Midupper Arm Circumference Outperforms Weight-Based Measures of Nutritional Status in Children with Diarrhea

Abstract

Background: Undernutrition contributes to 45% of all deaths in children <5 y of age worldwide, with a large proportion of those deaths caused by diarrhea. However, no validated tools exist for assessing undernutrition in children with diarrhea and possible dehydration.

Objective: This study assessed the validity of different measures of undernutrition in children with diarrhea.

Methods: A prospective cohort study was conducted at an urban hospital in Bangladesh. Children <60 mo of age presenting to the hospital rehydration unit with acute diarrhea were eligible for enrollment. Study staff randomly selected 1196 children for screening, of which 1025 were eligible, 850 were enrolled, and 721 had complete data for analysis. Anthropometric measurements, including weight-for-age z score (WAZ), weight-for-length z score (WLZ), midupper arm circumference (MUAC), and midupper arm circumference z score (MUACZ), were calculated pre- and posthydration in all patients. Measurements were evaluated for their ability to correctly identify undernutrition in children with varying degrees of dehydration.

Results: Of the 721 patients with full data for analysis, the median percent dehydration was 4%. Of the 4 measures evaluated, MUAC and MUACZ demonstrated 92-94% agreement pre- and posthydration compared with 69-76% for WAZ and WLZ. Although each 1% change in hydration status was found to change weight-for-age by 0.0895 z scores and weight-for-length by 0.1304 z scores, MUAC and MUACZ were not significantly affected by dehydration status. Weight-based measures misclassified 12% of children with severe underweight and 14% with severe acute malnutrition (SAM) compared with only 1-2% for MUAC and MUACZ.

Conclusions: MUAC and MUACZ were the most accurate predictors of undernutrition in children with diarrhea. WAZ and WLZ were significantly affected by dehydration status, leading to the misdiagnosis of many patients on arrival with severe underweight and SAM. This trial was registered at clinicaltrials.gov as NCT02007733.

Keywords: MUAC; dehydration; diarrhea; malnutrition; oral rehydration; severe acute malnutrition; undernutrition.

FIGURE 1

Flow diagram of study enrollment of patients. Nutritional measurements of dehydration status were performed in 721 patients <60 mo of age before and after achieving stable weight through an independent hydration method.

FIGURE 2

Changes in nutritional indicators between prehydration status and after rehydration to a stable weight; dehydration category assigned as no dehydration (<3% weight change with rehydration), some dehydration (3–9% weight change with rehydration), and severe dehydration (>9% weight change with rehydration); MUACZ, WLZ, and WAZ are all reported in z score units; MUAC is reported in millimeters. MUAC, midupper arm circumference; MUACZ, midupper arm circumference z score; WAZ, weight-for-age z score; WLZ, weight-for-length z score. *Signifies malnutrition indicators whose change with rehydration was signficantly different based on dehydration category.

FIGURE 3

Misclassification of malnutrition status in patients with complete data available. n = 680 for MUAC, n = 711 for MUACZ, and n = 721 for WAZ and WLZ. MAM, moderate acute malnutrition; MUAC, midupper arm circumference; MUACZ, midupper arm circumference z score; SAM, severe acute malnutrition; WAZ, weight-for-age z score; WLZ, weight-for-length z score.