Disease activity measures for rheumatoid arthritis.

Rheumatoid arthritis (RA) is an inflammatory autoimmune and progressive disease. In patients with RA, persistent disease activity ultimately results in irreversible radiographic damage of the joints with persistent functional loss as a consequence. Disease activity measures assess a disease state at a particular time point. In order to evaluate the course of the disease in daily clinical practice or to judge the efficacy of a treatment in a clinical trial, a measure should also comprise the dimension of time. Composite indices provide a comprehensive view of disease activity and include the Disease Activity Score 28, the American College of Rheumatology criteria and newer indices such as the Clinical Disease Activity Index, the Rheumatoid Arthritis Disease Activity Index, and the Simplified Disease Activity Index. The target of RA treatment is to suppress disease activity as completely as possible, with remission being the ultimate goal. The composite index chosen should, therefore, be applicable to the circumstance in which it will be used, with different requirements in clinical practice versus clinical trials. In addition to the choice of an assessment index, novel disease monitoring strategies have been used to optimize treatment and disease control, as in the TICORA and BeST studies. It is clear that the best benefit for the patient can be obtained by combining the optimal treatment strategy and the most appropriate outcome measure. Low disease activity, intensive monitoring, and rapid adjustments in treatment seem to promise the greatest benefit. Further studies are required to better evaluate the clinical relevance of methods for assessing disease activity in patients with RA.