Connective tissue diseases: evaluation of clinical response

Systemic connective tissue diseases (CTDs) are disease entities characterized by a systemic and heterogeneous spectrum of clinical symptoms. The treatment of CDTs has improved substantially, but with the developments of new and probably more expensive targeted therapies, there will be a need of rigorous evaluation in patient-oriented research. Proposed domains for outcome measurement of CTDs are activity, damage by disease and/or medications and quality of life. To evaluate the overall disease activity in CTDs, scores are developed that include typical signs and symptoms. For example, in systemic lupus erythematosus (SLE), various activity instruments have been developed and validated. Recently, a definition for significant reduction in activity based on these scores was proposed and has now to be validated in clinical trials. In addition, the American College of Rheumatology has framed recommendations for response criteria of major target organs. Besides, the rarity of CTDs other than SLE and the rare therapeutic options, especially the heterogeneous disease expression, has prevented development of instruments scoring the disease activity. In individual patients, there is need for a more organ-specific evaluation, and non-disease-specific and/or global health instruments may be used in evaluating the response of individual treatment regimen.