Efficacy and safety of baricitinib in rheumatoid arthritis patients with moderate renal impairment: a multicenter propensity score matching study

This study aimed to compare the efficacy and safety of baricitinib in patients with rheumatoid arthritis (RA) receiving different doses based on renal function. We conducted a retrospective study within the JAK Study Group, involving 23 facilities in Fukuoka Prefecture, examining patients treated with baricitinib for RA. Patients were categorized into two dose groups: 4 mg with normal/mild renal dysfunction and 2 mg with moderate renal dysfunction. Baricitinib's efficacy, retention rate, and safety were compared between the groups after propensity score matching. After propensity score matching, disease duration, methotrexate dosage, and anti-cyclic citrullinated peptide antibody positivity rate were balanced across 33 patients in both groups. No significant differences were observed between the groups in tender/swollen joint counts, changes in evaluator/patient global assessments, achievement rate of low disease activity, remission rate on clinical/simplified disease activity indices, or retention rate. Additionally, the incidence of adverse events aligned with previous reports, indicating similar drug safety profiles. Baricitinib 2 mg in RA patients with moderate renal dysfunction showed comparable efficacy and retention rate to 4 mg in patients with normal/mild renal dysfunction. The incidence and types of adverse events were consistent with previous studies, indicating the safety of the drug at these dosages.