Retention Rates of Biological Disease‐Modifying Antirheumatic Drugs in Patients With Rheumatoid Arthritis and Reduced Kidney Function: Analysis From the <scp>IORRA</scp> Cohort

ABSTRACT Introduction To compare the retention rate, hazard ratio of treatment discontinuation, and effectiveness of tumor necrosis factor inhibitor (TNFi), interleukin‐6 inhibitor (IL‐6i), and cytotoxic T lymphocyte‐associated antigen‐4‐Ig (CTLA4‐Ig) in patients with rheumatoid arthritis (RA) and reduced kidney function. Methods We analyzed data from patients with RA and reduced kidney function included in the large‐scale, real‐world observational cohort study in Japan. Patients who initiated treatment with biological disease‐modifying antirheumatic drugs (bDMARDs) between 2003 and 2018 were selected. Reduced kidney function was defined as an estimated glomerular filtration rate of &lt; 60 mL/min/1.73 m 2 . Drug retention, disease activity, and physical function were compared during the observational period using inverse probability of treatment weighting (IPTW). Results The study included 154 patients with 237 treatment courses. The overall drug retention rate was 54.6% at 3 years, while the individual rates of TNFi, IL‐6i, and CTLA4‐Ig were 54.9%, 61.1%, and 44.3%, respectively. Retention rates due to ineffectiveness were 72.4%, 67.7%, and 49.3%, and due to adverse drug reactions were 76.2%, 90.3%, and 89.9%, respectively. Adjusted hazard ratios of discontinuation were 0.85 (95% confidence interval [CI], 0.37–1.96) for IL‐6i and 1.31 (95% CI, 0.63–2.73) for CTLA4‐Ig compared to TNFi. After IPTW, mean scores for the clinical disease activity index and the Japanese version of the health assessment questionnaire at 3 years were similar across the three groups. Conclusion The drug retention rates and effectiveness of bDMARDs with different modes of action were comparable in patients with RA and reduced kidney function.