gastrointestinal disorders
Overview of Inflammatory Bowel Disease
Epidemiology
Inflammatory bowel disease (IBD) affects people of all ages but usually begins before age 30, with peak incidence from 14 to 24 ( General references ). IBD may have a second smaller peak between ages 50 and 70; however, this later peak may include some cases of ischemic colitis. IBD is most common among people of Northern European and Anglo-Saxon origin. It is 2 to 4 times more common among people of Ashkenazi Jewish ancestry (those from Central or Eastern Europe) than among non-Jewish White people from the same geographic location ( General references ). The incidence is lower in central and southern Europe and lower still in South America, Asia, and Africa. However, the incidence is increasing among Black and Latin American people living in North America. Both sexes are equally affected. First-degree relatives of patients with IBD have a 4- to 20-fold increased risk; their absolute risk may be as high as 7%. Familial tendency is much higher in Crohn disease than in ulcerative colitis. Several gene mutations conferring a higher risk of Crohn disease (and some possibly related to ulcerative colitis) have been identified. Cigarette smoking seems to contribute to development or exacerbation of Crohn disease but decreases risk of ulcerative colitis. Appendectomy done to treat appendicitis also appears to lower the risk of ulcerative colitis. Nonsteroidal anti-inflammatory drugs (NSAIDs) may exacerbate IBD. Oral contraceptives may increase the risk of Crohn disease. Some data suggest that perinatal illness and the use of antibiotics in childhood may be associated with an increased risk of IBD. For unclear reasons, people who have a higher socioeconomic status may have an increased risk of Crohn disease. 