Introduction:
A few real-world studies have investigated the effectiveness of antifibrotics in patients with progressive pulmonary fibrosis (PPF). The aim of this study was to evaluate the real-life efficacy of antifibrotics in PPF.

Material and methods:
In this real-world study, medical records of patients with non-idiopathic pulmonary fibrosis (IPF) fibrosing interstitial lung disease (ILD) between January 2013 and December 2023 were examined retrospectively. Patients with PPF were included and classified into two groups: the antifibrotic group (pirfenidone or nintedanib) and the non-antifibrotic group. Forced vital capacity (FVC), diffusing capacity of the lungs for carbon monoxide (DLCO) decline, exacerbations, and mortality were compared between the groups.

Results:
A total of 406 patients with ILD were examined. Of these, 262 patients had fibrotic ILD other than IPF, of whom 126 with a progressive phenotype were included. Among these, 41 (32.5%) had a connective tissue disease-associated ILD, 38 (30.2%) chronic fibrosing hypersensitivity pneumonitis, 21 (16.7%) unclassifiable idiopathic interstitial pneumonia, 16 (12.7%) idiopathic fibrosing non-specific interstitial pneumonia, and 10 (7.9%) other ILDs. At 36 months, FVC % predicted declined by 13% in the antifibrotic group vs. 25% in the non-antifibrotic group (p < 0.001); DLCO declined by 10% vs. 26%, respectively (p < 0.001). Exacerbations and mortality were lower in patients receiving antifibrotics (29% vs. 6%, OR = 6.38, p < 0.001; 21% vs. 5%, OR = 5.59, p = 0.006; respectively). The rate of adverse events leading to treatment discontinuation was 9% in patients receiving pirfenidone and 25.6% with nintedanib (p = 0.19).

Conclusions:
Our real-world results showed an association between antifibrotic treatment and slower DLCO and FVC decline, fewer exacerbations, and lower mortality in PPF. Adverse events that should not be neglected were associated with a considerable rate of discontinuation.