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

Abstract

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.

Keywords: AUC, area under ROC curve; Diagnosis; IQR, interquartile range; Infant; MUAC, mid-upper arm circumference; MUAC-to-length; MUAC/L, mid-upper arm circumference-to-length; ROC and wasting; ROC, receiver operating characteristic; WHO, World Health Organization; WLZ, weight-for-length Z-score.

Fig. 1.

Receiver's operating characteristic curve of mid-upper arm circumference-to-length (MUAC/L) ratio for detecting moderate wasting against weight-for-length in boys and girls.

Fig. 2.

Receiver's operating characteristic curves of mid-upper arm circumference-to-length (MUAC/L) ratio for detecting severe wasting against weight-for-length in boys and girls.