Clinical value of systemic symptoms in IgA nephropathy with ANCA positivity

Abstract

Our aim was to evaluate the pathogenic role of anti-neutrophil cytoplasmic antibodies (ANCAs) in patients with IgA nephropathy (IgAN). A total of 2390 patients with biopsy-confirmed IgAN were analyzed retrospectively. Thirty-five IgAN patients with ANCA and 40 IgAN patients without ANCA were enrolled. According to the Birmingham Vasculitis Activity Score (BVAS) items, the ANCA-positive patients were further divided into two subgroups which with or without systemic symptoms. The cumulative renal survival rate was calculated using Kaplan-Meier analysis. Comparisons between groups were made using the log rank test. Among the 35 ANCA-positive patients, 14 (40%) had systemic symptoms. Compared with ANCA-positive patients without systemic symptoms, ANCA-positive patients with systemic symptoms had a shorter duration of disease (1.0 [IQR, 0.3-6.8] vs. 6.0 [IQR, 2.0-21.0], P = 0.011); showed worse renal function with lower levels of eGFR (24.2 [IQR, 11.7-74.9] vs. 100.1 [IQR, 59.6-130.2] mL/min/1.73m2, P = 0.002), serum albumin (30.4 [IQR, 27.4-34.8] vs. 41.5 [IQR, 35.1-44.4] g/L, P = 0.001), and hemoglobin (96.1 ± 21.5 vs. 118.2 ± 22.4g/L, P = 0.006); and presented relatively higher incidences of rapidly deteriorating kidney function (28.6 vs. 0.0%, P = 0.039) and moderate-to-severe tubular atrophy (78.6 vs. 23.8%, P = 0.001). Kaplan-Meier analysis had shown that ANCA-positive patients with systemic symptoms had lower cumulative renal survival rate compared with both ANCA-positive patients without systemic symptoms and ANCA-negative patients (log rank = 14.40, P < 0.001). Evaluation of systemic symptoms is a simple, readily available clinical tool to predictive the pathogenic role of ANCA in IgAN.