F. Horak

Summary: Background Sensitization to house dust mite (HDM) is an important risk factor for the development of asthma and allergic disease in childhood. Higher levels of HDM allergen are linked to increased sensitization to HDM.Objective To study the effect of mite‐impermeable mattress encasings and an educational package on the development of allergies in a newborn cohort.Methods Six hundred and ninety‐six newborns at high risk of developing allergies were enrolled in three European countries (Germany, Austria, UK) in a prospective, randomized, controlled birth‐cohort study. Children were randomly assigned to an intervention and control group. Intervention measures included the use of mite‐impermeable mattress encasings for the child's bed and a simple educational package on allergen avoidance. The control group received basic information about allergies. Children were followed up at age 6, 12, 18 and 24 months.Results 80.9% of the children were followed up to the age of 24 months. No difference in the prevalence of sensitization to HDM (control vs. intervention group: 8.4% vs. 6.1%, P=0.33) or the development of symptoms (recurrent wheezing 10.3% vs. 10.7%, nocturnal cough 12.5% vs. 12.5%) or allergic diseases (asthma 3.5% vs. 5.1%, eczema 20.0% vs. 19.6%, rhinitis 28.9% vs. 25.8%) could be found between the control and intervention group.Conclusion In this study, HDM avoidance did not show a protective effect on the development of sensitization to HDM or symptomatic allergy in children at age 24 months.

In epidemiologic studies, it may be difficult to identify children with bronchial asthma. Since this is the most common chronic respiratory disease in childhood, and its prevalence is still increasing, reliable methods for identification of asthmatic children are required. This study evaluates the use of urinary eosinophil protein X (U-EPX) in epidemiologic studies in identifying atopic and asthmatic children. U-EPX was measured in 877 Austrian schoolchildren. The skin prick test (SPT) was performed with eight common aeroallergens, and established questionnaires were used to assess respiratory symptoms. Of our cohort, 2.8% reported physician-diagnosed asthma, 5.1% reported wheezing within the last 12 months, and 24.1% were found to be atopic. In children with physician-diagnosed asthma, as well as in atopic children (positive SPT), median U-EPX levels were significantly higher than in healthy subjects (142.8 and 89.6 vs 63.9 microg/mmol creatinine, P<0.0001 and P<0.0001, respectively). In addition, perennial sensitization to inhalant allergens resulted in higher U-EPX levels than did seasonal sensitization. The odds ratio for U-EPX levels over the 90th percentile was significantly elevated for asthma, for wheezing, for nocturnal cough, and for breathlessness at exercise, as well as for seasonal and perennial sensitization. Pulmonary function was negatively related to U-EPX levels. Measurement of U-EPX, which can be obtained easily, may be helpful in diagnosing both asthma and atopy in children. However, there is a great overlap between controls and symptomatics, a fact which reduces the sensitivity of U-EPX in determination of the prevalence of asthma in epidemiologic studies.

The effect of PM10 (particulate matter less than 10 microns in diameter) on respiratory symptoms and lung function was evaluated in 881 children (aged 8 to 11 years) in 8 communities in Lower Austria. In each community, air pollution data (PM10, SO2, NO2, O3) were collected. The examination of each child included a questionnaire (spring 1996), and two lung function tests (autumn 1995, spring 1996). Statistically significant relationships were observed between PM10 levels (annual mean, 15.8-26.9 micrograms/m3) and parameters of lung function (adjusted for sex, height, atopy, passive smoking, altitude, temperature). A 10 micrograms/m3 increase in the last two weeks' mean PM10 in spring 1996 was associated with a 0.05% decrease in FVC, a 0.05% decrease in FEV1, a 0.15% decrease in MEF50, and a 0.13% decrease in MEF75-25. Furthermore, a 10 micrograms/m3 increase in last year's mean PM10 was associated with a 0.07% decrease in FVC. No association between the prevalence of respiratory symptoms and the last year's mean PM10-exposure was found. Our study demonstrates a small effect of low-level particulate air pollution on lung function of healthy school children.