Correlation between Pathological Findings and the Usefulness of Clinical Guidelines for the Treatment of ANCA-Positive RPGN: A Retrospective Analysis

Abstract

Background: The physical condition of patients with anti-neutrophil cytoplasmic antibody (ANCA)-associated rapidly progressive glomerulonephritis (RPGN) is at times too critical for physicians to undertake a renal biopsy. In such cases, physicians need to start treatments without determining the pathological features of the disease. However, the prevalent clinical practice guidelines for ANCA-associated RPGN in Japan do not necessitate the pathological findings in a renal biopsy for determining first-line treatments. The aim of this study was to assess the correlation between the pathological findings and the clinical guideline-based treatments of ANCA-associated RPGN. Methods: We investigated clinical and pathological features of patients who were admitted to our hospital to undergo a percutaneous renal biopsy for the diagnosis of ANCA-associated RPGN and were treated per clinical practice guidelines formulated by the Japanese Society of Nephrology. We divided patients into the following three groups according to their treatments: (a) group A, oral intake of prednisolone (PSL) only; (b) group B, methylprednisolone (mPSL) pulse therapy followed by oral intake of PSL; and (c) group C, mPSL pulse therapy followed by oral intake of PSL and the administration of immunosuppressive agents. We compared the crescent formation ratio (CFR) in glomeruli in each treatment group. Results: The median CFR (%; ±standard deviation [SD]) in group A (8.7%±7.7%) was significantly lower than that in groups B (30.2%±15.7%) and C (71.3%±25.5%); group A vs. group B, P<0.05; group A vs. group C, P<0.0001. In addition, the median CFR in group B was significantly lower than that in group C (P<0.01). The median serum creatinine levels (mg/dL; ±SD) in both groups A (2.03±0.96 mg/dL) and B (1.90±0.86 mg/dL) were significantly lower than that in group C (4.30±1.63 mg/dL); group A vs. group C, P<0.01; group B vs. group C, P<0.01. No significant difference was observed in the serum levels of C-reactive protein and ANCA in each treatment group. Although the pathological features of renal biopsy are not included in the factors in the clinical scores described in the guidelines, guideline-based treatments reflected the severity of the crescent formation in each treatment group. Conclusions: This study suggests that the clinical practice guidelines for ANCA-associated RPGN used in Japan facilitate physicians to determine disease management in patients presenting difficulties in undergoing a renal biopsy.