SFTPD and pulmonary fibrosis: The study aimed to determine whether KL-6, SP-D, and TGF-β1 can serve as reliable biomarkers for lung fibrosis in IPAF and CTD-ILD, assess their predictive value in evaluating the short-term progression of pulmonary fibrosis, and explore their associations with the clinical, functional, and radiological features of established predictive significance.