Mid-Upper Arm Circumference Assessment and Comparison With Weight for Length Z-Score in Infants ≤6 Months as an Indicator of Severe Acute Malnutrition

Objective To assess the frequency of severe acute malnutrition (SAM) and to determine the validity of mid-upper arm circumference (MUAC) as compared to weight for length z-score (WLZ-score) as an indicator of the nutritional status in this age group. Methods A cross-sectional study, with a purposive sampling was conducted from March 2018 to November 2018 to enroll 540 infants <= 6 months of age from three different sites in Karachi, Pakistan. The anthropometric measurements (MUAC, length and weight) were taken by experienced community health workers. The data were analyzed using SPSS. MUAC was compared with WLZ-score for sensitivity and specificity to observe the concordant among the two diagnostic measures. The Youden Index was used to determine the ideal cut-off for infants less than 6 months of age in this population and the Kappa coefficient was also calculated to assess the agreement between MUAC and WLZ-score. Results The study findings revealed that SAM was found in 13.6% (n=74) of the children. MUAC cut-off <= 11.5 cm yielded the Youden Index of 0.31 with 59.5% sensitivity and 71.4% specificity. The total area under receiver operating characteristic curve was 0.70 (95% CI: 0.63, 0.77; P < 0.001). The degree of agreement between mid-upper arm circumference and weight for length z-score to diagnose SAM ranged from 0.2 to 0.3. Conclusion The Youden index implied that a MUAC cut-off of <= 11.5 cm can be used as an indicator with acceptable validity for diagnosing SAM in children <= 6 months of age in a low middle income developing country like Pakistan.