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Ontarians face 40% risk of developing asthma before age 40


Ontarians face about a 40% risk of developing asthma before they turn 40. This finding is part of a new report from the Institute for Clinical Evaluative Sciences (ICES) released today examining the effects of asthma on the under 40 population.

“According to Health Canada, asthma accounts for approximately 80% of chronic respiratory disease in Canada and affects 8.4% of the population,” said the report’s lead author Dr. Teresa To, an ICES senior adjunct scientist and a senior scientist at The Hospital for Sick Children. “Yet relatively little detail about the burden of asthma on individuals and society has been studied in Canada in general, and in Ontario specifically.”

The ICES Investigative Report The Burden of Asthma in Ontario takes a comprehensive look at asthma in Ontarians aged 0 to 39 years of age between 1994/95 and 2001/02, by asking the following questions:

  • Who has asthma?
  • What is the risk of an individual developing asthma?
  • What healthcare resources are being used by people with asthma?
  • How much does asthma cost the healthcare system? Is asthma more or less common in some areas of Ontario?

Overview of report findings:

  • Between 1994/95 and 2001/02, the prevalence of asthma in Ontario decreased modestly from 6.3% to 5.8% in people 39 years of age and younger. New cases of asthma from 1997/98 until 2001/02 appeared relatively stable at 10-12 cases per 1,000 population.
  • Individuals in Ontario have about a 40% risk of developing asthma before they turn 40 years of age. However, because asthma can develop after age 40 as well, the lifetime risk for developing asthma is significantly higher.
  • Overall, people with asthma have a significantly higher number of outpatient visits and hospitalizations than people without asthma and the additional visits are not explained solely by their condition.
  • Family doctors and pediatricians are the frontline care providers to asthma patients.
  • Expenditures for asthma-specific outpatient care decreased over the study period; however, overall outpatient expenditures for people with asthma were significantly greater than the outpatient expenditures of people without asthma. Outpatient expenditures are only a small part of the overall costs associated with asthma – the costs of asthma are much higher when hospitalizations, medications and indirect costs such as lost productivity are taken into account.
  • An almost four-fold variation was found in asthma hospitalizations across the province, which was explained mostly by high rates in the northwestern part of the province.

“Our results reinforce the fact that asthma is a societal problem and not just a disease that affects a few individuals,” said Dr. To. “This stresses the importance of developing and implementing effective interventions, as well as asthma education and disease management programs.

“Some of these initiatives should include targeting primary care physicians for continuing education in asthma care and optimizing the use of specialists. As well, a number of important interventions are known to improve asthma control, which can help to reduce the burden on patients, families, and the healthcare system. These include: recognizing and reducing exposure to asthma triggers (such as pets, dust, and smoke), appropriate medication, encouraging medication adherence and the use of asthma action plans, follow-up asthma care appointments, and asthma education and self-management programs.”

Dr. To also points out that this current report is just the beginning of detailed examinations into the impact of asthma on Ontarians. “There are a number of directions planned for future research, including expanding the study to individuals beyond the age of 39, looking at trends past 2001/02, exploring emergency department visits for asthma more closely, explaining the large gaps in costs between populations with and without asthma, and studying the additional illnesses patients with asthma may have.”

ICES is an independent, non-profit organization that uses population-based health information to produce knowledge on a broad range of healthcare issues. Our unbiased evidence provides measures of health system performance, a clearer understanding of the shifting healthcare needs of Ontarians, and a stimulus for discussion of practical solutions to optimize scarce resources. ICES knowledge is highly regarded in Canada and abroad, and is widely used by government, hospitals, planners, and practitioners to make decisions about care delivery and to develop policy.


  • Julie Dowdie
  • Media Relations Officer, ICES
  • (416) 480-4780 or cell (416) 432-8143


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