Predictors of Progressive Fibrosing Interstitial Lung Diseases and Survival in Fibrosing Interstitial Lung Disease-Related Usual Interstitial Pneumonia

TL;DR

This study identifies risk factors for progressive fibrosing lung disease in patients with fibrosing interstitial lung disease, finding similar outcomes to idiopathic pulmonary fibrosis.

Contribution

The study identifies baseline severity and specific clinical factors as predictors of progressive fibrosing interstitial lung disease in FILD-UIP patients.

Findings

Pulmonary hypertension and FVC%pred are risk factors for PF-ILD in FILD-UIP patients.

PF-ILD is associated with poor survival across all FILD-UIP subtypes.

KBILD score is a significant predictor of PF-ILD in FILD-UIP and IPF.

Abstract

Background and Objectives: Usual interstitial pneumonia (UIP) is associated with progressive fibrosing interstitial lung diseases (PF-ILD) and poor survival in patients with fibrosing interstitial lung disease (FILD). We aimed to investigate the predictors of PF-ILD and survival in patients with FILD-UIP. Materials and Methods: This retrospective study was conducted at a single, tertiary hospital in China. Patients underwent routine follow-up visits every 3 to 6 months according to standard operating procedures (SOPs). Patients with FILD-UIP were further stratified using the proposed PF-ILD criteria. Results: This retrospective study enrolled 150 patients with FILD-UIP between October 2020 and June 2025, with 117 patients completing follow-up for more than 12 months. FILD-UIP was categorized as idiopathic pulmonary fibrosis (IPF) (n = 67) and non-IPF-UIP (n = 50), which included connective tissue disease-associated UIP (n = 29), hypersensitivity pneumonitis-associated UIP (n = 7), and interstitial pneumonia with autoimmune features-associated UIP (n = 14). During the follow-up period, 32 (47.8%) patients with IPF and 19 (38.0%) non-IPF-UIP experienced PF-ILD. Pulmonary hypertension (PH) and predicted percentage of forced vital capacity (FVC%pred) were dependent risk factors for PF-ILD in patients with FILD-UIP, non-IPF-UIP, and IPF. King’s Brief Interstitial Lung Disease (KBILD) is a dependent risk factor for PF-ILD in patients with FILD-UIP and IPF. PF-ILD is similarly associated with poor survival in patients with FILD-UIP, non-IPF-UIP, and IPF. Conclusions: Baseline disease severity is closely associated with the incidence of PF-ILD, with all forms of FILD-UIP at risk of PF-ILD and showing similar outcomes to IPF-UIP/PF-ILD.

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