Clinicopathological prognostic stratification for proteinuria and kidney survival in IgA nephropathy: a Japanese prospective cohort study

Kentaro Koike, Tetsuya Kawamura, Keita Hirano, Masako Nishikawa, Akira Shimizu, Kensuke Joh, Ritsuko Katafuchi, Akinori Hashiguchi, Yuichiro Yano, Keiichi Matsuzaki, Masato Matsushima, Nobuo Tsuboi, Shoichi Maruyama, Ichiei Narita, Takashi Yokoo, Yusuke Suzuki

Research output: Contribution to journalArticlepeer-review


Background. We require a clinicopathological risk stratification method for immunoglobulin A nephropathy (IgAN) to predict kidney outcomes. We examined a renal failure risk group (RF-RG) classification system created following a prior multicentre, retrospective study to determine if RF-RG could predict kidney outcomes. Methods. We collected data from Japanese patients with IgAN registered between 1 April 2005 and 31 August 2015. The primary outcome was a composite 50% increase in serum creatinine from baseline or dialysis induction. The secondary outcomes were times to proteinuria remission (ProR) and haematuria remission (HemR). Results. The enrolled 991 patients from 44 facilities were followed for a median of 5.5 years (interquartile range 2.5-7.5), during which 87 composite events (8.8%) occurred. RF-RG was significantly associated with the primary outcome {hazard ratio [HR] II 2.78 [95% confidence interval (CI) 1.12-6.93], III 7.15 (2.90-17.6), IV 33.4 (14.1-79.0), I as a reference, P < .001}. The discrimination performance was good [C-statistic 0.81 (95% CI 0.76-0.86)] and the time-dependent C-statistics exceeded 0.8 over 10 years. Among the 764 patients with proteinuria and 879 patients with haematuria at baseline, 515 and 645 patients showed ProR and HemR, respectively. ProR was significantly less frequent in patients with advanced disease [subdistribution HR: II 0.79 (95% CI 0.67-0.94), III 0.53 (0.41-0.66), IV 0.15 (0.09-0.23), I as a reference, P < .001]. We also observed an association between HemR and RF-RG. Conclusions. RF-RG demonstrated good predictive ability for kidney outcomes.

Original languageEnglish
Article numbersfad294
JournalClinical Kidney Journal
Issue number1
Publication statusPublished - 2024 Jan 1


  • IgA nephropathy
  • clinicopathological grading
  • haematuria
  • kidney prognosis
  • proteinuria

ASJC Scopus subject areas

  • Nephrology
  • Transplantation


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