In Reply: Dr Roberfroid and colleagues have highlighted that different reference populations were used and that this may affect the internal validity of this study. We note, however, that the NCHS reference was used to determine eligibility for preventive supplementation or treatment in the local nutritional program and not to determine inclusion in the study's surveillance activities. Anthropometric data were collected on and available for all children in the study villages. In the survival analyses, children were only excluded if, according to the WHO growth standards, the outcome was present at baseline. Use of the WHO growth standards in the analysis was chosen to facilitate comparison with future studies in which the WHO standards will be increasingly adopted. As the WHO growth standards have been shown more inclusive in classifying children as malnourished than the NCHS reference,1 this decision resulted in the exclusion of a greater number of children from the analysis than if the NCHS reference population were used. This decision does not introduce a bias or reduce the internal validity of the study but rather limits the generalizability of the preventive effect of ready-to-use therapeutic foods to children classified as nonmalnourished by the WHO growth standards.
Isanaka S, Grais RF. Effect of Preventive Supplementation on Young Children in Niger—Reply. JAMA. 2009;301(21):2208-2209. doi:10.1001/jama.2009.741