A Health Surveillance Update on Canadian Children and Youth

Asthma Hospitalizations

From 1990-1995, asthma was responsible for 6.7% of all hospitalizations for children and youth less than 20 years of age.

From 1990-1995, asthma was responsible for 6.7% of all hospital separations for children and youth less than 20 years of age in Canada.⁽¹¹⁾ Hospital separation rates (hereafter referred to as hospitalization rates) refer to the number of people in a given population who leave a hospital either through a completed procedure, discharge or death in a given time period. Hospitalization data for asthma likely reflect the more severe and/or poorly controlled cases of asthma. These data are obtained from the Discharge Abstract Database and the National Morbidity Database, which are maintained by the Canadian Institute for Health Information (CIHI).

In the year 1995-96, there were 29,051 hospitalizations due to asthma among children and youth less than 20 years old in Canada (344 per 100,000). Of these, 17,582 or 60.5% occurred among children aged 0-4 years (890 per 100,000). Sex differences in the rates are notable. In the 0-4 year age group, the 1995-96 asthma hospitalization rate among males was almost double the female rate (1175 per 100,000 in boys vs. 592 per 100,000 in girls). Figure 3 illustrates the Canadian age-adjusted hospitalization rates due to asthma from 1971-1995 for two age groups of children and youth under 20 years old. The increasing asthma hospitalization rates, most notable in the 0-4 year age group, appear to have stabilized.

Note: Rates are standardized to the age distribution of the 1971 Canadian population.
Source: Bureau of Cardio-Respiratory Diseases and Diabetes, LCDC, based on CIHI data⁽¹¹⁾

Hospitalizations due to asthma have also increased until recently in other countries, including Australia, Great Britain and the United States.⁽⁹⁾ Figure 4 illustrates a trend similar to that observed in Canada in the rate of asthma-related hospitalizations in the United States.⁽¹⁰⁾

Note: Rates are standardized to the age distribution of the 1970 U.S. population.
Source: Centers for Disease Control and Prevention, United States⁽¹⁰⁾

Data limitations
There are several limitations in the asthma-related hospitalization data. First, hospitalization counts are based on the number of episodes (event based) rather than the number of patients (person based). As a result, five hospitalizations could indicate either five hospital separations for the same person or the single hospital separation of each of five different individuals. Second, the clinical criteria for diagnosing asthma have changed over time, and asthma is now more readily recognized than in the past.⁽¹²⁾ This may result in a shift in the classification of cause of hospitalization to asthma from other respiratory conditions. Finally, hospitalization rates are influenced by a number of other factors, including outpatient care, bed shortages and admissions for social and environmental reasons.

Summary
There has been a marked increase in the asthma hospitalization rates in the last two decades, particularly among children aged 0-4 years. Only recently has this increase halted, with a very recent decline in rates. The ability to track person-based rates would address one of the main limitations of the hospitalization data and permit a more accurate analysis of asthma hospitalizations. The Respiratory Disease Division in the Bureau of Cardio-Respiratory Diseases and Diabetes will continue to investigate methods of obtaining readmission data to more accurately track the trends of asthma hospitalizations over time.

Unless referenced otherwise, asthma hospitalization statistics are the product of the Bureau of Cardio-Respiratory Diseases and Diabetes, LCDC⁽¹¹⁾

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