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International comparison of the prevalence of asthma symptoms and bronchial hyperresponsiveness
M I Asher1, P K Pattemore, A C Harrison
1Department of Paediatrics, School of Medicine, University of Auckland, New Zealand.
Insights
New Zealand children have similar asthma symptoms and bronchial hyperresponsiveness (BHR) to Australian children. This suggests unidentified factors, not asthma prevalence, explain higher NZ asthma mortality and hospital admissions.
Area of Science:
- Pediatric respiratory health
- Epidemiology of asthma
- Comparative health studies
Background:
- New Zealand (NZ) exhibits higher asthma mortality and hospital admission rates compared to Australia.
- Increased asthma prevalence has been hypothesized as a potential contributing factor.
Purpose of the Study:
- To investigate whether higher asthma prevalence or bronchial hyperresponsiveness (BHR) explains elevated asthma mortality and hospital admissions in New Zealand children.
- To compare respiratory symptoms and BHR in children from Auckland, NZ, with those from two distinct locations in New South Wales (NSW), Australia.
Main Methods:
- A large community survey was conducted comparing children in Auckland, NZ, with children in Wagga Wagga (inland NSW) and Belmont (coastal NSW).
- Methodology involved parent-completed questionnaires for respiratory symptoms and BHR assessment via abbreviated histamine challenge.
- Study populations included 1,084 children from Auckland, 769 from inland NSW, and 718 from coastal NSW.
Main Results:
- Prevalence of respiratory symptoms and BHR was similar between Auckland and inland NSW children.
- Coastal NSW children exhibited lower rates of respiratory symptoms and BHR compared to Auckland and inland NSW children.
- Severity of BHR and the combination of BHR with symptoms were also comparable between Auckland and inland NSW, but lower in coastal NSW.
Conclusions:
- Asthma prevalence and bronchial hyperresponsiveness (BHR) do not fully account for the disparities in asthma mortality and hospital admissions between NZ and NSW.
- Unidentified environmental or genetic factors likely contribute to the higher rates of severe asthma outcomes in New Zealand.
Abstract:
Potential explanations for the higher rates of asthma mortality and hospital admissions in New Zealand (NZ) include greater prevalence of asthma. To evaluate this further, a large community survey has been undertaken. Rates of respiratory symptoms and bronchial hyperresponsiveness (BHR) for children in Auckland, NZ have been compared to those for children in two locations in New South Wales (NSW), Australia: Wagga Wagga (inland) and Belmont (coastal). The methodology used was the same in both studies: parent-completed questionnaire and BHR measured by response to an abbreviated histamine challenge. In Auckland, 1,084 children participated (84% of those selected) and were compared to 769 inland NSW and 718 coastal NSW children. The prevalence of respiratory symptoms, BHR, severity of BHR, and BHR combined with symptoms was similar among Auckland and inland NSW children but lower among coastal NSW children than those from the other two sites. It is concluded that other unidentified factors must be invoked to explain mortality and admission differences between these regions.