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Farm children protected from wheeze independently of atopy

Children raised in farm environments were protected against wheeze phenotypes independently of atopy by unknown mechanisms that excluded lung function or improved airway size in a recent study.

Researchers used survey data compiled by the multiphase, cross-sectional GABRIEL Advanced Studies to analyze the farm effect on asthma and allergic disease among children aged 6 to 12 years. From a random sample of 8,023 participants in Germany, Austria and Switzerland, data were collected and stratified to include details on wheeze type, farm exposure and immunoglobulin E levels. A subset included 858 children who underwent bronchodilator testing and exhaled nitric oxide analysis.

Wheeze was classified as transient (younger than age 3 years but not at school age), along with persistent (younger than age 3 years and at school age) and late-onset (aged 3 years or older) that were consolidated and defined as current wheeze.

Participants with transient wheeze were inversely associated with farm exposures. Researchers found an adjusted OR of 0.78 (95% CI, 0.64-0.96) for farm children representing participants with the greatest exposure compared with an unexposed nonfarm children reference group. They also saw a similar significant association of the farm effect with current wheeze among nonatopic participants (adjusted OR=0.45; 95% CI, 0.32-0.63) when comparing farm children with the unexposed population. Among the general study population, no farm effect was found for fraction of exhaled nitric oxide and lung function.

“Childhood exposure to farm environments not only protects against atopy but also against wheeze independently of atopy,” the researchers concluded. “This farm effect is not attributable to improved airway size and lung mechanics. The underlying mechanisms are unknown, but farm exposures might affect airway inflammation through antiviral properties and alternations of the airway microbiome.”

Disclosure: See the study for a full list of relevant disclosures.