The Childhood Asthma Prevention Study (CAPS): Design and research protocolof a randomized trial for the primary prevention of asthma

The Childhood Asthma Prevention Study is a randomized controlled trial to m easure whether the incidence of atopy and asthma can be reduced by house du st mite allergen reduction, a diet supplemented with omega-3 fatty acids, o r a combination of both interventions. Six hundred and sixteen pregnant wom en whose unborn children were at high risk of developing asthma because of a family history were randomized prenatally. Study groups are as follows: G roup A (placebo diet intervention, no house dust mite reduction), Group B ( placebo diet intervention, active house dust mite reduction), Group C (acti ve diet intervention, no house dust mite reduction), and Group D (active di et intervention, active house dust mite reduction). The house dust mite red uction intervention comprises use of physical and chemical methods to reduc e allergen contact. The dietary intervention comprises use of a daily oil s upplement from 6 months or at onset of bottle-feeding, and use of margarine and cooking oils based on sunflower or canola oils to increase omega-3 die tary intake. Data is collected quarterly until the infant is 1 year old and then half yearly until age 5 years. Questionnaires are used ti, collect re spiratory illness history and information about diet and home environment. Dust is collected from the child's bed and bedroom and playroom floors. Bli nded assessments are conducted at 18 months, 3 years, and 5 years. Skin pri ck tests to common allergens, blood tests, and detailed illness, medication use, and vaccination histories are collected. Primary outcomes will be the development of allergic sensitization and the presence and severity of ast hma. This study is designed to measure the effectiveness of allergen reduct ion and dietary supplementation, both separately and in combination, for th e primary prevention of atopy and asthma. The results of this study may hav e important implications for public health policies to reduce the incidence of childhood asthma. (C) Elsevier Science Inc. 2001.