A reflection on the 2021 Lancet Maternal & Child Nutrition Series through a WaSt lens

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This article provides a summary of the Lancet Maternal & Child Nutrition Series to date, reflecting upon the 2021 series from the perspective of the Wasting and Stunting Technical Interest Group.

Philip James is a Senior Technical Associate at Emergency Nutrition Network (ENN).

André Briend is an Adjunct Professor of International Health at Tampere University.

Sheila Isanaka is an Associate Professor of Nutrition at Harvard TH Chan School of Public Health.

Kieran O’Brien is an Assistant Professor at the University of California, San Francisco.

Natalie Sessions is a Senior Nutritionist at ENN.

Patrick Webb is a Professor of Nutrition at Tufts University.

Tanya Khara is a Technical Director at ENN. 

Key messages:

• In the earlier two Lancet Maternal & Child Nutrition Series in 2008 and 2013, stunting and wasting were discussed independently.
• In the latest Series in 2021, the overlap between these two forms of undernutrition was considered which strongly aligns with research done by the Wasting and Stunting Technical Interest Group.
• The new focus on the interrelationships between wasting and stunting provides further rationale for more programmes and policies to consider joint programming across the different manifestations of undernutrition.

The three Lancet Series on maternal and child undernutrition represent milestone publications for those working in public health and nutrition. They provided authoritative, influential collections of papers where current evidence was reviewed and the implications for programming outlined (see Box 1 for a summary of the evidence-based interventions recommended in each Series).¹

Given the significant influence of these Series on practice and policy, it is an opportune time to explore what has been said about the relationship between wasting and stunting in the latest Series and what gaps remain. In this article we reflect on the 2021 Series’ first paper (Victora et al) from the perspective of the Wasting and Stunting Technical Interest Group (WaSt TIG)².

Box 1: Evidence-based nutrition interventions recommended by the Lancet Series

First Series 2008: There was deemed sufficient evidence for the recommendation of the following interventions: iron folate supplementation, maternal multiple micronutrient supplementation, maternal calcium supplementation, interventions to reduce tobacco consumption or indoor air pollution, the promotion of breastfeeding (individual and group counselling), behaviour change communication for improved complementary feeding, zinc supplementation, zinc in the  management of diarrhoea, vitamin A fortification or supplementation, universal salt iodisation, handwashing or hygiene interventions and the treatment of severe acute malnutrition.

Second Series 2013: Ten effective interventions were outlined: 1) periconceptual folic acid supplementation or fortification, 2) maternal calcium supplementation, 3) maternal balanced energy protein supplementation, 4) maternal multiple micronutrient or iron-folic acid supplementation, 5) vitamin A supplementation, 6) the promotion of breastfeeding, 7) complementary feeding education and food provision (food insecure); complementary feeding education (food secure), 8) preventive zinc supplementation, 9) the management of moderate acute malnutrition and the treatment of severe acute malnutrition, 10) zinc for the management of diarrhoea.

Third Series 2021: Eleven effective interventions were summarised: 1) large-scale food fortification for the prevention of micronutrient deficiencies, 2) maternal calcium supplementation in low intake populations, 3) maternal balanced energy protein supplementation in undernourished populations, 4) maternal multiple micronutrient supplementation, 5) vitamin A supplementation in deficient contexts, 6) breastfeeding promotion and counselling, 7) complementary feeding education and food provision (food insecure); complementary feeding education (food secure), 8) preventive zinc supplementation, 9) ready-to-use foods for the management of acute malnutrition, 10) therapeutic zinc supplementation for diarrhoea, 11) preventive small quantity lipid nutrient supplementation for optimising health and growth in children.

The first paper by Victora et al (2021) describes analyses of national survey data from 50 low- and middle-income countries (LMICs) taken from two time periods which the authors broadly categorised into surveys from 2000 and those since 2015 (Victora et al, 2021). They summarise trends in nutrition indicators over the 15 years. Although associations between wasting and stunting are not referred to explicitly in the key messages panel, the topic is brought out clearly in the article summary and is covered in detail in the paper’s narrative.  Indeed, reference was made in this paper to an article written by members of the WaSt TIG that summarises many of the key concepts emerging from the group’s research (Wells et al, 2019).

This marks an encouraging development since the first two Lancet Series where stunting and wasting were discussed independently and where the overlap between these two forms of undernutrition was not considered. The new focus on the interrelationships between wasting and stunting provides further rationale for more programmes and policies to consider joint programming and policies across the different manifestations of undernutrition.

Some of the key points from Victora et al are:

• Increased mortality risk for children concurrently affected by wasting and stunting (WaSt): Three studies (each of which was co-authored by members of the WaSt TIG) are used to back up this statement. The first (Garenne et al, 2019) looks at a historic cohort of children in Senegal. Concurrent WaSt was a strong predictor of mortality explaining 51% of the mortality in the cohort. The second study (McDonald et al, 2013) is a meta-analysis of 10 cohorts from LMICs. Children who were wasted, stunted and underweight had more than 12 times the mortality risk of children with no anthropometric deficits. The third is a pooled analysis of 35 longitudinal cohorts (Mertens et al, 2020). Concurrent WaSt at 18 months of age was strongly associated with later mortality in the cohorts (RR=4.8, 95% CI: 3.9, 5.9).
• Prevalence of concurrent WaSt: The authors calculated the prevalence of concurrent WaSt in the 50 countries at both survey time points. This is something that is not yet routinely done with survey data, or in global estimates, despite the heightened mortality risk of those with concurrent WaSt and the fact that prevalence of concurrent WaSt can be similar, if not higher, than the prevalence of severe wasting. For example, the 2021 Joint Child Malnutrition Estimates (UNICEF, the WHO, World Bank Group, 2021) describe that wasting and stunting can co-exist but do not provide estimates for concurrent WaSt. In the Lancet article, the prevalence of concurrent WaSt is portrayed graphically and then described within its own narrative section. Concurrent WaSt prevalence was 7.0% in the surveys from 2000, reducing to 4.7% in the 2015 surveys (low-income countries only; prevalence of concurrent WaSt was very low in middle-income countries). The authors put this into the context of other estimates produced by members of the WaSt TIG, quoting Khara et al’s (2018) meta-analysis of survey data from 84 countries where the pooled prevalence of concurrent WaSt was 3.0%, 95% CI [2.97, 3.06] with peak timing of WaSt concurrence at 12-35 months of age. They also highlighted recent analyses of regional differences from Mertens et al (2020) which showed that concurrent WaSt prevalence was particularly high in South Asia (8%) with peak prevalence at age 12-18 months.
• Wasting increases the risk of subsequent stunting: Two studies were referenced to support the observation that wasting increases the risk of later stunting although neither of the study findings was elaborated upon. The first study (Schoenbuchner et al, 2019) used four decades of longitudinal growth data from The Gambia. The authors found that being wasted increased the odds of being stunted later (OR: 3.2; 95% CI: 2.7, 3.9). The second study (Richard et al, 2012) was an analysis of eight cohort studies which suggested a lagged effect between an episode of wasting and subsequent linear growth with the strongest adverse effect on linear growth found when the episode of wasting occurred in the preceding six months. A more recent study (Mertens et al, 2020) (not referenced by Victora et al) also provides robust longitudinal data to bolster evidence on this topic. The analysis of 18 longitudinal cohorts suggested that children who were ever wasted in the first six months of life were 1.8 (95% CI: 1.5, 2.3) times more likely to be concurrently WaSt between ages 18-24 months. Given the size of the datasets in this analysis, it is an important paper that underscores the associations between prior episodes of wasting and later vulnerability to growth failure (both wasting and stunting).

Other important points that Victora et al touched on have also been noted by the WaSt TIG as important lessons and concepts for the design of research related to wasting and stunting. These include:

• The importance of screening for those at highest risk of mortality: The authors highlighted that low mid-upper arm circumference (MUAC) could be used to identify children at risk of death and, furthermore, was a preferred screening tool due to its simplicity of use. Linking this to the conversation on concurrent WaSt, Myatt et al (2018) analysed 51 cross-sectional survey datasets and found that a MUAC <133mm had a sensitivity of detecting concurrent WaSt cases of 81.0% using ROC analysis.³ However, low weight-for-age z-scores (WAZ) had an even better sensitivity and specificity for capturing WaSt cases (as discussed below).
• The importance of moving away from a preoccupation with anthropometric cut-offs: Victora et al guided readers to consider the distribution of height-for-age z-scores (HAZ) and weight-for-height z-scores (WHZ) curves from the surveys and where these fall relative to the World Health Organization (2006) standards. In this paper, the Demographic and Health Surveys (DHS) had HAZ and WHZ distributions that were both shifted to the left of the growth standard curves. Two important reflections on this include:
  1. Populations represented by the DHS surveys not only had an increased proportion of stunted and wasted children compared to well-nourished populations, with their growth curves shifted to the left, the whole population had a lower WHZ or HAZ than if they had been well-nourished.
  2. This reinforces the focus on the process of wasting and stunting and how many children grow below their potential. It is not only where a child ends up (whether that child becomes stunted or wasted) that is important. It also means understanding that a child may have started with a healthy WHZ of +2 but then lost weight to WHZ -1.5 which would still not be classified as being wasted but would potentially still have implications on later linear growth.
• Common drivers of wasting and stunting: The article underscores that wasting and stunting already manifest at birth and that therefore the in utero period is important to consider for the prevention of both processes. This messaging was also highlighted in previous Lancet Series where the determinants of stunting and wasting were looked at and common pathways for prevention included maternal nutrition, postnatal diet, disease management and nurturing care. Members of the WaSt TIG have recently released a briefing note on the prevention of child wasting which explores these themes further.⁴

Conclusions

It was encouraging to see the prominence accorded to the links between wasting and stunting in the 2021 Lancet Series. Within an article that sought to capture so many themes, concurrent WaSt and the associations between wasting and stunting were given a lot of attention in both the summary and its own standalone section. Additional key messages not captured but important to consider are:

1. Boys tend to be at greater risk of concurrent WaSt than girls (Khara et al, 2018; Schoenbuchner et al, 2019; Myatt et al, 2018).
2. Low WAZ captures almost all concurrent WaSt cases and it therefore represents a simple screening tool for identifying those at higher risk of mortality.⁵ Myatt et al (2018) found that a WAZ <-2.8 had a 98.5% sensitivity and 91.1% specificity of identifying children with concurrent WaSt using ROC analysis. Using WAZ as a screening tool to identify children at highest risk is potentially simple to implement and scale up as growth monitoring programmes already monitor WAZ.
3. Thirdly, episodes of stunting also predict later wasting (Schoenbuchner et al, 2019) although the strength of association is not as strong as wasting predicting later stunting and the mechanisms are less clear. However, this observation still supports the consideration of both wasting and stunting prevention together in policy and practice.

With the publication of this Lancet Series, together with the rapidly expanding body of work arising from the WaSt TIG, we have a good foundation to maintain the focus on how concurrent WaSt is a marker of increased vulnerability to mortality, how wasting and stunting are interlinked and what should be done at the programmatic and policy levels to address these considerations.

References

Garenne M, Myatt M, Khara T, Dolan C, Briend A et al (2019) Concurrent wasting and stunting among under-five children in Niakhar, Senegal. Maternal & Child Nutrition, 15, 2, e12736.

Khara T, Mwangome M, Ngari M, Dolan C (2018) Children concurrently wasted and stunted: A meta-analysis of prevalence data of children 6-59 months from 84 countries. Maternal & Child Nutrition, 14, 2, e12516.

McDonald C, Olofin I, Flaxman S, Fawzi W, Spiegelman D, Caulfield L et al (2013) The effect of multiple anthropometric deficits on child mortality: meta-analysis of individual data in 10 prospective studies from developing countries. American Journal of Clinical Nutriiton, 97, 4, 896-901.

Mertens A, Benjamin-Chung J, Colford J, Coyle J, van der Laan M, Hubbard A et al (2020) Causes and consequences of child growth failure in low- and middle-income countries. medRxiv [preprint]

Mertens A, Benjamin-Chung J, Colford J, Hubbard A, van der Laan M, Coyle J et al (2020) Child wasting and concurrent stunting in low- and middle-income countries. medRxiv [preprint]

Myatt M, Khara T, Schoenbuchner S, Pietzsch S, Dolan C, Lelijveld N et al (2018) Children who are both wasted and stunted are also underweight and have a high risk of death: a descriptive epidemiology of multiple anthropometric deficits using data from 51 countries. Archives of Public Health, 76, 1, 28-28.

Richard S, Black R, Gilman R, Guerrant R, Kang G, Lanata C et al (2012) Wasting is associated with stunting in early childhood. The Journal of nutrition, 142, 7, 1291-6.

Schoenbuchner S, Dolan C, Mwangome M, Hall A, Richard S, Wells J et al (2019) The relationship between wasting and stunting: a retrospective cohort analysis of longitudinal data in Gambian children from 1976 to 2016. The American journal of clinical nutrition, 110, 2, 498-507.

UNICEF, WHO, World Bank Group (2021) Levels and trends in child malnutrition: UNICEF, WHO, World Bank Group Joint Child Malnutrition Estimates: Key findings of the 2021 edition. World Health Organization: Geneva.

Victora C, Christian P, Vidaletti L, Gatica-Dominguez G, Menon P, Black R (2021) Revisiting maternal and child undernutrition in low-income and middle-income countries: variable progress towards an unfinished agenda. Lancet, 397, 10282, 1388-1399.

Wells J, Briend A, Boyd E, Berkeley J, Hall A, Isanaka S et al (2019) Beyond wasted and stunted—a major shift to fight child undernutrition. Lancet, 3, 11, 831-834.