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Crohn disease (CD) and ulcerative colitis (UC), collectively known as inflammatory bowel disease (IBD), are idiopathic, lifelong, chronic inflammatory conditions of the gastrointestinal (GI) tract which typically manifest during late childhood to young adulthood. The physical and psychological burden of these chronic relapsing diseases and their devastating effects imposed on affected children and teenagers may be considerable. Crohn disease and ulcerative colitis are grouped together in view of many similarities in their epidemiologic, genetic, immunologic, and clinical features. Diagnostic approaches are similar, but treatment approaches and prognosis differ.


Inflammatory bowel disease (IBD) is unevenly distributed throughout the world with the highest disease rates occurring in industrialized countries of Europe, North America, and Australia.1,2However, the incidence of IBD is rapidly increasing in other emerging industrialized countries. European studies have suggested that the incidence of IBD in children and adolescents has significantly increased over the last 35 years.3Although population-based studies are difficult to perform in North America, an epidemiological population-based study in Wisconsin found the incidence of IBD to be 7 per 100,000 in children under 18 years of age.4 In children, about two thirds of IBD cases are Crohn disease (CD), and one half are ulcerative colitis (UC), and in the adult population the prevalence CD and UC are equal.5 The geographical and chronological variation of IBD since its description early in the 20th century is represented in eFigure 410.1.

Onset of disease has a bimodal distribution, with the greatest incidence being adolescents and young adults, with a second peak in the fifth to sixth decade of life. Median age of onset of disease is between 10 and 11 years and is not different from CD. However, significant IBD cohorts have been described under 5 years of age.6 Population-based studies have not demonstrated an altered risk of IBD associated with gender, ethnicity, or urban versus rural setting.4In adults, exposure to tobacco smoke is associated with a lower incidence of UC, but the opposite effect has been seen in CD.7,8 A prospective cohort study of childhood exposure to smoke (active or passive) showed an increased risk with smoke exposure for both CD and UC in adulthood.9 Appendectomy is associated with a decreased incidence of UC but appears to increase the risk for CD, especially for worsening of disease for the first year following surgery.10,11 Controversy exists regarding the clinical significance of this in UC and whether the risk associated with CD represents diagnostic bias.12,13...

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