Prevalence of sustained remission in rheumatoid arthritis: impact of criteria sets and disease duration, a Nationwide Study in Sweden.

Objectives: The aims of this national study in Sweden of patients with RA were to: examine the prevalence of sustained remission (SR), that is, remission lasting for at least 6 months; compare the prevalence of SR in patients with early RA and established RA; study the timing of onset of and time spent in SR; and study possible predictors of SR.
Methods: Adult patients with RA included in the Swedish Rheumatology Quality registry were studied. The registry was searched for patients fulfilling remission criteria: DAS28-ESR, Clinical Disease Activity Index (CDAI), Simplified Disease Activity Index (SDAI) and ACR/EULAR remission for at least 6 months. Early RA was defined as symptom duration ⩽6 months at inclusion in the Swedish Rheumatology Quality.
Results: Of 29 084 patients, 12 193 (41.9%) reached DAS28 SR at some time point during follow-up compared with 6445 (22.2%), 6199 (21.3%) and 5087 (17.5%) for CDAI, SDAI and ACR/EULAR SR, respectively. SR was more common in early RA (P < 0.001). The median time from symptom onset to SR was 1.9, 2.4, 2.4 and 2.5 years according to DAS28, CDAI, SDAI and ACR/EULAR criteria, respectively. Lower age, male sex and milder disease characteristics were associated with SR.
Conclusion: The majority of patients in this nationwide study never reached SR. Patients with early RA are more likely to reach SR than patients with established RA.