Randomized Controlled Trials: The case of Multiple Sclerosis - Refining the constraints of a treasure, a short outline
Randomized controlled trials (RCTs) are the most valid methodological tool for establishing causal relationships. Nevertheless, their validity is constrained by various methodological details concerning their design, conduction and implementation. Failure of successful randomization, absence of correction for multiple comparisons, use of noisy scales for measuring a disease parameter, are a few of these constraints. Furthermore, there are constraints inherent in the scientific research methodology, like the use of the p-value as a threshold of statistical significance and in succession of inferential reasoning, as a threshold of truth. In this work, the examples of RCTs illustrating these limitations are drawn from the field of multiple sclerosis (MS). In general, RCTs in MS mostly are well designed, adequately powered, and well conducted. Nevertheless, sometimes there are exceptions, leading to false conclusions and steering clinical practice toward wrong choices.