Clinical implications of traction bronchiectasis in IPF and fibrotic RA-ILD - a retrospective single-center cohort study.
Authors
Affiliations (11)
Affiliations (11)
- Department of Respiratory Medicine and Infectious Diseases, Hannover Medical School, Hannover, Germany.
- Biomedical Research in End-Stage and Obstructive Lung Disease (BREATH), Hannover Medical School (MHH), German Center for Lung Research (DZL), Hannover, Germany.
- Section of Pulmonary, Critical Care, and Sleep Medicine, Department of Medicine, Yale School of Medicine, New Haven, CT, USA.
- Department for Rheumatology and Immunology, Hannover Medical School, Hannover, Germany.
- Junior Research Group for Translational Immunology, TWINCORE, Centre for Experimental and Clinical Infection Research, Helmholtz Centre for Infection Research and the Hannover Medical School, Hannover, Germany.
- Clinic for Pneumology, University Hospital of Basel, Basel, Switzerland.
- Institute for Medical Microbiology and Hospital Epidemiology, Hannover Medical School, Hannover, Germany.
- Centre for Experimental and Clinical Infection Research, TWINCORE, Helmholtz Centre for Infection Research and the Hannover Medical School, Hannover, Germany.
- Institute of Diagnostic and Interventional Radiology, Hannover Medical School, Hannover, Germany.
- Department of Respiratory Medicine and Infectious Diseases, Hannover Medical School, Hannover, Germany. [email protected].
- Biomedical Research in End-Stage and Obstructive Lung Disease (BREATH), Hannover Medical School (MHH), German Center for Lung Research (DZL), Hannover, Germany. [email protected].
Abstract
Bronchiectasis is a common feature in idiopathic pulmonary fibrosis (IPF) and rheumatoid arthritis-associated interstitial lung disease (RA-ILD). While these so-called traction bronchiectasis are often considered a secondary phenomenon in fibrosing ILD, their prognostic significance and relationship to respiratory pathogen detection and outcomes remain unclear. We conducted a retrospective, single-center cohort study in IPF or fibrosing RA-ILD patients with available high-resolution computed tomography (HRCT) and lower-respiratory tract microbial samples between 2014 and 2024. Bronchiectasis was assessed using the bronchiectasis subscore of the Brody score; fibrosis was quantified by deep-learning-based automated HRCT analysis. Primary outcome was 5-year transplant-free survival; secondary outcomes included isolation of pathogens per CDC criteria, PFT trajectories, bronchiectasis-associated symptoms, and hospitalization. Statistical methods included Cox regression, linear mixed-effects modeling and correlation analysis. 267 IPF and 56 RA-ILD patients were included. Median modified Brody score was 11.5 (IQR 7-16; max possible range 0-72). Higher Brody scores strongly correlated with fibrotic extent (R = 0.6, P < 0.001). Higher scores had significantly lower baseline FVC and DLCO (P < 0.001), but no differences in PFT trajectories over time. In multivariable Cox regression, higher bronchiectasis scores were independently associated with mortality (HR 1.03 per point [95%CI 1.01-1.06], P = 0.003); fibrosis extent showed similar results (HR 1.02, CI 1.00-1.03, P = 0.017). Pathogens were found at a median of 3 months after baseline in 50.9% (IPF) and 46.4% (RA-ILD), without association with survival, symptoms or Brody scores. Staphylococcus aureus was most common (28.9%); Pseudomonas aeruginosa was rare (1.9%). In both IPF and RA-ILD, higher bronchiectasis scores were associated with fibrosis extent and mortality, but not classical clinical bronchiectasis features. This supports traction bronchiectasis as a marker of fibrotic remodeling rather than a distinct syndrome. Not applicable.