Pulmonary involvements of anti-neutrophil cytoplasmic autoantibody-associated renal vasculitis in Japan

Background Pulmonary involvement is one of the hallmark lesions of anti-neutrophil cytoplasmic autoantibody (ANCA)-associated vasculitis (AAV) as well as rapidly progressive glomerulonephritis (RPGN). However, the pulmonary involvement of AAV patients seems to differ between Europe and Japan, as does the ANCA serotype. Methods This retrospective and prospective multicenter cohort study collected the clinical data of the features and outcomes of 1772 RPGN patients treated from 1989 to 2007 in Japan. Based on this nationwide RPGN survey, we analyzed the cases of 1147 AAV patients. Results We found that 52.3% of the AAV patients had pulmonary involvements: 15.4% of the AAV patients had alveolar hemorrhage (AH), 26.2% had interstitial lung disease (ILD), 2.8% had bronchial asthma, 2.4% had pulmonary granuloma and 12.8% had a chest X-ray abnormality without AH, ILD or pulmonary granuloma. Patient survival was significantly different among the following six groups: the 5-year survival rate was 41.5% in the patients with AH, 50.2% in those with ILD, 67.9% in those with bronchial asthma, 62.5% in those with pulmonary granuloma, 55.8% in those with chest X-ray abnormality and 73.3% in those without pulmonary involvement. AH was one of the predictors of 1-and 5-year mortality for patient survival in AAV, and ILD was added as one of the predictors of 5-year mortality. Conclusion In these AAV patients, not only AH but also ILD was frequently observed. AH was associated with the prognosis, but ILD was associated with the long-term prognosis of AAV.