Closing the gap: testing treatment for severely underweight children not captured by wasting criteria

Children with severely low weight-for-age face a heightened risk of mortality but are often overlooked for treatment because they don't meet the standard criteria for wasting, defined by a low mid-upper arm circumference (a measurement based on arm size) or low weight-for-height (a comparison of weight to height). To address this gap, the IRC launched a groundbreaking randomized controlled trial (RCT) in Mali in 2022. This trial is the first of its kind, testing whether children with low weight-for-age (WAZ), or a measurement comparing a child's weight to what is expected for their age, can benefit from treatment and how they might be effectively treated using a simplified protocol.

From October 2022 to April 2024, the IRC treated 1,397 children who were severely underweight but had a normal MUAC measurement. This trial aims to inform the expansion of current admission criteria to better identify and treat at-risk children who are currently overlooked. Preliminary results indicate that simplified treatment significantly improved children's nutritional status compared to no treatment, and performed as well as the more complex standard treatment. Treatment also reduced the likelihood of children developing wasting. However, gains were modest — half of treated children remained in severe underweight after three months — raising important questions about whether nutritional treatment alone is sufficient for this group, and whether longer-term or alternative approaches may be needed. The manuscript is finalized and currently under review for publication.

The study also looked at body composition of severely underweight children and showed that regardless of treatment, children mostly gain lean tissue, thus reassuring practitioners that nutritional treatment with high energy products doesn’t lead to excessive adiposity. These results are currently in peer–review. Related to this study, several validation sub-studies were performed to ensure body composition of Malian children can be estimated accurately (deuterium dilution study). This will help any later research wishing to use field friendly methods to accurately estimate the body composition of Malian children.

In addition to the RCT, we are conducting a complementary analysis to better understand both the risks and benefits of treating children with low weight-for-age who are not currently eligible for care (high risk high benefit).

High risk high benefit: In addition to testing the effectiveness of treatment, the study is also analyzing which children with low weight-for-age but normal MUAC are at highest risk of worsening health if left untreated, and which are most likely to benefit from receiving supplementary food. This includes identifying specific characteristics, like age or history of malnutrition, that may signal a child is both vulnerable and responsive to treatment. The goal is to better target care by focusing on children who are most at risk and most likely to recover with support. These findings will help refine future guidelines so that life-saving treatment reaches the children who need it most but are currently missed by existing criteria.

Deuterium dilusion: The IRC has launched a sub-study to develop a robust equation for estimating body composition in Malian children using field-friendly bioimpedancemetry. To do this, we’re comparing results from bioimpedancemetry with those obtained through deuterium dilution—a gold-standard but technically demanding method for measuring body composition. This sub-study will strengthen the main trial by allowing us to accurately interpret body composition data and assess the potential impact of nutritional treatment.

These studies collectively aim to refine our treatment protocols and optimize our approach to combating malnutrition, ultimately guiding future interventions to save more lives.