The new ACR/EULAR remission criteria: rationale for developing new criteria for remission.

As more effective treatments for RA have become available, studies have demonstrated that in patients who attained remission, defined as a simplified disease activity index (SDAI) ≤3.3, not only disease activity but radiographic progression was reduced. The feasibility and the benefit of attaining remission led to the development of the ACR/European League Against Rheumatism (EULAR) 2011 remission criteria. These criteria employ either a Boolean definition, including tender and swollen joint counts ≤1, and CRP ≤1 mg/dl, or an index-based definition, SDAI ≤3.3, in combination with patient-reported outcomes on a scale of 0-10. It is expected that the ACR/EULAR criteria will be used as secondary outcomes in clinical trials. Some questions about the implementation of the new criteria include the availability of CRP values, and the possibility that patient-reported outcomes may skew the outcome if patients cannot distinguish other musculoskeletal conditions from RA. Several issues require further study, including the role of imaging, fatigue and the impact of the involvement of joints other than the 28 counted in the ACR/EULAR criteria.