C39-14 Incidence and Outcomes of Progressive Pulmonary Fibrosis Across Multiple Real World Data Sources

Abstract Rationale Progressive pulmonary fibrosis (PPF) describes a subset of patients with interstitial lung disease (ILD) other than idiopathic pulmonary fibrosis (IPF) who experience accelerated lung function decline. The incidence of PPF across ILD subtypes, and the clinical outcomes for affected patients, remain poorly characterized in real world settings. Methods This retrospective observational cohort study included adults with ILD other than IPF who were enrolled in the Pulmonary Fibrosis Foundation Patient Registry (Registry) between 2016-2021 or managed at Duke University Health System (DUHS) between 2016-2022. In both cohorts, PPF was defined as a ≥ 10% relative decline in forced vital capacity (FVC) % predicted within 2 years of baseline, with death and lung transplant considered as competing risks. Baseline was defined as the first observed FVC at DUHS or date of Registry enrollment. Participants were censored one year after last available FVC. Kaplan-Meier estimates were used to describe: 1) cumulative incidence of PPF, stratified by ILD subtype; and 2) risk of death or lung transplant after PPF development. Results The analysis included 3789 patients at DUHS and 668 participants enrolled in the Registry. Across both cohorts, systemic autoimmune rheumatic disease (SARD)-associated ILD was the most common subtype (DUHS: 59.5%; Registry: 45.7%). The median (Q1, Q3) baseline FVC % predicted was lower in the Registry compared to DUHS (66.2% 53.5, 79.6 vs. 77.8% 61.6, 93.2, p 0.001) and non-steroidal immunosuppressive medications were prescribed more frequently (Registry 62.0%; DUHS: 49.3%, p 0.001). By 2 years, PPF was observed in 879 (23.2%) DUHS patients and 187 (28.0%) Registry participants. The cumulative incidence function of PPF differed across ILD subtypes (DUHS p = 0.009; Registry p 0.001), occurring most frequently in patients with hypersensitivity pneumonitis in both cohorts (Figure). Competing risks of either death or lung transplant occurred in 309 DUHS patients (8.2%) and 65 Registry participants (9.7%). Following PPF development, the cumulative incidence of death or lung transplant at 1 and 3 years was 18.9% and 35.7% in DUHS, and 18.2% and 41.7% in the Registry, respectively. The proportion of patients prescribed antifibrotic therapy at the time of PPF development was low (4.2% DUHS, 2.1% Registry). Conclusions Despite differences in baseline ILD severity and treatment patterns across two large real-world cohorts, the progression to PPF occurred in similar proportions and followed comparable patterns by subtype in both groups. Prognosis after PPF development was likewise similarly poor. These findings underscore the need for novel management strategies following PPF development. This abstract is funded by: BMS