What proportion of children have a growth deficit?
Cross-sectional anthropometric survey data are frequently summarized to present estimates of the proportion of a child population who might be considered malnourished. A very commonly used summary statistic is the prevalence of standard deviation scores less than -2 (Pz < -2). Pz < -2 is not equivalent to the prevalence of growth retardation in the population, lambda. Identical values of Pz < -2 can arise as a result of a relatively low prevalence of predominantly severe malnutrition, or of universal or near-universal mild growth retardation. Alternative estimators which have been proposed give biased estimates of lambda. In this paper a simple statistical procedure using density ratios is described for estimating lambda from cross-sectional anthropometric data and international growth standards. This gives nearly unbiased estimates of lambda and of the distribution of the growth deficit in the growth retarded sub-set of the population. The analysis provides estimates of the probability that an individual child's growth is retarded. This is illustrated with data from the 1982/3 National Nutrition Survey of Papua New Guinea. Estimation of lambda for different indicators and for different populations could be useful in planning whether interventions should be targeted at the smallest children, or aimed at the population in general. The same estimates might also be used to help determine whether heterogeneity between countries in the reported associations between morbidity or mortality risks and anthropometric indices can be accounted for by differences in the amount of intrapopulation variation in growth retardation.
Smith
T
T
Department of Public Health and Epidemiology, Swiss Tropical Institute, Basel.
D000886:Anthropometry; D002648:Child; D006130:Growth Disorders / Q000453:epidemiology*; D006801:Humans; D008954:Models, Biological; D015233:Models, Statistical; D010219:Papua New Guinea / Q000453:epidemiology