Weight-for-height indices to assess nutritional status--a new index on a slide-rule.

The protein-energy malnutrition classification schemes of Waterlow and McLaren, although similar in other respects, assess the weight-for-height of children in quite different ways. The drawbacks of their two methods are described, and an alternative method is presented which overcomes them. The new index is called weight/height2-for-age, and consists of the ratio weight/height2 expressed as a percentage of the same ratio for a reference child of the same age. Although the index is not age independent, it is insensitive to all but the grossest errors in age for children over 12 months old. The index is equally appropriate for the assessment of obesity. A slide-rule based on the Tanner standard is available to do the calculation.