Validity of mid-upper arm circumference in assessing thinness among older children aged 5–9 years: a cross-sectional study

With the high burden of malnutrition, accurate yet convenient anthropometric measurements are vital. Although body mass index (BMI) for age and sex z score (BAZ) is the recommended assessment method for children aged 5–9 years, it is quite cumbersome. Uganda adopted use of the convenient mid-upper arm circumference (MUAC) for these children. However, the basis for MUAC use in this age-group is weak, requiring more evidence generation. We therefore determined validity of MUAC in assessing thinness among children aged 5–9 years. This was a cross-sectional study. Demographic and anthropometric data was taken from children aged 5–9 years who attended 3 health facilities in Kampala district. MUAC was measured using colour-coded MUAC tapes for children aged 5–9 years and compared with the BAZ. We used a MUAC cut-off of 145 mm for wasting and below 140 mm for severe wasting as per the national guidelines. The sensitivity, specificity, negative and positive predictive values of MUAC were determined using BAZ as the gold standard. Receiver Operating Characteristic curves were plotted to determine the validity of MUAC. Of the 767 children, 51.5% were female and the mean age was 7.2 +/-1.6 years. According to MUAC, 1% had severe acute malnutrition (SAM), 2.7% moderate acute malnutrition (MAM) and 96.2% had no acute malnutrition. The sensitivity and specificity of MUAC in assessment of acute malnutrition (SAM and MAM) were 22.7%, 95% CI (11.5–37.8) and 97.3%, 95% CI (95.9–98.4) respectively. The positive and negative predictive values were 34.5%, 95% CI (17.9–54.3) and 95.4%, 95% CI (93.6–96.8) respectively. The area under the ROC curve was 0.30, 95%CI (0.206–0.394), indicating MUAC was a poor assessment tool for thinness, even after stratifying for age and Human Immune-deficiency Virus status. Despite MUAC being convenient, it showed a low diagnostic performance in assessing thinness among children 5–9 years. This reiterates the need for more research on the correct MUAC cut-offs for this age-group.