title: Clinical features of IgA nephropathy with serum ANCA positivity: a retrospective case-control study.
abstract: BACKGROUND
  The coexistence of IgA nephropathy (IgAN) and antineutrophil cytoplasmic autoantibodies (ANCAs) is relatively rare. Only a few studies have reported the features of these patients.
  
  
  METHODS
  We studied the clinical and histological features of 20 ANCA-positive IgAN patients. They were compared with ANCA-negative IgAN patients (n = 40) and ANCA-associated systemic vasculitis (AASV) patients (n = 40) with a randomly selected and matched proportion of crescentic glomeruli. Furthermore, 9 ANCA-positive crescentic IgAN patients out of the 20 cases were compared with two control groups with crescentic nephritis.
  
  
  RESULTS
  ANCA-positive IgAN patients showed older age, lower haemoglobin and higher inflammatory indicator levels at baseline, and a higher percentage of general symptoms and pulmonary involvement, compared with ANCA-negative IgAN patients, and were comparable to AASV patients. Histologically, there was a significantly higher percentage of fibrinoid necrosis in glomeruli in ANCA-positive IgAN patients and in AASV patients compared with ANCA-negative IgAN patients (35, 25 and 0%, respectively, P = 0.003). After immunosuppressive therapy, ANCA-positive crescentic IgAN patients were more likely to withdraw from dialysis (75 versus 9.1%, P = 0.03) and not to reach end-stage renal disease within 6 months (11.1 versus 66.7%, P = 0.01) compared with ANCA-negative crescentic IgAN patients.
  
  
  CONCLUSIONS
  IgAN patients with ANCA positivity showed more severe clinical and histological features when compared with ANCA-negative IgAN patients and were comparable to AASV patients. However, renal prognosis was relatively better in ANCA-positive crescentic IgAN patients after aggressive immunosuppressive therapy in the short term, compared with ANCA-negative patients.
authors.affiliation: Renal Division, Key Laboratory of Renal Disease, Ministry of Health of China , Peking University First Hospital, Institute of Nephrology, Peking University , Beijing , PR China.
authors.forename: Ya-Zi
authors.initials: YZ
authors.lastname: Yang
authors.affiliation: Renal Division, Key Laboratory of Renal Disease, Ministry of Health of China , Peking University First Hospital, Institute of Nephrology, Peking University , Beijing , PR China.
authors.forename: Su-Fang
authors.initials: SF
authors.lastname: Shi
authors.affiliation: Renal Division, Key Laboratory of Renal Disease, Ministry of Health of China , Peking University First Hospital, Institute of Nephrology, Peking University , Beijing , PR China.
authors.forename: Yu-Qing
authors.initials: YQ
authors.lastname: Chen
authors.affiliation: Renal Division, Key Laboratory of Renal Disease, Ministry of Health of China , Peking University First Hospital, Institute of Nephrology, Peking University , Beijing , PR China.
authors.forename: Min
authors.initials: M
authors.lastname: Chen
authors.affiliation: Renal Division, Key Laboratory of Renal Disease, Ministry of Health of China , Peking University First Hospital, Institute of Nephrology, Peking University , Beijing , PR China.
authors.forename: Yi-He
authors.initials: YH
authors.lastname: Yang
authors.affiliation: Renal Division, Key Laboratory of Renal Disease, Ministry of Health of China , Peking University First Hospital, Institute of Nephrology, Peking University , Beijing , PR China.
authors.forename: Xin-Fang
authors.initials: XF
authors.lastname: Xie
authors.affiliation: Renal Division, Key Laboratory of Renal Disease, Ministry of Health of China , Peking University First Hospital, Institute of Nephrology, Peking University , Beijing , PR China.
authors.forename: Rong
authors.initials: R
authors.lastname: Zou
authors.affiliation: Renal Division, Key Laboratory of Renal Disease, Ministry of Health of China , Peking University First Hospital, Institute of Nephrology, Peking University , Beijing , PR China.
authors.forename: Ji-Cheng
authors.initials: JC
authors.lastname: Lv
authors.affiliation: Renal Division, Key Laboratory of Renal Disease, Ministry of Health of China , Peking University First Hospital, Institute of Nephrology, Peking University , Beijing , PR China.
authors.forename: Li-Jun
authors.initials: LJ
authors.lastname: Liu
authors.affiliation: Renal Division, Key Laboratory of Renal Disease, Ministry of Health of China , Peking University First Hospital, Institute of Nephrology, Peking University , Beijing , PR China.
authors.forename: Hong
authors.initials: H
authors.lastname: Zhang
keywords: ANCA positive; ANCA-associated systemic vasculitis; IgA nephropathy; antineutrophil cytoplasmic autoantibodies