Epidemiology

It is estimated that there are around 2.4 to 3.1 million adults affected with inflammatory bowel disease (either Crohn disease [CD] or ulcerative colitis) in the US.[10]

The onset of CD typically occurs in the second to fourth decade of life, with a smaller peak from 50-60 years.[11][12][13]​ CD is more common in the industrialized world, particularly in North America and Western Europe, but incidence is increasing in newly industrialized countries in Asia, South America, and the Middle East.[11][12][13][14][15][16]​ One systematic review reported CD annual incidences of 20.2 per 100,000 person-years in North America, 12.7 per 100,000 person-years in Europe, and 5.0 per 100,000 person-years in Asia and the Middle East.[13]

One pooled analysis of population-based cohorts reported that females from the Western countries had a lower risk of CD during childhood, until the age range of 10-14 years.[17]​ The risk of CD was higher thereafter and was statistically significant for women ages 25-29 years and >35 years.[17]​ In contrast, 36% to 64% higher incidence of CD was reported in males, compared with females, across most age groups (early adolescence to 50 years) in people from the Asia-Pacific region (P <0.001).[18]

CD appears to be more common in white people, and in individuals of Ashkenazi Jewish origin.[11][19][20]​ Around 10% to 25% of affected patients have a first-degree relative with CD.[21][22]​ A higher prevalence among smokers has been reported.[23][24][25][26]

One systematic review confirmed high prevalence values for CD in Europe (322 per 100,000 in Germany) and North America (319 per 100,000 in Canada).[14] However, incidence of CD appears to be stable or decreasing in these areas.[14]

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