TArget Trial Emulation Comparing Effectiveness of Tocilizumab vs Methotrexate In Corticosteroid-Treated GCA Patients

Study Design and Data Source This study is a retrospective nationwide cohort study using the SNDS database covering approximately 99% of the French population. We emulated a hypothetical randomized trial comparing two treatment strategies: initiation of tocilizumab versus methotrexate within 6 months after hospital discharge for incident giant cell arteritis. Eligible patients aged ≥50 years hospitalized for incident GCA between 2012 and 2024 were included. Statistical Analysis A clone-censor-weight approach was used to account for treatment initiation timing and avoid immortal time bias. Inverse probability of censoring weights were applied to adjust for informative censoring. Treatment effects were estimated using weighted Kaplan-Meier methods and Cox proportional hazards models. Outcomes The primary outcome was the occurrence of major adverse cardiovascular events (MACE), defined as myocardial infarction, ischemic stroke, or all-cause death. Secondary outcomes included individual cardiovascular components, aortic events, and major vascular relapse. Regulatory Compliance This study was conducted using the SNDS through the permanent access granted to Assistance Publique - Hôpitaux de Paris (AP-HP), in accordance with French Decree No. 2016-1871 and French Public Health Code (Art. R. 1461-13 and 14). The study was registered in the AP-HP internal registry of research projects before initiation. In compliance with the GDPR and French regulations, individual informed consent was not required as all data were fully anonymized