Quantifying environmental health impacts

Malnutrition: Quantifying the health impact at national and local levels

Environmental burden of diseases series, No. 12

By Monika Blössner and Mercedes de Onis

Summary

Malnutrition, defined as underweight, is a serious public-health problem that has been linked to a substantial increase in the risk of mortality and morbidity. Women and young children bear the brunt of the disease burden associated with malnutrition. In Africa and south Asia, 27-51% of women of reproductive age are underweight (ACC/SCN, 2000), and it is predicted that about 130 million children will be underweight in 2005 (21% of all children) (de Onis et al., 2004a). Many of the 30 million low-birth-weight babies born annually (23.8% of all births) face severe short-term and long-term health consequences (de Onis, Blössner & Villar, 1998).

In this guide we outline a method for estimating the disease burden at national or local level that is associated with maternal and child malnutrition. The goal is to help policy-makers and others quantify the increased risk associated with malnutrition, in terms of attributable mortality and morbidity, at country or local levels. The estimates will allow policy-makers to compare the disease burden of malnutrition for different countries, or regions within countries, and enable resources to be deployed more effectively. Repeated assessments will also allow trends to be monitored and the impact of interventions to be evaluated.

To quantify the disease burden, population attributable fractions are derived from the assessed exposure (malnutrition) and from the relative risk estimates of disease and death associated with malnutrition. The level of malnutrition in the population groups is assessed by anthropometry (i.e. measurements of body size and composition), using as indicators low birth weight in newborns, low weight-for-age in preschool children, and low body mass index in women. Relative risk estimates for diarrhoea, malaria, measles, acute respiratory infections and other infectious diseases are based on a meta-analysis that was part of a global comparative risk assessment project conducted by the World Health Organization (WHO) and its partners. Checklists for collecting and analysing data are also suggested, and a step-by-step example of how to quantify the health impact associated with malnutrition is given for Nepal, a country in the WHO SEAR D subregion.

Estimates of the disease burden of malnutrition give policy-makers an indication of the burden that could be avoided if malnutrition were to be eliminated. Disaggregated estimates (e.g. by age, sex, degree of malnutrition) can also help policy-makers identify the segments of a population most at risk, such as women and children, and direct resources where they will have the greatest effect. Although it is difficult to assess the avoidable burden because of the uncertainties around estimates of risk factors and disease burdens, the importance of the avoidable burden for policy-making justifies the effort (WHO, 2002).

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