Younger immigrants at greater risk of developing IBD: study
Andrea Janus, CTVNews.ca
Published Tuesday, March 10, 2015 11:09AM EDT
Last Updated Tuesday, March 10, 2015 10:04PM EDT
Young immigrants to Canada are at greater risk of developing inflammatory bowel disease -- including Crohn’s disease and ulcerative colitis -- according to the findings of a new Canadian study released Tuesday.
Researchers at the Institute for Clinical Evaluative Sciences (ICES) and the Children’s Hospital of Eastern Ontario (CHEO) say that children who immigrate to Canada appear to take on the same risk level that Canadian children face.
And the younger the age of the children when they arrive to Canada, the greater their risk of developing IBD.
IBD is a painful and debilitating condition that causes inflammation in the digestive tract.
The researchers compared health administration data and immigration data to establish Canadian incidence rates of IBD between 1994 and 2010.
They then compared rates of IBD among immigrants to Canada and their children with rates among non-immigrants.
Researchers found that the younger an immigrant was at the time of his or her arrival in Canada, the greater the risk for developing IBD.
The risk increased by 14 per cent per younger decade. That means a nine-year-old immigrant had a 14 per cent greater risk than a 19-year-old.
Children of immigrants from the Middle East, North Africa and South Asia had the same incidence rates of IBD as children of non-immigrants, according to the findings.
However, children of immigrants from East Asia, Eastern Europe, Central Asia, Latin America and the Caribbean had lower incidence rates of IBD compared to children of non-immigrants.
The findings establish a correlation between early exposure to the Canadian environment in immigrants and the risk of developing IBD, the researchers said.
"IBD is a disease of Westernized nations, with high rates in North America and Europe, and low rates in Asia, Africa, and South America,” researcher Dr. Eric Benchimol, adjunct scientist with ICES and pediatric gastroenterologist at CHEO, said in a statement.
“Rates increased dramatically in Eastern Europe in recent decades and are increasing in other nations as Western lifestyle becomes more prevalent.”
The findings were published Tuesday in the American Journal of Gastroenterology.
Patients with ulcerative colitis suffer from inflammation and sores, typically only in the large intestine, that can cause bloody diarrhea, abdominal and rectal pain, rectal bleeding, weight loss, fatigue and fever.
Crohn’s disease is also characterized by inflammation of the digestive tract that leads to similar symptoms to ulcerative colitis. However, the inflammation can occur anywhere along the digestive tract, leading to removal of the diseased portion.
Symptoms of IBD tend to first emerge when people are in their 20s and 30s.
Rasheed Clarke, the son of Indian immigrants, was born in Toronto. He developed ulcerative colitis during his mid-20s. At the time, he was in top physical shape and he was training for a marathon. But his stool was bloody and he couldn’t "hold it in."
“I may have had to go 25 to 30 times a day,” Clarke told CTV News.
After a few years, drugs to control his symptoms stopped working. In the end, his symptoms became so severe that he had surgery to remove his diseased colon. However, the operation is not a cure, he said.
“I tell people my quality of life is better now than when I had the active disease,” he said. “But it’s not as good as when I didn’t have the disease at all.”
According to Clarke, no one in his family in India had ever developed IBD.
“My family for generations in India had the same genetic makeup and never had a problem with this disease,” he said. “There is something in that genetic makeup that was ready to be triggered but required something in the environment to trigger it. And that happened to me in Canada.”
While it is unclear how environmental factors in Canada may contribute to IBD, Canada is among the countries that have the highest rates. Some 240,000 Canadians have IBD, either Crohn’s disease or ulcerative colitis.
Ontario has a particularly high rate of IBD at 1 in 160 people, and has the fastest growing rate of new diagnoses in children under age 10.
Researchers have identified more than 160 genes that can influence the development of IBD, Benchimol told CTV News. However, they only play a small role.
“That environmental risk factor, or probably multiple environmental risk factors, present in Canada result in our very high rates of inflammatory bowel disease,” Benchimol said.
The leading suspected culprits are low vitamin D levels due to our long, dark winters, extreme hygiene habits that limit children’s exposure to bacteria, and food additives that can affect the good bacteria in our digestive tracts.
A study out of Manitoba, Benchimol noted, found exposure to antibiotics within the first two years of life increases the chance of developing Crohn’s disease later on.
Dr. John Marshall, a gastroenterologist at McMaster University in Hamilton, Ont., said scientists hope to development a “preventative treatment” to administer at a young age, “perhaps in infancy.”
With a report from CTV’s medical specialist Avis Favaro and producer Elizabeth St. Philip