Simplified Disease Activity Index remission at month 6 is an independent predictor of functional and structural remissions at month 12 during abatacept treatment in patients with rheumatoid arthritis: A multi-center, prospective cohort study in Japan

OBJECTIVE: To evaluate association of clinical remission at month 6 with functional and structural remissions at month 12 during abatacept treatment in patients with rheumatoid arthritis (RA). METHODS: This 12-month prospective, multicenter cohort study enrolled 168 patients with RA who started abatacept. Outcomes were assessed using composite measures, quality of life indices, and the van der Heijde-modified total Sharp score (mTSS). The logistic regression analysis was applied to identify factors associated with outcomes and their odds ratios (OR) with 95% confidence interval (95% CI). RESULTS: At month 6 and 12, 21.4% and 26.2% of the patients achieved Simplified Disease Activity Index (SDAI) remission (SDAI <3.3), and 40.6% and 41.7% achieved Health Assessment Questionnaire-Disability Index (HAQ-DI <0.5) remission. Among 129 patients whose mTSS progression was evaluated at month 12, 83 (64.3%) achieved structural remission (ΔmTSS ≤0.5 for 12 months). SDAI remission at month 6 was identified as a significant predictor of both functional (OR, 3.732; 95% CI, 1.328-10.489) and structural remissions (OR, 4.301; 95% CI, 1.298-14.243) at month 12 after adjusting for covariates. CONCLUSIONS: Aiming for SDAI remission at month 6 is an appropriate strategy to obtain good functional and structural outcomes at month 12.