Progressive fibrosing interstitial lung disease: prevalence and clinical outcome

Abstract

Background: The progressive fibrosing (PF) phenotype of interstitial lung disease (ILD) is characterised by worsening respiratory symptoms, lung function, and extent of fibrosis on high-resolution computed tomography. We aimed to investigate the prevalence and clinical outcomes of PF-ILD in a real-world cohort and assess the prognostic significance of the PF-ILD diagnostic criteria.

Methods: Clinical data of patients with fibrosing ILD other than idiopathic pulmonary fibrosis (IPF) consecutively diagnosed at a single centre were retrospectively reviewed. A PF phenotype was defined based on the criteria used in the INBUILD trial.

Results: The median follow-up duration was 62.7 months. Of the total of 396 patients, the mean age was 58.1 years, 39.9% were men, and rheumatoid arthritis-ILD was the most common (42.4%). A PF phenotype was identified in 135 patients (34.1%). The PF-ILD group showed lower forced vital capacity and total lung capacity (TLC) than the non-PF-ILD group. The PF-ILD group also showed poorer survival (median survival, 91.2 months vs. not reached; P < 0.001) than the non-PF-ILD group. In multivariable Cox analysis adjusted for age, DL_CO, HRCT pattern, and specific diagnosis, PF phenotype was independent prognostic factor (hazard ratio, 3.053; P < 0.001) in patients with fibrosing ILD. Each criterion of PF-ILD showed similar survival outcomes.

Conclusions: Our results showed that approximately 34% of patients with non-IPF fibrosing ILD showed a progressive phenotype and a poor outcome similar to that of IPF, regardless of the diagnostic criteria used.

Keywords: Interstitial lung disease; Outcome; Phenotype; Prevalence; Progressive.

Fig. 1

Study flow chart. ILD interstitial lung disease, IPF idiopathic pulmonary fibrosis, PF progressive fibrosing, iNSIP idiopathic nonspecific interstitial pneumonia, HP hypersensitivity pneumonitis

Fig. 2

Prevalence of PF-ILD. PF progressive fibrosing, ILD interstitial lung disease, HP hypersensitivity pneumonitis, iNSIP idiopathic nonspecific interstitial pneumonia, RA rheumatoid arthritis, SSc systemic sclerosis, SJS SjÖgren syndrome

Fig. 3

Comparison of survival curves between the PF-ILD and non-PF-ILD groups among patients with fibrosing ILD. PF progressive fibrosing, ILD interstitial lung disease

Fig. 4

Comparison of survival curves in patients with PF-ILD according to PF-ILD diagnostic criteria. a Comparison of survival curves in patients with PF-ILD according to the diagnostic criteria used in this study. Criterion (i) a relative decline in FVC ≥ 10%; Criterion (ii) a relative decline in FVC of 5%–10% and worsening of respiratory symptoms or increased extent of fibrosis on HRCT; Criterion (iii) worsening of respiratory symptoms and increased extent of fibrosis on HRCT. b Comparison of survival curves in patients with PF-ILD according to the diagnostic criteria (INBUILD, Cottin et al., Behr et al., and George et al.)