Younger immigrants at higher risk of developing inflammatory bowel disease (IBD)

Posted on Tuesday, March 10, 2015

The younger people are when they immigrate to Canada, the higher their risk of developing inflammatory bowel disease (IBD) and its major subtypes, Crohn's disease and ulcerative colitis, according to a study by researchers at the University of Ottawa, the Institute for Clinical Evaluative Sciences (ICES) and the Children's Hospital of Eastern Ontario (CHEO).

Canada has one of the highest rates of IBD in the world, and while immigrants have lower rates of IBD than Canadian-born residents, the risk is higher for immigrants who are younger when they arrive in Canada.In addition, Canadian-born children of immigrants from some regions have a higher risk of developing IBD.

While their parents were at lower risk of developing IBD once they arrive, the study found that the children of immigrants from the Middle East, North Africa and South Asia had the same incidence of IBD as the children of non-immigrants. In fact, there was a 14 per cent increased risk for each decade less of life at time of immigration. That said, the children of immigrants from East Asia, Eastern Europe, Central Asia, Latin America and the Caribbean had a lower incidence of IBD than the children of non-immigrants.

“These findings suggest an increased risk of IBD when there is early-life exposure to the Canadian environment in immigrants from some regions,” said Dr. Eric Benchimol, adjunct scientist with ICES and pediatric gastroenterologist at CHEO.

The study, published today in the American Journal of Gastroenterology, is the first population-based study to demonstrate an increased risk in the children of immigrants to Canada. This indicates that environment plays an important role in IBD pathogenesis.

“IBD is a disease of Westernized nations, with high rates in North America and Europe, and low rates in Asia, Africa and South America. Rates increased dramatically in Eastern Europe in recent decades and are increasing in other nations as a Western lifestyle becomes more prevalent,” added Benchimol.

Canada has some of the highest rates of IBD (Crohn's disease and ulcerative colitis) in the world, with 240,000 people affected. Ontario has a very high rate of IBD (1 out of 160 people), and the fastest growing group for new diagnoses is children under 10 years of age. The recent rapid increase in IBD suggests environmental risk factors.

Authors: Eric I Benchimol, David R Mack, Astrid Guttmann, Geoffrey C Nguyen, Teresa To, Nassim Mojaverian, Pauline Quach and Douglas G Manuel.

“Inflammatory bowel disease in immigrants to Canada and their children: a population-based cohort study” was published in the American Journal of Gastroenterology.

About ICES

ICES is an independent, non-profit organization that uses population-based health information to produce knowledge on a broad range of health care issues. Our unbiased evidence provides measures of health system performance, a clearer understanding of the shifting health care needs of Ontarians and a stimulus for discussion of practical solutions to optimize scarce resources. ICES knowledge is highly regarded in Canada and abroad and is widely used by government, hospitals, planners and practitioners to make decisions about care delivery and to develop policy.

About the CHEO Research Institute

The CHEO Research Institute coordinates the research activities of the Children's Hospital of Eastern Ontario (CHEO) and is affiliated with the University of Ottawa. Its three programs of research include molecular biomedicine, health information technology, and evidence to practice research. Key themes include cancer, diabetes, obesity, mental health, emergency medicine, musculoskeletal health, electronic health information and privacy, and genetics of rare disease. The CHEO Research Institute makes discoveries today for healthier kids tomorrow.

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