Background: Acute exacerbation of idiopathic pulmonary fibrosis (AE-IPF) has an extremely poor prognosis. The role of ferritin in the pathogenesis of AE-IPF is not well known while serum ferritin is a key prognostic indicator for patients with clinically amyopathic dermatomyositis with rapidly progressive interstitial pneumonia.
Objective: To elucidate the clinical importance of serum ferritin in patients with AE-IPF.
Methods: Thirty-seven patients (48 episodes), who were diagnosed with AE-IPF and treated at our hospital between 1997 and 2015, were retrospectively studied.
Results: Patients with AE-IPF had significantly higher levels of serum ferritin than baseline levels at the first diagnosis of IPF (P = 0.0017). Receiver operating characteristic analysis showed the cut-off value 174 ng/mL for the separation of AE (area under the curve, 0.700). No patients with AE-IPF were positive for anti- melanoma differentiation-associated gene 5 antibody. Patients with AE-IPF and higher ferritin (≥174 ng/mL) had lower %FVC and %DLCO before AE, and those with much higher ferritin (≥500 ng/mL) had significantly worse prognosis than those with lower ferritin (log-rank, P = 0.024). Immunohistochemical staining in autopsy specimens showed alveolar macrophages that were producing ferritin. Finally, in multivariate Cox proportional hazards analyses, serum ferritin level of ≥500 ng/mL was a significant worse prognostic factor (hazard ratio 5.280, P = 0.046).
Conclusion: Higher serum ferritin may be related to a worse prognosis in patients with AE-IPF.
Keywords: acute exacerbation; anti-MDA5-antibody; ferritin; idiopathic pulmonary fibrosis; macrophage.
© 2018 John Wiley & Sons Ltd.