Eighteen-month outcomes of house dust mite avoidance and dietary fatty acid modification in the Childhood Asthma Prevention Study (CAPS)

Seema Mihrshahi, Jennifer K. Peat, Guy B. Marks, Craig M. Mellis, Euan R. Tovey, Karen Webb, Warwick J. Britton, Stephan R. Leeder, Childhood Asthma Prevention Study (CAPS) Team

Research output: Contribution to journalArticlepeer-review

173 Citations (Scopus)


Background: Observational studies have linked house dust mite (HDM) exposure and dietary fatty acid intake with asthma in childhood. However, definitive evidence of their role in the etiology of asthma requires a randomized controlled trial. Objective: We hypothesized that the incidence of asthma and allergy in high-risk children would be reduced by avoidance of HDM allergens, supplementation with omega-3 fatty acids, or the combination of these strategies. We present the results of an interim analysis reporting outcomes assessed at 18 months. Methods: A total of 616 pregnant women were randomized to an HDM avoidance intervention, comprising the use of impermeable mattress covers and an acaricide or control and the use of an oil supplement, margarines, and cooking oils containing high levels of omega-3 fatty acids or control. Atopic status was measured by skin prick testing. Symptoms, diagnoses, and medication histories were elicited by means of parental interviews. Results: The diet intervention resulted in a 9.8% absolute reduction (95% CI, 1.5-18.1; P = .02) in the prevalence of any wheeze and a 7.8% absolute reduction (95% CI, 0.5-15.1, P = .04) in prevalence of wheeze of >1 week, but it had no effect on serum IgE, atopy, or doctors' diagnosis of asthma. The HDM avoidance intervention did not affect these outcomes but was associated with a lower use of oral steroids. Conclusion: Increasing dietary omega-3 fatty acids might have a beneficial effect on the prevalence of wheeze during the first 18 months of life. Follow-up to age 5 years, when the effect of the interventions on asthma risk will be assessed, is underway.
Original languageEnglish
Pages (from-to)162-168
Number of pages7
JournalThe Journal of Allergy and Clinical Immunology
Issue number1
Publication statusPublished - Jan 2003
Externally publishedYes

Bibliographical note

A correction exists for this article and can be found in Journal of Allergy and Clinical Immunology (2003) 11(4) p. 735 at doi: 10.1016/S0091-6749(03)70098-0


  • allergen avoidance
  • asthma
  • atopy
  • fatty acids
  • house dust mite
  • primary prevention


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