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NEW YORK (Reuters Health) - Canada has one of the world’s highest rates of childhood inflammatory bowel disease (IBD), with new diagnoses increasing the most among Canadian children younger than 5, new research has found.
The rate of IBD among these younger children rose by more than 7 percent per year between 1999 and 2010.
IBD, which includes Crohn's disease and ulcerative colitis, is "still very rare in this age group compared to teenagers and young adults," said Dr. Eric Benchimol, a pediatric gastroenterologist at the Children’s Hospital of Eastern Ontario in Ottawa, in email to Reuters Health.
In a previous review of earlier research, Benchimol and colleagues found that global rates of childhood-onset IBD have increased rapidly over the past two decades, although most countries lack accurate estimates.
“We knew that the incidence of pediatric IBD was increasing in Ontario and around the world, but we didn’t have national numbers for Canada,” he said.
To investigate, Benchimol and colleagues analyzed provincial health administrative and population databases from five Canadian provinces (Alberta, Manitoba, Nova Scotia, Ontario and Quebec), which account for nearly 80% of the country’s population.
By combining these databases, "we had a large-enough number of cases and we were able to look at rates in these younger patients,” he said.
The rate of new cases per 100,000 children rose from 7.9 in 1999 to 10.6 in 2008, the researchers report in the American Journal of Gastroenterology. This represents a 2 percent annual increase in childhood IBD cases in the overall cohort - an increase so small that it might have been a coincidence.
However, the incidence increased sharply among children ages 6 months to 5 years, by roughly 7 percent per year. This is the first time an increase in this age group has been reported, according to the research team.
“We were surprised by the magnitude of the increase in children under 5, an age group that we previously almost never saw with IBD,” Benchimol said.
IBD prevalence - the total number of children living with the diseases - rose from 29 per 100,000 Canadian children in 1999 to 46 per 100,000 children in 2008, an increase of almost 60 percent. The increasing rate of new diagnoses among younger children may explain the increased prevalence, the researchers write.
There were some substantial differences between the provinces. For example, Nova Scotia had significantly higher IBD incidence and prevalence compared with the other provinces.
Most regions around the world that have reported their IBD rates have found that their overall rate of childhood-onset IBD is rising, Benchimol noted. “In addition, Ontario, Scotland, and France have all shown increases in rates in children less than 10 years old,” he said.
“Similarly, most pediatric gastroenterologists in North America report seeing more young children with IBD over the past 20 years, although the United States has not reported trends in rates in any nationwide study,” he said.
“Unfortunately, none of these studies tell us why IBD is becoming more common,” Dr. Athos Bousvaros, associate director of the Inflammatory Bowel Disease Center at Boston Children’s Hospital, told Reuters Health by email.
The increase “is too fast to be simply due to genetics, so an environmental cause is suspected,” said Bousvaros, who was not involved with the current study.
“While the authors hypothesize the rise may be due to lower vitamin D levels, increased antibiotic use, or a Westernized diet, we really do not know,” he said.
“The interaction between environmental risk factors, the intestinal microbiome, and genetic predisposition are important areas under investigation,” the authors wrote.
Because young children have a shorter history of exposure to environmental risk factors than do older children and adults, “researchers may be able to better isolate environmental risk factors for these children, determine how they interact with genes or change the microbiome, and eventually prevent the disease,” Benchimol said.
SOURCE: go.nature.com/2oovHE8 American Journal of Gastroenterology, online April 18, 2017.