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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) (I(2) = 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) (I(2) = 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) (I(2) = 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.

Background: Several cross-sectional studies during the past 10 years have observed an increased risk of allergic outcomes for children living in damp or mouldy environments., Objective: The objective of this study was to investigate whether reported mould or dampness exposure in early life is associated with the development of allergic disorders in children from eight European birth cohorts., Methods: We analysed data from 31 742 children from eight ongoing European birth cohorts. Exposure to mould and allergic health outcomes were assessed by parental questionnaires at different time points. Meta-analyses with fixed- and random-effect models were applied. The number of the studies included in each analysis varied based on the outcome data available for each cohort., Results: Exposure to visible mould and/or dampness during first 2 years of life was associated with an increased risk of developing asthma: there was a significant association with early asthma symptoms in meta-analyses of four cohorts [0-2 years: adjusted odds ratios (aOR), 1.39 (95% CI, 1.05-1.84)] and with asthma later in childhood in six cohorts [6-8 years: aOR, 1.09 (95% CI, 0.90-1.32) and 3-10 years: aOR, 1.10 (95% CI, 0.90-1.34)]. A statistically significant association was observed in six cohorts with symptoms of allergic rhinitis at school age [6-8 years: aOR, 1.12 (1.02-1.23)] and at any time point between 3 and 10 years [aOR, 1.18 (1.09-1.28)]., Conclusion: These findings suggest that a mouldy home environment in early life is associated with an increased risk of asthma particularly in young children and allergic rhinitis symptoms in school-age children., (© 2011 John Wiley & Sons A/S.)

It has been suggested that there are several distinct phenotypes of childhood asthma or childhood wheezing. Here, we review the research relating to these phenotypes, with a focus on the methods used to define and validate them. Childhood wheezing disorders manifest themselves in a range of observable (phenotypic) features such as lung function, bronchial responsiveness, atopy and a highly variable time course (prognosis). The underlying causes are not sufficiently understood to define disease entities based on aetiology. Nevertheless, there is a need for a classification that would (i) facilitate research into aetiology and pathophysiology, (ii) allow targeted treatment and preventive measures and (iii) improve the prediction of long-term outcome. Classical attempts to define phenotypes have been one-dimensional, relying on few or single features such as triggers (exclusive viral wheeze vs. multiple trigger wheeze) or time course (early transient wheeze, persistent and late onset wheeze). These definitions are simple but essentially subjective. Recently, a multi-dimensional approach has been adopted. This approach is based on a wide range of features and relies on multivariate methods such as cluster or latent class analysis. Phenotypes identified in this manner are more complex but arguably more objective. Although phenotypes have an undisputed standing in current research on childhood asthma and wheezing, there is confusion about the meaning of the term 'phenotype' causing much circular debate. If phenotypes are meant to represent 'real' underlying disease entities rather than superficial features, there is a need for validation and harmonization of definitions. The multi-dimensional approach allows validation by replication across different populations and may contribute to a more reliable classification of childhood wheezing disorders and to improved precision of research relying on phenotype recognition, particularly in genetics. Ultimately, the underlying pathophysiology and aetiology will need to be understood to properly characterize the diseases causing recurrent wheeze in children.

Airway disease in childhood comprises a heterogeneous group of disorders. Attempts to distinguish different phenotypes have generally considered few disease dimensions. The present study examines phenotypes of childhood wheeze and chronic cough, by fitting a statistical model to data representing multiple disease dimensions. From a population-based, longitudinal cohort study of 1,650 preschool children, 319 with parent-reported wheeze or chronic cough were included. Phenotypes were identified by latent class analysis using data on symptoms, skin-prick tests, lung function and airway responsiveness from two preschool surveys. These phenotypes were then compared with respect to outcome at school age. The model distinguished three phenotypes of wheeze and two phenotypes of chronic cough. Subsequent wheeze, chronic cough and inhaler use at school age differed clearly between the five phenotypes. The wheeze phenotypes shared features with previously described entities and partly reconciled discrepancies between existing sets of phenotype labels. This novel, multidimensional approach has the potential to identify clinically relevant phenotypes, not only in paediatric disorders but also in adult obstructive airway diseases, where phenotype definition is an equally important issue.

Background: Epidemiological data for south Asian children in the United Kingdom are contradictory, showing a lower prevalence of wheeze, but a higher rate of medical consultations and admissions for asthma compared with white children. These studies have not distinguished different asthma phenotypes or controlled for varying environmental exposures., Objective: To compare the prevalence of wheeze and related health-service use in south Asian and white pre-schoolchildren in the United Kingdom, taking into account wheeze phenotype (viral and multiple wheeze) and environmental exposures., Methods: A postal questionnaire was completed by parents of a population-based sample of 4366 white and 1714 south Asian children aged 1-4 years in Leicestershire, UK. Children were classified as having viral wheeze or multiple trigger wheeze., Results: The prevalence of current wheeze was 35.6% in white and 25.5% in south Asian 1-year-olds (P<0.001), and 21.9% and 20.9%, respectively, in children aged 2-4 years. Odds ratios (ORs) (95% confidence interval) for multiple wheeze and for viral wheeze, comparing south Asian with white children, were 2.21 (1.19-4.09) and 1.43 (0.77-2.65) in 2-4-year-olds after controlling for socio-economic conditions, environmental exposures and family history. In 1-year-olds, the respective ORs for multiple and viral wheeze were 0.66 (0.47-0.92) and 0.81 (0.64-1.03). Reported GP consultation rates for wheeze and hospital admissions were greater in south Asian children aged 2-4 years, even after adjustment for severity, but the use of inhaled corticosteroids was lower., Conclusions: South Asian 2-4-year-olds are more likely than white children to have multiple wheeze (a condition with many features of chronic atopic asthma), after taking into account ethnic differences in exposure to some environmental agents. Undertreatment with inhaled corticosteroids might partly explain their greater use of health services.

Respiratory symptoms are common in infancy. Nevertheless, few prospective birth cohort studies have studied the epidemiology of respiratory symptoms in normal infants. The aim of this study was to prospectively obtain reliable data on incidence, severity, and determinants of common respiratory symptoms (including cough and wheeze) in normal infants and to determine factors associated with these symptoms. In a prospective population-based birth cohort, we assessed respiratory symptoms during the first year of life by weekly phone calls to the mothers. Poisson regression was used to examine the association between symptoms and various risk factors. In the first year of life, respiratory symptoms occurred in 181/195 infants (93%), more severe symptoms in 89 (46%). The average infant had respiratory symptoms for 4 weeks and 90% had symptoms for less than 12 weeks (range 0 to 23). Male sex, higher birth weight, maternal asthma, having older siblings and nursery care were associated with more, maternal hay fever with fewer respiratory symptoms. The association with prenatal maternal smoking decreased with time since birth. This study provides reliable data on the frequency of cough and wheeze during the first year of life in healthy infants; this may help in the interpretation of published hospital and community-based studies. The apparently reduced risk in children of mothers with hayfever but no asthma, and the decreasing effect of prenatal smoke exposure over time illustrate the complexity of respiratory pathology in the first year of life., ((c) 2006 Wiley-Liss, Inc.)

Background: Studies of immigrants suggest that the environment during fetal life and duration of residence in the host country might influence the development of asthma. Little is known about the importance of the timing of the exposure in the host country and whether migrants might be especially vulnerable in certain age windows., Objective: We compared the reported prevalence of asthma between young white and south Asian women in the United Kingdom, and investigated associations with country of birth and age at immigration., Methods: A questionnaire on atopic disorders was posted to 2380 south Asian and 5796 white young mothers randomly sampled in Leicestershire. Data on ethnicity were also available from maternity records. Data were analysed using multivariable logistic regression and a propensity score approach. Results The reported prevalence of asthma was 10.9% in south Asian and 21.8% in white women. South Asian women who migrated to the United Kingdom aged 5 years or older reported less asthma (6.5%) than those born in the United Kingdom or who migrated before age 5 (16.0%), with an adjusted odds ratio of 0.38 [95% Confidence Interval 0.23-0.64, P<0.001]. For those who migrated aged over 5 years, the prevalence did not alter with the duration of residence in the United Kingdom. Current exposure to common environmental risk factors had relatively little effect on prevalence estimates., Conclusion: These data from a large population-based study support the hypothesis that early life environmental factors influence the risk of adult asthma.

The epidemiology of wheeze in children, when assessed by questionnaires, is dependent on parents' understanding of the term "wheeze". In a questionnaire survey of a random population sample of 4,236 children aged 6-10 yrs, parents' definition of wheeze was assessed. Predictors of a correct definition were determined and the potential impact of incorrect answers on prevalence estimates from the survey was assessed. Current wheeze was reported by 13.2% of children. Overall, 83.5% of parents correctly identified "whistling or squeaking" as the definition of wheeze; the proportion was higher for parents reporting wheezy children (90.4%). Frequent attacks of reported wheeze (adjusted odds ratio (OR) 3.0), maternal history of asthma (OR 1.5) and maternal education (OR 1.5) were significantly associated with a correct answer, while the converse was found for South Asian ethnicity (OR 0.6), first language not English (OR 0.6) and living in a deprived neighbourhood (OR 0.6). In summary, the present study showed that misunderstanding could lead to an important bias in assessing the prevalence of wheeze, resulting in an underestimation in children from South Asian and deprived family backgrounds. Prevalence estimates for the most severe categories of wheeze might be less affected by this bias and questionnaire surveys on wheeze should incorporate measures of parents' understanding of the term wheeze.

In a prospective healthy birth cohort, we determined whether levels of exhaled nitric oxide (eNO) in healthy unselected infants at the age of 1 month were associated with maternal atopic disease and prenatal and early postnatal environmental exposures. Tidal eNO was measured in 98 healthy, unsedated infants (35 from mothers with atopy) (mean age +/- SD, 36.0 +/- 6.2 days) and was compared with histories taken in standardized interviews. eNO was higher in males compared with females (17.7 vs. 14.6 ppb, p = 0.042) and infants exposed to postnatal maternal smoking (+4.4 ppb, p = 0.027), adjusting for weight and tidal breathing parameters. Prenatal tobacco exposure was associated with higher eNO (+12.0 ppb, p = 0.01) in infants of mothers with asthma and lower eNO (-5.7 ppb) in infants of mothers without asthma (p for interaction < 0.0001). Coffee consumption in pregnancy decreased eNO (-6.0 ppb, p = 0.008) only in children of mothers with atopy (p for interaction = 0.015). Paternal atopy had no influence. In the early phase of immunologic development, before the onset of infections and allergic disease, the effect of prenatal or early postnatal environmental factors on eNO was modified by the presence of maternal atopic disease. This underlines the complex interaction of maternal and environmental factors in the development of airway disease.

The aim of the present study was to determine the economic impact in the UK of wheezing disorders in preschool children. Health, societal and family-borne costs were calculated for a sample of 94 preschool children who attended hospital with a primary diagnosis of wheeze or asthma during 1998/1999. Sample costs were calculated using data from a structured interview schedule and from symptom diaries completed by trial parents, patients' general practice and hospital records, and hospital finance data. Health costs for 1-5-yr-olds in the UK were calculated using data from a postal population survey in the same region. It is estimated that 1-5-yr-old children with wheeze in the UK cost the health service a total of 53 million UK pounds (GBP). The greatest expenditure, 34 million GBP, was for primary care, representing 65.2% of total healthcare costs. Prescription costs represented 20.4% (11 million GBP) of total healthcare costs. Caring for preschool children with wheeze in the UK cost the health service 0.15% of its total budget in 1998/1999. The total costs to society of caring for the 0.88% of preschool children who attended hospital for asthma or wheeze in a year represented a further 2.6 million UK pounds. Primary prevention strategies at the population level promise more cost savings than any attempt at decreasing hospitalisations in those more severely ill.

Current guidelines specify the goals of asthma treatment in children and propose a stepwise approach to achieve them. The authors sought to determine whether these goals were attained in children of different age groups in the community and to assess treatment in those with unsatisfactory asthma control. A cross-sectional postal questionnaire survey was performed in 1998 in all members of the major Swiss parents organisation for childhood asthma. With a response rate of 85%, data from 572 Swiss-German children aged 4-16 yrs with wheeze were analysed. Asthma control was excellent in 18% of the children, satisfactory (only episodic symptoms) in 33%, and unsatisfactory in 49% with disturbed sleep, restricted activities and school absences. When stratified by age, excellent or satisfactory control was attained by 66% of children aged 13-16 yrs, but only by 56%, 44%, and 38% of those aged 10-12, 7-9 and 4-6 yrs, respectively. Although the majority were followed-up by a doctor (95%) and were receiving beta2-agonists (82%) and inhaled corticosteroids (68%), intensity and duration of treatment were not sufficiently matched to asthma severity. In virtually all children there was scope to improve medical treatment, preventive measures and knowledge of asthma management, with very few if any children with therapy-resistant asthma. Even in children with poor asthma control, 89% of parents were satisfied with the results of treatment. The goals of asthma treatment were attained in one-half of the children, particularly in younger age groups. Although inhaler use was common, detailed assessment showed evidence for undertreatment, especially in the youngest age group, and insufficient adherence to preventive measures. Parental expectations of asthma control, which were lower than those outlined in guidelines, might be an important but underestimated factor in paediatric asthma management.

Background: Distinct wheezing disorders co-exist in young (preschool) children, some of which (early transient wheeze and viral wheeze) are thought to be unrelated to atopy. Investigation of changes in prevalence of wheezing disorders in preschool children could provide important clues about underlying mechanisms responsible for increasing prevalence of asthma in schoolchildren., Methods: Repeated population surveys of the prevalence of respiratory symptoms were done by parent-completed postal questionnaires in random samples of 1650 (1990) and 2600 (1998) caucasian children aged 1-5 years living in the county of Leicestershire, UK., Findings: The response rates were 86% (1422 of 1650) in 1990 and 84% (2127 of 2522) in 1998. Between 1990 and 1998, there was a significant increase in the prevalance of reported wheeze ever (16% to 29%, p<0.0001), current wheeze (12% to 26%, p<0.0001), diagnosis of asthma (11% to 19%, p<0.0001), treatment for wheeze (15% to 26%, p<0.0001), and admission for wheeze or other chest trouble (6% to 10%, p<0.0001). The increase occurred both in children with viral wheeze (9% to 19%) and in those with the classic asthma pattern of wheezing with multiple triggers (6% to 10%). There was also an increase in transient early wheezers (3% to 5%), persistent wheezers (5% to 13%), and late-onset wheezers (6% to 8%), and in all severity groups. The increase could not be accounted for by putative household risk factors because these declined between the 2 years., Interpretation: The fact that all preschool wheezing disorders increased (including viral wheeze) makes it probable that factors unrelated to atopy are implicated in the changing epidemiology of wheeze in childhood.

Questionnaire surveys are an appropriate instrument to assess epidemiologic data on respiratory ill health, to analyse influences of environmental factors on respiratory morbidity and to evaluate treatment strategies. To investigate the prevalence rates of asthma and symptoms suggestive of asthma we performed population surveys in Swiss school children. Special attention is drawn to particular aspects such as atypical symptoms, underdiagnosis and undertreatment of asthma.