Mid-upper-arm circumference (MUAC) based on a single cut-off value for all the children less than 5 years of age has been used for many years as an alternative nutritional status index for children during famines or refugee crises, and as an additional screening tool in nonemergencies. However, it has recently been questioned whether MUAC is age- and sex-independent. After reviewing the scientific evidence underlying the use and interpretation of MUAC, a WHO Expert Committee recommended a new MUAC-for-age reference for under-5-year-olds. In some settings, however, it is difficult to assess a child's age and in such circumstances MUAC-for-height may be a good alternative. The height-based QUAC stick is a simple means of adjusting MUAC cut-offs according to height, and the MUAC-for-height reference and the construction and use of the QUAC stick are described in this article. Described also is the use of the receiver operating characteristic (ROC) curve method to evaluate the performance of MUAC, MUAC-for-age, and MUAC-for-height in screening malnourished children.

The World Health Organization (WHO) convened an Expert Committee to reevaluate the use of anthropometry at different ages for assessing health, nutrition, and social wellbeing. The Committee’s task included identifying reference data for anthropometric indexes when appropriate, and providing guidelines on how the data should be used. For fetal growth, the Committee recommended an existing sex-specific multiracial reference. In view of the significant technical drawbacks of the current National Center for Health Statistics (NCHS)/WHO reference and its inadequacy for assessing the growth of breast-fed infants, the Committee recommended the development of a new reference concerning weight and length/height for infants and children, which will be a complex and costly undertaking. Proper interpretation of midupper arm circumference for preschoolers requires age-specific reference data. To evaluate adolescent height-for-age, the Committee recommended the current NCHS/WHO reference. Use of the NCHS body mass index (BMI) data, with their upper percentile elevations and skewness, is undesirable for setting health goals; however, these data were provisionally recommended for defining obesity based on a combination of elevated BMI and high subcutaneous fat. The NCHS values were provisionally recommended as reference data for subscapular and triceps skinfold thicknesses. Guidelines were also provided for adjusting adolescent anthropometric comparisons for maturational status. Currently, there is no need for adult reference data for BMI; interpretation should be based on pragmatic BMI cutoffs. Finally, the Committee noted that few normative anthropometric data exist for the elderly, especially for those > 80 y of age. Proper definitions of health status, function, and biologic age remain to be developed for this group.

In reviewing the growth of infants who live under favourable conditions and are fed according to WHO feeding recommendations, the Working Group found significant differences between the growth patterns of these infants and the patterns reflected in the NCHS-WHO international reference. Given the short- and long-term consequences of growth failure, and the dangers of both the premature introduction of complementary foods and their undue delay - described as the "weanling's dilemma", the Working Group concluded that use of the current NCHS-WHO reference appears to accentuate the difficulty of avoiding these extremes rather than to help ensure optimal infant nutritional management. The Working Group identified the following requirements: (a) a new reference which will enhance the nutritional management of infants; (b) the reference population should reflect current health recommendations because of the frequent use of such reference data as standards; (c) evaluation, in a broad range of settings, of the practical utility of using reference data based on infants for whom the WHO feeding recommendations are being followed; (d) close investigation of the effects of different complementary foods on the growth of infants who are being fed according to the WHO recommendations; (e) criteria for evaluating abnormal growth patterns, (f) research for identifying proxy measures for length; and (g) evaluation of reference data based on other anthropometric measurements, such as skinfold thickness and arm and head circumferences.

Four issues in the use and interpretation of anthropometry are discussed at the level of the population and of the individual. The first issue is the index or indices of choice: weight-for-height versus height-for-age versus weight-for-age. The selection of an index or indices depends upon many factors, and no one index is completely adequate in all situations. Proposed criteria are provided to assess the severity of low anthropometry within populations. The second issue is the scale of the index: z-scores (or standard deviations) versus percentiles versus percent-of-median. z-Scores have several properties that make them superior to the other two scales. A third issue deals with limitations in the current growth reference; one of these is the disjunction between the growth curves at 2 years of age, resulting from the use of two different populations in the reference. It is important that this disjunction be recognized by researchers so that the anthropometric findings are interpreted correctly for this age range. Lastly, some issues to do with the collection of single versus multiple anthropometric measurements on children are discussed.

Using the WHO Global Database on Child Growth, which covers 87% of the total population of under-5-year-olds in developing countries, we describe the worldwide distribution of protein-energy malnutrition, based on nationally representative cross-sectional data gathered between 1980 and 1992 in 79 developing countries in Africa, Asia, Latin America, and Oceania. The findings confirm that more than a third of the world's children are affected. For all the indicators (wasting, stunting, and underweight) the most favourable situation--low or moderate prevalences--occurs in Latin America; in Asia most countries have high or very high prevalences; and in Africa a combination of both these circumstances is found. A total 80% of the children affected live in Asia--mainly in southern Asia--15% in Africa, and 5% in Latin America. Approximately, 43% of children (230 million) in developing countries are stunted. Efforts to accelerate significantly economic development will be unsuccessful until optimal child growth and development are ensured for the majority.