is what Mark and others have issues with, and why I find it difficult to call it “a growth standard” rather than just another growth reference. Certain growth patterns are likely to confer short and long-term advantages in certain environments as well as penalties. These advantages and penalties are likely to be different in different environmental settings.

Nonetheless, I see the value of having a common yardstick, as Mark suggested, so that we can understand how much growth varies across the globe, and the reasons behind this variability.

Rosemary Atieno

Nutritionist- MOH

Normal user

30 Jun 2015, 09:15

This debate is quite interesting but I would really agree with Jane Hirst that the WHO guidelines for growth standards were given for standardized guidelines and there is no need for normalizing abnormal growth on the excuse of environmental difficulties. I have seen short people in areas of low altitudes and I want to suggest if there are deviance's for the sake of given guidelines let the cause of deviance be researched on in order to institute appropriate measures that have been known to be of High Impact

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