Clinical significance of myeloperoxidase-anti-neutrophil cytoplasmic antibody in idiopathic interstitial pneumonias

PLoS One. 2018 Jun 21;13(6):e0199659. doi: 10.1371/journal.pone.0199659. eCollection 2018.


Objective: Although a possible association among myeloperoxidase-anti-neutrophil cytoplasmic antibody (MPO-ANCA), microscopic polyangiitis (MPA), and idiopathic pulmonary fibrosis (IPF) has been suggested, the clinical significance of MPO-ANCA in idiopathic interstitial pneumonias (IIPs), including IPF and non-IPF, remains unclear. We aimed to investigate the frequency of MPO-ANCA positivity, as well as MPA incidence and risk factors for development in patients initially diagnosed with IIP.

Methods: We retrospectively analysed 305 consecutive patients who were initially diagnosed as IIP and had MPO-ANCA results available.

Results: Of the 305 patients, 26 (8.5%) were MPO-ANCA-positive. Baseline characteristics were similar between the MPO-ANCA-positive and -negative patients. The cumulative 5-year MPA incidence was 24.3% in the MPO-ANCA-positive patients and 0% in the -negative patients (P < 0.0001). MPO-ANCA was positive in 15 of 133 (11.3%) patients initially diagnosed with IPF and in 11 of 172 (6.3%) patients initially diagnosed with non-IPF (P = 0.56), with cumulative 5-year MPA incidence of 6.2% and 1.0%, respectively (P = 0.10). Multivariate analysis revealed that UIP pattern on HRCT (HR = 3.20, P < 0.01) and no treatment for IIP (HR = 3.52, P < 0.01) were independently associated with MPA development in MPO-ANCA-positive patients.

Conclusion: MPO-ANCA positivity was uncommon, but was associated with subsequent MPA development in patients initially diagnosed with IIP, including both IPF and non-IPF cases. The study suggested that attention should be paid to MPA development in MPO-ANCA-positive IIP patients with UIP pattern on HRCT and those without treatment for IIP.

MeSH terms

  • Aged
  • Antibodies, Antineutrophil Cytoplasmic / blood*
  • Disease Progression
  • Female
  • Follow-Up Studies
  • Humans
  • Idiopathic Interstitial Pneumonias / blood*
  • Idiopathic Interstitial Pneumonias / complications
  • Idiopathic Interstitial Pneumonias / epidemiology
  • Incidence
  • Male
  • Microscopic Polyangiitis / blood*
  • Microscopic Polyangiitis / complications
  • Microscopic Polyangiitis / epidemiology
  • Middle Aged
  • Peroxidase / blood*
  • Retrospective Studies
  • Risk Factors


  • Antibodies, Antineutrophil Cytoplasmic
  • Peroxidase

Grants and funding

The authors received no specific funding for this work.