To examine the frequency of 6 definitions for remission and 4 definitions for low disease activity (LDA) after starting a disease-modifying antirheumatic drug (DMARD) in patients with rheumatoid arthritis (RA) in clinical practice, and to study whether predictors for achieving remission after 6 months are similar for these definitions.
Remission and LDA were calculated according to the 28-joint Disease Activity Score (DAS28), the Clinical Disease Activity Index (CDAI), the Simplified Disease Activity Index (SDAI), the Routine Assessment of Patient Index Data (RAPID3), and both the American College of Rheumatology (ACR)/European League Against Rheumatism (EULAR) Boolean remission definitions 3 and 6 months after 4992 DMARD prescriptions for patients enrolled in the NOR-DMARD, a 5-center Norwegian register. Prediction of remission after 6 months was also studied.
After 3 months, remission rates varied between definitions from 8.7% to 22.5% and for LDA from 35.5% to 42.7%, and increased slightly until 6 months of followup. DAS28 and RAPID3 gave the highest and ACR/EULAR, SDAI, and CDAI the lowest proportions for remission. Positive predictors for remission after 6 months were similar across the definitions and included lower age, male sex, short disease duration, high level of education, current nonsmoking, nonerosive disease, treatment with a biological DMARD, being DMARD-naive, good physical function, little fatigue, and LDA.
In daily clinical practice, the DAS28 and RAPID3 definitions identified remission about twice as often as the ACR/EULAR Boolean, SDAI, and CDAI. Predictors of remission were similar across remission definitions. These findings provide additional evidence to follow treatment recommendations and treat RA early with a DMARD.