Drug retention of TNF versus IL-23 inhibitors in psoriatic arthritis: a multicenter real-life cohort study

bstract Background: Psoriatic arthritis (PsA) is a chronic inflammatory disease characterized by musculoskeletal and cutaneous involvement. While TNF inhibitors (TNFi) are commonly used as first-line biologic therapies, treatment failure is frequent. IL-23 inhibitors (IL23i) represent an alternative mechanism of action (MoA), but direct real-world comparisons between these drug classes remain limited. Objectives: To compare the effectiveness of TNFi versus IL23i in real-life PsA patients. Design: This multicenter retrospective observational study is part of the BIRRA (BIologics Retention Rate Assessment) project. Consecutive patients with PsA—classified according to the CASPAR criteria—were screened across 29 Italian rheumatology referral centers. Methods: We analyzed 1418 therapeutic lines for PsA initiated between 2019 and 2024 across 29 Italian rheumatology centers. Treatment lines were categorized as TNFi or IL23i based on the drug’s MoA. Demographic, clinical, and treatment-related data were collected. The primary outcome was treatment retention, evaluated by Kaplan–Meier survival analysis. A Cox proportional hazards model adjusted for a propensity score (PS) was used to account for confounding factors. Results: Among 1418 prescriptions (1270 TNFi; 148 IL23i), IL23i lines were associated with older age, longer disease duration, higher baseline disease activity, and more prior biologic disease-modifying antirheumatic drugs exposure. Despite this, no significant difference in crude retention was observed. After PS adjustment, IL23i prescriptions showed significantly longer treatment retention than TNFi (hazard ratio 0.53; 95% confidence interval: 0.31–0.90; p = 0.02). Axial or mixed PsA phenotype and higher baseline Disease Activity in Psoriatic Arthritis score were associated with lower retention. Conclusion: In this real-world cohort, IL23i prescriptions demonstrated comparable treatment persistence compared to TNFi, even in more challenging clinical scenarios. These findings support the inclusion of IL23i as a valid therapeutic option in PsA. Prospective studies are needed to confirm their positioning in treatment algorithms.