Prevalence and risk factors of progressive pulmonary fibrosis(PPF) in patients with Interstitial Lung Disease(ILD) in a tertiary care center in India

<bold>Background:</bold> A subset of patients with ILDs other than Idiopathic Pulmonary Fibrosis (IPF) develop progressive decline and are termed PPF. We evaluated the prevalence and risk factors of PPF in our prospective ILD cohort. Methodology: Between July 2022 & Oct 2023, ILD patients recruited as a part of an ongoing registry were screened. We reviewed the clinical, lab & imaging data of all non-IPF patients and identified those who fulfilled at least 2 of the 3 criteria for PPF within 1 year. Those who did not fulfil criteria for PPF, after at least 1 year follow up, were labelled non-PPF. These groups were compared. <bold>Results:</bold> In all, there were 558 patients with ILD (IPF=56, non-IPF=502) during the study period. After the stipulated exclusions (Fig 1), 33 (20%) who met PPF criteria & 132 non-PPF controls proceeded for analysis. A prior diagnosis of Idiopathic Interstitial Pneumonia (IIP), ANA negativity, clubbing and velcro crackles were associated with PPF in the univariate analysis. In the multivariate analysis, clubbing [OR = 3.9 (95% CI 1.2 to 12.5)], crackles [OR = 9.6 (95% CI 3.1 to 29.9)] and IIP [OR = 2.9 (95% CI 1 to 8.2)] were independently associated. None with sarcoidosis had PPF. <bold>Conclusions:</bold> One fifth of non-IPF ILD met the criteria for PPF. A diagnosis of IIP was a risk factor for PPF. Larger studies are required to accurately assess the risk factors. <fig><object-id>erj;64/suppl_68/PA5152/F1</object-id><object-id>F1</object-id><object-id>F1</object-id><graphic></graphic></fig>