Safety and effectiveness of abatacept in Japanese non-elderly and elderly patients with rheumatoid arthritis in an all-cases post-marketing surveillance

<b>Objectives:</b> To investigate the safety, effectiveness, and risk-benefit balance of intravenous abatacept (ABA) in non-elderly (&lt;65 years: NEG) and elderly (≥65 years: EG) rheumatoid arthritis patients. <b>Methods:</b> This sub-analysis of an all-cases postmarketing surveillance in Japan assessed safety in all enrolled patients and effectiveness in those with Disease Activity Score 28 based on C-reactive protein (DAS28-CRP) measurements at ≥2 time points including baseline. Risk-benefit was evaluated based on infections and DAS28-CRP improvement &gt;1.2. <b>Results:</b> The NEG and EG of the safety analysis set comprised 2,170 and 1,712 patients, respectively; corresponding 6-month ABA retention rates were 80.2% and 77.1%. The NEG had fewer adverse drug reactions (14.5% vs. 17.2%, <i>p</i> = .021) and infections (4.8% vs. 7.2%, <i>p</i> = .002) than the EG. DAS28-CRP changed similarly between groups. The proportion of patients with low-risk/high-benefit and high-risk/low-benefit were 33.1% and 6.9% (NEG) and 29.7% and 9.0% (EG). Low-risk/high-benefit patients were younger, had shorter disease duration and fewer comorbidities, and were with less use of oral glucocorticoid and prior biologics, more use of methotrexate and higher DAS28-CRP than high-risk/low-benefit patients at baseline. <b>Conclusion:</b> ABA was well tolerated and similarly efficacious in the EG and NEG. Identification of factors related to low-risk/high-benefit may aid appropriate patient selection.