Objective: To prospectively evaluate the safety and efficacy profile of abatacept in patients with rheumatoid arthritis–associated interstitial lung disease (RA-ILD). Methods: We performed a prospective observational multicenter study of a cohort of patients with RA-ILD treated with abatacept between 2015 and 2021. Patients were evaluated using high-resolution computed tomography and pulmonary function tests at initiation, 12 months, and the end of follow-up. The effectiveness of abatacept was evaluated based on whether ILD improved, stabilized, progressed, or was fatal. We also evaluated factors such as infection, hospitalization, and inflammatory activity using the 28-joint Disease Activity Score with the erythrocyte sedimentation rate (DAS28-ESR). Cox regression analysis was performed to identify factors associated with progression of lung disease. Results: The study population comprised 57 patients with RA-ILD treated with abatacept for a median (IQR) of 27.3 (12.2–42.8) months. Lung disease had progressed before starting abatacept in 45.6% of patients. At the end of follow-up, lung disease had improved or stabilized in 41 patients (71.9%) and worsened in 13 (22.8%); 3 patients (5.3%) died. No significant decreases were observed in forced vital capacity (FVC) or in the diffusing capacity of the lung for carbon monoxide (DLCO).The factors associated with progression of RA-ILD were baseline DAS28-ESR (OR [95% CI], 2.52 [1.03–3.12]; p = 0.041), FVC (OR [95% CI], 0.82 [0.70–0.96]; p = 0.019), and DLCO (OR [95% CI], 0.83 [0.72–0.96]; p = 0.018). Only 10.5% of patients experienced severe adverse effects. Conclusion: Pulmonary function and joint inflammation stabilized in 71% of patients with RA-ILD treated with abatacept. Abatacept had a favorable safety profile.
