Clinical Characteristics and Prognosis of Patients with Anti-Neutrophil Cytoplasmic Antibody-Associated Vasculitis According to Serotype: A Retrospective Study of 349 Chinese Patients

Abstract

Objective: According to clinical phenotypic classification, there is a significant overlap of clinical features between different anti-neutrophil cytoplasmic antibody (ANCA) associated vasculitis (AAV), and disease classification based on ANCA subtype helps to differentiate clinical phenotypes. We investigated the clinical features and outcomes of patients based on ANCA serotype classification. Methods: Clinical and laboratory data were collected retrospectively. We compared clinical manifestations and organ involvement based on serotype. The risk factors for death and renal survival were investigated with univariate and multivariate Cox regression models. Results: Patients with MPO-ANCA were predominant, whose median age and lung involvement at diagnosis was higher than that of the PR3-ANCA patients. Compared to the AAV patients without renal involvement, those with renal involvement have older, anemia, low complement C3, and hypoproteinemia, more likely to have cardiovascular and abdominal involvement, and have less lung involvement. Multivariate Cox analysis revealed that age ≥ 65 years (HR = 2.611, p < 0.001), serum creatinine (SCR) ≥ 500 μmol/L (HR = 1.546, p = 0.019), BVAS ≥ 15 (HR = 1.943, p = 0.001), low C3 (HR = 1.696, p = 0.008), and hypoproteinemia (HR = 1.438, p = 0.044) were associated with mortality. SCR ≥ 500 μmol/L (HR = 13.583, p < 0.001), BVAS ≥ 15 (HR = 1.660, p = 0.020), low C3 (HR = 1.506, p = 0.049) were independent detrimental factors for renal survival, and immunosuppressive treatment was a protective factor for renal survival (HR = 0.523, p = 0.003). Conclusions: Clinical manifestations varied by AAV categories. Age, SCR, BVAS, low C3 and hypoproteinemia at diagnosis were