[From the explanatory to the pragmatic].

The classical methodology of clinical trials has been conceived for improving scientific knowledge in therapeutic research. This methodology is often unsuitable for evaluating a treatment in clinical practice, i.e. taking into account all its advantages and disadvantages. For that very reason two approaches, explanatory and pragmatic, which differ in many aspects, were developed during the 1970's. This distinction is very useful in the design of a trial, but two main difficulties are related to the assessment criteria and the method of analysis. A possible solution is to use the decision-making procedures but it's still a research problem.