[A methodology for clinical trials in parenteral nutrition]

Recent and progressive knowledge on parenteral nutrition has not been accompanied by due attention to the methodology for clinical testing in this therapeutical field. Although many different laws, guidelines or norms do exist which can be applied to any clinical test, in the case of parenteral nutrition several characteristic aspects arise that should be taken into account in the design of clinical tests. This review places special emphasis on the definition of clinical testing, the role of the researcher and the ethical, methodological and design-related requirements to be considered when preparing a protocol for study. Not only is the importance of the selection and the size of the sample mentioned, but also the different variables normally used in parenteral nutrition. The correct follow-up, measurement, evaluation and statistical analysis of these variables makes it possible to reach valid conclusions, and provide the basic information for later study. The application of ethical norms and the control of adverse conditions guarantees the correct undertaking of this type of clinical research.