Status versus changes, onset of action, and sustainability--how do we define and present these concepts in clinical trial reports in rheumatology?

Since the main objective of therapies in rheumatology is not only to improve the patient condition but also to prevent a further disability and because of the emergence of new and very effective therapies, the outcome measures used to evaluate treatments in rheumatology have been revisited. The major changes are that in addition to the concept of improvement (achievement of a relevant level of change), other concepts have been recognized as important, such as status (achievement of an acceptable condition), onset of action (the quickest is the better), and sustainability. In order to evaluate these concepts, new tools have been recently elaborated (for example, the ACR-EULAR remission criteria in rheumatoid arthritis) and several statistical approaches can be used for an optimal presentation of the data observed in clinical trials (in particular to assess the concepts of onset of action and sustainability).