Background Undernutrition is a public health problem worldwide. Tanzania has made significant achievements in the reduction of childhood undernutrition over the past two decades. However, the exact burden of undernutrition was under-estimated when using conventional indices of stunting, wasting and underweight. The objective of this study was to determine the overall prevalence of undernutrition, describe the trends and examine the correlates associated with undernutrition among children under-five years using the composite index of anthropometric failure (CIAF). This study aims to understand the real burden and drivers of undernutrition to improve design, implementation and monitoring of appropriate interventions to ameliorate all form of childhood undernutrition in the country. Methods About 37,205 mother-child pairs were retrieved and analyzed from the Tanzania Demographic and Health Surveys (TDHS) conducted in various years from 1991, 1996, 1999, 2004-05, 2009-10, to 2015-16. The anthropometric data of children under-five years were used to determine the overall burden and trends of undernutrition using CIAF. The recent TDHS surveys from 2005 to 2015 were used to examine the correlates of CIAF. To determine the correlates, multivariate analysis was conducted to estimate the prevalence ratios (PR) with 95% confidence intervals (CI) using Poisson regression with robust variance. Results The prevalence of CIAF declined significantly from 50% in 1991 to 38.2% in 2015 (p <0.001). The correlates of CIAF vary across surveys. The multivariate analysis of recent 2015 survey revealed that the prevalence of CIAF was significantly higher for older children (p <0.001), children living in rural areas (p = 0.028), and those born with non-educated (p = 0.009) or single mothers (p = 0.008). The prevalence of CIAF was significantly lower for girls (p <0.001), being born with overweight/obese mothers (p <0.001), living with older head of the household (p <0.001) or living in richest household (p <0.001). Moreover, children who were born with low birth weight (p <0.001), or having fever (p = 0.044) were most likely to have anthropometric failure. However, consumption of diversified diet was not found to be associated with anthropometric failure (p > 0.05). Conclusion About one in every three under-five years children are suffering from either one or multiple forms of anthropometric failure in Tanzania. There is a significant decline trends in overall burden of undernutrition in Tanzania from the past 25 years, as measured by CIAF. Multiple factors including those related to mothers, children and household socio-economic characteristics have the potential to influence childhood undernutrition. Efforts to reduce the burden of undernutrition should mainly focus on reducing poverty and raising people's living standards.
- Anthropometric failure