title: The incidence and severity of Henoch-Schönlein purpura nephritis over a 22-year period in Fukushima Prefecture, Japan.
abstract: BACKGROUND
  Recently, there have been a few reports on the decrease in the incidence of severe Henoch-Schönlein purpura nephritis (HSPN) in Japan. To evaluate the incidence and the severity of HSPN, we examined the epidemiology and clinical manifestations of HSPN in Fukushima Prefecture over a 22-year period.
  
  
  METHODS
  We enrolled 61 patients (Group 1) diagnosed with HSPN between 1987 and 1997 and a further 59 patients (Group 2) diagnosed with HSPN between 1998 and 2008. Epidemiology, clinical features, laboratory data, pathological findings, treatment and outcome were retrospectively compared between the two groups.
  
  
  RESULTS
  The mean number of patients per 100,000 children per year was 3.5 ± 1.2 in Group 1 and 3.6 ± 0.8 in Group 2. The clinical manifestations and laboratory findings at onset were comparable between Groups 1 and 2. Pathological findings in Group 1 and Group 2 were classified as ISKDC grade IIIa in 16 (26%) and 14 cases (24%), grade IIIb in 26 (43%) and 27 cases (46%), grade IV in 5 (8%) and 6 cases (10%)), grade V in 1 (2%) and 5 cases (8%), and grade VI in 2 (3%) and 2 cases (3%), respectively. There were no inter-group differences in ISKDC classification or rate of crescentic formation.
  
  
  CONCLUSIONS
  Our findings suggest that the incidence of HSPN and the severity of HSPN in patients between 1987 and 1997 were similar to those in patients between 1998 and 2008 and that the number of patients with severe HSPN has not decreased.
authors.affiliation: Department of Pediatrics, Fukushima Medical University School of Medicine, 1 Hikariga-oka, Fukushima City, Fukushima, 960-1295, Japan. kyuki@fmu.ac.jp
authors.forename: Yukihiko
authors.initials: Y
authors.lastname: Kawasaki
authors.forename: Kazuhide
authors.initials: K
authors.lastname: Suyama
authors.forename: Eichi
authors.initials: E
authors.lastname: Yugeta
authors.forename: Masahiko
authors.initials: M
authors.lastname: Katayose
authors.forename: Shigeo
authors.initials: S
authors.lastname: Suzuki
authors.forename: Hiroko
authors.initials: H
authors.lastname: Sakuma
authors.forename: Kenji
authors.initials: K
authors.lastname: Nemoto
authors.forename: Akira
authors.initials: A
authors.lastname: Tsukagoshi
authors.forename: Katsutoshi
authors.initials: K
authors.lastname: Nagasawa
authors.forename: Mitsuaki
authors.initials: M
authors.lastname: Hosoya
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D011695:IgA Vasculitis / Q000453:epidemiology*; D015994:Incidence; D007564:Japan / Q000453:epidemiology; D008297:Male; D009393:Nephritis / Q000453:epidemiology*; D012189:Retrospective Studies; D012720:Severity of Illness Index; D013997:Time Factors