Validity of mid arm circumference to detect protein energy malnutrition among 8-11 months old infants in a rural medical college of West Bengal.

This institution-based cross-sectional observational validation study was conducted in the immunisation clinic of North Bengal Medical College and Hospital, Sushrutanagar. The objective was to identify the validity characteristics of mid arm circumference to detect protein energy malnutrition among 8-11 months infants and to find out a suitable cut-off value if any. Study variables were age, sex, body weight and mid arm circumference. Mid arm circumference was validated against weight for age criteria (gold standard) of malnutrition. The mean mid arm circumference of the infants was found to be almost constant with only about 2.22% change over 4 months, signifying that single cut-off point can be used to detect protein energy malnutrition. Mid arm circumference values from 13.0 to 12.5 cm were found to have the highest accuracy to detect protein energy malnutrition (about 86%). The cut-off values of 12.5 and 12.6 cm were noted to have a sensitivity and specificity of about 52% and 96% respectively, a false negativity of 48% but a false positivity of only 4%. Receiver operating characteristics curve detected 12.5(12.6) cm as the best diagnostic cut-off point which can detect more than 50% of the malnourished babies with very little false positivity/misdiagnosis (only 4%). A simple measuring tape with some reorientation of the health workers can detect the beginning of childhood malnutrition.