Table 1.

Selected mono- and multifaceted studies investigating primary and secondary prevention measures in asthma

Study	Interventions	Key findings
Primary prevention measures16
Monofaceted interventions
Manchester Allergy and Allergy Study (NACMAAS)50	• Randomized controlled trial investigating whether a low-allergen environment reduces the risk of primary sensitization and development of atopic disease in high-risk children • HDM allergen avoidance vs no intervention	• Reduction of some respiratory symptoms in the first year of life in high-risk infants in the intervention group vs the control51 • Increased risk of mite sensitization, but lower specific airway resistance in high-risk children in the intervention group vs the control at 3 years of age52
Prevention and Incidence of Asthma and Mite Allergy (PIAMA) study53	• Population-based study in the Netherlands with follow-up until the age of 18 years investigating the influence of lifestyle and environment on the development of asthma and allergy • Reduced exposure to HDM, beginning during the prenatal period	• The intervention had no effect on sensitization or atopy up to the age of 4 years, or on asthma and allergy outcomes up to the age of 8 years53,54
Study of Prevention of Allergy in Children in Europe (SPACE)56	• European population-based study that aimed to prevent sensitization to HDM and food allergens, and the development of atopic symptoms, during infancy in high-risk children • HDM reduction strategies and education on the reduction of food and inhaled allergens	• The rate of sensitization to aero- and food allergens was decreased in the intervention group vs the control at 1 year of age55 • At 2 years of age, there was no protective effect of HDM avoidance on the development of sensitization or symptomatic allergy vs the control group56 • In 5- to 7-year-olds, HDM sensitization was reduced in the intervention group vs the control group57
Zeiger study58	• A prospective, randomized, controlled study of food allergen avoidance in infancy • Reduced exposure to allergenic food during the last trimester of pregnancy; staged introduction of foods in infancy	• A significant reduction in food allergy and milk sensitization was found before the age of 2 years • At age 7 years, there was no difference between the intervention and control groups in food allergy, atopic dermatitis, allergic rhinitis, asthma, any atopic disease, lung function, food/aeroallergen sensitization, serum IgE level, or the presence of nasal eosinophils or nasal basophilic cells58
Multifaceted interventions
Canadian Asthma Primary Prevention Study (CAPPS)14	• The study aimed to minimize exposure to allergens (HDM, pet allergens, food allergens) and environmental tobacco smoke • Breastfeeding was encouraged in the first year of life (diet supplemented with hypoallergenic formula if required) • Strict elimination of allergenic foods to 12 months	• At 2 years of age, significantly fewer children had asthma in the intervention group compared with the control group (16.3% vs 23.0%)14 • At 7 years, there was a 56% reduction in the prevalence of pediatric asthma among high-risk children13 • Reduced risk of physician-diagnosed asthma, but not of other allergic outcomes, among females aged 15 years (RR 0.37, 95% CI 0.13–0.90)59
Isle of Wight Prevention Study60	• Study aimed to minimize exposure to food allergens during the prenatal period and to food and pet allergens, as well as HDM during infancy • Stepwise introduction of allergenic foods	• Demonstrated that allergic diseases (asthma, atopic dermatitis, rhinitis, atopy) can be reduced for at least the first 8 years of life by combined food- and HDM-allergen avoidance in infancy60
Prevention of Asthma in Children (PREVASC) study17	• Aimed to reduce allergen (HDM, food allergens, and indoor pet allergens) exposure during the prenatal period and during early infancy • Exclusive breastfeeding to 6 months was encouraged, with the nonstandardized introduction of solid food thereafter	• No significant differences in total and specific IgE were found between the groups • The intervention was not effective at reducing asthma-like symptoms in high-risk children during the first 2 years of life, although it was modestly effective at 2 years17
Secondary prevention measures
Prevention of Early Asthma in Kids (PEAK) study61	• Children (aged 2 and 3 years) who had a positive asthma predictive index score received either fluticasone (88 μg) or placebo bid for 2 years, followed by 1 year with no study medication	• No disease-modifying effect on asthma symptoms or lung function was observed during the treatment-free period61
Inhaled Fluticasone Propionate in Wheezy Infants (IFWIN) study62	• Infants received fluticasone propionate (100 μg bid) and were followed up until 5 years of age	• Early use of inhaled fluticasone propionate in preschool children with wheeze had no effect on the development of asthma or wheeze later in childhood62
Preventive Allergy Treatment (PAT) study63	• This study evaluated the preventive effect of SIT on asthma development over 7 years	• A 3-year course of SIT with standardized allergen extracts may prevent asthma development in children with allergic rhinoconjunctivitis up to 7 years after treatment63

Abbreviations: bid, bis in die (twice daily); CI, confidence interval; HDM, house dust mite; IgE, immunoglobulin E; RR, risk reduction; SIT, specific immunotherapy.