A critical assessment of the width coefficient, K, as an indicator of nutritional status

The width coefficient, K, was assessed critically to examine its underlying assumptions, its relationship to absolute dimensions of body size, and its ability to identify children classified as malnourished by internationally accepted criteria. The scientific integrity of the formula to calculate K depended on the assumption that the body could be viewed as a cylinder with a density of 1.0 g/ml. The empirical testing of the former assumption showed that the body could not be viewed as a cylinder and papers describing body density suggest that age and sex dependency militate against the acceptance of an age- and sex-independent value of 1.0 g/ml. As an indicator of nutritional status K performed well in that it identified children below 75% of weight for age, but it could only identify 47% of children below 90% weight for height. The relative complexity of its calculation and interpretation militate against the use of K as an indicator of malnutrition for the general health worker, but its ability to identify moderately malnourished children by weight for age gives it credibility in the absence of an age assessment.