n e w e ng l a n d j o u r na l
m e dic i n e
Silvio Danese, M.D., and Claudio Fiocchi, M.D. lcerative colitis was first described in the mid-1800s,1 whereas Crohn’s disease was first reported later, in 1932, as “regional ileitis.”2 Because Crohn’s disease can involve the colon and shares clinical manifestations withulcerative colitis, these entities have often been conflated and diagnosed as inflammatory bowel disease, although they are clearly distinct pathophysiological entities. Ulcerative colitis is the most common form of inflammatory bowel disease worldwide. In contrast to Crohn’s disease, ulcerative colitis is a disease of the mucosa that is less prone to complications and can be cured by means ofcolectomy, and in many patients, its course is mild.3 The literature on the pathogenesis and treatment of so-called inflammatory bowel disease has tended to focus on Crohn’s disease,4-7 and few articles expressly discuss ulcerative colitis.8,9 Here we review our current understanding of the pathophysiology, diagnosis, and treatment of ulcerative colitis to date; we also compare ulcerative colitis withCrohn’s disease and refer to both as inflammatory bowel disease according to the context.
From the Department of Gastroenterology, Istituto Clinico Humanitas, Milan (S.D.); and the Department of Gastroenterology and Hepatology, Digestive Disease Insti tute, and Department of Pathobiology, Ler ner Research Institute, Cleveland Clinic, Cleveland (C.F.). Address reprint requests to Dr. Fiocchiat the Cleveland Clinic Foun dation, Lerner Research Institute, Depart ment of Pathobiology/NC22, 9500 Euclid Ave., Cleveland, OH 44195. N Engl J Med 2011;365:171325.
Copyright © 2011 Massachusetts Medical Society.
Patho gene sis
Ulcerative colitis and Crohn’s disease are disorders of modern society, and their frequency in developed countries has been increasingsince the mid-20th century. When inflammatory bowel disease is identified in a new population, ulcerative colitis invariably precedes Crohn’s disease and has a higher incidence. The incidence of ulcerative colitis is 1.2 to 20.3 cases per 100,000 persons per year, and its prevalence is 7.6 to 246.0 cases per 100,000 per year, as compared with an incidence of 0.03 to 15.6 cases and a prevalence of3.6 to 214.0 cases per 100,000 per year for Crohn’s disease.10 Among children, however, ulcerative colitis is less prevalent than Crohn’s disease.11 The highest incidence and prevalence of inflammatory bowel disease are seen in the populations of Northern Europe and North America and the lowest in continental Asia, where ulcerative colitis is by far the most common form of inflammatory boweldisease.12 A westernized environment and lifestyle is linked to the appearance of inflammatory bowel disease, which is associated with smoking, diets high in fat and sugar, medication use, stress, and high socioeconomic status.13 Inflammatory bowel disease has also been associated with appendectomy.13 Of these factors, only cigarette smoking and appendectomy are reproducibly linked to ulcerativecolitis. Smoking is associated with milder disease, fewer hospitalizations, and a reduced need for medications.14 Removal of an inflamed appendix in early life is associated with a decreased incidence of ulcerative colitis,15 whereas the opposite is true for Crohn’s disease.
The discovery that NOD2 variants are associated with susceptibility to Crohn’s disease opened a new era inthe study of the genetic basis of inflammatory bowel disease.16,17
n engl j med 365;18 nejm.org november 3, 2011
The New England Journal of Medicine Downloaded from nejm.org on November 3, 2011. For personal use only. No other uses without permission. Copyright © 2011 Massachusetts Medical Society. All rights reserved.
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