Clinical characteristics and prognosis of ANCA-associated vasculitis in patients with renal injury

Objective To investigate the characteristics and outcome of anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) in patients with renal injury. Methods AAV patients with renal injury diagnosed in the Department of Nephrology, Renmin Hospital of Wuhan University, from January 2012 to January 2017 were included into this study. Patients were divided into MPO-ANCA positive and PR3-ANCA positive groups for further study. The clinical characteristics, pathological and laboratory indexes, treatment and prognosis were retrospectively analyzed. Results A total of 68 cases were enrolled, among which 52 cases (76.5%) were MPO-ANCA positive and 16 cases (23.5%) were PR3-ANCA positive, and 41 patients (60.3%) were over 65 years old. The incidences of interstitial lung disease, digestive and nervous system damage in PR3-ANCA positive group were significantly higher than those MPO-ANCA positive group (P<0.05). There were significant differences of hemoglobin, complement C3, complement C1q, IgE, 24 h urinary protein, erythrocyte sedimentation rate, procalcitonin, BVAS score and eGFR in two groups (P<0.05). 19 cases had done renal biopsy, among them 14 cases were MPO-ANCA positive and 5 cases were PR3-ANCA positive. Incidence of crescentic necrotizing glomerulonephritis in PR3-ANCA positive group was significantly higher than that in MPO-ANCA positive group, and incidence of diffuse global glomerulosclerosis in MPO-ANCA positive group was significantly higher than that in PR3-ANCA positive group (all P<0.05). At the median follow-up time of 32 months, the relapse rate at 6 month of MPO-ANCA-positive and PR3-ANCA-positive patients were 46.2% and 75.0%, respectively (P<0.05). Multivariate logistic regression analysis showed that PR3-ANCA positive, age≥65 years old, baseline eGFR<30 ml·min-1·(1.73 m2)-1, and combined with pulmonary interstitial lesions were all independent risk factors for relapse. And the incidence of ESRD were 42.3% and 75.0% during the follow-up period and 10 patients (14.7%) died. COX regression analysis showed that patients older than 65 years old, BVAS score≥18 points, eGFR<30 ml·min-1·(1.73 m2)-1 and complicated with pulmonary interstitial disorders at the onset were independent risk factors causing ESRD or death. Conclusion The PR3-ANCA-positive patients had more severe renal injury than those with MPO-ANCA-positive patients, and the injury of extrarenal organs was more serious, recurrence rate was higher, and the prognosis was worse. Key words: Vasculitis; Prognosis; Renal pathology