Preliminary results from the first study to gauge how many Canadians are living with food allergies indicate significantly higher rates of both peanut and tree nut allergies among Canadian children compared to those in the United States. On the other hand, rates of shellfish allergy, particularly in adults, appear to be much higher in the United States.
The data from the nation-wide Surveying Canadians to Assess the Prevalence of Common Food Allergies and Attitudes towards Food Labelling and Risk (SCAAALAR) telephone survey, sponsored by Health Canada and the AllerGen research network, was presented at the American Academy of Allergy, Asthma & Immunology’s conference in March, 2009.
While the information is not complete – it reflects about 90 per cent of the 9,000 individuals on whom data was collected: “We do find a greater prevalence of peanut allergy in Canadian children, and a greater prevalence of tree nut allergy overall, and in Canadian children,” says Dr. Ann Clarke, an allergist at the McGill University Health Centre, who discussed the results with Allergic Living.
In Canada, 1.52 per cent of children are allergic to peanuts, based on a history of allergic reaction. The comparable figure in the U.S., from a 2002 survey, is .83 per cent, representing an 83 per cent higher rate in Canada. Similarly, the rate of tree nut allergy is about 120 per cent higher for Canadian children: 1.13 per cent have a history of reaction here, compared to .51 per cent in the United States.
When Clarke and her team looked at the rates of shellfish allergy in both countries, they found a 50 per cent higher rate of the allergy in U.S. adults compared to Canadian adults.
Clarke cautions, however, that the differences come with a few caveats: the Canadian data was collected six years after the U.S. data, and some of the difference could be attributed to an increase in food allergies over that time. Also, the SCAAALAR team has not analyzed the demographics of the Canadian survey respondents yet, so it’s unclear if the studies represent the same socio-economic groups. This analysis will be done before the final results are published next year. (Updated U.S. statistics are also coming next year.)
While the rates of allergy that Clarke and her team used to compare to U.S. figures are based on having a history of food allergy reactions, they also collected data on those who have had a medical diagnosis of food allergy, without a previous reaction. “It might mean that the parent is going in with a child and saying, well, his brother has peanut allergies so I’m concerned he might be allergic, but he’s never eaten it,” says Clarke.
The physician then does a skin or blood test and makes a diagnosis based on the results. The SCAAALAR team is currently contacting all physicians who made the diagnoses in these cases to confirm that yes, that patient is deemed to have a true food allergy.
The final figures for food allergy prevalence in Canada for individual foods, as well as overall incidence figures, will be based on those who have had a history of allergic reaction, as well as those who have a confirmed physician diagnosis.
First published in the Summer 2009  issue of Allergic Living.
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