C103-21 Real-World Experience With Antifibrotic Therapy in Idiopathic and Progressive Pulmonary Fibrosis: Insights From a Decade of Interstitial Lung Disease Care at a Tertiary Centre

Abstract Background Antifibrotic agents such as pirfenidone and nintedanib slow disease progression in idiopathic pulmonary fibrosis (IPF) and progressive pulmonary fibrosis (PPF). However, treatment-related adverse events (AEs) often limit their use through dose reductions, interruptions, or discontinuation. Objective To evaluate the real-world use and tolerability of antifibrotic therapy in patients with IPF and PPF attending the interstitial lung disease (ILD) service at our tertiary centre. Methods We conducted a retrospective review of electronic medical records for patients attending the ILD clinic at Cork University Hospital between 2014 and 2025. Data collected included diagnosis (IPF or PPF), antifibrotic agent initiated, and treatment outcomes including dose adjustments, drug switches, and discontinuation due to AEs. Results A total of 518 patients were treated with antifibrotic therapy (IPF 70%, PPF 30%). Nintedanib was initiated in 60% (n = 312) and pirfenidone in 40% (n = 206). Among those on nintedanib, 7% (n = 22) required dose reductions, 8% (n = 24) discontinued therapy, and 21% (n = 66) switched to pirfenidone, most commonly due to gastrointestinal symptoms (18%, n = 55) and liver enzyme elevations (9%, n = 27). Among those started on pirfenidone, 5% (n = 10) required dose reductions, 5% (n = 11) discontinued therapy, and 19% (n = 40) switched to nintedanib, mainly due to gastrointestinal symptoms (9%, n = 19) and rash (6%, n = 13). Of those switched from pirfenidone to nintedanib, 23% (n = 9) required further dose reduction and 18% (n = 7) discontinued treatment due to AEs. Among those switched from nintedanib to pirfenidone, 11% (n = 7) required dose reduction and 26% (n = 17) discontinued therapy due to AEs. Conclusion In this large real-world cohort, antifibrotic therapy was frequently limited by tolerability issues, with gastrointestinal AEs being the most common. Our findings are consistent with prior observational studies, including the PASSPORT study, which highlighted discontinuation rates approaching 30%, with nausea, weight loss, and rash being the commonest reasons for discontinuation. Further strategies to mitigate AEs and improve treatment adherence are warranted to optimize long-term outcomes in IPF and PPF. This abstract is funded by: None