Disease-modifying therapy in MS: a critical review of the literature. Part II: Assessing efficacy and dose-response.

The use of so-called evidence-based medicine represents a structured way in which to critically assess the medical literature with the goal of defining the value of different therapeutic interventions and, ultimately, improving both physician decision-making and patient outcome. This is not a consensus-based process of the type that has often been employed previously in the development of treatment guidelines. Rather, these assessments involve a series of structured steps. Initially, the specific clinical questions to be answered are defined and the evidence is assembled following a structured literature search. Then, the individual studies are classified as to the quality of the evidence provided, and, finally, using a set of pre-specified rules, this evidence is translated into specific recommendations and conclusions. In this manner, evidence-based medicine can be a very powerful tool for practicing physicians and, consequently, it is important that they become familiar with the fundamentals of this analytical approach. It is the purpose of this manuscript, therefore, to provide an overview of this process using examples from two recently completed assessments on disease-modifying therapies in multiple sclerosis.