27 January 2016

The Access to Nutrition Index 2016 (ATNI) - A Strong Second Showing

I am a fan of the Access to Nutrition Index (ATNI). 

ATNI collects data (including a big chunk of self-reported) from 25 of the largest food and beverage companies in the world.  This is the first report since 2013 (19 of the 25 companies are featured in both 2013 and 2016 reports, although the numbers are not comparable since there are many new questions).

I am a fan because, like the Global Nutrition Report, ATNI seeks to both shine a light on practices and commitments and also to serve as a beacon on the way forward.  The index scores companies across 7 categories, with an additional breast milk substitutes (BMS) category for the companies that derive more than 5% of their sales from baby foods.

So what are the key findings of the newly released 2016 report (the second after the first in 2013)?

The scores are pretty bad.  The median score for the companies across all 7 categories (out of 10) is 2.4.  The top score is 6.4 (Unilever). Five companies scored below 1, principally because they did not provide data to Sustainalytics the firm that conducted the data collection for ATNI. And remember these scores don’t have to max out at 10 because this merely signifies that a company is achieving best practice against the current state of knowledge—companies could do better than best practice.

Some categories of performance are a real problem for the sector: accessibility (are healthy and fortified foods affordable and accessible to those who need them most?) has an average score  of 1.2 and engagement with governments scored an average of 1.0 largely because many companies were unwilling to disclose their activities in this area.

None of the 6 breast milk substitute companies in the set of 25 companies (Danone, Nestle, FrieslandCampina, Heinz, Abbot and Mead Johnson) apply their policies in all markets as recommended by the BMS Code—instead they apply them differentially in high risk and low risk markets. All 5 companies other than Nestle state they will follow local regulations even if weaker than their own policies (which are weaker than the code).  This is a really depressing failure of leadership and one with potentially fatal consequences for children.

None of the companies have integrated undernutrition at a strategic level.  Businesses have not grasped the nettle of developing affordability healthy products for potential customers at the bottom of the pyramid.

Most companies do not systematically or structurally implement and report on their stated nutrition commitments.  This is pretty troubling from an accountability perspective. 

Reflections on ATNI 2016?  I have not read the full report, only the 35 page summary, but here goes:

*I would like to see more reflection on how ATNI is being used, especially by the food and beverage investment advisors—does it change their recommendations to their clients?  I would also like to know more about why some companies provide data and some don’t—good to interview the latter.

*The BMS adjustment seems timid.  At one extreme, one could say that any BMS violations, because of their serious impacts on mortality, should result in a zero overall score.  Another less radical approach would be to multiply the other scores by the proportional BMS score, so if a company with a non BMS score of 5.0 overall gets a BMS score of 2/10, their overall score would be adjusted to 5x0.2=1.0.  At the moment the BMS score is deducted from the overall score.  Currently its BMS scores are keeping Nestle from attaining the overall number 1 spot, but the overall rankings of the 6 BMS manufacturers are not altered that dramatically.

*I can’t figure out why the weighting for “promoting healthier lifestyles among employees and customers” provides such a low contribution to the overall score (2.5%).  If there is a mounting global crisis and if companies have powerful global reach, surely their efforts to do more in this area would attract more than 2.5% of the overall score?

ATNI is on the way towards becoming a really powerful tool to effect change. To do that it needs to rely more on the kinds of in country research it undertook in Indonesia and Vietnam.  This is where we see how policies, values and governance plays out at the front line.

I would also like to see the Access to Nutrition Foundation (who are behind ATNI) be more ambitious on strengthening the public dialogue around business and nutrition. 

As my colleagues will tell you I am puzzled as to why more companies are not stepping up and going beyond best practice when it comes to advancing nutrition.  Surely there is money in it, as well as nutrition.  Dialogue might uncover the win-wins we are all looking for (or perhaps it will reveal they are far and few between, I don’t know).      


All in all, and based on the extensive summary document, this is a strong second showing for ATNI and my congratulations to the team who produced it and the funders who had the vision to supported it.

26 January 2016

What can the Philippines do to accelerate nutiriton improvement?

The Philippine launch of the GNR, brilliantly organized by the Government of the Philippines and UNICEF, was timely (slides here).  The country is coming to the end of its current economic development plan as well as its nutrition strategy and new plans are being developed for the 2017-2022 period.  The GNR data, messaging and calls to action were all cited by the National Economic Development Agency (NEDA) and the National Nutrition Council (NNC) in the Ministry of Health, as useful inputs into the process of developing the new plans.  In addition the Philippines is a relative newcomer to SUN (it is the 51st member) and is just setting up its networks, so GNR messages and data were also able to be fed into the development of their workplans. 

GNR as an input to Philippine Plan of Action for Nutrition
The nutrition situation in the Philippines is mixed.  The latest survey shows stunting rates have declined at a rate rapid enough to put the country on course to meet the global WHA goals—but only if that rate of decline is maintained for the next 10 years.  Under 5 overweight is below the WHA 7% threshold, but it is increasing, and so the GNR assigns an “on course, at risk” assessment.  All other WHA indicators are off course, including adult overweight, obesity and diabetes. 

Health Undersecretary of State Gako, reading you know what
There is some optimism, though.  There is a new Early Childhood Care and Development programme which has been allocated about $6 million by the government. The ongoing conditional cash transfer programme is seen as a promising avenue for scaling up nutrition BCC.  NEDA, the economic planning unit, understands the role of nutrition as a maker and marker of broader development processes.  Finally, the commitment and experience of the amazing NNC leadership, staff and broader set of stakeholders (including the Undersecretary of Health, Dr. Gako) is clear to see.

However there are some big challenges:

*Decentralisation of government has given mayors a lot of power.  Responsibility for nutrition has also been decentralized as part of the bundle.  In theory this could be a good thing for nutrition action if people organized themselves into effective local lobby groups to hold mayors to account.  But that requires recognition of the problem, organization, capacity and data.  None of these things seemed in abundance from talking to the participants at the day-long meeting

*The Philippines is a disaster prone country—conflict, and natural disasters—and with climate change the latter are becoming less predictable.  This makes it challenging to get out of emergency mode and plan longer term. 

*Only 2% of the government’s budget is allocated to nutrition—from across all sectors according to estimates from the country’s own SUN members.  The average for 30 SUN countries is 4%.

These challenges could be turned into opportunities.  For example:

*There is a Presidential campaign coming up in May and it would be great to try to get each of the 6 candidates to sign up to a nutrition pledge card (as was done in Peru about 10 years ago).  One of the pledges could be to make a commitment at the Rio Nutrition for Growth event in August this year.  This would be something for civil society to organize around.   

*A nutrition scorecard at the municipality level (the mayor’s patch) could be generated by constructing a malnutrition map using small area techniques and the recent national nutrition survey and the latest census data. This could be published by Mayor.  It would help raise consciousness on the issue and may help civil society members to engage with local government units on the issue.

*The nutrition community could seek to make common cause with the disaster risk community—how can nutrition interventions become more disaster prepared?

*Work hard to make nutrition sensitivity work in the conditional cash transfer (CCT) programme. To the bureaucratic leaders of the CCT, stress the legacy aspects of the impacts of their CCT.  Income transfers can lift a household out of poverty, but the gains can be quickly lost. The impacts of income transfers that can only be received if a pregnant woman gets antenatal care and a mother receives advice on complementary feeding, for example, are much harder to undo. In addition, train the CCT staff on how to liaise with the nutrition frontline staff.

*Train media to become more nutrition-savvy.  The Philippines has a vibrant media.  The members of the media that showed up at our press briefing were a bit shocked by the numbers of malnourished kids (nearly 4 million in the country) and the fact that their country had stunting rates higher than Kenya and Ghana and only just below the much poorer Cambodia.  The SUN movement would do well to engage the media not as outlets for their own messages, but as real partners who can shape opinion about norms. 

Among many great comments from the floor, one stood out for me because it gave me pause for thought on the politics of data.  One participant said that the “on course” assessment of the country on stunting might make it harder for her to make the case for funding for nutrition. I replied that the rates are still very high and that people like to invest in things that seem to be working, but still, we need to be careful of unintended consequences of our actions. 

I have a soft spot for the Philippines-it is where I did my fieldwork for my PhD 30 years ago (in Bukidnon Province, Mindanao) and so it was great to be back again.  I just hope we don’t have to wait 30 years to get stunting rates below 10%.  With all the advantages the country has it could get there in half the time.

24 January 2016

Can Thailand Write Us a New Story for Nutrition Improvement in the 21st Century?

The Minister of Health reading GNR's Nutrition Country Profile of Thailand
When I was first learning about nutrition, the community based model of nutrition improvement in Thailand was the “go-to” success story of how to reduce undernutrition rapidly and sustainably. 

The famous  nutritionist Kraisid Tontisirin has been a great communicator and researcher on the Thai nutrition experience. 


So one of the big surprises of the Global Nutrition Report was to find Thailand off course on all 8 WHA nutrition indicators tracked in the report (under 5 stunting, wasting and overweight, exclusive breastfeeding rates, anemia in women, adult overweight, adult obesity and adult diabetes).

How could this be?  Looking at the numbers more closely the three under 5 anthropometry indicators are driven by a 2012 MICS survey in the WHO database.  That shows rising levels for these three indicators. 
The GNR 2015 launch in Bangkok last week was an opportunity to discuss the issues: are the numbers telling a true story and what to do?
Before the launch the 3 co-chairs of the Global Nutrition Report (me, Corinna Hawkes and Emorn Udomkesmalee) met with the recently appointed Minister of Health who was about to give the keynote.  He was visibly shocked at the conclusions drawn in the report: Thailand, the poster child of successful nutrition improvement efforts was “off course” across the board.  To his great credit, his surprise was channelled in an entirely positive way--as we sat with him he was on the phone to his senior advisors asking then to comment on the data and the assessment.  When he gave his speech he held up the 2 page Nutrition Country Profile for Thailand and said “this situation will change” and “nutrition improvement” will be one of the main priorities of his tenure.   These promises need to be monitored.

So, what did our Thai colleagues think of the data?  The MICS 2012 survey conducted by UNICEF in partnership with the Government (and released in 2014) was contrasted with a brand new Government survey which confirmed upward trends in wasting and under 5 overweight, but not stunting which was quite a bit lower.  Reasons for the discrepancies?  It was not clear.  Perhaps because the MICS survey is not confined to Thai citizens unlike the 2014 survey.  But both surveys indicated that 2 of 3 dimensions on under 5 malnutrition were worsening against a backdrop of stagnating adult anemia rates, slow improvements in exclusive breastfeeding rates and a worsening of all 3 adult overweight, obesity and diabetes rates. 
For an economy as wealthy as Thailand, how can this be?  Several reasons were put forward:

*Income inequality remains high – perhaps this is preventing the decline in stunting and wasting we would expect to see and is driving up other indicators
*High levels of in-migration might be affecting overall national nutrition rates
*The increasing levels of overweight, obesity and diabetes might have led to policymakers taking their eye off the undernutrition ball.

There are undoubtedly other reasons too, but it is surprising how little we in the nutrition community have to say about why some countries are doing better than others.  Kenya and Ghana were two of the big success stories highlighted in the GNR 2015, but there is little consensus as to what were the key drivers of that change.  We do need more research and analysis on the big picture changes. 

The event was brilliantly led by Emorn Udomkesmalee and hosted by the Institute of Nutrition at Mahidol University. The launch events are valuable, I think, because they allow outsiders like me to present data with inconvenient implications; implications that those working in the country might find uncomfortable to share (my slides are here). This sparks conversations and hopefully action to get countries back on course.  We wish the Minister of Health well in his attempts to do this for Thailand in the next few years. 

Thailand wrote the book on undernutrition reduction in the 20th century.  Now we look to it to write the 21st century book on ending malnutrition in all its forms by 2030.  

12 January 2016

What is Your Country's Nutrition Profile?



We have finally completed the rather mammoth task of updating all 193 nutrition country profiles for the latest version of the Global Nutrition Report.

Thanks to our fantastic data analysts and data management team at IFPRI.

The country profiles can be downloaded as 2 page PDF files here.  All the data can also be downloaded as spreadsheet and STATA files.

Regional, sub-regional and a global profiles will follow shortly.

The profiles really are fantastic resource.  For each country we have over 80 indicators, pulled together from various UN and other sources.

The indicators address both undernutrition and obesity, overweight and diabetes.  They cover nutrition status, programme coverage, policies, underlying determinants, spending, legislation and institutional transformation.

Please use them and let us know how to make them more useful!

02 January 2016

Five Resolutions for 2016

I'm not great at keeping New Year's Resolutions, but maybe blogging about them will help me stick to them.  Here they are.

1.  Don't use the word "overnutrition".  It is so tempting to use this as shorthand for overweight/obesity and nutrition related non-communicable diseases (for obvious reasons), but whereas undernutrition really does describe scarcity of nutrition inputs, the manifestations above are about imbalances in diet, exercise and enabling environments, not deficits or excess. Much better to talk of malnutrition in all its forms.

2. Work harder to identify interventions that work for malnutrition in all its forms.  This means contributing to efforts to unify the nutrition field.  Which interventions serve multiple duties (i.e. prevent or reduce all forms of malnutrition), which involve tradeoffs, which are completely ineffective and which are always negative?

3. Make communications about nutrition more sticky.  Over the holiday season I met lots of people for the first time (parties, friends of friends etc) who ask "what do you do?".  Whenever I mention nutrition they think I'm a diet guru (maybe in a later life).  I don't even bother with stunting, wasting or micronutrients.  We need to do research on what forms of communication will help nutrition "break out" of its bubble.

4. Work hard to learn the practicalities of RCTs.  Shock horror you may say, but for the 2 intervention impact evaluations I am involved in (mobile phones and community accountability) RCTs seem like the way to go.  But as I am learning there is a big difference between knowing how they work on paper versus in practice.  The critics out there might want to get more involved in one--working on them is much more like the research the critics do (i.e. messy and unpredictable) than the drug trials they have in their heads while making their (often well taken) critiques.

5. Be a better colleague.  The Global Nutrition Report has a punishing production schedule (November 2014, September 2015, June 2016) and this has made me sometimes skimp on the things that make for a good colleague---the kinds of things that you do when no-one is looking: a quiet word with a colleague who looks to be struggling with something, sharing a paper or report that a partner might be interested in, saying thank you when it is not expected etc.

24 December 2015

For many countries a "Christmas mobile phone fast" would lead to hunger and malnutrition

The Archbishop of York, Dr John Sentamu, recently called for a UK “mobile phone fast” on Christmas Day so that families could reconnect and bond.  My kids are glued to their phones much of the time and I have been known to sneak a few looks at my email on the 25th, so I can definitely relate.  But many people around the world do not have the luxury of laying down their phones, because their mobiles are essential to their livelihoods and to their health.  

Consider the following: fishing communities rely on weather data from mobile phones to help them work out the best times to take their boats out; farmer clubs using text messaging to help farmers to share information about growing conditions; market traders who use apps to tell them which locations are offering the best prices for different commodities; medical staff who use cameras on mobile phones to remote diagnose and prescribe treatment; HIV positive individuals who are reminded to adhere to their antiretroviral regimes; and communities that can the world know if government services fail to reach them.  These mechanisms, if effective, are probably helpful to accelerating development and the reduction of hunger and malnutrition. 

But, with a few exceptions, there are far too few mobile services designed to focus exclusively on just that: the reduction of malnutrition. 

Why should such services exist?  Malnutrition in all its forms—children who can't realise their rights and develop to their full potential, women with not enough iron in their blood carry their children, adults who are at risk of diabetes, hypertension, strokes and heart disease due to obesity—affects 1 in 3 people world-wide.  The consequences of malnutrition are devastating.  45% of all under 3 mortality is related to malnutrition and the economic losses are enormous—trapping people, families and communities in poverty and acting as a drag on sustainable development.  

And the returns to the scaling up of high impact interventions are astonishing.  The Global Nutrition Report has shown that the median benefit-cost ratio of expanding programme coverage is 16 to 1.  In other words for every dollar, birr, rupee or peso invested in scaling up high impact nutrition interventions, 16 will flow back to individuals, communities and nations from improved schooling and labour force outcomes.

Despite these impressive returns, the scaling up of programmes is challenging.  Lack of finance and human capacity are familiar barriers.  Frontline health workers have heavy case loads and are burdened with paperwork.  Finance to develop messaging around preferred nutrition practices and to provide appropriate technology to record, aggregate and analyse nutrition measurements quickly and efficiently is hard to find from public sources. 

Can mobile operators help?  Mobile networks are re run for profit.  But they do offer a broad potential platform for the delivery of government approved nutrition messaging.   Can they be geared to reminding pregnant women about receiving antenatal care, to change the attitudes of mothers of newborns about the need to breastfeed within an hour of birth, and exclusively for 6 months thereafter? Can they be designed to help mothers wean their children onto the right semi-solid foods at 6 months of age? Can they help children understand what a balanced diet looks like?  Can they persuade and help adults to consume diets that are lower in sugar, salt and saturated fats?  We simply don’t know.
 
The nutrition community has been slow to experiment with (and then evaluate) mobile technology. Similarly mobile operators have been slow to recognize the potential for attracting customers to their services through offering nutrition information, free or even at a price.  Let’s be clear: mobiles are not a panacea. There are important and significant challenges to their effective use for nutrition. For example, will mothers be able to read the information sent?  Will they trust nutrition information via mobile services and will the quality be sufficiently good?  Will the information be acted on? And will mobile operators be able to find a sustainable business model? 

But the potential is great: mobiles offer a way to personalize information, to allow customers to engage with information services rather than simply be passive receivers of messages, to scale geographically and to generate knowledge spillovers for those who do not have direct access to phones.

As the 2015 Global Nutrition Report suggests, the mobile network industry offers the potential to scale up nutrition interventions that are reliant on behavior change.  These two communities – public nutrition professionals and private mobile operators-- need to begin innovating, piloting and evaluating their joint efforts to accelerate the reduction of malnutrition. 


Can we really “Dial N for Nutrition”?  Let’s at least try, and turn the conversation to the avoidance of enforced fasting of food, care and health services rather than the promotion of voluntary phone fasting.

18 December 2015

Catching up with the debate on catch up growth and development for young children

Below are two posts from important researchers working on infant and young child growth.  They both agree that the first 1000 day period after conception is a key intervention opportunity because growth velocity is so high.  They also agree that we should not restrict interventions to this period—we should take whatever opportunity in the life cycle that presents itself to invest in better nutrition.

Where the 2 sets of authors part company is on the nature of the evidence that supports their arguments for investments post the first 1000 day period.  Both authors think such investment is essential (we should never give up on a child!), but the Young Lives authors’ bolster their argument with the fact that for the children in their cohort studies, their standardised height for age scores (HAZ) improve between ages 5 and 8. 

Jef Leroy argues that the movements of HAZ do not reflect improvements in linear growth but are simply due to bigger standard deviations of HAZ as we move up the age groups.  Leroy says a better marker of any catch up growth would be the absolute difference between measured height and the median age- and sex-specific height obtained from the growth standards (HAD).  In addition, Leroy says while height is important for human development, the main story is in the things height is a marker for such as cognitive development and attainment.

If I were the Young Lives research team I would see if I can replicate my HAZ results with HAD.  I would also look at potential catch up in other markers of development such as cognitive attainment scores. 

Either way the policy implications are not very different for the 1000 Day period, but they could be for the post 1000 Day period: interventions to stimulate catch up in growth may be different from those to stimulate catch up in, say, cognitive attainment.  So it is important to air contrasting views.

Thanks to both blog authors and let the debate continue! 

Early is best… but it’s never too late to help stunted children

Paul Dornan and Andreas Georgiadis, Young Lives

The scale of the problem is immense: WHO global estimates suggest 162 million children under five are stunted (that is, too short for their age). Stunting is an indicator of chronic under-nutrition resulting from inadequate food intake, poor health, and poor child care. It is hard to underestimate the consequences of under-nutrition for child survival, health, and development, as it contributes to the deaths of 3.1 million children per year. Improving children’s nutrition should be at the heart of development policy.

There is consensus that good early nutrition is the foundation of children’s survival, growth, and learning. The Sustainable Development Goals reiterate earlier commitments to reduce the number of stunted children under-5 by 40% by 2025. How would it be possible to achieve and surpass this target? Considerable recent attention has been given to nutrition and care during the first 1000 days after conception. Although this period of time is critical, there is growing evidence that improvements in children’s nutrition beyond that early period could yield additional benefits in terms of child development and well-being. That’s encouraging, as we need to make use of every opportunity to improve children’s nutrition. The evidence for this is set out in a new policy brief from Young Lives.

The good news is the attention nutrition has received in recent years. The London Olympics of 2012 was used by the British and Brazilian Governments, along with the Children’s Investment Fund Foundation to initiate the Global Nutrition for Growth Compact, with the stated aim of putting nutrition at the centre of development policy, which has now been signed by 26 Governments. Rio 2016 marks the point at which governments have committed to check in on the progress and to gather more supporters. The same initiative also saw the launch of the Global Nutrition Report, an authoritative advocacy tool providing strong evidence that emphasises the importance of action to improve nutrition.

Powerful arguments have emerged suggesting that experiences during the first 1000 days after conception (up to 2 years old) are critical for children’s later development. Some go further, arguing that beyond the first 1000 days, stunting and its implications for development are irreversible. The prioritisation of a focus on nutrition during infancy has important merits: children are most vulnerable and more likely to die as a result of poor nutrition and diseases during this period. And for those who survive, there are other important reasons to increase the focus on the very early years – with James Heckman, for example, identifying this period as the most efficient point to intervene to secure long-term benefits.

But while prevention is better than cure, there are increasing reasons to think that alone it isn’t enough. The evidence produced from analysis of the Young Lives cohort data, summarised in the policy brief, suggests that – first, while child growth is more plastic in infancy and early childhood, there is still potential for recovery of growth deficits and there is a risk for growth faltering  after the first 1000 days.

Therefore, interventions implemented during the first 1000 days should be sustained in order to promote growth recovery and prevent further faltering. Among the factors found to be associated with changes in growth after the first 1000 days were parental schooling, household poverty, maternal height, and community health infrastructure and these are some of the factors to be prioritised by policy interventions aiming to promote child growth and nutrition.

Alongside Young Lives, other studies have also produced evidence of post infancy growth changes. Analysis of the Cebu cohort study in the Philippines identified change in stunting and growth between age 2 and age 8 years and a recent multi-country analysis published by UNICEF’s Office of Research also emphasised the potential for catch-up growth. Evidence from Young Lives indicates that post-infancy physical recovery is associated with school attainment, suggesting that the gains may extend to other domains of children’s lives. While prevention of under-nutrition during the early days should be prioritised, there is still potential for interventions in later periods to tackle early nutrition and growth deficits.
Headlines from the YL policy brief

So what does this evidence mean for policy and what should change?

1.     Nothing should undermine the central importance of the first 1000 days for child nutrition. But, the focus on the first 1000 days should not inhibit efforts to improve child nutrition in later periods.
2.     While it’s a traditional complaint that researchers always call for more research, in this case not enough is known about interventions which might bring about post-infancy recovery. Improving the knowledge base by trialling or testing post-infancy nutrition interventions may help to open up new opportunities to remedy under-nutrition and some of its consequences.
3.     One stand-out conclusion is that there is more potential in the role of the school for improving children’s nutrition, and that doing so can support better school attainment. Young Lives evidence suggests that school feeding programmes may promote growth recovery, particularly for children who were severely under-nourished in infancy. There is also evidence that nutritional supplementation in school-aged children can yield benefits in terms of children’s learning and performance in school. In short – let us have more thinking about the role of schools as a platform for interventions to support better nutrition.

Our new policy brief summarises the latest findings from an ongoing programme of work. We hope this work will open up new opportunities for sustaining and supporting children’s healthy development, showing that opportunities exist for a longer time window than sometimes thought. For the central message we end where we began: early is best, but it’s never too late.

Counterpoint

Jef Leroy, IFPRI

I read the Dornan and Georgiadis post with great interest.  I strongly agree with their bottom-line conclusions (1) we should continue to focus on the first 1,000 Days (2) but there is a need to also study children’s potential to benefit from interventions after 2 years of age (and pre-pregnancy).  This is the conclusion my coauthors and I reached after analyzing growth of around 300,000 children from 51 countries (see Journal of Nutrition).  

However, I don’t think that the evidence cited by Dornan and Georgiadis really supports this conclusion.

Here is my thinking:

* Height-for-age Z-scores (HAZ) are a useful tool to (1) describe groups of children at a specific point in time (e.g., “mean HAZ in Burundi in 2010 was -2.2”), (2) compare groups of children (e.g., “mean HAZ in 2010 in Burundi was higher than in Rwanda”), and (3) assess changes in groups of children over time (e.g. “mean HAZ in Rwanda decreased from -1.8 in 2010 to -1.6 in 2014/5”).

* But, as we demonstrated in two recent publications (Journal of Nutrition and BMC Pediatrics), HAZ is not the right tool to assess changes in children’s height as they age.  Why?  First, the standard deviations (SDs) used to construct HAZ (they are in the denominator) are cross-sectional in nature (they reflect the variance in height for children of specific age and sex). As a consequence, they are inappropriate to measure changes in linear growth over time (i.e. as children age).  Second, the SDs of HAZ increase as we move up age groups, so we do not know whether changes in HAZ as children grow older are due to changes in the numerator (the difference in the child’s height for age from the median age- and sex- specific height for age of a healthy reference population) or the denominator (SD).  Changes in linear growth as children age should be analyzed using height-for-age differences (HAD), the absolute difference between measured height and the median age- and sex-specific height obtained from the growth standards.

* As far as I can tell, none of the articles referred to in the blogpost (Young Lives analyses, CEBU work, UNICEF study) look at child growth. They assess changes in HAZ as children grow older. The problem with the analyses of these “HAZ trajectories” is that there is no evidence showing that growing children track along specific HAZ-trajectories.

* As there is no “expected HAZ trajectory”, I do not see how one can formulate meaningful hypotheses to be tested or how one can interpret deviations from HAZ trajectories.  If there is literature on HAZ trajectories, the authors should refer to it.

* None of the articles cited define catch-up growth properly. My view is that the only meaningful definition of catch-up growth is (partial) recovery from a linear growth deficit accumulated in the past (see BMC Pediatrics). Catch-up growth in height is only possible when children grow faster than the expected velocity (for their age and sex) so they can make up for the lost growth in height (see this video for a visual demonstration with Duplo blocks). The only way then to assess catch-up growth is in absolute terms (that is, cm), as expected velocity can only be defined in absolute terms (there is no “expected HAZ trajectory”). As a consequence, none of the articles referred to in the post provide evidence of catch-up growth.
Jef Leroy explaining how lost growth can be made up

* Given that HAZ cannot be used to establish catch-up growth, the YL findings boil down to the following. First, children who have a taller mother, whose parents have gone to school longer, who live in less poor households based in communities with better health infrastructure are taller. Second, taller children do better in school. These findings are interesting and relevant, and they confirm what we have known for long time. The studies do not provide evidence, however, of catch-up growth, they do not identify the determinants of catch-up growth, nor do they establish that catch-up growth has long-term consequences in other domains.

The recent focus on catch-up growth potentially distracts from the most important issues. We care about growth faltering as a development outcome per se because short stature increases the odds of obstructed labor; stunted mothers also have smaller babies. That is it. Linear growth is not a causal determinant of poor development, schooling, productivity, etc.  It is a marker.  So if we care about these last outcomes (we do), we should focus on them directly, and not get sidetracked with doing more and more catch-up in linear growth analyses.