ArticlesEarly exposure to house-dust mite and cat allergens and development of childhood asthma: a cohort study
Introduction
Epidemiological surveys indicate that there has been a notable increase in the prevalence of both asthma and other allergic symptoms in children and young adults.1, 2 Since it seems unlikely that genetic factors contribute to this rising trend, environmental factors might play a major part in the development of childhood asthma. Several potential determinants have been proposed, such as lack of severe or repeated infections,3, 4 obesity and lack of physical exercise,5 decreased family size,6 changing dietary habits,7, 8 and increase of indoor allergen exposure.9
There is some evidence that the level of indoor allergen exposure is related to an individual's capacity to mount specific IgE responses towards these allergens.10, 11, 12 Some recently published cross-sectional studies assessing cat exposure retrospectively failed to detect a positive association.13, 14 However, the extent to which the inception of childhood asthma is also determined by the level of indoor allergen exposure remains unclear.15, 16 Epidemiological surveys of children raised in environments with very low exposure to dust-mite allergen indicate that the prevalence of asthma is not decreased compared with children in mite-infested areas.17, 18
We prospectively investigated the relation between indoor allergen exposure and the development of asthma in a large cohort of German children up to age 7 years.
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Study design
In the German Multicentre Allergy Study, 7609 newborn infants were recruited in five German cities (Berlin, Düsseldorf, Freiburg, Mainz, and Munich) during 1990. Of these 7609 children, 1314 were selected for the prospective study. 499 infants (38%) were included as being at high risk of developing asthma (having at least two atopic first-degree family members or raised cord-blood IgE >0·9 kU/L). 815 infants (62%) were chosen at random from the remaining newborn infants (one or no atopic family
Results
At age 7 years, 939 children presented for check-up Complete data from questionnaires, indoor allergen exposure, and specific sensitisation were available for 648 children (table 1). To assess potential participation bias, participating children were compared with all other children in the Multicentre Allergy Study birth cohort, on the basis of data collected at birth (for pet ownership and indoor allergen exposure data based on the first 3 years of life). The study population (648 children)
Discussion
In this large prospective study, the development of childhood asthma was not related to cat and mite allergen exposure in the first years of life or to cat ownership, although sensitisation to mite and cat allergens was associated with indoor allergen exposure, as reported previously.10, 11, 12 The association between allergic sensitisation to indoor allergens and the prevalence of bronchial hyper-responsiveness and asthma, which has been shown in cross-sectional studies,22, 23, 24 was
References (34)
- et al.
Measles and atopy in Guinca- Bissau
Lancet
(1996) - et al.
Indoor allergen exposure is a risk factor for sensitization during the first three years of life
J Allergy Clin Immunol
(1997) - et al.
High mite allergen exposure increases the risk of sensitization in children and young adults
J Allergy Clin Immunol
(1989) - et al.
Role of current and childhood exposure to cat and atopic sensitization
J Allergy Clin Immunol
(1999) - et al.
Mite allergen (Der p 1) concentration in houses and its relation to the presence and severity of asthma in a population of Sydney schoolchildren
J Allergy Clin Immunol
(1995) - et al.
Quantitative assessment of exposure to dog (Can f 1) and cat (Fel d 1) allergens: relation to sensitization and asthma among children living in Los Alamos, New Mexico
J Allergy Clin Immunol
(1995) - et al.
Evaluation of air and dust sampling schemes for Fel d 1, Der f 1, and Der p 1 allergens in homes in the Detroit area
J Allergy Clin Immunol
(1999) - et al.
Short-term effect of solidified benzyl benzoate on miteallergen concentrations in house dust
J Allergy Clin Immunol
(1991) - et al.
Preventive effect of bedding encasement with microfine fibers on mite sensitization
J Allergy Clin Immunol
(1998) Is there a dose-response relationship between exposure to indoor allergens and symptoms of asthma?
J Allergy Clin Immunol
(1995)