title: Crohn's disease: influence of age at diagnosis on site and clinical type of disease.
abstract: OBJECTIVE
  Crohn's disease has a bimodal age distribution of disease onset diagnosis. The peaks (20 and 50 years) may represent different phenotypes or different genetic and/or environmental influences between younger- and older-onset individuals. The aim of this study was to examine the influences of age at diagnosis of Crohn's disease on disease site, type, and course.
  
  
  METHODS
  Records of 552 consecutive patients with Crohn's disease were reviewed retrospectively.
  
  
  RESULTS
  Younger age at diagnosis (younger than 20 years), compared with an older age (40 years or older), was associated with a greater prevalence of a family history of Crohn's disease (29.9% vs. 13.6%), greater small bowel involvement (88.7% vs. 57.5%), more stricturing disease (45.8% vs. 28.8%), and a higher frequency of surgery (70.6% vs. 55.3%). Older age at diagnosis was associated with a greater prevalence of colonic disease (84.8% vs. 71.2%) and the inflammatory subtype (54.5% vs. 34.4%). A conditional logistic regression analysis confirmed an independent effect of age at diagnosis on ileal disease and surgery for intractable disease.
  
  
  CONCLUSIONS
  In Crohn's disease, early age at diagnosis is associated with more complicated disease and a greater likelihood of having affected relatives. Stratification of Crohn's disease by age at diagnosis provides support for the concept of genetic heterogeneity.
authors.affiliation: Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
authors.forename: J M
authors.initials: JM
authors.lastname: Polito
authors.forename: B
authors.initials: B
authors.lastname: Childs
authors.forename: E D
authors.initials: ED
authors.lastname: Mellits
authors.forename: A Z
authors.initials: AZ
authors.lastname: Tokayer
authors.forename: M L
authors.initials: ML
authors.lastname: Harris
authors.forename: T M
authors.initials: TM
authors.lastname: Bayless
mesh_terms: D000328:Adult; D017668:Age of Onset; D003424:Crohn Disease / Q000145:classification* / Q000453:epidemiology* / Q000235:genetics / Q000601:surgery; D005192:Family Health; D005260:Female; D006801:Humans; D008297:Male; D008499:Medical Records; D012044:Regression Analysis; D012189:Retrospective Studies