Why do so many people in Ontario have inflammatory bowel disease? One in every 200 Ontarians has been diagnosed with IBD, an increase by 64 percent between 1999 and 2008, according to a study by researchers at the Institute for Clinical Evaluative Sciences (ICES), the Children's Hospital of Eastern Ontario (CHEO), and the Ottawa Hospital Research Institute.

That puts Ontario in the 90th percentile for IBD prevalence in the world.

The study in Inflammatory Bowel Diseases is the first and largest Canadian study of IBD – including Crohn's disease and ulcerative colitis ─ to demonstrate trends in incidence over time, and the first to review the rate of IBD in different age groups.

"The number of new diagnoses each year increased from 2,444 in 1999 to 3,342 in 2008. That means that standardized incidence has increased by an average of nearly two and a half per cent per year since the 90s," said Dr. Eric Benchimol, adjunct scientist with ICES, and pediatric gastroenterologist at CHEO.

IBD image: Cedars-Sinai Medical Center

The population-based study of all Ontario residents living with IBD from 1999-2008 found:

• There were more than 68,000 Ontario residents with IBD living in the province in 2008.
• The number of new cases of IBD rose significantly in children under 18, and adults 18 to 64-years-old.
• The number of new cases of IBD was stable in elderly patients older than 65; however, the prevalence (the number of people living with IBD) rose the most during the study period in patients older than 65.
• The elderly population with IBD represents the fastest growing group living with IBD.
• The group with the fastest growing number of new cases are children under 10 years.

"This important study confirms, once again, that Canadians have more reasons to be concerned about Crohn's disease and ulcerative colitis than anyone else in the world," says Lindee David, CEO of Crohn's and Colitis Canada. "These are the "Canadian diseases," which place a significant burden on families and Canada's healthcare system. Dr. Benchimol's work provides further proof that we need to continue our fight to cure Crohn's and colitis and improve the lives of children and adults living with these chronic diseases. "

According to the 2012 Impact of IBD report from Crohn's and Colitis Canada, IBD cost the Canadian health system approximately $2.8 billion in 2012, more than $11,900 per person with IBD every year.

Environmental exposure and changing demographic trends have been reported as possible causes of earlier-onset disease. For example, increasing rates of antibiotic use, birth by Caesarian section, changes in diet, or use of other medications, all may have resulted in changes to the microbiome of Ontarian children and earlier-onset disease.

"The peak number of new cases of IBD is still in young adults who are 20 to 40-years of age, but the most rapidly rising incidence is in children under 10 followed by those aged 10 to 19-years. This may be due to earlier onset of disease, or better recognition and earlier diagnosis," added Benchimol.