Diagnostic performance of MUAC and MUACZ in screening acute malnutrition among children aged 6–23 months in Amhara Region, Ethiopia

Mid-Upper Arm Circumference (MUAC), Mid-Upper Arm Circumference-for-Age Z-Score (MUACZ), or Weight-for-Length Z-Score (WHZ) are used to screen for acute malnutrition in children. Studies conducted in various countries, including Ethiopia, have indicated variability in the agreement between these assessments at the World Health Organization recommended cutoffs across different ethnic groups with varying body frames. The low sensitivity of MUAC at standard cutoffs has important implications for program effectiveness. Therefore, this study aimed to validate the diagnostic performance of MUAC and MUACZ in screening for acute malnutrition among children aged 6-23 months in Ethiopia. A community-based cross-sectional study was conducted on 457 randomly selected children aged 6-23 months in the Amhara Region, Ethiopia, from February 2-18, 2023. The Spearman's rank correlation test, Cohen's kappa statistics, and Receiver Operating Curve analysis were conducted. The optimal cutoff points for MUAC and MUACZ were determined by selecting the points that maximized the Youden index. Statistical significance was determined with a p-value < 0.05, using a 95% confidence interval. MUAC, MUACZ, and WHZ results revealed that 11.0%, 8.6%, and 13.2% of children were wasted, respectively, and the percentage of misclassification in screening acute malnutrition was approximately 16%. MUAC and MUACZ had low sensitivity but high specificity in screening for acute malnutrition. MUAC and MUACZ showed poor correlation with WHZ when screening subjects for acute malnutrition using the World Health Organization standard cutoffs. In the Receiver Operating Characteristics curve analysis, significant predictive ability was only observed with MUAC when screening global acute malnutrition cases, and it showed a poor predictive ability (AUC = 0.61, 95% CI: 0.53, 0.70) (p < 0.001). The Youden index statistics revealed that the optimal cutoff for MUAC and MUACZ to define global acute malnutrition at WHZ < -2 SD was 13.6 cm and -0.43 SD, respectively. In addition, the optimal cutoffs for diagnosing severe acute malnutrition in children with WHZ of < -3 SD were found to be 13.1 cm and -1.91 SD for MUAC and MUACZ, respectively. The optimal cutoff values also vary in sex and age categories. Both MUAC and MUACZ had poor performance in screening acute malnutrition, and a significant proportion of children were missed despite they were wasted as compared to WHZ at the standard cutoffs. The optimal cutoff levels differ for different age and sex categories. This may affect admission and discharge rates and have a significant impact on children's health. Modifications in the standard cutoffs are needed to ensure the quality of acute malnutrition screening and treatment services.