Asthma, rhinitis, other respiratory diseases
The Canadian asthma primary prevention study: outcomes at 2 years of age

https://doi.org/10.1016/j.jaci.2004.01.754Get rights and content

Abstract

Background

Avoidance of individual risk factors have not been successful in preventing the development of asthma.

Objective

We sought to determine the effectiveness of a multifaceted intervention program in primary prevention of asthma in high-risk infants.

Methods

We identified 545 high-risk infants on the basis of an immediate family history of asthma. Families were randomized into intervention or control groups. Intervention measures included avoidance of house dust mite, pet allergen, and environmental tobacco smoke. Breast-feeding was encouraged with formula supplementation if necessary, and introduction of solid foods was delayed.

Results

At 2 years of age, 19.5% of the children had asthma, and 14.7% had atopy (positive skin test response to one or more common allergens). Significantly fewer children had asthma in the intervention group compared with in the control group (16.3% vs 23.0%), with 60% less persistent asthma at 2 years. There was a 90% reduction for recurrent wheeze in the intervention group compared with that seen in the control group. Exposure to maternal environmental tobacco smoke during pregnancy or the first year was a risk factor for asthma at 2 years of age. A positive skin test response, particularly to food, at 12 months predicted asthma at 2 years. There was no significant difference for atopy between the intervention and control groups, but daycare reduced atopy at 2 years.

Conclusion

This multifaceted intervention program during a window of opportunity in the first year of life was effective in preventing asthma in high-risk children at 2 years of age. Future studies with this cohort at school age are important.

Section snippets

Study population

Our Canadian Asthma Primary Prevention study is a prospective, prenatally randomized, controlled clinical trial in a cohort of children at high risk for development of asthma on the basis of an immediate family history. This cohort has been described in a previous communication.16 Briefly, high-risk infants, defined as those with at least one first-degree relative with asthma or 2 first-degree relatives with other classic IgE-mediated allergic diseases, had families identified during the

Efficacy of interventions

We previously reported the success of our multifaceted intervention program.16., 20. In summary, we successfully decreased HDM exposure in the first and second year (first-year average Der p 1 plus Der f 1: intervention vs control, 1.69 vs 2.70 μg/g; second year: 1.28 vs 2.45 μg/g). Although prevalence of pets did not change, there was significantly less cat allergen exposure at 2 weeks and 4 months in intervention homes (first-year average Fel d 1, 1.68 vs 2.09 μg/g; second year, 2.24 vs 2.5

Discussion

We have undertaken a prospective, randomized, controlled study of a multifaceted intervention designed to decrease exposure to allergens (both inhaled and ingested) and exposure to ETS in the first year of life of infants at high risk for asthma because of their family history. We previously reported a significant reduction in asthma in the intervention group at 12 months of age.16 We now report a significant difference in the prevalence of asthma at 2 years of age between the children in the

Acknowledgements

We thank Marilyn Lilley, Michelle Ditrick, Maureen Sigurdson, Joan Brooks, Roxanne Rousseau, Henry Chan, Anne DyBuncio, Judy Passante, Homa Ahmed, Kathy Lee, and Brenda Gerwing for their hard work, which made this study possible.

References (38)

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Supported by The Respiratory Health Network of Centres of Excellence, Canada; Vancouver General Hospital Foundation; Children's Hospital Foundation of British Columbia; and the British Columbia Lung Association.

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