We have stated in the conclusion that while individual methods show bias relative to the 4-component reference, the high correlations indicate that all the methods perform well in ranking individual children as having high or low FFM and fat mass. This ranking is itself very valuable in routine clinical care, particularly for longitudinal assessment. We have provided new evidence for the Mexican population that all the methods have utility for this purpose. Furthermore, some of the biases for individual methods can be resolved by the publication of method-specific reference data, whereby all data can be converted to method-specific z-scores. Publishing such reference data is a further aim of our project.
Much of the Discussion addresses strengths and weaknesses of the different BC methods, as if to provide guidance for clinicians in selecting the best techniques according to their needs and capabilities. None of the methods are ideal – all are flawed (in comparison with a gold standard). Yet a firm conclusion seems to be lacking. Concluding that methods differ is not surprising. One may be better served by discussing how the differences in methods (i.e. over or under estimating FM) may affect health assessments. That is, what impact may underestimating FM, by relying on one particular method, have on child care? How critical is the method selection? Somehow this needs to be tied more firmly to the population and environment being studied.