Background/Purpose: Criteria for remission in rheumatoid arthritis (RA) have been developed according to DAS28 (disease activity score), CDAI (clinical disease activity index), and two recent proposals by an American College of Rheumatology/European League Against Rheumatism (ACR/EULAR) committee: “Boolean” with 4 measures – tender joint count (TJC28), swollen joint count (SJC28), C-reactive protein (CRP), and patient global estimate (PATGL), all ≤1; and SDAI (simplified disease activity index). All require formal joint counts, which are not performed at most visits in usual care, and all but CDAI require a laboratory test, which often is not available. Therefore, we explored 4 descriptions of remission for usual care, based on RAPID3 (routine assessment of patient index data), a composite index including function, pain and PATGL – without a laboratory test or formal joint count, but with a careful joint examination and physician global estimate (DOCGL; 0-10 scale).

Methods: The ESPOIR cohort includes 756 patients recruited between Dec 2002 and March 2005. Post hoc analyses were performed to identify the number of patients in remission 6 months after enrollment according to 4 descriptions requiring a formal joint count (and 3 a laboratory test): DAS28 ≤2.6, CDAI ≤2.8, and the two proposed by the ACR/EULAR committee – Boolean ≤1 for TJC28, SJC28, CRP and PATGL; and SDAI ≤3.3. Four descriptions based on RAPID3 that require neither a laboratory test nor formal joint count, but a careful joint examination and DOCGL were evaluated, “RAPID3R” (RAPID3 ≤3.0), and three more stringent descriptions: “RAPID3R+J1” (RAPID3 ≤3.0 and £1 swollen joint; if >1 swollen joint, the criterion is not met); “RAPID3R+J1D1” (RAPID3 ≤3.0 and £1 swollen joint and DOCGL ≤1); and “RAPID3R+J0D1” (RAPID3 ≤3.0 and no swollen joint and DOCGL ≤1). Agreement of all 7 descriptions with the ACR Boolean definition was assessed using kappa statistics.

Results: Among the 756 ESPOIR patients, 734 had complete 6-month data to calculate all 8 descriptions. The highest percentage of patients in remission was seen with DAS28 and RAPID3R, the least stringent descriptions, and the lowest percentage with the Boolean definition. Good agreement with the Boolean ACR/EULAR definition was seen for SDAI, CDAI, RAPID3R+J1, RAPID3R+J1D1 and RAPID3R+J0D1 (92.6%-94.7%, kappa 0.70-0.79), versus only moderate agreement for DAS28 and RAPID3R (79.9%-85.8%, kappa 0.46-0.55) (Table).

Conclusion: Description of remission according to SDAI, CDAI, RAPID3R+J1, RAPID3R+J1D1 and RAPID3R+J0D1 is similar to Boolean ACR/EULAR, while DAS28 and RAPID3R are less stringent. The more stringent RAPID3-based indices may be useful in usual clinical care, as they require neither laboratory tests nor formal joint counts, but do require a DOCGL and careful joint examination.