Difference in Relapse-Rate and Clinical Phenotype by Autoantibody-Subtype in Japanese Patients with Anti-Neutrophil Cytoplasmic Antibody-Associated Vasculitis.

Objective: To correlate the serotype specificity to myeloperoxidase (MPO) and proteinase-3 (PR3) with clinical characteristics in anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV).Methods: Clinical characteristics and outcomes of patients with AAV in our division from 2005 to 2014 were retrospectively compared on the basis of ANCA subtype.Results: We collected the data from 88 patients with MPO-ANCA vasculitis, and 17 with PR3-ANCA vasculitis. Patients with PR3-ANCA vasculitis were younger, and had higher involvement-rates in the eye, nose, and ear. In both MPO- and PR3-ANCA vasculitis, the most frequently involved organ was the respiratory system. Interstitial pneumonia was more frequent in MPO-ANCA vasculitis (52.3% versus 5.9%, p<0.01), whereas nodular shadow was more frequent in PR3-ANCA vasculitis (9.1% versus 58.8%, p<0.01). Multivariable Cox proportional hazard regression analysis showed that the hazard ratio of PR3-ANCA for relapse was 2.48 (95% confidence interval 1.14-5.42, p=0.02). There was no difference in the survival and the progression to end-stage kidney disease and respiratory failure between the two vasculitides.Conclusion: MPO-ANCA vasculitis was a predominant form of AAV in Japan. Classification based on ANCA subtype would be clinically relevant in the prediction of organ involvement and relapse.