This Article Full Text Full Text (PDF) All Versions of this Article: 200907-1035OCv1 181/4/337    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by To, T. Articles by Gershon, A. S. PubMed PubMed Citation Articles by To, T. Articles by Gershon, A. S.

What Is the Lifetime Risk of Physician-diagnosed Asthma in Ontario, Canada?

¹ Child Health Evaluative Sciences, Research Institute, Hospital for Sick Children, ² Institute for Clinical Evaluative Sciences, and ³ University of Toronto, Toronto, Ontario, Canada

Correspondence and requests for reprints should be addressed to Teresa To, Ph.D., Child Health Evaluative Sciences, Hospital for Sick Children, 555 University Avenue, Toronto, ON, M5G 1X8 Canada. E-mail: teresa.to{at}sickkids.ca

Rationale: Asthma is the most common chronic respiratory disease in Canada. The estimates of risk of developing asthma may help researchers and health planners set research agendas, predict the burden of asthma on society, and target the at-risk population for asthma prevention, management, and control.

Objectives: To estimate the lifetime risk of physician-diagnosed asthma.

Methods: All individuals aged 0–79 years living in Ontario, Canada on April 1, 1996 who had not been diagnosed with asthma were monitored for 11 years until March 31, 2007. They were censored when they were diagnosed with asthma, turned age 80 years, or died. The lifetime risk (from birth to age 79 yr) of physician-diagnosed asthma was calculated by a modified survival analysis technique. Results were stratified by sex, rurality, and neighborhood income.

Measurements and Main Results: Overall, the lifetime risk of physician-diagnosed asthma was 33.9%. Whereas the overall lifetime risk was higher in females (35.0 vs. 32.9%; P < 0.001), the cumulative risk was higher in males in early years. The lifetime risk was higher in individuals living in urban areas (34.5 vs. 30.1%; P < 0.001) or low-income neighborhoods (35.0% in the lowest income quintile vs. 32.2% in the highest; P < 0.001).

Conclusions: Our estimated overall lifetime risk indicates that one of every three individuals in Ontario, Canada has physician-diagnosed asthma during one's lifetime.

Key Words: asthma • population surveillance • chronic disease • incidence • longitudinal studies

AT A GLANCE COMMENTARY Scientific Knowledge on the Subject Asthma is the most common chronic respiratory disease in Canada. The prevalence of asthma is increasing worldwide, particularly in children. Although lifetime risk estimates are commonly used in measuring burden of chronic diseases such as cardiovascular disease, cancer, diabetes, osteoporosis, and Alzheimer's disease, it has not yet been adopted in chronic respiratory diseases. What This Study Adds to the Field Our estimated overall lifetime risk indicates that one of every three individuals in Ontario, Canada has physician-diagnosed asthma during one's lifetime.