[Methods in equivalence and non-inferiority trials]

The randomized clinical trial (RCT) is accepted as the best method for comparing therapeutic effects. Most RCTs are superiority trials that aim to show that a new therapy is superior to a control therapy. However, some RCTs are equivalence trials or non-inferiority trials. Their aim is to show that a new therapy is equivalent to or at least not inferior to the control therapy. The various types of trials differ significantly in terms of methodology. Few are aware of these differences. This paper reviews the methodology of these trials with a particular focus on planning, performance, analysis and reporting of the trial.