Minimal disease activity, remission, and the long-term outcomes of rheumatoid arthritis

Objective. To determine the prevalence of minimal disease activity (MDA) and remission in patients with rheumatoid arthritis (RA), to assess the effect of anti-tumor necrosis factor (anti-TNF) therapy on MDA, and to determine the extent to which MDA status improves long-term outcomes. Methods. Using the Patient Activity Scale (PAS) as a surrogate, we assessed the prevalence of MDA and remission in 18,062 patients with RA using the newly developed Outcome Measures in Rheumatology Clinical Trials (OMERACT) criteria for MDA. Results. MDA was noted in 20.2% of 18,062 patients and persistent MDA, operationally defined as having MDA during ≥2 consecutive 6-month observation periods, occurred in 13.5% of 7,433 patients followed longitudinally. Disease activity at remission levels was noted in 7%. Among patients with MDA, 82% received disease-modifying antirheumatic drugs or biologic agents. Following anti-TNF initiation, the cumulative probability of achieving MDA at 2 and 6 years was 4.1% and 7.6%, respectively, and persistent MDA probabilities were 2.7% and 4.5%, respectively. Regardless of RA duration, patients with MDA had substantially better outcomes, including a 10-fold reduction in work disability and an approximately 2-fold reduction in total joint replacement and mortality. Conclusion. Remission remains uncommon in RA, and the prevalence of new remission in community practice is substantially lower than noted in published trials of biologic therapy. On average, persons with MDA appear to have persistently mild RA. This might be the effect of milder RA and/or more effective treatment in early RA. The PAS had satisfactory levels of agreement with the full MDA criteria and appears suitable for use in clinical and epidemiologic research.