Characteristics of granulomatosis with polyangiitis patients in Japan.

Objectives: Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is a disease with significant ethnic differences. Reports on characteristics of Japanese granulomatosis with polyangiitis (GPA) patients are limited, and this study was undertaken to determine the characteristics of Japanese GPA patients.

Methods: This was a retrospective chart study of 24 Japanese GPA patients. GPA was defined according to the European Medicines Agency algorithm.

Results: The percentage of MPO-ANCA-positive patients was 33.3%, higher than the percentages reported in studies from Western countries. MPO-ANCA-positive GPA patients differed from PR3-ANCA-positive GPA patients in organs involved at diagnosis with MPO-ANCA-positive patients having nose and sinus involvement less frequently compared to PR3-ANCA-positive patients. Interstitial lung infiltrates were more common among MPO-ANCA-positive GPA patients compared to PR3-ANCA-positive GPA patients.

Conclusion: Among Japanese GPA patients, the proportion of MPO-ANCA-positive patients is higher compared to reports from Western countries, and those patients are often different from the classical picture of GPA.