To assess the 6-month effectiveness of the first rituximab (RTX) course in rheumatoid arthritis (RA) and to identify possible predictors of response.

10 European registries submitted anonymised datasets (baseline, 3- and 6-month follow-up) from patients with RA who had started RTX, and datasets were pooled and analysed. Heterogeneity between countries was analysed by analysis of variance. Predictors of response were identified by logistic regression.

2019 patients were included (mean age/disease duration 53.8/12.1 years, 80.3% female, 85.6% rheumatoid factor (RF) positive and 76.8% (456/594 patients) anti-cyclic citrullinated peptide antibodies (anti-CCP) positive). For these patients an average of 2.7 disease-modifying antirheumatic drugs (DMARDs) (range 0–10) had failed, and RTX was given as the first biological agent in 36.6% of patients. There was significant heterogeneity between countries for several baseline characteristics, including the number of previous biological agents. Disease Activity Score based on 28 joint counts (DAS28) decreased from 5.8±1.4 at baseline to 4.2±1.4 at 6 months (p<0.0001) and 22.2%/42.5% achieved European League Against Rheumatism (EULAR) good/moderate response. Larger 6-month improvement in DAS28 was observed in RF-positive and anti-CCP-positive versus seronegative patients. The following predictors of EULAR good response at 6 months were identified in a multivariate analysis: anti-CCP positivity (OR=2.86, p=0.003), number of previous DMARDs (OR=0.84, p=0.06), ≤1 previous biological agents (OR=1.89, p=0.04), baseline DAS28 level (OR=0.74, p=0.003).

In this large observational cohort of patients with RA treated with RTX, seropositive patients achieved significantly greater reductions in DAS28 at 6 months than seronegative patients. Effectiveness was best when RTX was used as the first biological agent or after failure of no more than one anti-tumour necrosis factor agent.