Is MUAC-only screening and admission good enough for early detection and management of acute malnutrition? Lessons from a retrospective birth cohort in Bangladesh refugee camps

Background and objectives: For the sake of simplification, active screening with Mid-Upper Arm Circumference (MUAC) below 125mm has become the unique strategy to identify Acute Malnutrition (AM) in children aged more than 6 months. Low Weight-for-Height Z-score (WHZ), a criterion similarly acknowledged as defining AM, is however known to detect an additional number of cases. The large proportion of the caseload missed when using only MUAC has been well described in cross-sectional nutritional surveys. Yet, this is not reflecting the current practice of repeatedly screening the same children with MUAC in the community. Methods: We have built an unselected retrospective cohort of children in tracking the monthly anthropometric measurements performed as per the Growth Monitoring and Promotion program implemented by ACF since 2009 in the Refugees Camps of Bangladesh. An episode of AM was defined as presence of MUAC below 125mm and/or WHZ below -2, in a child previously free of AM. Results: Follow-up information was collected for 4131 children born since 2012. In this cohort, 51% of the 2164 AM episodes occurring after 6 months of age were first detected only through WHZ below -2, and 65% of these cases were associated with a short-term history of weight loss, i.e. a decrease in weight during the previous month. In contrast with that, 27% of all AM episodes were first detected only through MUAC below 125mm, and these were associated with an observable weight loss in 35% of the cases. Of note, being measured with a MUAC below 125mm yet with a WHZ above or equal -2 at any point of time after 6 months of age failed to display any significant association with short-term history of weight loss. Conclusions: Using MUAC below 125mm as the only screening tool, even on a monthly basis, would have missed more than half the caseload of AM episodes occurring from birth till 24 months. Besides, the question also arises as to the possible lack of specificity of MUAC below 125mm as an independent proxy indicator of the rapid loss of body tissue that is supposed to characterise acute malnutrition.