Crohn’s Disease – EPIDEMIOLOGY

Posted by Alex

CD occurs among all age groups but have a peak incidence in the second and third decades. CD incidence has risen over the past 20 years; CD has an incidence and prevalence rates of 5 per 100,000. The combined prevalence of the two diseases is approximately 100 per 100,000 population. CD are seen most commonly in Northern Europe and North America and in relatives of European immigrants in the cities of South Africa, Australia, and New Zealand. Inflammatory bowel disease (IBD) included Crohn’s disease and Crohn’s disease. IBD is rare in Central America, South America, Africa, the Middle East, and Asia. Although CD can be seen in all ethnic groups, there is an increased prevalence in Jews who have immigrated from Northern Europe. This Jewish predisposition is not seen in Sephardic (Mediterranean or Middle-Eastern) Jews. Although less common in the nonwhite population, more cases are being recognized in black, Hispanic, and Asian immigrants to western cities.

A presumed genetic influence is derived from family studies, in which approximately 20% of individuals with IBD have a relative with CD. The pattern of inheritance is more complicated than that of a simple mendelian trait, and the risk is spread across families. In children with IBD the likelihood of another family member having the diagnosis is > 40%. Although the risk to a child of a parent with IBD is < 5%, when both parents have IBD the risk to offspring is > 50%. A stronger concordance exists within families and in twin studies for CD than for UC. The only epidemiologic difference between UC and CD pertains to cigarette smoking. Cigarette smoking appears to protect against UC and is associated with CD. More than 80% of patients with UC are nonsmokers, whereas 80% of patients with CD smoke cigarettes. Often, UC begins after a “predisposed” individual stops smoking.

Attempts have been made to implicate a number of environmental factors in the development of IBD, including atypical mycobacterium, diets high in refined sugar (including corn flakes), increased consumption of polyunsaturated fats (margarine), and oral contraceptive pills, but none has been proven.