Inger Kull

Breastfeeding and allergic disease: a multidisciplinary review of the literature (1966-2001) on the mode of early feeding in infancy and its impact on later atopic manifestations

Background:  Strategies to prevent children from developing allergy have been elaborated on the basis of state‐of‐the‐art reviews of the scientific literature regarding pets and allergies, building dampness and health, and building ventilation and health. A similar multidisciplinary review of infant feeding mode in relation to allergy has not been published previously. Here, the objective is to review the scientific literature regarding the impact of early feeding (breast milk and/or cows milk and/or formula) on development of atopic disease. The work was performed by a multidisciplinary group of Scandinavian researchers.

MMP12, lung function, and COPD in high-risk populations.

BACKGROUND Genetic variants influencing lung function in children and adults may ultimately lead to the development of chronic obstructive pulmonary disease (COPD), particularly in high-risk groups. METHODS We tested for an association between single-nucleotide polymorphisms (SNPs) in the gene encoding matrix metalloproteinase 12 (MMP12) and a measure of lung function (prebronchodilator forced expiratory volume in 1 second [FEV(1)]) in more than 8300 subjects in seven cohorts that included children and adults. Within the Normative Aging Study (NAS), a cohort of initially healthy adult men, we tested for an association between SNPs that were associated with FEV(1) and the time to the onset of COPD. We then examined the relationship between MMP12 SNPs and COPD in two cohorts of adults with COPD or at risk for COPD. RESULTS The minor allele (G) of a functional variant in the promoter region of MMP12 (rs2276109 [-82A-->G]) was positively associated with FEV(1) in a combined analysis of children with asthma and adult former and current smokers in all cohorts (P=2x10(-6)). This allele was also associated with a reduced risk of the onset of COPD in the NAS cohort (hazard ratio, 0.65; 95% confidence interval [CI], 0.46 to 0.92; P=0.02) and with a reduced risk of COPD in a cohort of smokers (odds ratio, 0.63; 95% CI, 0.45 to 0.88; P=0.005) and among participants in a family-based study of early-onset COPD (P=0.006). CONCLUSIONS The minor allele of a SNP in MMP12 (rs2276109) is associated with a positive effect on lung function in children with asthma and in adults who smoke. This allele is also associated with a reduced risk of COPD in adult smokers.

Fish consumption during the first year of life and development of allergic diseases during childhood

Background:  Fish consumption during infancy has been regarded as a risk factor for allergic disease but later evidence suggests a protective role. However, methodological limitations in the studies make conclusions uncertain. The aim of this study was to assess the association between fish consumption during the first year of life and development of allergic diseases by age 4.

Does Pet Ownership in Infancy Lead to Asthma or Allergy at School Age? Pooled Analysis of Individual Participant Data from 11 European Birth Cohorts

Objective To examine the associations between pet keeping in early childhood and asthma and allergies in children aged 6–10 years. Design Pooled analysis of individual participant data of 11 prospective European birth cohorts that recruited a total of over 22,000 children in the 1990s. Exposure definition Ownership of only cats, dogs, birds, rodents, or cats/dogs combined during the first 2 years of life. Outcome definition Current asthma (primary outcome), allergic asthma, allergic rhinitis and allergic sensitization during 6–10 years of age. Data synthesis Three-step approach: (i) Common definition of outcome and exposure variables across cohorts; (ii) calculation of adjusted effect estimates for each cohort; (iii) pooling of effect estimates by using random effects meta-analysis models. Results We found no association between furry and feathered pet keeping early in life and asthma in school age. For example, the odds ratio for asthma comparing cat ownership with “no pets” (10 studies, 11489 participants) was 1.00 (95% confidence interval 0.78 to 1.28) (I2 = 9%; p = 0.36). The odds ratio for asthma comparing dog ownership with “no pets” (9 studies, 11433 participants) was 0.77 (0.58 to 1.03) (I2 = 0%, p = 0.89). Owning both cat(s) and dog(s) compared to “no pets” resulted in an odds ratio of 1.04 (0.59 to 1.84) (I2 = 33%, p = 0.18). Similarly, for allergic asthma and for allergic rhinitis we did not find associations regarding any type of pet ownership early in life. However, we found some evidence for an association between ownership of furry pets during the first 2 years of life and reduced likelihood of becoming sensitized to aero-allergens. Conclusions Pet ownership in early life did not appear to either increase or reduce the risk of asthma or allergic rhinitis symptoms in children aged 6–10. Advice from health care practitioners to avoid or to specifically acquire pets for primary prevention of asthma or allergic rhinitis in children should not be given.

The BAMSE Project: presentation of a prospective longitudinal birth cohort study

The aims of this prospective and longitudinal project are to establish crucial risk factors for asthma and other allergic diseases in childhood, and to study factors of importance for prognosis at already established allergic disease. Socio‐economic factors, such as inequality in health, are also to be addressed. The project started in February 1994. To reach sufficient power, 4,000 children had to be included. In November 1996, this number was reached (4,093). Inclusion in the study was made at 3–4 months of age. At that time, and before induction of allergic disease/asthma of the child, a questionnaire focused on exposure, genetics and socio‐economic factors was answered. Settled dust was sampled for later analysis of furred animal and mite allergens. When the children were aged both 1 and 2 years, their parents were asked to fill in new questionnaires focusing on respiratory and allergic (skin, gastrointestinal) symptoms, but also key variables of exposure. Cases with asthma are identified and, for every case, two matched controls drawn. During the following winter, the homes of cases and controls were investigated and the temperature, indoor humidity, air change rate and NO2 measured. Two hundred cases (5%) were expected to be identified during the first 2 years of the childrens lives. Some 479 homes have now been investigated and 97.7% of the original 4,093 children still remain in the cohort. The 2‐year symptom follow‐up ended in November 1998. The 4‐year follow‐up started on 1 September 1998 and was planned to be finished in June 2000. Questionnaires (allergic and respiratory symptoms, key variables of exposure at home and day care) are sent out to all 4,093 families. All children are invited for examination, lung function tests (PEF, flow‐volume, MVV and oxygen clearance) and physical performance. Blood is taken from all children (20 ml). Allergy screening is performed and specific IgE examined. Blood cells will be frozen to allow for later DNA extraction. In subsets (children with any allergic and/or respiratory manifestation and controls), markers of inflammation in blood and urine will be examined, as well as eosinophils in nasal smear. Interviews are carried out to assess the severity of asthma, type/periodicity of health care given, asthma medication and parental sick leave when appropriate. As a separate project, financed by the EU, outdoor pollution as risk factors for asthma and allergies are to be studied within the BAMSE cohort. A follow‐up of 8–9 years is underway.

Breast-feeding in relation to asthma, lung function, and sensitization in young schoolchildren

BACKGROUND The evidence from previous studies on beneficial effects of breast-feeding in relation to development of asthma is conflicting. OBJECTIVE To investigate the relation between breast-feeding and asthma and/or sensitization during the first 8 years of life. METHOD In a birth cohort, children were followed up to 8 years by questionnaires at ages 2 months and 1, 2, 4, and 8 years to collect information on exposures and health effects. Determination of serum IgE antibodies to common inhalant and food allergens was performed at 4 and 8 years. Longitudinal analyses were applied by using general estimated equations. The study population consisted of 3825 children (93% of the original cohort), of whom 2370 gave blood and 2564 performed lung function measurements at 8 years. RESULTS Children exclusively breast-fed 4 months or more had a reduced risk of asthma during the first 8 years of life (adjusted odds ratio [OR], 0.63; 95% CI, 0.50-0.78) compared with children breast-fed less than 4 months. At 8 years, reduced risks of sensitization (adjusted OR, 0.79; 95% CI, 0.64-0.99) and asthma in combination with sensitization (adjusted OR, 0.59; 95% CI, 0.37-0.93) were seen among children exclusively breast-fed 4 months or more. This group also had a significantly better lung function measured with peak expiratory flow. CONCLUSION Breast-feeding for 4 months or more seems to reduce the risk of asthma up to 8 years. At this age, a reduced risk was observed particularly for asthma combined with sensitization. Furthermore, breast-feeding seems to have a beneficial effect on lung function.

Development and comorbidity of eczema, asthma and rhinitis to age 12 : data from the BAMSE birth cohort

Allergy‐related diseases are a public health issue, but knowledge on development and comorbidity among children is scarce. The aim was to study the development of eczema, asthma and rhinitis in relation to sex and parental allergy, in a population‐based cohort, during childhood.

Selective IgA deficiency in early life: association to infections and allergic diseases during childhood.

Selective IgA deficiency in early life is quite common in Caucasian populations, but it is unclear whether it increases the risk of infections and allergic diseases during childhood. Serum IgA levels were measured in 2423 children at 4 years of age in a Swedish population based birth cohort (BAMSE). Parental questionnaires were repeatedly sent out during the childs first 8 years of life, collecting information about infections and allergic diseases. 14 children (1:173) were found to be IgA deficient at 4 years of age. These children had an increased risk of pseudocroup at year 1 (p<0.01) and food hypersensitivity at year 4 (p<0.05) as compared to IgA sufficient children. No increased risk was observed in the partial IgA deficiency group. The findings suggest that selective IgA deficiency may increase the risk of parentally reported pseudocroup and food hypersensitivity during early childhood.

Meta-analysis of mould and dampness exposure on asthma and allergy in eight European birth cohorts: an ENRIECO initiative

To cite this article: Tischer CG, Hohmann C, Thiering E, Herbarth O, Müller A, Henderson J, Granell R, Fantini MP, Luciano L, Bergström A, Kull I, Link E, von Berg A, Kuehni CE, Strippoli M‐PF, Gehring U, Wijga A, Eller E, Bindslev‐Jensen C, Keil T, Heinrich J & as part of the ENRIECO consortium. Meta‐analysis of mould and dampness exposure on asthma and allergy in eight European birth cohorts: an ENRIECO initiative. Allergy 2011; 66: 1570–1579.

Pregnancy and Birth Cohort Resources in Europe: a Large Opportunity for Aetiological Child Health Research

BACKGROUND During the past 25 years, many pregnancy and birth cohorts have been established. Each cohort provides unique opportunities for examining associations of early-life exposures with child development and health. However, to fully exploit the large amount of available resources and to facilitate cross-cohort collaboration, it is necessary to have accessible information on each cohort and its individual characteristics. The aim of this work was to provide an overview of European pregnancy and birth cohorts registered in a freely accessible database located at http://www.birthcohorts.net. METHODS European pregnancy and birth cohorts initiated in 1980 or later with at least 300 mother-child pairs enrolled during pregnancy or at birth, and with postnatal data, were eligible for inclusion. Eligible cohorts were invited to provide information on the data and biological samples collected, as well as the timing of data collection. RESULTS In total, 70 cohorts were identified. Of these, 56 fulfilled the inclusion criteria encompassing a total of more than 500,000 live-born European children. The cohorts represented 19 countries with the majority of cohorts located in Northern and Western Europe. Some cohorts were general with multiple aims, whilst others focused on specific health or exposure-related research questions. CONCLUSION This work demonstrates a great potential for cross-cohort collaboration addressing important aspects of child health. The web site, http://www.birthcohorts.net, proved to be a useful tool for accessing information on European pregnancy and birth cohorts and their characteristics.