The natural history of progressive fibrosing interstitial lung diseases

Abstract

A proportion of patients with certain types of interstitial lung disease (ILD), including chronic hypersensitivity pneumonitis and ILDs associated with autoimmune diseases, develop a progressive fibrosing phenotype that shows similarities in clinical course to idiopathic pulmonary fibrosis. Irrespective of the clinical diagnosis, these progressive fibrosing ILDs show commonalities in the underlying pathogenetic mechanisms that drive a self-sustaining process of pulmonary fibrosis. The natural history of progressive fibrosing ILDs is characterized by decline in lung function, worsening of symptoms and health-related quality of life, and early mortality. Greater impairment in forced vital capacity or diffusion capacity of the lungs for carbon monoxide, and a greater extent of fibrotic changes on a computed tomography scan, are predictors of mortality in patients with fibrosing ILDs. However, the course of these diseases is heterogenous and cannot accurately be predicted for an individual patient. Data from ongoing clinical trials and patient registries will provide a better understanding of the clinical course and impact of progressive fibrosing ILDs.

Keywords: Connective tissue diseases; Mortality; Pulmonary fibrosis; Rheumatic diseases; Systemic sclerosis; Vital capacity.

Fig. 1

Types of interstitial lung disease associated with a risk of developing a progressive fibrosing phenotype. HP, hypersensitivity pneumonitis; ILD, interstitial lung disease; IIP, idiopathic interstitial pneumonia; IPF, idiopathic pulmonary fibrosis

Fig. 2

Factors that reflect progression of interstitial lung diseases. DLco, diffusion capacity of the lungs for carbon monoxide; FVC, forced vital capacity; HRCT, high-resolution computed tomography; PFTs, pulmonary function tests

Fig. 3

Decline in FVC % predicted in patients with SSc-ILD categorized by survival time from diagnosis of ILD. Adapted from [31]. Reprinted with permission of the American Thoracic Society. Copyright© 2019 American Thoracic Society. Guler SA et al. 2018. Does systemic sclerosis-associated interstitial lung disease burn out? Specific phenotypes of disease progression. Ann Am Thorac Soc 2018;15:1427–1433. Annals of the American Thoracic Society is an official journal of the American Thoracic Society

Fig. 4

The proportions of patients with FVC < 50% predicted and DLco < 40% predicted in the 10 years from diagnosis of ILD associated with RA. Adapted from [4]