Background Granulomatosis with polyangiitis (GPA, formerly Wegener’s granulomatosis), Churg-Srauss syndrome (CSS) and microscopic polyangiitis (MPA) constitute the ant-neutrophil cytoplasmic antibody (ANCA)-associated vasculitides (AAV), but disease evolution, organ involvement and prognosis differ substantially between them. A previous study suggests the predominance of MPA in Japanese AAV patients¹⁾, the survey was limited to the local geographical territories.

Objectives To further determine the epidemiological feature of Japanese patients with AAV.

Methods The RemIT-JAV study, a prospective cohort study, has been undertaken to clarify the effectiveness and safety of the initial remission induction therapy employed for Japanese patients with AAV. 156 patients enrolled in the study were classified according to the European Medicines Agency (EMEA) algorithm with the addition of surrogate markers for pulmonary vasculitis.

Results Based on the EMSA classification algorism for AAV, 17 patients (female/male=12/5; mean ± SEM=58±16 years old) were classified as having CSS, 34 patients (22/12; 63±12 years old) were GPA, and 94 patients (54/40; 70±10 years old) were MPA. By applying surrogate markers for pulmonary vasculitis, 16 unclassifiable patients could be classified into the pulmonary limited type of MPA. 9 patients with CSS were positive for MPO-ANCA (53%); 15 patients with GPA were positive for MPO-ANCA (44%), while 19 patients positive for PR3-ANCA; and 92 patients were positive for MPO-ANCA with only 2 patients being positive for PR3-ANCA. In CSS patients, skin and neurologic manifestations were more common (77% and 94%, respectively), followed by ENT, lung/air way, and renal diseases (ca. 30%). Both GPA and MPA patients often presented with constitutional symptoms (>70%), renal involvement (>60%), neurologic diseases (ca. 30%); severe nephritis was more common in MPA. GPA patients had more ENT (82%) and lung diseases (68%).

Conclusions Japanese patients with CSS, GPA, and MPA respectively showed clinical presentation similar to the patients in western countries, but MPO-ANCA-positive MPA patients were predominating. In addition, the majority of GPA patients showed MPO-ANCA-positive. Surrogate markers for pulmonary vasculits may be useful for MPA classification in Japanese AAV patients.

1. Fujimoto S, et al. Comparison of the epidemiology of ant-neutrophil cytoplasmic antibody-associated vasculitis between Japan and the UK. Rheumatology (Oxford) 50;707-8, 2011.

Disclosure of Interest None Declared