Explaining Within- vs Between-Population Variation in Child Anthropometry and Hemoglobin Measures in India: A Multilevel Analysis of the National Family Health Survey 2015-2016

Abstract

Background: The complex etiology of child growth failure and anemia-commonly used indicators of child undernutrition-involving proximate and distal risk factors at multiple levels is generally recognized. However, their independent and joint effects are often assessed with no clear conceptualization of inferential targets. Methods: We utilized hierarchical linear modeling and a nationally representative sample of 139,116 children aged 6-59 months from India (2015-2016) to estimate the extent to which a comprehensive set of 27 covariates explained the within- and between-population variation in height-for-age, weight-for-age, weight-for-height, and hemoglobin level. Results: Most of the variation in child anthropometry and hemoglobin measures was attributable to within-population differences (80-85%), whereas between-population differences (including communities, districts, and states) accounted for only 15-20%. The proximate and distal covariates explained 0.2-7.5% of within-population variation and 2.1-34.0% of between-population variation, depending on the indicator of interest. Substantial heterogeneity was observed in the magnitude of within-population variation, and the fraction explained, in child anthropometry and hemoglobin measures across the 36 states=union territories of India. Conclusions: Policies and interventions aimed at reducing between-population inequalities in child undernutrition may require a different set of components than those concerned with within-population inequalities. Both are needed to promote the health of the general population, as well as that of high-risk children.