Researchers at the Children’s Hospital of Eastern Ontario (CHEO) and the Institute for Clinical Evaluative Sciences (ICES) in Canada recently showed that children of immigrants to Canada have an increased risk for developing inflammatory bowel disease (IBD). The study was published in The American Journal of Gastroenterology (AJG) and is entitled “Inflammatory Bowel Disease in Immigrants to Canada And Their Children: A Population-Based Cohort Study.”
IBD is a chronic inflammatory condition of the digestive tract that primarily comprises ulcerative colitis and Crohn’s disease. It is characterized by vomiting, abdominal pain, rectal bleeding, diarrhea, internal cramps in the pelvis region, fatigue and weight loss. IBD can lead to life-threatening complications such as iron deficiency anemia. Canada has one of the highest IBD rates in the world with approximately 240,000 Canadians with the disease. Ontario in particular has a very high IBD rate of 1 per 160 individuals, and the fastest growing group of new IBD diagnoses is children under 10 years of age. It is thought that this recent rapid IBD increase might be linked to environmental risk factors.
“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 Western lifestyle becomes more prevalent,” noted the study’s first author Dr. Eric Benchimol in a news release.
The aim of this study was to elucidate the link between IBD risk and environmental factors. A population-based cohort study was conducted where the incidence of IBD was assessed between immigrants from low disease prevalence countries to Ontario in Canada, and their respective Canadian-born infants, and nonimmigrants in the period between 1994 and 2010.
Researchers found that IBD incidence was lower in immigrants (around 7.3 per 100,000 person-years) than in Canadian-born individuals (23.9 per 100,000 person-years) in agreement with the fact that Canada has one of the highest IBD rates in the world. Interestingly, the risk for IBD was found to rise in immigrants who are younger when they arrive in Canada, suggesting that an increased age at immigration is associated with a decreased risk of IBD. It was in fact estimated that per younger decade of life at immigration, there is a 14% increase in IBD risk. Children of immigrants from Western Europe /North America, North Africa, Sub-Saharan Africa, Middle East and South Asia were found to have a similar IBD risk as children of nonimmigrants; on the other hand, children of immigrants from East Asia, Central Asia, Eastern Europe, Latin America and the Caribbean exhibited a lower IBD incidence in comparison with children of nonimmigrants.
The research team believes that the environment plays an essential role in determining IBD pathogenesis, where the younger the person is upon immigration to Canada, the higher is the risk for developing IBD. “These findings suggest an increased risk of IBD when there is early-life exposure to the Canadian environment in immigrants from some regions,” concluded Dr. Benchimol.