Prevalence of asthma, rhinitis and eczema among children in 2 Canadian cities: the International Study of Asthma and Allergies in Childhood

Background: Wide variations in the prevalence of asthma, rhinitis and eczem a have been reported between regions within Canada and between different co untries. The International Study of Asthma and Allergies in Childhood (ISAA C) was developed to provide a standardized tool and methodology to ascertai n the prevalence of asthma and allergies in different regions. Comparisons of prevalence rates across geographic regions and at different times may he lp tp identify factors that contribute to the development of these conditio ns in individuals. Methods: Two Canadian centres, Hamilton and Saskatoon, participated in the ISAAC. A standard questionnaire was distributed through schools and complet ed by 13- and 14-year-old children and by the parents of 6- and 7-year-old children. Prevalence rates and 95% confidence intervals were calculated for asthma, wheezing, rhinitis and eczema. Results: The overall response rates were 75.1% among the children 6 and 7 y ears old and 68.6% among those 13 and 14 years old. Among the younger child ren, the lifetime prevalence of asthma was 17.2% in Hamilton and 11.2% in S askatoon; the corresponding rates among the older children were 19.2% and 1 2.2% respectively. The prevalence of wheezing in the 12 months before the s urvey in the younger group was 20.1% in Hamilton and 14.1% in Saskatoon; in the older group it was 30.6% and 24.0% respectively. The prevalence of rhi nitis in the 12 months before the survey was 28.6% in Hamilton and 22.6% in Saskatoon in the younger group and 45.8% and 33.8% respectively in the old er group. The prevalence of eczema was slightly higher in Saskatoon in both age groups. Interpretation: High prevalence rates of asthma, rhinitis and eczema exist among school children in Hamilton and Saskatoon, similar to rates in other Western countries. Further studies are required to determine the factors as sociated with the high rates in the 2 regions and possible reasons for the higher rates in Hamilton.