Can environment or allergy explain international variation in prevalence of wheeze in childhood?

Area of Science:

• Pediatric Allergy and Immunology
• Environmental Epidemiology
• Global Health

Background:

• Childhood asthma prevalence exhibits considerable international variation.
• The specific contribution of known risk factors to this global disparity remains unclear.

Purpose of the Study:

• To investigate how individual and ecological risk factors impact the variation in childhood wheeze prevalence across different global centers.
• To identify key environmental factors contributing to international differences in childhood asthma.

Main Methods:

• Utilized data from the International Study of Asthma and Allergies in Childhood (ISAAC) Phase Two.
• Employed multilevel logistic regression modeling on data from 8-12-year-old children across 30 international centers.
• Included parent-completed questionnaires on symptoms/risk factors and aeroallergen skin prick testing.

Main Results:

• Adjusting for individual risk factors minimally impacted or even increased center-level variation in wheeze prevalence.
• Simultaneous modeling of 11 influential environmental factors showed little overall change in center-level variation.
• A combination of 6 key factors (bedding, maternal smoking, heating, dampness) significantly reduced variance by 21%.
• Ecological (center-level) factors explained more variation than individual-level factors.

Conclusions:

• Individual-level environmental factors and aeroallergen sensitization do not substantially explain global variations in childhood wheeze prevalence.
• Ecological factors, including specific home environmental exposures, play a more significant role in the international variation of childhood asthma.
• Targeting specific environmental risk factors at a community level may be crucial for reducing global disparities in childhood asthma.