Epidemiology of Inflammatory Bowel Disease

Crohn's disease and ulcerative colitis are the two major subtypes of idiopathic inflammatory bowel disease. The incidence of both diseases continues to rise in both the developed and developing world. The best established environmental factors are cigarette smoking (protective for ulcerative colitis, risk factor for Crohn's) and appendectomy (protective colitis). Antibiotic use, especially early in life, may be a risk factor for both conditions. Up to 30% of ulcerative colitis patients and 60-80% of Crohn's disease patients require surgery. Colorectal cancer risk is increased in ulcerative colitis and Crohn's disease with colonic involvement, while Crohn's disease patients with small bowel involvement are at increased risk for small bowel cancer. Mortality rates in Crohn's disease are increased, while mortality data in ulcerative colitis are conflicting.