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Canadian immigrants, their children less likely to develop IBD than natives
ORLANDO, Fla. — Immigrants to Canada, and the children of those immigrants, are less likely to develop inflammatory bowel disease than non-immigrants, with increased risk associated with younger age at immigration, according to a presenter here.
“Immigrants overall had a lower risk of developing IBD when they arrived in Canada. … Younger age at immigration did confer a higher risk,” Eric Benchimol, MD, PhD, FRCPC, of the CHEO Inflammatory Bowel Disease Centre, Children’s Hospital of Eastern Ontario, said during the Advances in IBD Meeting. “Earlier exposure to the Canadian environment seems to confer an increased risk of developing IBD and [the] why is something that’s actively being sought. We are trying to look for environmental risk factors in Canada that may predispose people to this high rate of developing IBD.”
Eric Benchimol
Recent data has shown a rise in IBD incidence in Ontario, leading Benchimol and colleagues to query the available databases, such as the Ontario Crohn’s and Colitis Cohort and the Landed Immigrant Dataset, to determine the risk of immigrants and their children developing IBD after being in the Canadian environment.
Benchimol and colleagues looked at 2,144,660 immigrants, of which 1,325 had incident IBD; and 12,036,921 non-immigrants, of which 25,939 had incident IBD. They then considered 277,008 children of immigrants with 150 cases of incident IBD and 1,024,049 children of non-immigrants with 1,161 cases of incident IBD.
Overall, the data showed an incidence of 7.3 per 100,000 person-years among immigrants and an incidence of 23.9 per 100,000 person-years among non-immigrants. Additionally, the researchers found that every additional decade of age at arrival of immigration lowered risk of IBD by 9.9%. East Asia-Pacific immigrants had the lowest risk of IBD development while those from Northern Africa, Europe and the Middle East had the highest risks.
“For every decade that immigrant was older on arrival in Canada, there was about a 10% lower risk of developing IBD later,” Benchimol said, though they have not yet concluded why that happens.
Among children of immigrants, incidence of IBD was 4.6 per 100,000 while children of non-immigrants had an incidence of 7.2 per 100,000. Median age of diagnosis was the same for both groups (age 11 years) and gender ratio was the same (44.7% vs. 43.9% female). Interestingly, Benchimol said, children of immigrants were less likely to be diagnosed with Crohn’s disease than non-immigrants (44.7% vs. 58.0%, respectively; P=.002); children of immigrants were more likely to develop ulcerative colitis.
“The Canada-born children of immigrants from some regions such as Europe, North Africa, the Middle East and South Asia, had a similar risk of IBD as the Canada-born children of non-immigrants,” Benchimol told Healio Gastroenterology. “Therefore, early exposure to the Canadian environment seemed to result in a high incidence of IBD in those people.” — by Katrina Altersitz
For more information:
Benchimol E. Presented at: 2014 Advances in Inflammatory Bowel Diseases, Dec. 4-6, 2014; Orlando, Fla.
Disclosures: Financial disclosures could not be confirmed at this time.