The relationship between wasting and stunting in young children: A systematic review
This article was written by Susan Thurstans, PhD candidate at the London School of Hygiene and Tropical Medicine and consultant to ENN on the Wasting and Stunting project, and Natalie Sessions, Senior Nutritionist at ENN. This is a summary of the following paper:
Thurstans S, Sessions N, Dolan C, Sadler K, Cichon B, Isanaka S et al (2022) The relationship between wasting and stunting in young children: A systematic review. Maternal & Child Nutrition, 18, e13246. Available at: https://pubmed.ncbi.nlm.nih.gov/34486229/
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Background
In 2014, the Wasting and Stunting Technical Interest Group (WaSt TIG) published a technical briefing paper on the relationship between wasting and stunting. Building on this, a systematic review was conducted to explore evidence generated since 2014 to understand the current evidence on the relationship between wasting and stunting and the implications of the relationship on interventions to improve child health, nutrition and survival.
Methods
Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were followed and search terms were identified to describe wasting and stunting and the relationship between the two conditions and run through Medline, Embase and global health databases. Studies addressing wasting and stunting separately or studies that did not report on either condition in relation to the other were excluded. Three main themes were identified including a physiological understanding of the similarities in wasting and stunting, the interrelationship between the two conditions and the implications of this relationship. A total of 45 studies and reports were included.
Findings
Interconnected physiological processes in wasting and stunting
Wasting and stunting both occur when nutrient intakes are insufficient to meet the requirements for growth and/or to support the immune response to infection. When this happens, the body draws on nutritional reserves, mainly fat and muscle. The loss of fat and muscle, the interaction with infection and the ensuing reduced production of hormones such as leptin have all been identified as important physiological processes linking wasting and stunting but further research is warranted. In particular, further work is needed to better understand the role of gut health/inflammation, body composition and its relationship with anthropometric indicators and functional outcomes, the contribution of lean and fat tissue during and after recovery from wasting and the role of environmental factors.
The timing of wasting and stunting
The targeting of nutrition interventions often focuses on children from 6-59 months of age. However, evidence shows that wasting and stunting incidence peaks between birth and three months, with implications for further deterioration in infancy and childhood. With a significant degree of child undernutrition also established before birth, greater coordination between interventions targeting adolescent girls and mothers and those aiming to prevent child undernutrition is needed.
Evidence for the relationship between wasting and stunting
Analysis of both population-level cross-sectional datasets and longitudinal data is supportive of a link between wasting and stunting that is more than just chance. Likewise, within treatment programmes for severe acute malnutrition (SAM), evidence of a relationship is also apparent in that children with SAM are often also stunted.
Research has also shed light on the processes involved in this relationship. Wasting has been found to lead to stunting and, to a lesser extent, stunting to lead to wasting, although the physiological mechanisms are less clear for this direction of the relationship. In the case of wasting leading to stunting, evidence suggests that the body’s response to weight faltering is to slow or halt linear growth until weight is gained and any infection is treated. These findings highlight the importance of integrated medical and nutritional care of children receiving wasting treatment to ensure the effects of wasting on linear growth are minimised. Seasonal patterns also contribute. Research from the Gambia (Schoenbuchner et al, 2019) showed that wasting in a child’s first wet season (hungry season) increased the odds of wasting in their second wet season by a factor of 3.2, even if they had recovered in the intervening harvest period. Likewise, infants born at the start of the wet season did not catch up in weight to the same extent as their peers born in other months and experienced both more wasting during childhood and an increased risk of becoming stunted by two years of age.
Concurrent wasting and stunting
A large number of children experience concurrent wasting and stunting and this can vary by context. Fragile and conflict-affected states appear to be disproportionately affected with higher rates of concurrent wasting and stunting than stable contexts (Khara et al, 2018). A number of studies also show that wasting, stunting and concurrent wasting and stunting are all more prevalent in boys than girls, and in younger children between 12 and 30 months of age.
Mortality implications of concurrent wasting and stunting
Children with concurrent wasting and stunting have been shown to have a 12-fold increased risk of mortality compared with children who are not wasted or stunted (McDonald et al, 2013). This highlights the need to focus on considerations around the risk of death within treatment programmes.
Wasting treatment outcomes and stunting
The findings regarding the response to SAM treatment for children who are both wasted and stunted are inconsistent although, overall, evidence suggests that outcomes are suboptimal for children with concurrent wasting and stunting. Treatment programmes should be optimised to identify those children most at-risk. Research is needed to determine if the treatment of wasting could be adapted to better lay the foundation for linear growth.
Anthropometric indices and the identification of risk
Research is ongoing into the most effective identification of children at high risk of mortality. Evidence suggests that the combined use of weight-for-age z-scores (WAZ) and mid-upper arm circumference (MUAC) identifies all near-term deaths (i.e., within six months of measurement) associated with concurrent wasting and stunting. The use of MUAC and WAZ is also effective in identifying high-risk infants under six months of age. This has important implications in reaching the most vulnerable children in a way that is programmatically practical. These findings indicate the need for further operational research into the most optimal anthropometric identification and assessment of undernutrition.
Conclusion
A significant and still-growing body of evidence supports the existence of a strong relationship between wasting and stunting with important implications for policy and practice. Wasting and stunting, driven by common factors, frequently occur in the same child, either at the same time or through their life course, with important interactions between them. This demonstrates the need for a more integrated approach to prevention and treatment strategies in order to interrupt this process and halt the spiralling of vulnerabilities associated with early growth deficits. To achieve this, further progress is needed to overcome the divide in undernutrition policy, programme, financing and research initiatives.
References
Khara T, Mwangome M, Ngari M and 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 propsective studies from developing countries. American Journal of Clinical Nutrition, 97, 896-901.
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. American Journal of Clinical Nutrition, 110, 498–507.