Real-world comparative effectiveness study of Janus kinase inhibitors compared to biologic disease-modifying antirheumatic drugs in Korean patients with rheumatoid arthritis

Objectives: To evaluate the real-world effectiveness and safety of Janus kinase inhibitors (JAKis) compared to biologic disease-modifying antirheumatic drugs (bDMARDs) in Korean patients with rheumatoid arthritis (RA) who have not previously been treated with either JAKis or bDMARDs. Methods: This prospective, multicenter, observational study was conducted at 17 centres in the Republic of Korea. Patients with an inadequate response to methotrexate were enrolled and started treatment with either JAKis or bDMARDs. The primary endpoint was the proportion of patients achieving low disease activity (LDA) at 24 weeks, measured by the disease activity score (DAS) 28-erythrocyte sedimentation rate (ESR). Secondary endpoints included the remission rate at 24 weeks, and LDA and remission rates at 48 weeks. Safety was assessed by the exposure-adjusted event rate (EAER) of adverse events (AEs), adjusted for length of the follow-up period and presented per 100 person-years. Results: A total of 506 patients were enrolled, with 253 patients in each group. Among bDMARD users, 60.1 % received tumour necrosis factor inhibitors (TNFis; n = 152) and 39.9 % received non-TNFis (n = 101). At 24 weeks, 48.2 % of the JAKi group achieved LDA, as did 42.7 % of the bDMARD group. Remission rates at 24 weeks were 28.9 % for the JAKi group and 27.3 % for the bDMARD group. At 48 weeks, there were no significant intergroup differences in the EAER of overall AEs. Conclusions: In this observational real-world study of Korean patients with RA who were eligible for targeted therapy, JAKis demonstrated comparable effectiveness and safety to bDMARDs.