Utility of interval kidney biopsy in ANCA-associated vasculitis

Abstract

Objectives Anti-neutrophil cytoplasm antibody (ANCA)-associated vasculitis (AAV) is a rare autoimmune disorder that commonly involves the kidney. Early identification of kidney involvement, assessing treatment-response and predicting outcome are important clinical challenges. Here, we assessed the potential utility of interval kidney biopsy in AAV. Methods In a tertiary referral centre with a dedicated vasculitis service, we identified patients with AAV who had undergone interval kidney biopsy, defined as a repeat kidney biopsy (following an initial biopsy showing active AAV) undertaken to determine the histological response in the kidney following induction immunosuppression. We analysed biochemical, histological and outcome data, including times to kidney failure and death for all patients. Results We identified 57 patients with AAV who underwent at least one interval kidney biopsy (59 interval biopsies in total; median time to interval biopsy ∼130 days). Of the 59 interval biopsies performed, 24 (41%) patients had clinically suspected active disease at time of biopsy which was confirmed histologically in only 42% of cases; 35 (59%) patients were in clinical disease-remission, and this was correct in 97% of cases. The clinician’s impression was incorrect in 1 in 4 patients. Hematuria at interval biopsy did not correlate with histological activity. Interval biopsy showed fewer acute lesions and more chronic damage compared to initial biopsy and led to immunosuppressive treatment-change in 75% (44/59) of patients. Clinical risk prediction tools tended to operate better using interval biopsy data. Conclusion Interval kidney biopsy is useful for determining treatment-response and subsequent disease management in AAV. It may provide better prognostic information than initial kidney biopsy and should be considered for inclusion into future clinical trials and treatment protocols for patients with AAV.

Challenges of defining renal response in ANCA-associated vasculitis: call to action?

“…Studies using repeated kidney biopsies in the case of persistent or worsening hematuria are essential to answer these questions. A small study with interval biopsies after a median time of 130 days indicated low agreement with clinically suspected active disease, which was found in only 41% of patients [ 41 ]. More important information might be related to changes in the severity of hematuria [i.e.…”

“…A small study on repeated protocol kidney biopsies revealed a progression of the Berden score in almost all investigated cases, suggesting ongoing disease activity despite initiation of immunosuppressive therapy [ 72 ]. Sequential assessment of the Berden classification indicated a class switch in 50%, with a histologic progression reported in 30% [ 41 ]. Consequently, implementation of protocol biopsies might be a useful tool to determine therapy response.…”

Diagnostic and Therapeutic Approach in ANCA-Associated Glomerulonephritis: A Review on Management Strategies

“…Clinical biomarkers, such as hematuria and serum creatinine do not reflect disease activity specifically and sensitively enough, thus they can be mistaken for relapses. Approximately half of the patients who underwent rebiopsy had alteration in the Berden classification, up-or downstepping in the classification hierarchy (105,106). This finding suggests that interval biopsy could aid clinicians to develop more appropriate and personalized treatment and predict kidney outcomes more precisely than the initial biopsy.…”

Novel aspects in the pathophysiology and diagnosis of glomerular diseases

“…The inflammatory response seen in many diseases with immune deposits will eventually lead to chronic lesions with global glomerulosclerosis and interstitial fibrosis (IF) as characteristic features of common final pathways of kidney damage, if the respective processes are not terminated early 26 55. Repeat kidney biopsy (either protocol biopsies or as per indication) indicated that the number of globally sclerosed glomeruli and the proportion of patients with severe IF/tubular atrophy (IF/TA) increased in ANCA-GN with evidence of active disease despite immunosuppressive treatment 56. This indicates that despite treatment and clinical remission, sub-clinical inflammation and disease progression may still progress unnoticed.…”