A disease activity index: its use in clinical trials and disease assessment in patients with rheumatoid arthritis.

Measuring disease activity is important in the assessment of patients with rheumatoid arthritis (RA). The value of composite indices in determining activity is discussed. A validated index, the Stoke index, has been used in clinical trials of combination therapy in patients with RA, both to evaluate efficacy and to stratify response to single-agent therapy before randomization to combination treatment. Disease activity determines the use of disease-modifying antirheumatic drugs. Should these drugs be used in mild RA when disease activity is low? Results of a study comparing hydroxychloroquine with placebo in this situation suggest that they should. Finally, the outcome of suppressing disease activity over a 5- to 10-year period is unknown. Measured either radiologically or functionally, preliminary data suggest that the lower the mean disease activity over time, the more favorable the outcome.