Repeat protocol renal biopsy in ANCA-associated renal vasculitis

Area of Science:

• Nephrology
• Rheumatology
• Immunology

Background:

• Renal biopsy findings at ANCA-associated vasculitis (AAV) diagnosis are well-documented.
• Protocolized repeat renal biopsies in AAV are rarely performed, limiting understanding of long-term disease activity.
• This study investigates the clinical significance of repeat renal biopsies in AAV patients.

Purpose of the Study:

• To evaluate the histopathological changes and clinical outcomes in patients with ANCA-associated vasculitis (AAV) who underwent protocolized repeat renal biopsies.
• To assess the disease activity and progression under immunosuppressive treatment.
• To correlate initial biopsy findings with long-term renal function.

Main Methods:

• A cohort of 17 ANCA-associated vasculitis (AAV) patients with renal involvement underwent protocolized repeat renal biopsies after a median of 13 months in remission.
• Biopsies were independently assessed by two pathologists blinded to clinical data.
• Clinical data, including follow-up for a median of 189 months, were collected retrospectively.

Main Results:

• Renal relapse occurred in 47.1% of patients; mortality and end-stage renal failure were significant.
• Repeat biopsies showed a decrease in acute lesions (e.g., crescents, P < 0.001) and an increase in chronic lesions (e.g., fibrosis, P ≤ 0.01).
• Initial percentage of normal glomeruli correlated with final estimated GFR (rs = 0.509, P = 0.05).

Conclusions:

• This is the first study using protocolized repeat biopsies to examine ANCA-associated vasculitis (AAV) disease activity under immunosuppression.
• Findings suggest persistent "grumbling disease" with ongoing activity in many AAV patients.
• This ongoing activity contributes to the accumulation of chronic kidney lesions over time.