C39-12 Risk of Progressive Pulmonary Fibrosis Among Patients With Systemic Autoimmune Rheumatic Diseases in a Multi-center Real-world Cohort

Abstract Rationale Patients with interstitial lung disease related to systemic autoimmune rheumatic diseases (SARD-ILD) may develop progressive pulmonary fibrosis (PPF), characterized by irreversible loss of lung function and high mortality risk. The risk of PPF by SARD subtype is not well characterized in large, representative real-world data sources. We characterized patients with SARD-ILD and compared the risk of PPF by SARD subtype in a multicenter cohort derived from the national Patient-Centered Clinical Research Network (PCORnet). Methods Harmonized electronic health record (EHR) data was collected from seven PCORnet centers. Included patients had at least two ICD-9/ICD-10 codes for ILD between 2015-2021, an ILD diagnosis that persisted following chest CT and/or lung biopsy, at least one year of potential follow-up, and sufficient lung function data to assess PPF. The presence of SARD, subtypes of which were classified by ICD codes, was also required. PPF was defined by ≥ 5% absolute decline in FVC, lung transplantation or death. The incidence of PPF was compared across SARD subtypes using Kaplan Meier estimates and Cox proportional hazards models adjusted for age, sex, enrolling center and baseline FVC. Results The cohort included 6,288 patients with SARD-ILD, of whom 68.4% were female, with a mean (SD) age of 61.2 (13.9) years. The most common underlying SARD was rheumatoid arthritis (RA, 42.8%), followed by systemic sclerosis (SSc, 22.3%), mixed connective tissue disease (MCTD, 21.5%), Sjögren’s syndrome (16.9%), systemic lupus erythematosus (SLE, 14.5%) and polymyositis/dermatomyositis (PM/DM, 12.0%). Mean FVC and DLCO at baseline were 78.7 (22.9) % and 51.9 (21.3) % of predicted, respectively. Patients with PM/DM had the lowest mean FVC (70.4 SD 21.3) % of predicted) and DLCO (45.1 SD 18.5 % of predicted). During the follow-up period, antifibrotic, corticosteroid, and non-steroidal immunosuppressive drugs were used by 7.6%, 89.3% and 77.5% of the overall cohort, respectively. The cumulative incidence of PPF, transplant or death at one year ranged from 20.6% to 29.0%, depending on SARD-ILD subtype, with higher risk among those with RA, SSc or MCTD as compared with PM/DM (figure). Conclusions In a large, harmonized EHR dataset, the risk of PPF at one year among patients with SARD-ILD was high. Variability of PPF risk by SARD-ILD subtype was similar to that observed in traditional cohort studies, with lower risk among patients with myositis despite poorer lung function at baseline. These findings establish the feasibility of PCORnet as a tool to understand PPF among patients with SARD-ILD. This abstract is funded by: Genentech