Childhood asthma in four countries: a comparative survey

Area of Science:

• Pediatric Respiratory Medicine
• Epidemiology
• Environmental Health

Background:

• Childhood asthma mortality shows significant international variation.
• Geographical differences in asthma prevalence are suspected but lack robust evidence due to inconsistent survey methods.
• This study addresses the need for multicenter surveys with standardized protocols to investigate geographical asthma patterns.

Purpose of the Study:

• To investigate geographical variations in childhood asthma prevalence and mortality.
• To determine if asthma prevalence and mortality rates exhibit parallel geographical differences.
• To explore potential environmental factors, such as animal allergen exposure, contributing to these variations.

Main Methods:

• A survey was conducted among 12-year-old children in New Zealand, Wales, South Africa, and Sweden.
• Parental questionnaires collected data on asthma history and respiratory symptoms.
• Children underwent a simple exercise challenge test to assess respiratory response.

Main Results:

• Asthma prevalence varied geographically: 16.8% in New Zealand, 12.0% in Wales, 11.5% in South Africa, and 4.0% in Sweden.
• This pattern was consistent across multiple asthma indicators, including symptoms, inhaler use, exercise response, and mortality.
• Pet ownership, particularly cat ownership, was highest in New Zealand and lowest in Sweden, with a notable negative association with wheezing in Sweden.

Conclusions:

• Childhood asthma prevalence demonstrates geographical variation, mirroring patterns in asthma mortality.
• New Zealand shows high asthma prevalence and mortality, while Sweden exhibits low rates.
• Differential exposure to animal allergens is a potential contributing factor to the observed geographical variations in childhood asthma.