Randomized Clinical Trials
In a Randomized Clinical Trial (RCT), a group of patients is randomized into an experimental group and a control group. These groups are followed up for the variables or outcomes of interest. A RCT is, after meta-analysis, the highest form of evidence. Advantages are the unbiased distribution of confounders and the randomization, which facilitates statistical analysis. Disadvantages are the time, expense, and ethical problems in indications with an established therapy standard different from placebo.