title: The epidemiology and natural history of Crohn's disease in population-based patient cohorts from North America: a systematic review.
abstract: OBJECTIVE
  To quantify, through systematic review, the epidemiology and natural history of Crohn's disease in North America.
  
  
  METHODS
  The selected articles contained: (i) population-based samples of patients followed from the time of diagnosis; and (ii) objective diagnostic criteria for disease. Studies on the natural history of Crohn's disease also contained sufficient follow-up.
  
  
  METHODS
  For prevalence studies, data on the incidence, prevalence, gender and age at diagnosis were extracted. For natural history studies, data on the disease activity, use of medications and surgery were extracted.
  
  
  RESULTS
  The prevalence of Crohn's disease in North America ranges from 26.0 to 198.5 cases per 100,000 persons. The incidence rates range from 3.1 to 14.6 cases per 100,000 person-years. Most patients have a chronic intermittent disease course, while 13% have an unremitting disease course and 10% have a prolonged remission. Less than half require corticosteroids at any point. During any given year, approximately 10% are treated with corticosteroids and 30% are treated with 5-aminosalicylates. Up to 57% of patients require at least one surgical resection.
  
  
  CONCLUSIONS
  Between 400,000 and 600,000 patients in North America have Crohn's disease, and the natural history is marked by frequent exacerbations requiring treatment with corticosteroids, 5-aminosalicylate products and surgery.
authors.affiliation: Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, MN 55905, USA. loftus.edward@mayo.edu
authors.forename: E V
authors.initials: EV
authors.lastname: Loftus
authors.forename: P
authors.initials: P
authors.lastname: Schoenfeld
authors.forename: W J
authors.initials: WJ
authors.lastname: Sandborn
mesh_terms: D000293:Adolescent; D000305:Adrenal Cortex Hormones / Q000627:therapeutic use; D000328:Adult; D000367:Age Factors; D000368:Aged; D002648:Child; D002675:Child, Preschool; D002908:Chronic Disease; D003424:Crohn Disease / Q000453:epidemiology* / Q000473:pathology*; D016021:Epidemiologic Studies; D005260:Female; D006801:Humans; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D009656:North America / Q000453:epidemiology; D011159:Population Surveillance; D015995:Prevalence; D012737:Sex Factors
chemical_list: D000305:Adrenal Cortex Hormones