Diagnostic ability of mid-upper arm circumference-to-length ratio in detecting wasting among infants aged 1-6 months in Ethiopia

Mid-upper arm circumference (MUAC) is an age-sensitive anthropometric measurement in infants. However, exact age is difficult to know, particularly in low-income countries. We evaluated the diagnostic accuracy of an age-independent mid-upper arm circumference-to-length (MUAC/L) ratio measurement in detecting wasting among infants aged 1-6 months in Ethiopia. A facility-based diagnostic accuracy study was conducted on 467 in-patient infants aged 1-6 months from March to May 2019. The receiver operating characteristic (ROC) curve was used to evaluate the ability of MUAC/L to detect wasting. Sensitivity, specificity, positive likelihood ratio, negative likelihood ratio and positive and negative predictive values were calculated. The magnitude of severe wasting was 21.6 % and moderate wasting was 13.0 %. The area under the ROC curve (AUC) of MUAC/L was 0.77 (95 % CI 0.73, 0.81) for detecting moderate wasting and 0.92 (95 % CI 0.89, 0.94) for detecting severe wasting. MUAC/L had a sensitivity of 91.1 % (95 % CI 81.3, 94.4), a specificity of 84.7 % (95 % CI 80.6, 88.2), a positive likelihood ratio of 5.82 (95 % CI 4.53, 7.48) and a negative likelihood ratio of 0.13 (95 % CI 0.07, 0.22) in total infants. The optimal MUAC/L cut-off was <0.190 for boys and <0.185 for girls. MUAC/L had an AUC of 0.77 and 0.92 in predicting moderate and severe wasting in infants aged 1-6 months, respectively. Using MUAC/L to treat Ethiopian infants with severe wasting and infants with similar characteristics in other countries could improve treatment coverage.