In preschool children at high risk for asthma, two years of inhaled-corticosteroid therapy did not change the development of asthma symptoms or lung function during a third, treatment-free year. These findings do not provide support for a subsequent disease-modifying effect of inhaled corticosteroids after the treatment is discontinued. (ClinicalTrials.gov number, NCT00272441.).
Background-Preliminary evidence is equivocal regarding the role of exhaled nitric oxide in clinical asthma management. This study evaluates the usefulness of eNO as an adjunct to asthma guidelines-based clinical care among inner-city adolescents and young adults.
Background
Wheezing illnesses cause major morbidity in infants and are frequent precursors to asthma.
Objective
To examine environmental factors associated with recurrent wheezing in inner-city environments.
Methods
The Urban Environment and Childhood Asthma (URECA) study examined a birth cohort at high risk for asthma (n=560) in Baltimore, Boston, New York, and St. Louis. Environmental assessments included allergen exposure, and in a nested case-control study of 104 children, the bacterial content of house dust collected in the first year of life. Associations were determined among environmental factors, aeroallergen sensitization, and recurrent wheezing at age three.
Results
Cumulative allergen exposure over the first three years was associated with allergic sensitization, and sensitization at age three was related to recurrent wheeze. In contrast, first year exposure to cockroach, mouse and cat allergens was negatively associated with recurrent wheeze (OR 0.60, 0.65, and 0.75, p≤0.01). Differences in house-dust bacterial content in the first year, especially reduced exposure to specific Firmicutes and Bacteriodetes, was associated with atopy and atopic wheeze. Exposure to high levels of both allergens and this subset of bacteria in the first year of life was most common among children without atopy or wheeze.
Conclusions
In inner-city environments, children with the highest exposure to specific allergens and bacteria during their first year were least likely to develop recurrent wheeze and allergic sensitization. These findings suggest that concomitant exposure to high levels of certain allergens and bacteria in early life may be beneficial, and suggest new preventive strategies for wheezing and allergic diseases.
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