title: Development and validation of a prediction rule using the Oxford classification in IgA nephropathy.
abstract: OBJECTIVE
  The risk assessment for developing ESRD remains limited in patients with IgA nephropathy (IgAN). The aim of this study was to develop and validate a prediction rule for estimating the individual risk of ESRD in patients with IgAN.
  
  
  METHODS
  A total of 698 patients with IgAN diagnosed by renal biopsy at Kyushu University Hospital (derivation cohort) between 1982 and 2010 were retrospectively followed. The Oxford classification was used to evaluate the pathologic lesions. The risk factors for developing ESRD were evaluated using a Cox proportional hazard model with a stepwise backward elimination method. The prediction rule was verified using data from 702 patients diagnosed at Japanese Red Cross Fukuoka Hospital (validation cohort) between 1979 and 2002.
  
  
  RESULTS
  In the derivation cohort, 73 patients developed ESRD during the median 4.7-year follow-up. The final prediction model included proteinuria (hazard ratio [HR], 1.30; 95% confidence interval [95% CI], 1.16 to 1.45, every 1 g/24 hours), estimated GFR (HR, 0.84; 95% CI, 0.74 to 0.96, every 10 ml/min per 1.73 m(2)), mesangial proliferation (HR, 1.85; 95% CI, 1.10 to 3.11), segmental sclerosis (HR, 3.21; 95% CI, 1.37 to 7.51), and interstitial fibrosis/tubular atrophy (T1: HR, 5.30; 95% CI, 2.63 to 10.7; T2: HR, 20.5; 95% CI, 9.05 to 46.5) as independent risk factors for developing ESRD. To create a prediction rule, the score for each variable was weighted by the regression coefficients calculated using the relevant Cox model. The incidence of ESRD increased linearly with increases in the total risk scores (P for trend <0.001). Furthermore, the prediction rule demonstrated good discrimination (c-statistic=0.89) and calibration (Hosmer-Lemeshow test, P=0.78) in the validation cohort.
  
  
  CONCLUSIONS
  This study developed and validated a new prediction rule using clinical measures and the Oxford classification for developing ESRD in patients with IgAN.
authors.affiliation: Department of Medicine and Clinical Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan;, †Kidney Unit, National Fukuoka-Higashi Medical Center, Fukuoka, Japan;, ‡Division of Nephrology and Dialysis Center, Japanese Red Cross Fukuoka Hospital, Fukuoka, Japan, §Department of Integrated Therapy for Chronic Kidney Disease, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
authors.forename: Shigeru
authors.initials: S
authors.lastname: Tanaka
authors.forename: Toshiharu
authors.initials: T
authors.lastname: Ninomiya
authors.forename: Ritsuko
authors.initials: R
authors.lastname: Katafuchi
authors.forename: Kosuke
authors.initials: K
authors.lastname: Masutani
authors.forename: Akihiro
authors.initials: A
authors.lastname: Tsuchimoto
authors.forename: Hideko
authors.initials: H
authors.lastname: Noguchi
authors.forename: Hideki
authors.initials: H
authors.lastname: Hirakata
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Tsuruya
authors.forename: Takanari
authors.initials: T
authors.lastname: Kitazono
mesh_terms: D000328:Adult; D001706:Biopsy; D016009:Chi-Square Distribution; D003661:Decision Support Techniques; D016002:Discriminant Analysis; D018450:Disease Progression; D005260:Female; D005919:Glomerular Filtration Rate; D005922:Glomerulonephritis, IGA / Q000145:classification / Q000453:epidemiology* / Q000473:pathology / Q000503:physiopathology; D006785:Hospitals, University; D006801:Humans; D015994:Incidence; D007564:Japan / Q000453:epidemiology; D053208:Kaplan-Meier Estimate; D007668:Kidney / Q000473:pathology / Q000503:physiopathology; D007676:Kidney Failure, Chronic / Q000453:epidemiology*; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D016017:Odds Ratio; D011237:Predictive Value of Tests; D011379:Prognosis; D016016:Proportional Hazards Models; D015203:Reproducibility of Results; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D013997:Time Factors; D055815:Young Adult