Inflammatory bowel disease (IBD) is an immune-mediated chronic intestinal condition. Ulcerative colitis (UC) and Crohn’s disease (CD) are the two major types of IBD.
GLOBAL CONSIDERATIONS: EPIDEMIOLOGY
The incidence and prevalence of IBD are highest in Westernized nations, with UC incidence estimates ranging from 0.6 to 24.3 per 100,000 in Europe, 0 to 19.2 per 100,000 in North America, and 0.1 to 6.3 per 100,000 in the Middle East and Asia and CD estimates ranging from 0.3 to 12.7 per 100,000 in Europe, 0 to 20.2 per 100,000 in North America, and 0.04 to 5.0 per 100,000 in the Middle East and Asia (Table 351-1). For prevalence rates, the UC estimates range from 4.9 to 505 per 100,000 in Europe, 37.5 to 248.6 per 100,000 in North America, and 4.9 to 168.3 per 100,000 in the Middle East and Asia, and the CD estimates range from 0.6 to 322 per 100,000 in Europe, 16.7 to 318.5 per 100,000 in North America, and 0.88 to 67.9 per 100,000 in Asia and the Middle East. The highest reported incidence rates are in Canada (19.2 per 100,000 for UC and 20.2 per 100,000 for CD), with approximately 0.6% of the Canadian population having IBD. Countries in the Pacific, including New Zealand and Australia, which share many possible environmental risk factors and similar genetic background as northwest Europe and North America, have high incidence rates of IBD.
TABLE 351-1Epidemiology of IBD |Favorite Table|Download (.pdf) TABLE 351-1 Epidemiology of IBD
| ||Ulcerative Colitis ||Crohn’s Disease |
|Incidence (North America) per person-years ||0–19.2 per 100,000 ||0–20.2 per 100,000 |
|Age of onset ||Second to fourth decades and seventh to ninth decades ||Second to fourth decades and seventh to ninth decades |
|Ethnicity ||Jewish > non-Jewish white > African American > Hispanic > Asian |
|Female/male ratio ||0.51–1.58 ||0.34–1.65 |
|Smoking ||May prevent disease (odds ratio 0.58) ||May cause disease (odds ratio 1.76) |
|Oral contraceptives ||No increased risk ||Odds ratio 1.4 |
|Appendectomy ||Protective (risk reduction of 13–26%) ||Not protective |
|Monozygotic twins ||6–18% concordance ||38–58% concordance |
|Dizygotic twins ||0–2% concordance ||4% concordance |
|Antibiotic use in the first year of life ||2.9× the risk of developing childhood IBD || |
In countries that are becoming more Westernized, including China, South Korea, India, Lebanon, Iran, Thailand, and countries in the French West Indies and North Africa, IBD appears to be emerging, emphasizing the importance of environmental factors in disease pathogenesis. In Japan, the prevalence of CD has risen rapidly from 2.9 cases per 100,000 in 1986 to 13.5 per 100,000 in 1998, whereas in South Korea, the prevalence of UC has quadrupled from 7.6 per 100,000 in 1997 to 30.9 per 100,000 in 2005. In Hong Kong, the prevalence of UC almost tripled from 2.3 in 1997 to 6.3 per 100,000 over a 9-year period. In Singapore, the prevalence of CD increased ...