Weight-for-height and mid-upper-arm circumference should be used independently to diagnose acute malnutrition: policy implications

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Why is it important?

There has recently been debate and a number of publications describing the practical and public health advantages of using only mid-upper-arm circumference (MUAC) to identify children at needing treatment and advocating for the abandonment of the traditional measurement – weight-for-height (WHZ) – as impractical and imprecise. However, the relationship between the estimated prevalence of acute malnutrition based on MUAC vs. WHZ has not been adequately examined. If different children are selected by one or the other criteria with minimal concordance then using only one criterion for admission will potentially deny treatment to many children. If the prevalence is different with the two criteria then some countries may be denied aid. If the two conditions are additive then without measuring both all surveys which report only one criterion will underestimate the true extent of acute malnutrition. To better understand the proportion of cases of acute malnutrition when the diagnosis is based either on MUAC or WHZ, we have examined the relationship between MUAC and WHZ by analysis of anonymous data collected from 1,832 anthropometric surveys from 47 countries. The prevalence of acute malnutrition was calculated using either absolute-MUAC or WHZ. For each country, the total number of children diagnosed as acutely malnourished by either criterion alone or by both criteria were summed from all the surveys conducted in that country. In all countries a minority of children were diagnosed as malnourished by both criteria. The magnitude and direction of the discrepancy varied dramatically between countries with some having most children diagnosed as malnourished by MUAC and others where nearly all the children were diagnosed by WHZ alone. To our knowledge, this is the first analysis to clearly show that this is a general phenomenon in all the countries examined. There is great variation in the diagnosis of acute malnutrition using WHZ or MUAC in the developing world. This discrepancy was not explained by the hypotheses that have been advanced, such as variation in relative leg to body length. The perceived need for humanitarian intervention can be affected by the measurement chosen to assess the prevalence of malnutrition which will vary from region to region. It is recommended that MUAC measurement be included in all anthropometric surveys and that the two criteria are not alternative measures of the loss of body tissue leading to an increased risk of death, but complementary variables that should both be used independently to guide admission for treatment of malnourished children. The findings of the following study should provide clarity to both therapeutic feeding programs and the perception of nutritional risk within a country of moving to MUAC alone as the sole admission criteria and suggest any such revision to operational guidance should be context-specific.