Evaluation of established rheumatoid arthritis.

There are two major aspects to evaluate in patients with established RA, namely (i) the state or progress of the disease, and (ii) the effects of specific interventions. The evaluation should include reliable, valid and sensitive measures of disease activity, tissue damage and health status. It is important to recognise that measures of disease activity can be influenced by tissue damage as well. Also, in established RA, health status is likely to be influenced by both disease activity and tissue damage. Whether current rules concerning improvement or remission, which were developed in the context of early RA, can be applied to established disease has to be investigated. While use of radiographs is the current standard method of assessing damage in established RA, range-of-motion measures and muscle strength indices may be a more practical and an equally valid alternative. When selecting health status instruments one should carefully explore and pretest possible health status measures for specific clinical or study settings.