Clinical outcomes of Japanese MPO-ANCA-related nephritis: significance of initial renal death for survival.

Objective: Anti-myeloperoxidase anti-neutrophil cytoplasmic antibody (MPO-ANCA)- related nephritis constitutes 60% of rapidly progressive glomerulonephritis (RPGN) in Japan. The reported 1-year survival rate is over 80%, however, the long-term prognosis remains unknown. We therefore investigated the prognosis and factors affecting the clinical course of patients.
Methods: We retrospectively investigated 74 patients (female, n=42; median age, 73.0 years) with MPO-ANCA-related nephritis. The patients were admitted to Fukushima Medical University and two affiliated hospitals between 2000 and 2010.
Results: Median estimated GFR (eGFR) was 12.1 mL/min/1.73 m2 at admission. The Birmingham Vasculitis Activity Score (BVAS version 3: max 63 points) at diagnosis and at 4 weeks after start of treatment were 15.0 and 5.0, respectively. Twenty-three patients (31%) died during a median observation period of 30.5 months. Sixteen patients (22%) presented with end-stage renal disease (ESRD) at the initial phase, and needed regular dialysis therapy. Multivariate Cox proportional hazards model analysis revealed that renal death at the initial phase was a significant risk factor for all-cause death (Hazard ratio, 5.72; 95% confidence interval, 2.49-13.09; p<0.001). Furthermore, BVAS>6, evaluated 4 weeks after start of treatment, is an independent risk factor for ESRD and patient survival.
Conclusion: This is the first investigation to demonstrate clinical features focusing on MPO-ANCA-related nephritis. Renal death at the initial phase of treatment is a powerful risk factor for all-cause death in patients with MPO-ANCA-related nephritis. Patients at high risk of death and ESRD could be stratified according to BVAS.