title: The predictive value of attenuated proteinuria at 1 year after steroid therapy for renal survival in patients with IgA nephropathy.
abstract: BACKGROUND
  The relationship between the urinary protein excretion (UPE) initially achieved after steroid therapy and the long-term renal outcome of IgA nephropathy (IgAN) has not been clarified. We investigated the threshold UPE at 1 year after steroid therapy which predicts a favorable renal survival.
  
  
  METHODS
  We enrolled 141 IgAN patients who received 6 months of steroid therapy. The endpoint was defined as a 50 % increase in serum creatinine from baseline. The spline model was used to define the threshold UPE predicting renal survival.
  
  
  RESULTS
  Thirteen patients (9.2 %) reached the endpoint at a median follow-up of 3.8 years. When evaluating the relative hazard ratio (HR) of the UPE at 1 year for the endpoint, we found an inflection point at 0.40 g/day on the spline curve. The multivariate Cox model revealed that, in addition to the Disappeared category of UPE (range <0.30 g/day), the Mild category (range 0.30-0.39 g/day) was associated with more reduced risk of the endpoint [HR 0.02, 95 % confidence intervals (CI) 0.00-0.29] relative to the Severe category (range ≥1.00 g/day), whereas the Moderate category (range 0.40-0.99 g/day) was not. The estimated glomerular filtration rate <60 ml/min/1.73 m(2) was also an independent predictor of the endpoint. When renal survival was adjusted with pathological parameters in the Cox model, UPE <0.40 g/day was still an independent favorable predictor (HR 0.08, 95 % CI 0.01-0.45).
  
  
  CONCLUSIONS
  In IgAN patients receiving 6 months of steroid therapy, the achievement of proteinuria <0.4 g/day at 1 year could be a therapeutic indicator for a favorable renal outcome.
authors.affiliation: Division of Kidney and Hypertension, Department of Internal Medicine, Jikei University School of Medicine, 3-25-8 Nishi-Shinbashi, Minato-Ku, Tokyo, 105-8461, Japan.
authors.forename: Keita
authors.initials: K
authors.lastname: Hirano
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Kawamura
authors.forename: Nobuo
authors.initials: N
authors.lastname: Tsuboi
authors.forename: Hideo
authors.initials: H
authors.lastname: Okonogi
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Miyazaki
authors.forename: Masato
authors.initials: M
authors.lastname: Ikeda
authors.forename: Masato
authors.initials: M
authors.lastname: Matsushima
authors.forename: Kazushige
authors.initials: K
authors.lastname: Hanaoka
authors.forename: Makoto
authors.initials: M
authors.lastname: Ogura
authors.forename: Yasunori
authors.initials: Y
authors.lastname: Utsunomiya
authors.forename: Tatsuo
authors.initials: T
authors.lastname: Hosoya
mesh_terms: D000305:Adrenal Cortex Hormones / Q000627:therapeutic use*; D000328:Adult; D015331:Cohort Studies; D003404:Creatinine / Q000097:blood; D005260:Female; D005919:Glomerular Filtration Rate; D005922:Glomerulonephritis, IGA / Q000188:drug therapy*; D006801:Humans; D008297:Male; D011379:Prognosis; D016016:Proportional Hazards Models; D011507:Proteinuria / Q000188:drug therapy / Q000652:urine*
chemical_list: D000305:Adrenal Cortex Hormones; D003404:Creatinine