Relapse rate and renal prognosis in ANCA‐associated vasculitis according to long‐term ANCA patterns.

Summary: Long‐term observation of patients with ANCA‐associated vasculitis (AAV) allows the identification of different longitudinal patterns of ANCA levels during follow‐up. This study aimed to characterize these patterns and to determine their prognostic significance. All ANCA determinations performed in two university hospitals during a 2‐year period were retrospectively reviewed. Patients were included in the analysis if they had high titers of anti‐myeloperoxidase (anti‐MPO) or anti‐proteinase 3 (anti‐PR3) antibodies at least once, ≥ 5 serial ANCA determinations and AAV diagnosed by biopsy or American College of Rheumatology (ACR) classification criteria. Patients' time–course ANCA patterns were classified as monophasic, remitting, recurrent or persistent. Associations between ANCA patterns and prognostic variables (relapse rate and renal outcome) were analysed by univariate and multivariate statistics. A total of 99 patients [55 with microscopic polyangiitis (MPA), 36 with granulomatosis with polyangiitis (GPA) and eight with eosinophilic granulomatosis with polyangiitis (EGPA)] were included. Median follow‐up was 9 years. Among patients diagnosed with MPA or GPA, recurrent or persistent ANCA patterns were associated with a higher risk of clinical relapse [hazard ratio (HR) = 3·7, 95% confidence interval (CI) = 1·5–9·1 and HR = 2·9, 95% CI = 1·1–8·0, respectively], independently of clinical diagnosis or ANCA specificity. In patients with anti‐MPO antibodies, the recurrent ANCA pattern was associated with worsening renal function [odds ratio (OR) = 5·7, 95% CI = 1·2–26·0]. Recurrent or persistent ANCA patterns are associated with a higher risk of clinical relapse. A recurrent ANCA pattern was associated with worsening renal function in anti‐MPO‐associated vasculitis. [ABSTRACT FROM AUTHOR]