Asthma diagnosis and treatment
Prevention of asthma during the first 5 years of life: A randomized controlled trial

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Background

Early life exposures may be important in the development of asthma and allergic disease.

Objective

To test house dust mite (HDM) avoidance and dietary fatty acid modification, implemented throughout the first 5 years of life, as interventions to prevent asthma and allergic disease.

Methods

We recruited newborns with a family history of asthma antenatally and randomized them, separately, to HDM avoidance or control and to dietary modification or control. At age 5 years, they were assessed for asthma and eczema and had skin prick tests for atopy.

Results

Of 616 children randomized, 516 (84%) were evaluated at age 5 years. The HDM avoidance intervention resulted in a 61% reduction in HDM allergen concentrations (μg/g dust) in the child's bed but no difference in the prevalence of asthma, wheeze, or atopy (P > .1). The prevalence of eczema was higher in the active HDM avoidance group (26% vs 19%; P = .06). The ratio of ω-6 to ω-3 fatty acids in plasma was lower in the active diet group (5.8 vs 7.4; P < .0001). However, the prevalence of asthma, wheezing, eczema, or atopy did not differ between the diet groups (P > .1).

Conclusion

Further research is required to establish whether other interventions can be recommended for the prevention of asthma and allergic disease.

Clinical implications

House dust mite avoidance measures and dietary fatty acid modification, as implemented in this trial during infancy and early childhood, did not prevent the onset of asthma, eczema, or atopy in high-risk children.

Section snippets

Methods

The study design has been described in detail previously,13 and only key features are presented here. The study was a randomized, parallel-group controlled trial using a factorial design that separately tested 2 interventions.

The study was approved by the Human Research Ethics Committees of the University of Sydney, Children's Hospital Westmead, and Western and South Western Sydney Area Health Services.

Results

As previously reported,21 7171 women were screened, of whom 2095 (29%) were eligible for the study, and 616 (29% of those eligible) were enrolled as participants. A survey of 200 eligible nonparticipants revealed that, compared with participants, a lower proportion of parents were tertiary-educated but the parents did not differ in age or proportion who were Australian-born, in full time employment, or primigravida.21

At age 5 years, outcome data were available for 516 (84%) of the 616

Discussion

We have shown that the implementation of feasible strategies directed at reducing exposure to HDM allergens and decreasing the ratio of ω-6 to ω-3 long-chain polyunsaturated fatty acids in the diet during the first 5 years of life does not reduce the prevalence of asthma, other wheezing illness, cough, rhinitis, eczema, or atopic sensitisation at age 5 years in children with a family history of asthma and wheezing. These negative results were obtained despite a 61% reduction in the

Conclusion

The institution of HDM avoidance measures and dietary fatty acid modification, as implemented in this trial, in infancy and early childhood to prevent the onset of asthma and allergic disease in children at increased risk of asthma cannot be recommended. Indeed, the former may be contraindicated because of an increased risk of eczema. The positive findings from some other intervention trials and the observed temporal and geographic variation in the prevalence of asthma support the view that,

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  • Cited by (0)

    Supported by National Health and Medical Research Council of Australia, Cooperative Research Centre for Asthma, New South Wales Department of Health, Children's Hospital Westmead. Dr Almqvist was funded by the Swedish Heart Lung Foundation and Swedish Society of Medicine. Contributions of goods and services were made by Allergopharma Joachim Ganzer KG Germany, John Sands Australia, Hasbro, Toll Refrigerated, AstraZeneca Australia, and Nu-Mega Ingredients Pty Ltd. Goods were provided at reduced cost by Auspharm, Allersearch, and Goodman Fielder Foods.

    Disclosure of potential conflict of interest: C. M. Mellis has consultant arrangements with Merck Sharp & Dohme, Altana Pharma. The rest of the authors have declared that they have no conflict of interest.

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