Abstract
Objective: Interstitial lung disease（ILD）is a serious complication that can affect the prognosis for with rheumatoid arthritis（RA）patients, but appropriate treatment has not been established to address this issue. This study aimed to clarify the efficacy and safety of Janus kinase inhibitors （JAKi）in RA patients with ILD.
Methods: This non-interventional observational study included 26 RA patients with ILD complications who were treated with JAKi. ILD was evaluated by changes in computed tomography（CT）scores（fibrosis and ground-glass opacity [GGO]）12 months after JAKi initiation. The safety evaluation items were acute exacerbation of ILD and severe infections requiring hospitalization.
Results: In total, 17 patients were able to continue JAKi for over 12 months, while 9 discontinued. f these 17 patients, 12 patients were analyzed using CT scores. The CT-GGO scores were significantly decreased, but the CT-fibrosis scores remained steady throughout the 12 months. （p=0.037 and p=0.813, respectively）. The DAS28-CRP and prednisolone dosage were significantly decreased from the initiation to 12 months later（p<0.001 and p=0.031, respectively）. Among the 26 patients, no exacerbation of existing ILD and two infections（same patient）requiring hospitalization were observed（6.4/100 person-year）.
Conclusion: Although this study has several limitations, such as a small sample size and limited observation period, the results support that JAKi may be a therapeutic option for RA-ILD patients due to its efficacy for arthritis and safety.
