Long-term sustained remission in a cohort study of patients with rheumatoid arthritis: choice of remission criteria

OBJECTIVES Remission is a widely accepted goal for treatment of rheumatoid arthritis (RA) but has to be sustained to arrest joint damage and disability. However, appropriate criteria for the assessment of sustained remission in long-term studies are not established. Therefore, we have compared the disease activity score calculated on 28 joints (DAS28) remission criterion, the Simplified Disease Activity Index less than 3.3 remission criterion (SDAI Cr) and the new Boolean-based set of criteria (Boolean Cr), and assessed the association of these criteria with radiographic and functional outcome. DESIGN Prospective, long-term observational study of patients with early RA. SETTING Secondary level of care; six participating centres from southern Sweden; both urban and rural populations. PARTICIPANTS 698 patients were consecutively included in the study and 527 remained at the 8-year follow-up visit. Almost all patients were Caucasians, of which 64% were women. To be included, a patient, 18 years or older, had to fulfil the 1987 American College of Rheumatology criteria for RA and have a disease duration of no more than 1 year. RESULTS Sustained remission was most common by the DAS28 Cr (14%), while 3% met the Boolean Cr and 5% the SDAI Cr, the latter figures increasing to 9% and 8%, respectively, when the patient's global assessment was excluded. Radiographic joint damage was common but least pronounced in patients in sustained remission by all criteria. Sustained remission was associated with rapid and lasting improvement in function assessed by the Health Assessment questionnaire, irrespective of criteria. CONCLUSIONS The DAS28 Cr acquired more patients in sustained remission compared with the other criteria. In spite of that, radiographic damage and disability were not worse than that seen by other criteria and the patients' perspective was preserved. The DAS28 Cr may therefore still be used in long-term observational studies until more accurate criteria are available.