Progressive Fibrosing Interstitial Lung Diseases: Prevalence and Characterization in Two Italian Referral Centers.

BACKGROUND The prevalence and natural history of progressive fibrosing interstitial lung diseases (PF-ILDs), and their response to commonly used treatments in real life are largely unknown. OBJECTIVES The aim of the study was to describe the prevalence, clinical characteristics, management, and outcomes of PF-ILD patients attending 2 Italian referral centers (San Gerardo Hospital, Monza, and San Giuseppe Hospital, Milan) from January 1, 2011, to July 31, 2019. METHODS From a cohort of non-idiopathic pulmonary fibrosis fibrosing ILD patients with at least 2-year follow-up, we selected only those with progressive disease, defined as per the INBUILD trial, collecting their demographical, clinical, and functional data. RESULTS Out of the 245 fibrosing ILD patients, 75 (31%) were classified as PF-ILDs (median age 66 years, 60% males), most frequently idiopathic non-specific interstitial pneumonia (28%), followed by connective tissue disease-associated ILD (20%), chronic hypersensitivity pneumonitis, and sarcoidosis (17% each). Most patients (81%) were categorized as PF-ILDs because of forced vital capacity (FVC) decline ≥10%, while 19% experienced a marginal FVC decline (between 5 and 10%) associated with worsening respiratory symptoms or increasing extent of fibrotic changes on high-resolution computed tomography. Disease progression occurred after a median of 18 months from ILD diagnosis. The vast majority (93%) of PF-ILD patients received prednisolone, alone (40%) or associated with steroid-sparing agents (52%), and 35% of treated patients developed treatment-related adverse events. After ILD progression, the median survival was 3 (interquartile range (IQR) 2-5) years, with a 2- and 3-year mortality rate of 4 and 20%, respectively. CONCLUSIONS In a real-life setting, approximately one-third of the fibrosing ILD patients showed a progressive course despite treatment. Studies aimed to better phenotype this subgroup of patients are needed.