Towards an epidemiology of rheumatoid arthritis outcome with respect to treatment: randomized controlled trials overestimate treatment response and effectiveness.

The results and outcomes of randomized clinical trials of leflunomide and anti-TNF therapy are much better than are seen in rheumatoid arthritis patients in the community. This appears to be an effect of the clinical trial system. The consequence of deriving effectiveness estimates from clinical trials is to overestimate the effectiveness and thereby the cost-effectiveness of rheumatoid arthritis treatments.