Detecting malnutrition at age 6-12 months: international comparisons of arm circumference v. standard anthropometry.

Growth faltering, which may herald protein-energy malnutrition (PEM) usually begins between ages 6 and 12 months. However, arm circumference (AC or MUAC) has mainly been used to screen for PEM between 12 and 60 months of age, when AC is age-independent. This study of 378 infants aged 6-12 months in Pakistan, Nepal, Sierra Leone, and Papua New Guinea showed that a cut-off 12.5 cm AC selects infants < 80 per cent weight-for-age (WA) with 76 per cent sensitivity and 90 per cent specificity. Of the 378 infants studied 131 (35 per cent) had WA < 80 per cent and 126 (33 per cent) had AC < 12.5 cm. Weight-for-length agreed less well with AC. The inter-regional prevalence range of AC < 12.5 cm was 29-40 per cent, while the WA < 80 per cent range was 27-45 per cent. When AC is plotted against age, a flat 'plateau' (slope = 0.04) shows age-independence between 6 and 12 months in these 378; this contrasts to the 10 per cent AC increase in European reference populations. Because this AC plateau parallels the WA plateau seen between 6 and 12 months of age in most developing nations, AC < 12.5 cm may provide a simple and valid screening test for early PEM in this crucial age bracket. Conformatory studies elsewhere are indicated.