This study compared a standard nutritional program for the treatment of uncomplicated SAM using WHZ and/or MUAC for admission and discharge to a MUAC-only program where MUAC was used as the sole anthropometric criterion for admission and discharge. The MUAC-only program used a MUAC threshold of < 120 mm, higher than the standard threshold < 115 mm, for admission in order to increase the sensitivity of the MUAC-only threshold to offer treatment to children with a MUAC between 115 and < 120 mm who may be potentially at increased risk of morbidity and mortality. This operational experience with a MUAC-only model of care found overall higher recovery and a lower defaulter rate than in the standard program.
In this setting, the use of different anthropometric admission criteria resulted in admitting children of different nutritional profiles in the two outpatient therapeutic feeding centers, consistent with previous reports [10,11,12,13]. Children included in the MUAC-only program were shorter and more often stunted but had fewer morbidities on admission. Consistent with the admission criteria in the MUAC-only program, children included in Sabon Guida had a higher mean MUAC and WHZ, with substantial proportion of children enrolled with moderate acute malnutrition (> 25% with MUAC between 115 and 119 mm and a WHZ between − 2 and ≥ − 3 on admission) and would not have been included in a standard program. It may be expected that the more favorable anthropometric profile of children included in the MUAC-only program would contribute to improved nutritional recovery, as seen elsewhere [15, 18, 20]. While we did observe greater recovery in the MUAC-only program compared to the standard program (70.1% vs. 51.6%), the difference in recovery remained after statistical adjustment for MUAC and WHZ on admission. Differential recovery may therefore be due to differences in the ease of reaching the respective definitions of recovery that differed by site (e.g. MUAC ≥125 mm at 2 consecutive visits in the MUAC-only program vs MUAC ≥125 mm and WHZ ≥ − 2 at 2 consecutive visits in the standard program), but further research is required.
Overall, the risk of non-response was high in this study. One-fifth of the children in the MUAC-only program and one-third of the children in the standard program did not meet the discharge criteria from their respective centers after having completed eight weeks of treatment. The high burden of non-response should be of particular concern as the majority of these children were SAM, frequently with a MUAC < 115 mm, despite being treated for 8 weeks. Qualitative results suggest that non-response was not well understood by caregivers, indicating that clear, adapted and positive communication should be ensured by the health staff during treatment and at the time of discharge. Further consideration of the reasons for high non-response in this setting, including the appropriate discharge threshold within a MUAC-only program, is warranted.
The risk of death and default was below the international recommendations [21], but the risk of default was notably twice as high in the standard program than in the MUAC-only program. Qualitative interviews among caregivers in the standard program support a variety of barriers to accessing care (e.g. financial constraints, geography, insecurity) but also highlight areas for program improvement (e.g. improved staff communication and relationships with caregivers), which may have varied by site.
Among the children who recovered and were admitted with MUAC ≥115 mm, the average duration of treatment tended to be shorter in the MUAC-only program. This result may be associated with the discharge criteria of the MUAC-only program not additionally requiring WHZ ≥ − 2 during two consecutive visits. The average daily weight gain (g/kg/day) was higher in the standard program than in the MUAC-only program, which may be expected given the more severe WHZ on admission [15, 18] .
In previous analysis, we reported on program outcomes achieved using a MUAC-based anthropometric discharge in Burkina Faso [15]. That previous study showed overall favorable program outcomes using MUAC ≥124 mm as the sole anthropometric criterion for discharge compared to proportional weight gain, but did not include post discharge follow-up. In the present study that included follow up three months after post discharge, we found that re-admission was more frequently observed in the MUAC-only program compared to the standard program where WHZ and/or MUAC were used as the anthropometric criteria for discharge. This may be in part attributed to the fact that readmission was based on the broader eligibility criteria of a MUAC < 120 mm, which would have (re-)admitted children with moderate acute malnutrition not otherwise eligible for (re-)admission in a standard program. Three months post discharge, children in the MUAC-only program had lower WHZ and MUAC compared to the standard program, which might suggest a weaker nutritional recovery in the MUAC-only program. Appropriate post-discharge care to support sustained recovery remains an important area where additional evidence is needed to inform effective interventions.
While increasing the eligibility threshold of MUAC on admission from 115 to 120 mm was intended to increase the sensitivity of the admission criterion, we anticipated that a certain number of children would be deemed newly ineligible for treatment under the MUAC-only program, as MUAC and WHZ are known to identify different children. Contrary to what has been reported elsewhere [22, 23], we found a very small number of children to be excluded from treatment using a MUAC-only model with admission defined by MUAC < 120 mm and the absence of bipedal edema (n = 63 ineligible compared to 1019 children admitted at the same site). After 12 weeks of at-home follow-up, the majority of these children (69.8%) did not deteriorate (i.e. MUAC ≥120 mm) despite not immediately receiving treatment in the MUAC-only program.