The 'natural' history of active rheumatoid arthritis over 3-6 months--an analysis of patients enrolled into trials of potential disease-modifying anti-rheumatic drugs, and treated with placebo.
The natural history of RA over a period of 6 months is not known, but this is of central importance to the design and interpretation of drug trials of possible DMARDs. We analysed the disease activity of 142 rheumatoid patients who were randomized to receive placebo in five double blind, placebo-controlled trials of possible disease-modifying drugs conducted in a single unit. There was no significant change in ESR, duration of morning stiffness or platelet count over a period of 6 months; the mean change in ESR at 3 months was an increase of 2 mm/h (99% C.I. -3, +7), and only 5% of patients more than halved their ESR over 6 months. There was a small significant fall in articular index over 6 months of placebo treatment. There is no measurable placebo effect on ESR, morning stiffness or platelet count when these are used as measures of disease activity in trials of drug therapy in RA. ESR is an informative, stable measure of disease activity; the duration of morning stiffness may be more useful than the articular index. The use of these results as the basis of a historical cohort to help design future placebo-controlled trials, and to interpret uncontrolled trials of putative anti-rheumatic drugs is discussed.