H.J.A.M. Schonberger

The PREVASC study: the clinical effect of a multifaceted educational intervention to prevent childhood asthma

As asthma is the most common chronic disease in childhood, much attention is directed towards primary prevention. Here, the clinical effectiveness of a multifaceted educational prevention was studied. A total of 476 high-risk children were recruited during the prenatal period by general practitioners and randomised to either: 1) a control group, receiving usual care; or 2) an intervention group in which families received instruction from nurses on how to reduce exposure of newborns to mite, pet and food allergens, and passive smoking. A total of 443 infants were followed-up for 2 yrs. At 2 yrs of age, the intervention group (n = 222) had less asthma-like symptoms, including wheezing, shortness of breath and night-time cough, than the control group (n = 221). No significant differences in total and specific immunoglobulin E were found between the groups. During the first 2 yrs of life, the incidence of asthma-like symptoms was similar in both groups; however, subanalysis revealed a significant reduction in the female, but not in the male, intervention group. In conclusion, the intervention used in this study was not effective in reducing asthma-like symptoms in high-risk children during the first 2 yrs of life, although it was modestly effective at 2 yrs. Follow-up is necessary to confirm whether the intervention can actually prevent the development of asthma.

Compliance of asthmatic families with a primary prevention programme of asthma and effectiveness of measures to reduce inhalant allergens – a randomized trial

Background Compliance to and the effect of pre‐ and post‐natal exposure reduction measures to prevent asthma in high‐risk children from asthmatic families were studied.

Prevention of asthma in genetically predisposed children in primary care—from clinical efficacy to a feasible intervention programme

Wheezing in infancy and asthma in children are growing health problems. Worldwide the prevalence of asthma in children is high and it still seems to be on the increase [1– 4]. Changes in the domestic environment might be an underlying cause [5,6]. Asthma in childhood is, apart from social and economic consequences, a disruptive burden for these children and their parents [5,7–11] Therefore, much attention is paid to how asthma can be prevented. Besides secondary prevention, such as pharmacotherapy or immunotherapy, there is growing interest in the primary prevention of asthma. Primary prevention of asthma implies that the development of asthma is averted through eliminating the causes of the disease which can be modified before sensitization actually occurs. It is general agreed that asthma is a multifactorial disease which develops when genetically predisposed children are exposed to relevant environmental irritants in very early life or even in utero [12,13]. Because it is (at present) not possible to manipulate the ‘asthmatic’ genotype of the child, we can only try to influence the environmental factors, which are known to enhance the development of asthma [14]. These factors have been repeatedly determined in observational studies [15–21] and are summarized in several reviews [22–24]. Male sex, birth order, birth month, size of families, preand dysmaturity, and age of the mother, have all proven to influence the likelihood of the development of childhood asthma. These factors, however, cannot be (easily) manipulated. The role of other, to a certain extent modifiable, risk factors such as the intake of antioxidants (e.g. vitamins A, C, E and Selenium) [25,26], is not clear yet. The same holds for air pollutants [27,28] and respiratory (viral) infections [18,29– 35]. Respiratory infections may be stimulating or inhibiting the immune system, they can modulate the developing autoimmune mechanism of the genetically predisposed infant in the direction of either the TH 2 (allergic) or the TH1 (nonallergic) phenotype. In which of the two directions the immune mechanism is driven may depend upon which period in the development of the immune mechanism of the infant a virus infection occurs, and perhaps also on the frequency of exposure and/or the dose of the viral antigen. The well-known risk factors, such as the exposure to respiratory [36–38] and food allergens [39–54] as well as environmental tobacco smoking (ETS) [55–57] seem to have more possibilities for intervention. In this paper the possibilities for a feasible and applicable prevention of the development of asthma in a primary care setting are discussed. As the general practitioner plays a key role in family health care, the preconditions of primary prevention of asthma seem to be best met in primary care. The central issue is the question whether our knowledge is nowadays sufficient to implement a comprehensive prevention programme for asthma in primary care on a large scale. To answer this question, the conditions, first postulated by Wilson and Jungner in 1968 for screening programmes aiming on the early detection of diseases [58] are used here as a guideline. The conditions are summarized in an adapted form in Table 1. The most important ones are discussed in this paper. Firstly, it has to be known whether the selection of high risk children of asthma is possible and feasible in primary care (conditions 3 and 4). Furthermore, it has to be proven whether the planned preventive measures are efficacious and cost-effective (conditions 5 and 6). In addition, the preventive actions must be acceptable and applicable for the parents and their infants. Finally, the programme has to be feasible in daily work of the caregivers, such as general practitioners, practice assistants, district nurses and paediatricians (conditions 7 and 8). To what extent are these conditions fulfilled at this moment?

Prenatal exposure to mite and pet allergens and total serum IgE at birth in high‐risk children

To examine the relationship between prenatal exposure to mite, cat and dog allergens and total serum IgE at birth in newborns at high risk of asthma. In the homes of 221 newborns with at least one first‐degree relative with asthma, concentrations (ng/g dust) of allergens of house dust mite (mite), cat and dog were measured at the fourth to sixth month of pregnancy in dust samples from the maternal mattress and living room. At day 3–5 after birth, total IgE was measured in capillary heel blood. A total number of 174 blood samples were available (11 mothers refused newborns blood sampling, and in 36 cases the blood sample was too small for analysis). In 24% of the newborns, total IgE was elevated (cut‐off value 0.5 IU/ml). A significant dose response relationship was found between increasing mite allergen levels [divided in quartiles ng/g dust (qrt)] and the percentage of elevated IgE: first qrt (0–85 ng/g) 13%; second qrt (86–381) 19%; third qrt (382–2371) 26%; fourth qrt (≥2372) 42%, respectively, p = 0.01. This relationship remained significant after adjusting for passive smoking, maternal and paternal mite allergy, socio‐demographic factors, birth characteristics and (breast) feeding practice in the first week of life. In high‐risk newborns, prenatal exposure to mite allergens, but not to cat and dog allergens from dust of the living room and of the maternal mattress was associated with total serum IgE at birth.

Association between first‐degree familial predisposition of asthma and atopy (total IgE) in newborns

It is generally thought that infants with a first‐degree familial predisposition of asthma are at higher risk of developing asthma than infants without predisposition.

Towards improving the accuracy of diagnosing asthma in early childhood

Objectives: Early and correct diagnosis of asthma in wheezing children is essential for early treatment and prevention of under-or over-treatment. The aim was to study whether combining frequency and age of onset of wheezing illness with respiratory and atopic morbidity at age 0–6 years and sociodemographic parameters for asthma might be helpful for the general practitioner to diagnose asthma early and accurately. Methods: Birth cohort, mean follow-up 20 years (SD 4.8) in general practice. The outcome, adolescent asthma, was analysed in relation to wheezing and non-wheezing respiratory and personal and familial atopic morbidity. All diagnoses were from the Continuous Morbidity Registration of the Department of General Practice of the University of Nijmegen, the Netherlands. Results: 1586 (64%) of the children could be followed. Adolescent asthma occurred in 6.4%. There were indications for under-and over-diagnosis of asthma at age 0–6 years. Non-recurrent wheezing (only one episode) and recurrent wheezing (2 episodes) in the first three years of life, and recurrent wheezing at age 4–6 increased the risk with odds ratios (95% confidence interval) of 3.3 (1.9–5.6), 4.7 (2.8–8.2) and 15.4 (7.1–33.7), respectively. The risk additionally increased independently with a family history for asthma, (2.0 [1.1–3.6]), atopic dermatitis (1.7 [1.1–2.7]) and sinusitis (2.9 [1.3–6.4]) and decreased for 2nd born children (0.38 [0.19–0.74]) and those with a low social-economic status (0.61 [0.39–0.94]). Conclusion: Easily available history and clinical data may facilitate the early diagnosis of asthma in children with wheezing illness.

Environmental exposure reduction in high-risk newborns: where do we start?

BACKGROUND When analyzing the effect of environmental exposure reduction measures on asthma in high-risk children, one must know how far asthmatic families already have applied such measures, because this would affect the effectiveness and efficiency of interventions aimed at reducing environmental exposure. OBJECTIVE To describe the room for improvement by asthmatic families in mite, pet, and food allergen reducing measures and in parental passive smoking and to determine the resulting levels of mite and pet allergens by the applied sanitation measures. METHODS Data were sampled by observation, weekly diary entries, and questionnaire when the infant was 6 months old and 1 year old. Dust samples were collected by vacuuming the living room floor and the parental and infant mattresses. Multiple logistic regression analyses were applied with the use of mattress encasing, having a smooth floor covering, having pets, exclusive breast-feeding and/or hypoallergenic formula during the infants first 6 months, and passive smoking as the dependent variables. RESULTS Frequencies of applied measures were as follows: having a smooth floor covering, 36%; daily house cleaning, 27%; use of parental and infant antimite mattress encasings, 13% and 9%, respectively; keeping no pets, 66%; no cows milk-based regular formula, 13%; no solid foods in the first 6 months of life, 28%; and abstinence of smoking by the mother prenatally, 89%; by the mother postnatally, 85%; and by her partner, 76%. Having a smooth floor covering and daily cleaning but not use of antimite mattress encasings resulted in significantly lower mite and pet allergen levels. CONCLUSIONS There is (still) enough room for improvement to reduce exposure to inhalant and food allergens, especially by application of mattress encasings, exclusive breast-feeding and/or hypoallergenic formula feeding, and postponing the time until first solids are given.

Distribution of house dust mite allergen: comparing house dust mite allergen levels in dust samples collected from different sites on living room floors with smooth coverings.

Background: The distribution of house dust mite allergen (Der p1) in living rooms with smooth floor coverings, as measured in the middle compared with the border of the floor was investigated. It was hypothesized that activity causes displacement of Der p1, from the middle towards the border.