Agreement between random upper arm circumference and standard mid-upper arm circumference for identifying acute malnutrition among children aged 6–59 months in Southwest Ethiopia

BACKGROUND: Mid-Upper Arm Circumference (MUAC) is a widely used, rapid, and low-cost anthropometric tool for community-based screening of acute malnutrition among children. However, accurate MUAC assessment requires identification of the midpoint of the upper arm and proper tape placement, which may contribute to inter-observer variability and inconsistencies in field measurements. Random Upper Arm Circumference (RUAC) has been proposed as a simpler alternative for community screening. Nevertheless, evidence regarding the agreement and validity of RUAC compared with standard MUAC for identifying wasting among Ethiopian children remains limited. Therefore, this study aimed to assess the concordance and validity of RUAC compared with MUAC in identifying wasting among children aged 6-59 months in Southwest Ethiopia. METHODS: A community-based cross-sectional study was conducted among 591 children aged 6-59 months in Southwest Ethiopia from June 2 to June 30, 2023. Participants were selected using simple random sampling from child registration lists used as the sampling frame. Paired RUAC and standard MUAC measurements were obtained from each child to assess agreement between the two methods. Children were classified as wasted using the MUAC cut-off value of < 12.5 cm, and RUAC was categorized using the same threshold. Data were analyzed using SPSS version 26. Agreement between RUAC and MUAC was evaluated using Cohen's Kappa for categorical measures and Bland-Altman analysis for continuous measurements. Diagnostic performance was assessed using sensitivity, specificity, positive predictive value, negative predictive value, and receiver operating characteristic (ROC) curve analysis. Assumptions for statistical analyses were checked before analysis. RESULTS: Among the participants, 61 (10.4%) children were classified as wasted using standard MUAC measurements. Significant agreement was observed between RUAC and standard MUAC classifications (κ = 0.69; 95% CI: 0.60-0.79; p < 0.001). Using standard MUAC as the reference method, RUAC demonstrated a sensitivity of 81.6% (95% CI: 71.9%-89.0%) and specificity of 95.2% (95% CI: 93.1%-96.9%) for identifying wasting among children aged 6-59 months. The positive predictive value and negative predictive value of RUAC were 66.2% (95% CI: 55.0%-76.2%) and 97.8% (95% CI: 96.1%-98.9%), respectively. RUAC also demonstrated excellent diagnostic performance, with an area under the curve of 0.99 (95% CI: 0.98-0.99) for severe acute malnutrition and 0.94 (95% CI: 0.93-0.96) for moderate acute malnutrition. CONCLUSION: RUAC showed substantial agreement with standard MUAC and acceptable diagnostic performance for identifying wasting among children aged 6-59 months in Southwest Ethiopia. However, the evidence is limited to a single-site cross-sectional study, therefore, generalization beyond the study population is not justified. Further validation across different Ethiopian settings is recommended.