Poor renal outcomes in patients with anti-neutrophil cytoplasmic antibody-associated crescentic glomerulonephritis and normal renal function at diagnosis

The aim of this study is to investigate the renal outcomes of anti-neutrophil cytoplasmic antibody (ANCA)-associated crescentic glomerulonephritis in patients with normal estimated glomerular filtration rate (eGFR) at diagnosis. Twenty-seven patients with biopsy-proven ANCA-associated crescentic glomerulonephritis were retrospectively recruited and were divided into 12 with normal eGFR (≥60 ml/min/1.73 m²) and 15 with low eGFR (<60 ml/min/1.73 m²) at baseline. Clinical and renal pathological findings at diagnosis and renal outcomes for up to 3 years were compared between the two groups. Two patients in the low eGFR group died of severe bacterial pneumonia. In the normal eGFR group, the following characteristics were observed: younger age at diagnosis (p = 0.04), diagnosis of granulomatosis polyangiitis (GPA) (p < 0.01), and lower frequency of cyclophosphamide treatment (p = 0.03). On renal pathological analysis, the normal eGFR group had a significantly lower proportion of cellular crescent formation (p = 0.01), fibrinoid necrosis (p = 0.01), interstitial fibrosis (p = 0.02), and tubular atrophy (p = 0.02). As a result, the two groups did not significantly differ in remission rates, relapse rates, Birmingham vasculitis score, vasculitis damage index, or eGFR on 3-year follow-up. Patients with biopsy-proven ANCA-associated glomerulonephritis and normal eGFR at diagnosis have poor renal outcomes and may require standard intensive immunosuppressive treatment to prevent accrual of damage.