Trajectories of progressive pulmonary fibrosis and outcomes in connective tissue disease associated interstitial lung disease (CTD-ILD).

BACKGROUND AND AIM: Progressive pulmonary fibrosis (PPF) can develop in various interstitial lung diseases (ILD), including connective tissue disease-associated ILD (CTD-ILD). This study aimed to examine the longitudinal trajectory and transition of PPF status in patients with CTD-ILD. METHODS: In this single-center study at a tertiary referral hospital, we analyzed patients with CTD-ILD who underwent consecutive chest computed tomography (CT) scans and pulmonary function tests over two-year period. Patients were categorized into four groups based on annual PPF status. RESULTS: Among the 144 patients, the majority (n = 75) maintained a non-PPF status throughout follow-up (Group 1), while 25 patients developed PPF at year 2 (Group 2), 12 showed PPF improvement (Group 3), and 31 had persistent PPF (Group 4). The persistent PPF group showed significantly higher mortality risk (p = 0.007). Based on PPF status at 2 years, annual changes in forced vital capacity (FVC) and diffusing capacity of carbon monoxide (DLCO) were more pronounced in PPF groups than in non-PPF groups (FVC: -3.72 ± 0.52 %/year vs. 2.82 ± 0.41 %/year; DLCO: -4.30 ± 0.75 %/year vs. 3.64 ± 0.60 %/year). Patients treated with immunomodulating agents showed a reduced risk of progression to PPF, although the association was not statistically significant (Group 2, adjusted odds ratio: 0.26, 95% CI: 0.02-4.43, p = 0.351). CONCLUSIONS: Regular pulmonary function monitoring and continuous assessment of PPF progression are essential for patients with CTD-ILD. Disease-directed treatment may reduce the risk of PPF development.