Clinical consequence and significance of anti-neutrophil cytoplasmic antibody positivity in anti-glomerular basement membrane disease

Abstract

Patients with renopulmonary syndrome who have both anti-neutrophil cytoplasmic and anti-glomerular basement membrane antibodies have been described since 1989. The aim of the authors was to analyse the data of "double positive" patients diagnosed in their department, and compare these with previous studies. During the last 16 years, 87 anti-neutrophil cytoplasmic antibody positive and 11 anti-glomerular basement membrane antibody positive patients were diagnosed. Four patients with anti-glomerular basement membrane antibodies (36%) had detectable anti-neutrophil cytoplasmic antibodies, 2 patients were positive for anti-myeloperoxidase and 2 patients for anti-proteinase 3. In comparison with patients having anti-glomerular basement membrane antibodies, the double-positive patients were characterized by older age (median of 46 vs. 24 years), lack of male dominance (50% vs. 71%), more frequent presence of previous extrarenal symptoms (50% vs. 0%), and lower anti-glomerular basement membrane antibody levels (<100EU/ml: 100% vs. 29%). The double-positive patients had more favourable 1-year survival (100% vs. 71%), despite their older age and similar treatment regimen (immunosuppression 100% in both groups, plasmapheresis in 75% vs. 86%), but 1-year renal survival was not different (25% vs. 14%). In agreement with literature data, about one third of patients with anti-glomerular basement membrane antibodies had detectable anti-neutrophil cytoplasmic antibodies, and the coexistence of the two antibodies may have clinical consequences.