Objectives 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 one in four patients. Hematuria at interval biopsy did not correlate with histological activity. Interval biopsy showed fewer acute lesions and more chronic damage compared with 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.

中文翻译：

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间隔肾活检在 ANCA 相关性血管炎中的应用

目的 ANCA 相关性血管炎 (AAV) 是一种罕见的自身免疫性疾病，通常累及肾脏。早期识别肾脏受累、评估治疗反应和预测结果是重要的临床挑战。在这里，我们评估了间隔肾活检在 AAV 中的潜在效用。方法 在具有专门血管炎服务的三级转诊中心，我们确定了接受过肾活检的 AAV 患者，定义为重复肾活检（在初始活检显示活跃 AAV 之后），以确定诱导后肾脏的组织学反应免疫抑制。我们分析了所有患者的生化、组织学和结果数据，包括肾衰竭和死亡时间。结果 我们确定了 57 名 AAV 患者，他们至少接受了一次间隔肾活检（总共 59 次间隔活检；间隔活检的中位时间约为 130 天）。在进行的 59 次间隔活检中，24 名 (41%) 患者在活检时有临床疑似活动性疾病，只有 42% 的病例在组织学上得到证实；35 名 (59%) 患者处于临床疾病缓解期，这在 97% 的病例中是正确的。在四分之一的患者中，临床医生的印象是不正确的。间隔活检血尿与组织学活动无关。与初始活检相比，间隔活检显示出更少的急性病变和更多的慢性损伤，并导致 75% (44/59) 的患者改变免疫抑制治疗。临床风险预测工具倾向于使用间隔活检数据更好地运行。结论 间隔肾活检有助于确定 AAV 的治疗反应和随后的疾病管理。它可能比初始肾活检提供更好的预后信息，应考虑纳入未来 AAV 患者的临床试验和治疗方案。