Our study showed that the clinical parameters related to infection and inflammation (WBC counts, CRP, ESR, and LDH), body metabolism (TG, Apo AI, AIB, and GLU), and disease severity (D-dimer, PaO2/FiO2 ratio, HRCT score, PAH, FVC, DLCO, GAP scores, and stages) were significantly different between patients with S-IPF and AE-IPF. Here, AOPEP is linked to infection.