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One in three Ontarians at risk of being diagnosed with asthma


New research from the Institute for Clinical Evaluative Sciences (ICES), The Hospital for Sick Children (SickKids), and Sunnybrook Heath Sciences Centre has found that one in three Ontarians are at risk of being diagnosed with asthma during their lifetimes.

“The implication of our finding, that one in every three individuals has physician-diagnosed asthma, calls for public health actions to minimize disease burden, potential productivity loss, and economic costs attributable to asthma,” says Dr. Teresa To, principal investigator and senior scientist and head of the Child Health Evaluative Sciences program at SickKids Research Institute, scientist at ICES and associate professor in the Dalla Lana School of Public Health, Departments of Paediatrics, Health Policy, Management and Evaluation and Paediatrics and Institute for Medical Sciences at the University of Toronto.

The study followed more than nine million Ontario residents for more than 16 years from April 1, 1991 to March 31, 2007 and found that:

  • The lifetime risk of developing asthma was 33.9 per cent.
  • A person who had not been diagnosed with asthma by age 10 still had a 20 per cent risk of being diagnosed with asthma during the rest of their lifetime. Likewise, a person who had not been diagnosed by age 30 still had a 13 per cent risk of being diagnosed.
  • Individuals of all ages were at risk of being diagnosed with asthma, however, the risk was highest in children.
  • The lifetime risk of being diagnosed with asthma was comparable to that of diabetes or cancer (any type), but while these other chronic diseases tend to onset in older people, asthma is more likely to onset in the young and last a lifetime.
  • Women, people of lower socioeconomic status, and people living in rural areas had a higher risk of being diagnosed with asthma than men, people of higher socioeconomic status, and people living in urban areas.

"Asthma is a disease that affects a huge number of people, either because they suffer from it personally or because they have a child, another relative or a friend who does,” says Dr. Andrea Gershon, the paper’s co-author, ICES scientist and SickKids adjunct scientist, and respirologist at Sunnybrook Health Sciences Centre.

Author affiliations: ICES (T. To, J. Guan, A. Gershon); Child Health Evaluative Sciences, Research Institute Hospital for Sick Children (T. To, C. Wang, S. McLimont, A. Gershon) and University of Toronto, Ontario (T. To, A. Gershon).

The study “What is the lifetime risk of physician-diagnosed asthma in Ontario, Canada?” appears in the February 15, 2010, issue of the American Journal Of Respiratory And Critical Care Medicine.

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.

The Hospital for Sick Children (SickKids) is recognized as one of the world’s foremost paediatric health-care institutions and is Canada’s leading centre dedicated to advancing children’s health through the integration of patient care, research and education. Founded in 1875 and affiliated with the University of Toronto, SickKids is one of Canada’s most research-intensive hospitals and has generated discoveries that have helped children globally. Its mission is to provide the best in complex and specialized family-centred care; pioneer scientific and clinical advancements; share expertise; foster an academic environment that nurtures health-care professionals; and champion an accessible, comprehensive and sustainable child health system. SickKids is proud of its vision of Healthier Children. A Better World.™For more information, please visit www.sickkids.ca.



Contributing ICES Scientists

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