Concomitant methotrexate has little effect on clinical outcomes of abatacept in rheumatoid arthritis: a propensity score matching analysis.

OBJECTIVE: To compare the clinical outcomes of abatacept between rheumatoid arthritis patients with and without concomitant methotrexate (MTX) treatment in daily clinical practice. METHODS: A retrospective cohort study was performed using data from a multicentre registry. A total of 176 consecutive rheumatoid arthritis patients treated with abatacept were included. The propensity score based on multiple baseline characteristic variables was calculated, and 41 of 86 patients treated without MTX (MTX(-)) and 41 of 90 patients treated with concomitant MTX (MTX(+)) were statistically extracted and analysed. Clinical outcomes were evaluated and compared between the two groups over a 52-week period. RESULTS: Baseline characteristics were statistically comparable. No significant differences were observed in the following clinical outcomes from baseline throughout the 52-week period: drug retention rate (MTX(-)/MTX(+) 79.1%/80.5%), mean change in disease activity score based on 28 joints (DAS28-CRP) from baseline (- 1.35/- 1.54), low disease activity rate (48.8%/43.9%), clinical remission rate (31.7%/36.6%), moderate European League Against Rheumatism (EULAR) response rate (68.3%/68.3%), and good EULAR response rate (36.6%/41.1%) at 52 weeks. CONCLUSION: In rheumatoid arthritis patients with similar background characteristics undergoing abatacept treatment, concomitant MTX does not seem to affect clinical outcomes. Abatacept would be a suitable treatment option in daily clinical practice in patients with contraindications to MTX. KEY POINTS: • This is the first study to directly compare the clinical efficacy and safety of abatacept between patients with and without concomitant methotrexate (MTX) treatment in 'real-world' settings using the propensity score matching method. • There were no significant differences in clinical outcomes of abatacept between patients with and without concomitant MTX treatment. • We used data from a large Japanese multicentre registry for biologics in rheumatoid arthritis, thereby decreasing selection bias based on the personal preferences of physicians.