Assessing remission in clinical practice

Remission constitutes the best achievable state in patients with rheumatoid arthritis. We aimed at evaluating sustained remission in a large cohort of patients followed prospectively in clinical practice and to evaluate available instruments to define remission for their stringency in defining this state.

We analysed remission and sustained remission in 621 patients who had two consecutive and complete clinical observations; the average period between the two visits was 92 days (median; quartiles: 82; 105). Remission was evaluated according to modified ACR (mACR), 28 Joint Disease Activity Score (DAS28), Simplified Disease Activity Index (SDAI) and Clinical Disease Activity Index (CDAI) criteria. Sustained remission was defined as remission at both consecutive visits. Patients were treated with traditional disease- modifying antirheumatic drugs, mainly methotrexate, and partly with biological agents (approximately 11%).

Remissions at any one of the two visits were seen in 33.5% of patients by SDAI or CDAI, 42.7% by DAS28, and 38.6% by mACR criteria (P < 0.01). Sustained remission was observed in much lower proportions of patients (between 16.7 and 19.6%, dependent on the instrument). Agreement between classifications of remission by kappa-statistics was very good for SDAI vs CDAI, good for DAS28 vs SDAI or CDAI, and only moderate for mACR vs the three other scores. Residual swollen joints were observed in 15% of patients in DAS28 remission (range 1-9), 6% of patients in mACR remission (range 1-8), but only approximately 5% of patients in CDAI or SDAI remission (range 1-2) (P < 0.01).

Sustained remission can be observed in 17-20% of patients in clinical practice. CDAI and SDAI remission criteria are more stringent than DAS28 and mACR criteria, since they allow for lesser residual disease activity. Consequently, smaller proportions of patients are classified as in remission by SDAI and CDAI than by DAS28 and mACR criteria. Sustained remission is an achievable goal in clinical practice even with the most stringent of the definitions studied.