Determining the Etiology of Progressive Pulmonary fibrosis in an Indian CohorT of Interstitial Lung Disease Patients-the DEPICT ILD prospective study

Abstract Introduction: Non-Idiopathic Pulmonary Fibrosis (Non-IPF) interstitial lung diseases (ILDs) may develop a progressive pulmonary fibrosis (PPF) phenotype. This study evaluated the causes, outcomes, and predictors of adverse outcomes in non-IPF PPF. Methods : This single-centre prospective cohort study at Rajagiri Hospital, Kochi, enrolled adults with PPF and followed them for 12 months. Baseline clinical, functional, and etiological assessments were performed, with multidisciplinary evaluation. Outcomes included PPF etiology, lung function, exacerbations, hospitalizations, mortality, and antifibrotic treatment-related adverse events. Results : A total of 104 patients (mean age 64.8 years, 58.7% females) were included. Connective tissue disease–associated interstitial lung disease (CTD-ILD) was the commonest etiologic subtype. Radiologically, usual interstitial pneumonia (UIP) was identified in 46.2% of patients. The mean forced vital capacity and DLCO changed from 67.7% to 62.4% and 56.3% to 49.8%, respectively, from baseline to 12 months. The 55.8% received antifibrotic therapy, of whom 93.10% received nintedanib. The patients experiencing ≥ 2 exacerbations and requiring ≥ 2 hospitalizations per year decreased from 71.2% to 29.3% and 59.6% to 10.6% after treatment, respectively (P < 0.001). During the follow-up, 26.9% of patients died. Low baseline oxygen saturation, 6 MWD < 300 metres as baseline ≥ 2 exacerbations at baseline were predictive of poor outcomes. Conclusion: CTD related ILD was the most common cause of PPF in the present study. Most patients with PPF continued to have fall in lung functions during follow up. Antifibrotic therapy decreases exacerbation rates in PPF. Poor baseline lung function and frequent exacerbations are predictors of poor outcomes.