title: Clinical manifestations of Henoch-Schönlein purpura nephritis and IgA nephropathy: comparative analysis of data from the Japan Renal Biopsy Registry (J-RBR).
abstract: BACKGROUND
  The clinical presentation of Henoch-Schönlein purpura nephritis (HSPN) has not been thoroughly investigated among patients of different ages. We therefore compared the features of HSPN and IgA nephropathy (IgAN) based on data from the Japan Renal Biopsy Registry (J-RBR).
  
  
  METHODS
  This cross-sectional study analyzed data from patients who were registered in the J-RBR between 2007 and 2012. Clinico-pathological findings at diagnosis were compared among children (aged ≤18 years), adult (aged 19-64 years) and elderly (aged ≥65 years) patients with HSPN (n = 513) and IgAN (n = 5679).
  
  
  RESULTS
  The age at diagnosis considerably differed between HSPN and IgAN; HSPN peaked at 1-19 and at 60-69 years, whereas IgAN peaked at 30-39 years. The clinical features were significantly more severe for HSPN than IgAN, especially proteinuria (children, 1.28 vs. 0.57; adult, 1.95 vs. 1.05; elderly patients, 2.71 vs. 1.64 g/day), and low albumin levels (children, 3.72 vs. 4.13; adults, 3.62 vs. 3.99; elderly patients, 3.07 vs. 3.57 g/dL). The rate (%) of histologically classified endocapillary proliferative or crescentic glomerulonephritis was higher in patients with HSPN than with IgAN. Multiple regression analysis revealed that low albumin level and high BP were independent factors associated with decreased estimated glomerular filtration rates in adult and elderly patients with HSPN.
  
  
  CONCLUSIONS
  Age at HSPN diagnosis was bimodally distributed, and the clinical features of HSPN were more severe than those of IgAN across all age groups.
authors.affiliation: First Department of Internal Medicine, University of Miyazaki Hospital, 5200 Kihara, Kiyotake, Miyazaki, 889-1692, Japan. hiroyuki_komatsu@med.miyazaki-u.ac.jp.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Komatsu
authors.affiliation: Department of Hemovascular Medicine and Artificial Organs, Faculty of Medicine, University of Miyazaki, Miyazaki, Japan.
authors.forename: Shouichi
authors.initials: S
authors.lastname: Fujimoto
authors.affiliation: Center for Clinical Research and Development, National Center for Child Health and Development, Tokyo, Japan.
authors.forename: Norishige
authors.initials: N
authors.lastname: Yoshikawa
authors.affiliation: Department of Pathology, Clinical Research Center, National Hospital Organization Chiba East National Hospital, Chiba, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kitamura
authors.affiliation: Department of Medicine and Clinical Science, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Science, Okayama, Japan.
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Sugiyama
authors.affiliation: Division of Nephrology, Kanazawa Medical University School of Medicine, Ishikawa, Japan.
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Yokoyama
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D005260:Female; D005922:Glomerulonephritis, IGA / Q000453:epidemiology*; D006801:Humans; D011695:IgA Vasculitis / Q000453:epidemiology*; D007223:Infant; D007564:Japan / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D012042:Registries; D055815:Young Adult
keywords: Age distribution; Glomerulonephritis; Henoch–Schönlein purpura nephritis; IgA nephropathy; Registry; Renal biopsy