Academic journal article Bulletin of the World Health Organization

Measuring Nutritional Status in Relation to Mortality

Academic journal article Bulletin of the World Health Organization

Measuring Nutritional Status in Relation to Mortality

Article excerpt

In 1956, Federico Gomez and colleagues described the clinical picture preceding death and the apparent cause of death in malnourished children admitted to the Nutrition Department of the children's hospital in Mexico City (1). The main purpose of their article, a classic in the history of nutritional sciences, was to provide information on clinical profiles of child malnutrition and their associated risk of mortality. What made this paper a landmark contribution was the use of a simple anthropometric measurement -- weight -- to develop an indicator (weight-for-age) and, on this basis, a classification of varying degrees of malnutrition. To do this, Gomez and his colleagues relied on the average "theoretical weight" they had found among Mexican children (2). Patients were classified into three groups according to severity of malnutrition, namely, first degree (76-90% of the "theoretical weight" average for the child's age), second degree (61-75%), and third degree (60% and less). Their article linked this classification system to the precise health outcome -- mortality -- and assigned to varying degrees of malnutrition not only a clinical value but also a prognostic significance. The authors documented that the type of prognosis depended mainly on the severity of malnutrition, measured as weight deficit. Subsequently, reference to first, second and third degrees of malnutrition became common jargon not only among nutritionists, but also among others working in the field of child health. With time, the so-called "Gomez classification" (using the Harvard reference values (3) and different cut-off points, i.e., 80%, 70% and 60% of median) was used widely both to classify individual children for clinical referral and to assess malnutrition in communities.

The paper by Gomez et al. raised two interrelated issues that are discussed below. The first, which describes how to measure malnutrition, considers such methodological issues as selecting anthropometric indicators, choosing reference data and establishing cut-off points. The second issue concerns the relationship between malnutrition, as measured by child anthropometry, and mortality.

Measuring nutritional status

The classification developed by Gomez et al. was based on three prior selections: an anthropometric indicator, a reference population with which to compare the index child or community, and cut-off points to classify children according to variable degrees of malnutrition. Classifications developed after Gomez have all relied on these same three elements.

Anthropometric indicator

Nutritional status can be assessed using clinical signs of malnutrition, biochemical indicators and anthropometry. Inadequacies in nutritional intake eventually alter functional capacity and result in many adverse health outcomes that are distinct expressions of malnutrition's different levels of severity. Initially, children adapt to inadequate diets through reduced physical activity and slowed rates of growth. At moderate degrees of malnutrition activity and growth rates are affected to a greater degree and, in addition, signs of wasting and some biochemical abnormalities (e.g. reduction in serum albumin) begin to show. At advanced stages of severity, all linear growth ceases, physical activity is severely curtailed, body wasting is marked, and clinical signs (e.g. oedema, hair and skin changes) are noticeable. Anthropometry thus has an important advantage over other nutritional indicators: whereas biochemical and clinical indicators are useful only at the extremes of malnutrition, body measurements are sensitive over the full spectrum. In addition, anthropometric measurements are non-invasive, inexpensive and relatively easy to obtain. The main disadvantage of anthropometry is its lack of specificity, as changes in body measurements are also sensitive to several other factors, including intake of essential nutrients, infection, altitude, stress and genetic background. …

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