Determinants of renal outcome in anti-myeloperoxidase-associated necrotizing crescentic glomerulonephritis

Patients with anti-myeloperoxidase (MPO)-associated necrotizing crescentic glomerulonephritis (NCGN) may develop chronic renal failure (CRF) leading to end-stage renal disease despite an initially favorable response to treatment. The aim of this study was to determine the prognostic value of clinical, laboratory, and histopathologic features at the time of presentation and during follow-up for the development of CRF in 21 consecutive anti-MPO-positive patients with NCGN. Renal function did not recover in two of five patients who were dialysis-dependent at presentation. The remaining 19 patients all went into remission and were off dialysis at 3 mo after diagnosis. At long-term follow-up, nine of these patients had stable renal function and did not relapse (group A), five patients developed CRF without signs of relapse (group B), and five patients relapsed (group C). At diagnosis, serum creatinine, C-reactive protein, and anti-MPO levels did not differ between groups A, B, and C. Microscopic erythrocyturia resolved in all patients within 4 mo of treatment. BP at presentation and during follow-up did not differ between groups A, B, and C. Proteinuria at diagnosis and in the first 6 mo after diagnosis was higher in patients who developed CRF than in patients with a stable renal function. Anti-MPO levels at 3 mo had decreased compared with anti-MPO levels at diagnosis in groups A and C, whereas anti-MPO levels did not fall significantly in patients who developed CRF. The predictive value of a renal biopsy at diagnosis on long-term renal outcome was limited. In conclusion, a higher degree of proteinuria at diagnosis and during follow-up as well as persistently elevated anti-MPO levels after induction of remission are associated with the development of CRF and are predictive of poor renal outcome in anti-MPO-associated NCGN.