The effect of body shape on weight-for-height and mid-upper arm circumference based case definitions of acute malnutrition in Ethiopian children.

BACKGROUND: Nutritional anthropometry surveys from Somalia and Ethiopia have reported that standard weight-for-height z-score (WHZ) and mid-upper arm circumference (MUAC) case definitions return different estimates of the prevalence of acute malnutrition in pastoralist livelihood zones but similar estimates of the prevalence of acute malnutrition in the agrarian livelihood zones. A study undertaken in Somalia to investigate this finding reported that children from pastoralist livelihood zones tended to have longer limbs and lower SSRs than children from agrarian livelihood zones.

AIM: The present study investigated the relationship between weight-for-height and body shape and the relationship between MUAC and body shape in different populations of Ethiopian children.

SUBJECTS AND METHODS: Six cross-sectional nutritional anthropometry surveys were undertaken. The combined survey datasets form the study sample. Data sources were grouped according to the livelihood zone from which data originated (either settled agrarian or semi-nomadic pastoralist). Case definitions of acute malnutrition using WHZ calculated using the NCHS and WHO reference populations and MUAC uncorrected for age or height were used. The SSR was used as an index of body shape. The association between body shape and the different case definitions of acute malnutrition were investigated using standard statistical techniques.

RESULTS: Weight-for-height and MUAC case definitions yielded similar estimates of the prevalence of acute malnutrition in agrarian children but different estimates of the prevalence of acute malnutrition in pastoralist children. These populations also exhibit different SSRs. The SSR is an important predictor of weight-for-height. The SSR is a poor predictor of MUAC.

CONCLUSION: WHZ and WHZ case status in children are associated with body shape and may overestimate the prevalence of acute malnutrition in some populations. Consideration should be given as to whether WHZ should be replaced by MUAC for the purposes of estimating the prevalence of acute malnutrition.