The new criteria are designed to provide information that can be used in clinical trials, as well as a goal towards which rheumatologists and their patients can aspire.
Remission Defined
The committee overseeing the development of the new criteria—which included members of the ACR, EULAR, and OMERACT—specified that the definition should be stringent, with little, if any, active disease. A key goal was for the criteria to predict good X-ray and functional outcomes. To achieve that end, the committee compared candidate definitions with clinical trial data.
The committee actually came up with two definitions for RA remission, “but we ask in the paper that one be selected in advance for any study and that both be reported,” says Dr. Felson, adding that the two definitions are “very similar to each other.” One definition specifies that scores be less than or equal to 1 for tender joint count, swollen joint count (both using the 28-joint count), C-reactive protein (in mg/dL), and patient global assessment (0–10 scale). “As rheumatoid arthritis often targets the feet, we recommend doing full joint counts; however, we also found that limited [28] joint counts can perform acceptably in trials,” says Dr. Boers.
The second definition is a score of 3.3 or less on the simple disease activity index (SDAI) for RA. The SDAI includes tender and swollen joint count (based on a 28-joint assessment), patient and physician global assessment of disease activity on a scale of 1–10, and C-reactive protein (mg/dL).
The committee came up with two definitions for RA remission, but we ask in the paper that one be selected in advance for any study and that both be reported.
—David Felson, MD, MPH
Limitations of the New Criteria
While the new criteria do set a standard definition of RA remission that can be widely applied to clinical trials, they do have some limitations and highlight areas where more research and data are needed.
For example, patient groups, including the patient perspective group within OMERACT, and other stakeholders have emphasized the importance of fatigue as an outcome and have recommended that it be reported in clinical trials. However, there were no data on fatigue that could have shown how it would perform as part of the criteria, Dr. Boers says. Therefore, fatigue was not used to derive the remission criteria. “Other measures patients feel are important include sleep quality, which currently is imperfectly measured.” Dr. Boers emphasizes that such measures may become very informative in the near term.
