Risk factor associations with wheezing patterns in children followed longitudinally from birth to 3(1/2) years

Paternal heredity and housing characteristics affect childhood asthma and allergy morbidity

A birth cohort was initiated when each pregnant woman was asked for her own and her husband's history of asthma and allergic diseases at the time of recruitment. They were further inquired to verify their housing conditions, and current health status of children 3 to 5 years old at the time of interview. Paternal history was the most significant risk factor associated with reporting childhood morbidities at age of 3 to 5 years. Housing characteristics became meaningful variables only if the fathers were asthmatic or atopic. A 9-fold increase of risk was found if children with paternal history and also exposed to incense burning and water damage at home. This is the first epidemiological evidence of East Asia suggesting paternal heredity, with concurrent indoor hazardous exposures, as a predominant risk on developing childhood asthma and allergy.

Association between maternal allergic rhinitis and asthma on the prevalence of atopic disease in offspring

BACKGROUND

Asthma is a common co-morbidity of allergic rhinitis (AR). The prevalence of these two allergic diseases has increased in China and has been shown to cluster in families independently. This study evaluated the association between maternal AR (presenting with or without asthma) and the allergic conditions in offspring.

METHODS

Women (n = 592) diagnosed with AR were recruited for this study; 379 patients presented with AR and 213 presented with both AR and asthma. Total serum IgE levels and nasal eosinophil counts were analyzed and correlated with disease presentation.

RESULTS

The prevalence of allergic conditions in offspring of mothers diagnosed with AR and asthma was significantly higher than the prevalence observed in children born to mothers presenting with AR only. Maternal total serum IgE and eosinophil counts were predictive of atopy in offspring. Children born to mothers presenting with persistent moderate-to-severe AR had the highest risk of developing atopic conditions (OR 6.26, 95% CI 3.26-12.02). Maternal age of 25-30 years at delivery was also associated with a higher risk for the allergic disease in offspring compared to maternal age of 36-40 (OR 2.13, 95% CI 1.31-3.47).

CONCLUSIONS

The severity of maternal AR, asthma co-morbidity, elevated serum IgE levels and nasal eosinophilia were all associated with an increased risk of offspring developing allergic conditions. Children born to older mothers were protected against developing atopic disease.

Assessing quality of life among British older people using the ICEPOP CAPability (ICECAP-O) measure

BACKGROUND

The Investigating Choice Experiments for the Preferences of Older People (ICEPOP) programme developed a capability-based measure of general quality of life (QOL): the ICEPOP CAPability (ICECAP-O) instrument. ICECAP-O was originally intended for use in the economic evaluation of health and social care interventions, but there is increasing interest in using it to quantify differences in QOL in cross-sectional data.

OBJECTIVE

The objective of this study was to assess the construct validity of the overall ICECAP-O scores and quantify differences in QOL associated with various factors in a multivariable regression model among residents of a British city.

METHODS

ICECAP-O was administered as part of a survey of 4304 citizens of a British city. QOL values in only those respondents aged ≥65 years (n = 809) were compared across subgroups using univariable analyses and multivariable regression models.

RESULTS

QOL values were associated with differences in responses to a variety of questions about respondents' socioeconomic status, locality, contact with others, participation, health and social support. Multivariable regression results showed that poor physical and psychological health were associated with 4-7% lower QOL. Living alone and infrequent socializing were each associated with an approximately 2.5% impairment in QOL. Feeling unsafe after dark was associated with an 8% impairment, whilst those without a faith experienced 5% lower QOL on average. Distribution of ICECAP-O values by electoral ward enabled the identification of areas of deprivation, although the associations were strong only for enjoyment and control.

CONCLUSION

ICECAP-O provides policy makers with robust quantitative evidence of differences in QOL. It offers local government an opportunity to evaluate the effects of health and other interventions, and to make comparisons across sectors for which it is responsible. It also demonstrates good ability to compare impairments in QOL associated with sociodemographic, health and attitudinal variables.

Relationship between maternal demoralization, wheeze, and immunoglobulin E among inner-city children

BACKGROUND

Prior research has linked maternal prenatal and postnatal mental health with the subsequent development of asthma in children. However, this relationship has not been examined in inner-city African Americans and Hispanics, populations at high risk for asthma.

OBJECTIVE

To determine the relationship of maternal demoralization with wheeze, specific wheeze phenotypes, and seroatopy among children living in a low-income, urban community.

METHODS

African American and Dominican women aged 18 to 35 years residing in New York City (the Bronx and Northern Manhattan) were recruited during pregnancy (n = 279). Maternal demoralization (ie, psychological distress) was measured both prenatally and postnatally by validated questionnaire. Outcomes included wheeze, transient (birth to 2.5 years of age), late onset (3-5 years), and persistent (birth to 5 years of age), evaluated via questionnaire and total and indoor allergen specific IgE (at birth and ages 2, 3, and 5 years). Logistic regression with generalized estimating equations assessed the association of demoralization with wheeze and atopy. Multinomial regression explored associations between demoralization and specific wheeze phenotypes.

RESULTS

Prenatal demoralization significantly predicted overall wheeze (adjusted odds ratio OR, 1.66; 95% confidence interval [CI], 1.29-2.14), transient wheeze (OR, 2.25; 95% CI, 1.34-3.76), and persistent wheeze (OR, 2.69; 95% CI, 1.52-4.77). No association was found between demoralization and IgE after adjustment (total IgE: OR, 1.04; 95% CI, 0.74-1.45; any specific IgE: OR, 0.96; 95% CI, 0.57-1.60).

CONCLUSIONS

In this inner-city cohort, prenatal demoralization was associated with transient and persistent wheeze. Understanding how maternal demoralization influences children's respiratory health may be important for developing effective interventions among disadvantaged populations.

Rhinovirus-associated wheeze during infancy and asthma development

Rhinovirus is commonly associated with bronchiolitis - only second to RSV during the first year life. The prevalence of HRV-bronchiolitis may be very high in predisposed infants. HRV diagnosis is almost exclusively based on PCR, which detects respiratory infections with or without symptoms. Two immunologic factors, interferon responses and atopy, have been associated with susceptibility to HRV-bronchiolitis in multiple studies. The current data supports the hypothesis that susceptibility to HRV-bronchiolitis is likely to be an early manifestation of biased immune responses, which are linked to both decreased viral defence and atopic airway inflammation. Prospective studies have consistently shown that early wheezing associated with HRV infection is closely associated with recurrent wheezing and the development of asthma in children. Collectively, these studies suggest that HRV infection in wheezing children could serve as a clinically useful marker for early identification of asthma prone children. The findings to date provide the rationale for future studies to incorporate rhinovirus illnesses into asthma risk indices.

Exploring modifiable risk factors for wheezing in African American premature infants

OBJECTIVE

To examine the degree to which obesity during infancy, consistent exposure to secondhand smoke, and parenting (positive attention, maternal involvement, and negative control) were related to early development of wheezing in a cohort of African American premature infants at 2, 6, 12, 18, and 24 months corrected age.

DESIGN

Secondary analysis of a subset of variables from a larger nursing support intervention study.

SETTING

Two regional perinatal centers in the southeastern United States.

PARTICIPANTS

One hundred and sixty-eight African American premature infants (70 boys, 98 girls) who weighed less than 1,750 g or required mechanical ventilation and their mothers.

METHODS

The presence of wheezing was obtained from maternal report at 2, 6, 12, 18, and 24 months. Infants were considered to have medically significant wheezing if they were using bronchodilators or pulmonary anti-inflammatory medications.

RESULTS

The percentage of infants who had medically significant wheezing increased from 12% at 2 months to 24% at 24 months corrected age. Infants who received more positive attention from their mothers had a slightly higher increase in the probability of developing wheezing over time. Infants of mothers who received public assistance had an increased probability of wheezing. Consistent exposure to secondhand smoke, obesity during infancy, maternal negative control, and maternal involvement were not related to the development of wheezing.

CONCLUSION

These findings suggest that the likelihood of developing wheezing in African American premature infants is associated with receiving more positive attention from their mothers and having mothers who receive public assistance. Because modifiable risk factors were not highly related to wheezing, intervention efforts need to focus on early identification and treatment of wheezing and asthma-related symptoms.

Pattern recognition receptors and genetic risk for rsv infection: value for clinical decision-making?

Respiratory syncytial virus (RSV) causes respiratory tract infections, especially among young infants. Practically, all infants are infected during epidemics and the clinical presentation ranges from subclinical to fatal infection. Known risk factors for severe RSV infection include prematurity, age of <2 months, underlying chronic lung or heart diseases, serious neurological or metabolic disorders, immune deficiency (especially a disorder of cellular immunity), crowded living conditions, and indoor smoke pollution. Twin studies indicate that host genetic factors affect susceptibility to severe RSV infection. Pattern recognition receptors (PRRs) are the key mediators of the innate immune response to RSV. In the distal respiratory tract, RSV is recognized by the transmembrane Toll-like receptor 4 (TLR4) and adapter proteins, which lead to production of proinflammatory cytokines and subsequent activation of the adaptive immune response. Surfactant proteins A and D are able to bind both RSV and TLR4, modulating the inflammatory response. Genetic variations in TLR4, SP-A, and SP-D have been associated with the risk of severe RSV bronchiolitis, but the results have varied between studies. Both the homozygous hyporesponsive 299Gly genotype of TLR4 and the non-synonymous SP-A and SP-D polymorphism influence the presentation of RSV infection. The reported relative risks associated with these markers are not robust enough to justify clinical use. However, current evidence indicates that innate immune responses including pattern recognition receptors (PRRs) and other components in the distal airways and airspaces profoundly influence the innate immune responses, playing a key role in host resistance to RSV in young infants. This information is useful in guiding efforts to develop better means to identify the high-risk infants and to treat this potentially fatal infection effectively.

Does airway allergic inflammation pre-exist before late onset wheeze in children?

Epidemiological studies show that some children develop wheezing after 3 yr of age which tends to persist. It is unknown how this starts or whether there is a period of asymptomatic inflammation. The aim of this study is to determine whether lower airway allergic inflammation pre-exists in late onset childhood wheeze (LOCW). Follow-up study of children below 5 yr who had a non-bronchoscopic bronchoalveolar lavage (BAL) performed during elective surgery. The children had acted as normal controls. A modified ISAAC questionnaire was sent out at least 7 yr following the initial BAL, and this was used to ascertain whether any children had subsequently developed wheezing or other atopic disease (eczema, allergic rhinitis). Cellular and cytokine data from the original BAL were compared between those who never wheezed (NW) and those who had developed LOCW. Eighty-one normal non-asthmatic children were recruited with a median age of 3.2. Of the 65 children contactable, 9 (16.7%) had developed wheeze, 11 (18.5%) developed eczema and 14 (22.2%) developed hay fever. In five patients, wheeze symptoms developed mean 3.3-yr (range: 2-5 yr) post-BAL. Serum IgE and blood eosinophils were not different in the LOCW and NW, although the blood white cell count was lower in the LOCW group. The median BAL eosinophil % was significantly increased in the patients with LOCW (1.55%, IQR: 0.33 to 3.92) compared to the children who never wheezed, NW (0.1, IQR: 0.0 to 0.3, p = 0.01). No differences were detected for other cell types. There were no significant differences in BAL cytokine concentrations between children with LOCW and NW children. Before late onset childhood wheezing developed, we found evidence of elevated eosinophils in the airways. These data suggest pre-existent airways inflammation in childhood asthma some years before clinical presentation.

International study of wheezing in infants: risk factors in affluent and non-affluent countries during the first year of life

Risk factors for wheezing during the first year of life (a major cause of respiratory morbidity worldwide) are poorly known in non-affluent countries. We studied and compared risk factors in infants living in affluent and non-affluent areas of the world. A population-based study was carried out in random samples of infants from centres in Latin America (LA) and Europe (EU). Parents answered validated questionnaires referring to the first year of their infant's life during routine health visits. Wheezing was stratified into occasional (1-2 episodes, OW) and recurrent (3 + episodes, RW). Among the 28687 infants included, the most important independent risk factors for OW and RW (both in LA and in EU) were having a cold during the first 3 months of life [OR for RW 3.12 (2.60-3.78) and 3.15 (2.51-3.97); population attributable fraction (PAF) 25.0% and 23.7%]; and attending nursery school [OR for RW 2.50 (2.04-3.08) and 3.09 (2.04-4.67); PAF 7.4% and 20.3%]. Other risk factors were as follows: male gender, smoking during pregnancy, family history of asthma/rhinitis, and infant eczema. Breast feeding for >3 months protected from RW [OR 0.8 (0.71-0.89) in LA and 0.77 (0.63-0.93) in EU]. University studies of mother protected only in LA [OR for OW 0.85 (0.76-0.95) and for RW 0.80 (0.70-0.90)]. Although most risk factors for wheezing are common in LA and EU; their public health impact may be quite different. Avoiding nursery schools and smoking in pregnancy, breastfeeding babies >3 months, and improving mother's education would have a substantial impact in lowering its prevalence worldwide.

Poverty-associated risk factors for wheezing in the first year of life in Honduras and El Salvador

BACKGROUND

Risk factors for wheezing specifically during the first year of life have been studied in well-developed countries, but the information from developing countries is very scarce. There are no such studies focusing on factors derived from poverty. The aim of the present study was to determine if risk factors related to poverty are associated to wheezing during the first year of life in infants from Honduras and El Salvador.

METHODS

A survey, using a validated questionnaire, was carried out in the metropolitan area of San Pedro Sula (Honduras) and in La Libertad (El Salvador) in centres where infants attended for a scheduled vaccination shot or a healthy child visit at 12 months of age. Fieldworkers offered questionnaires to parents and helped the illiterate when necessary. The main outcome variable was wheezing during the first year of life, as reported by parents.

RESULTS

A total of 1047 infants in El Salvador and 780 in Honduras were included in the analysis. The prevalence of wheeze in the first year was higher in El Salvador (41.2%) than in Honduras (27.7%), as was recurrent wheezing defined as three or more episodes (18.4% vs. 11.7%). Wheezing and recurrent wheezing was associated to unpaved floor in the household (summary odds ratios for both countries 1.55, p=0.036 and 1.72, p=0.054 for any wheeze and recurrent wheezing, respectively); dust entering from streets (1.30, p=0.052 and 1.67, p=0.008); living in a heavily polluted area (1.33, p=0.037 and 1.52, p=0.033); and having mould stains on the household walls (1.36, p=0.072 and 1.76, p=0.007). Furthermore, marginal associations were found for additional person at home and use of kerosene as cooking fuel. University studies in the mother (0.34, p=0.046 and 0.32, p=0.022) and a professional occupation in the father (0.34, p=0.046 and 0.26, p=0.047) were associated to a lower risk.

CONCLUSIONS

The prevalence of wheezing and recurrent wheezing is notoriously high in El Salvador and Honduras. In those populations factors related to poverty are associated to a higher prevalence of wheezing and recurrent wheezing, whereas higher maternal education and paternal professional occupation behave as protective factors.

The role of paracetamol in the pathogenesis of asthma

Paracetamol use represents a putative risk factor for the development of asthma. There is convincing epidemiological evidence that the risk of asthma may be increased with exposure to paracetamol in the intrauterine environment, infancy, later childhood and adult life. A dose-dependent association has also been observed in these different age groups in different populations world-wide. An association has also been shown between paracetamol use in both rhinoconjunctivitis and eczema. There is biological plausibility with paracetamol use leading to decreased glutathione levels resulting in increased oxidant-induced inflammation and potentially enhanced T-helper type 2 responses. At the population level, patterns of paracetamol use might explain, to some extent, the world-wide variation in the prevalence of asthma and related disorders, particularly the high rates in English-speaking countries, which have high per capita prescription and over-the-counter use of paracetamol. A temporal association also exists between the international trends of increasing paracetamol use and increasing prevalence of asthma over recent decades. Further research is urgently required, in particular randomized-controlled trials (RCTs) into the long-term effects of frequent paracetamol use in childhood, to determine the magnitude and characteristics of any such risk. Importantly, RCTs will also enable evidence-based guidelines for the recommended use of paracetamol to be developed.

Phenotypes of childhood asthma: are they real?

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.

Risk for asthma in offspring of asthmatic mothers versus fathers: a meta-analysis

BACKGROUND

Many human epidemiologic studies demonstrate that maternal asthma confers greater risk of asthma to offspring than does paternal disease. However, a handful have shown the opposite. Given this disparity, a meta-analysis is necessary to determine the veracity and magnitude of the "maternal effect."

METHODOLOGY/PRINCIPAL FINDINGS

We screened the medical literature from 1966 to 2009 and performed a meta-analysis to compare the effect of maternal asthma vs. paternal asthma on offspring asthma susceptibility. Aggregating data from 33 studies, the odds ratio for asthma in children of asthmatic mothers compared with non-asthmatic mothers was significantly increased at 3.04 (95% confidence interval: 2.59-3.56). The corresponding odds ratio for asthma in children of asthmatic fathers was increased at 2.44 (2.14-2.79). When comparing the odds ratios, maternal asthma conferred greater risk of disease than did paternal asthma (3.04 vs. 2.44, p = 0.037). When analyzing the studies in which asthma was diagnosed by a physician the odds ratios were attenuated and no significant differences were observed (2.85 vs. 2.48, N = 18, p = 0.37). Similarly, no significant differences were observed between maternal and paternal odds ratios when analyzing the studies in which the patient population was 5 years or older (3.15 vs. 2.60, p = 0.14). However, in all cases the trend remained the same, that maternal asthma was a greater risk factor for asthma than paternal.

CONCLUSIONS/SIGNIFICANCE

The results show that maternal asthma increases offspring disease risk to a greater extent than paternal disease.

Prevalence and risk factors of wheeze in Dutch infants in their first year of life

Factors operating in the first year of life are critical in determining the onset and persistence of wheezing in preschool children. This study was designed to examine the prevalence and risk factors of wheeze in the first year of life in Dutch infants. This was a population-based survey of 13-month-old infants visiting well baby clinics for a scheduled immunization. Parents/caregivers completed a standardized validated questionnaire on respiratory symptoms in the first year of life and putative risk factors. The independent influence of these factors for wheeze was assessed by multiple logistic regression analysis. A total of 1,115 questionnaires were completed. Wheeze ever (with a prevalence in the first year of life of 28.5%) was independently associated with male gender, eczema, sibs with asthma, any allergic disease in the family, day care, damp housing, and asphyxia. Recurrent wheeze (prevalence 14.5%) showed independent associations with eczema, sibs with asthma, and day care. In addition to these factors, severe wheeze (prevalence 15.4%) was also associated with premature rupture of membranes during birth, and with damp housing. Wheeze is common during the first year of life, and places a major burden on families and the health care system. Factors associated with wheeze are mainly related to markers of atopic susceptibility, and to exposure to infections. The strongest modifiable risk factor for wheeze in the first year of life is home dampness. Interventions to reduce home dampness to reduce wheeze in infancy should be examined.

A disease model for wheezing disorders in preschool children based on clinicians' perceptions

BACKGROUND

Wheezing disorders in childhood vary widely in clinical presentation and disease course. During the last years, several ways to classify wheezing children into different disease phenotypes have been proposed and are increasingly used for clinical guidance, but validation of these hypothetical entities is difficult.

METHODOLOGY/PRINCIPAL FINDINGS

The aim of this study was to develop a testable disease model which reflects the full spectrum of wheezing illness in preschool children. We performed a qualitative study among a panel of 7 experienced clinicians from 4 European countries working in primary, secondary and tertiary paediatric care. In a series of questionnaire surveys and structured discussions, we found a general consensus that preschool wheezing disorders consist of several phenotypes, with a great heterogeneity of specific disease concepts between clinicians. Initially, 24 disease entities were described among the 7 physicians. In structured discussions, these could be narrowed down to three entities which were linked to proposed mechanisms: a) allergic wheeze, b) non-allergic wheeze due to structural airway narrowing and c) non-allergic wheeze due to increased immune response to viral infections. This disease model will serve to create an artificial dataset that allows the validation of data-driven multidimensional methods, such as cluster analysis, which have been proposed for identification of wheezing phenotypes in children.

CONCLUSIONS/SIGNIFICANCE

While there appears to be wide agreement among clinicians that wheezing disorders consist of several diseases, there is less agreement regarding their number and nature. A great diversity of disease concepts exist but a unified phenotype classification reflecting underlying disease mechanisms is lacking. We propose a disease model which may help guide future research so that proposed mechanisms are measured at the right time and their role in disease heterogeneity can be studied.

[Incidence of wheezing and associated risk factors in the first 6 months of life of a cohort in Valencia (Spain)]

OBJECTIVES

To determine the incidence of wheezing at 6 months of life in the town of Alzira (Valencia, Spain), and to analyse associated risk factors.

METHODS

We included 636 newborns in a longitudinal birth cohort study between March 2007 and November 2008. Data were collected from hospital and primary care medical records and from questionnaires sent at 6 months post-natal. Bivariate and multivariate Cox regression analysis were performed to examine the risk factors associated with wheezing.

RESULTS

At 6 months, 25.2% of infants had had 1 or more episodes of wheezing, whereas 5.6% had had 3 or more episodes. Emergency visits were reported in 11.6% of the infants, treatment with oral corticosteroids in 6.6% and admission to hospital in 4%. Independent risk factors for wheezing were male sex (relative risk [RR]: 2.1, 95% confidence interval [95% CI]: 1.5 to 2.9), younger gestational age (RR: 1.1, 95% CI: 1.0 to 1.2), season of birth between July and September (RR: 3.5, 95% CI: 2.0 to 5.9) and between October and December (RR: 2.0, 95% CI: 1.1 to 3.6), younger maternal age (RR: 1.0, 95% CI: 1.0 to 1.1), having siblings (RR: 3.1, 95% CI: 2.2 to 4.5), exposure to smoke (RR: 1.4, 95% CI: 12.0 to 2.0) and history of maternal asthma (RR: 1.7, 95% CI: 1.0 to 3.0). Breast feeding for at least 3 months (RR: 0.6, 95% CI: 0.4 to 0.8) and having immigrant parents (RR: 0.6, 95% CI: 0.4 to 0.9) were protective against wheezing.

CONCLUSION

A high cumulative incidence of wheezing in the first 6 months of life was found in our population, in comparison with data reported in other cohort studies. Estimated risk factors were generally in accordance with those described by other authors. Having siblings and season of birth between July and September were the most important risk factors, reflecting the role of viral infections in the pathogenesis of wheezing in early childhood.

The relationship between household income and childhood respiratory health in the United Kingdom

Growing empirical evidence on the association between household income and adverse child health outcomes has generated mixed results with some North-American studies showing a significant inverse relationship and some British studies identifying a much weaker association. We use data from the rich UK Millennium Cohort Study (MCS) dataset and check the robustness of these recent findings by focusing on the impact of household income on adverse childhood respiratory outcomes (i.e. asthma and wheezing). We also identify pathways, such as mother's child-health-related behaviours, parental health and grandparental socioeconomic status, through which income might influence child health. Our econometric strategy is to use, both in a cross-sectional and in a panel data context, detailed information in the MCS dataset to directly account for as many potential confounding factors as possible that might bias the income-child health nexus. Overall our results show that household income has a weak direct effect on child health after we control for potential mechanisms that mediate the income-child health association. We argue that our evidence should inform government health and broader fiscal policies aimed at reducing health inequalities in childhood.

Bronchial obstructive phenotypes in the first year of life among Paris birth cohort infants

As the natural history of respiratory and allergic manifestations is unclear, our ongoing Paris birth cohort study prospectively assesses the onset of these symptoms in early childhood. Data were collected by five questionnaires sent at regular intervals during the first year of life. Partitioning around medoids (PAM) was used to classify infants according to their bronchial obstructive symptoms. A polytomous logistic regression was performed to assess the eventual predictable power of various respiratory events and perinatal factors. Results are given for 2698 infants. Atopic dermatitis occurred in 17.9% of infants. The main respiratory symptoms in infancy were wheeze in the chest (22%), dyspnoea responsible for sleep disturbance (23.7%), nocturnal dry cough (14.5%) and shortness of breath (4.2%). The PAM method identified three groups of infants. Apart from the G0 group of infants mostly asymptomatic, two distinct clinical phenotypes (G1 and G2: 8.7% and 23.5% of total infants respectively) emerged. G2 was defined by severe bronchial obstructive disorders as all cases of dyspnoea with sleep disturbance were included in this group, while all infants assigned in G1 suffered from nocturnal dry cough. G2 group infants had significantly higher rates of respiratory events while a parental history of asthma, symptoms suggestive of rhino-conjunctivitis and birth season clearly differentiated the G1 group. Finally, G1 and G2 group infants should be closely followed up as they are expected to develop allergic and asthmatic phenotypes, possibly in relation to environmental and behavioural risk factors.

Breastfeeding protects against adverse respiratory outcomes at 15 months of age

The relationship between breastfeeding, respiratory and other allergic disorders has been controversial. Our aim was to investigate the relationships between breastfeeding, respiratory outcomes, eczema and atopy at 15 months of age in a prospective birth cohort in New Zealand. A total of 1105 children were enrolled at birth, and 1011 (91.2%) were followed up at 15 months. Logistic regression was used to model associations between breastfeeding duration and respiratory outcomes, eczema and atopy after adjusting for relevant confounding variables: ethnicity, socio-economic status, parity, body mass index, smoking in pregnancy, gender and respiratory infections in the first 3 months of life. Breastfeeding was associated with a significant reduction in the risk of adverse respiratory outcomes at 15 months. After adjustment for confounders, each month of exclusive breastfeeding reduced the risk of doctor-diagnosed asthma by 20% (odds ratio 0.80, 95% confidence interval 0.71 to 0.90), wheezing by 12% (0.88, 0.82 to 0.94) and inhaler use by 14% (0.86, 0.78 to 0.93). Associations for both exclusive and additional breastfeeding durations, and respiratory outcomes remained independently significant when modelled simultaneously. Although independently associated with all respiratory outcomes, adjusting for parental history of allergic disease or maternal history of asthma did not alter our findings. Breastfeeding was not associated with eczema or atopy at 15 months. In conclusion, there was a significant protective effect of breastfeeding on infant wheezing and other adverse respiratory outcomes that may be early indicators of asthma in New Zealand children.

Innate immune response and bronchiolitis and preschool recurrent wheeze

Bronchiolitis and preschool recurrent wheeze (PSRW) are common paediatric problems causing significant morbidity and mortality in the first years of life. Respiratory syncytial virus (RSV) and rhinoviruses are the commonest pathogens associated with these illnesses. Why some infants are severely affected, requiring admission to hospital, whilst others experience a simple cold is not fully understood: research has suggested that the innate immune response to these viruses is important. The innate immune system has many components and activation or deficiency in one or many areas may explain the different clinical presentations and disease severities that can occur in these infants. This review will summarize the recent evidence highlighting how RSV and rhinoviruses may modulate the innate immune response in both bronchiolitis and PSRW, and discuss how these illnesses affect the long-term development of the infant lung and the possible susceptibility to persistent airway disease.

Association between paracetamol use in infancy and childhood, and risk of asthma, rhinoconjunctivitis, and eczema in children aged 6-7 years: analysis from Phase Three of the ISAAC programme

BACKGROUND

Exposure to paracetamol during intrauterine life, childhood, and adult life may increase the risk of developing asthma. We studied 6-7-year-old children from Phase Three of the International Study of Asthma and Allergies in Childhood (ISAAC) programme to investigate the association between paracetamol consumption and asthma.

METHODS

As part of Phase Three of ISAAC, parents or guardians of children aged 6-7 years completed written questionnaires about symptoms of asthma, rhinoconjunctivitis, and eczema, and several risk factors, including the use of paracetamol for fever in the child's first year of life and the frequency of paracetamol use in the past 12 months. The primary outcome variable was the odds ratio (OR) of asthma symptoms in these children associated with the use of paracetamol for fever in the first year of life, as calculated by logistic regression.

FINDINGS

205 487 children aged 6-7 years from 73 centres in 31 countries were included in the analysis. In the multivariate analyses, use of paracetamol for fever in the first year of life was associated with an increased risk of asthma symptoms when aged 6-7 years (OR 1.46 [95% CI 1.36-1.56]). Current use of paracetamol was associated with a dose-dependent increased risk of asthma symptoms (1.61 [1.46-1.77] and 3.23 [2.91-3.60] for medium and high use vs no use, respectively). Use of paracetamol was similarly associated with the risk of severe asthma symptoms, with population-attributable risks between 22% and 38%. Paracetamol use, both in the first year of life and in children aged 6-7 years, was also associated with an increased risk of symptoms of rhinoconjunctivitis and eczema.

INTERPRETATION

Use of paracetamol in the first year of life and in later childhood, is associated with risk of asthma, rhinoconjunctivitis, and eczema at age 6 to 7 years. We suggest that exposure to paracetamol might be a risk factor for the development of asthma in childhood.

Associations of wheezing phenotypes in the first 6 years of life with atopy, lung function and airway responsiveness in mid-childhood

Background:

Patterns of wheezing during early childhood may indicate differences in aetiology and prognosis of respiratory illnesses. Improved characterisation of wheezing phenotypes could lead to the identification of environmental influences on the development of asthma and airway diseases in predisposed individuals.

Methods:

Data collected on wheezing at seven time points from birth to 7 years from 6265 children in a longitudinal birth cohort (the ALSPAC study) were analysed. Latent class analysis was used to assign phenotypes based on patterns of wheezing. Measures of atopy, airway function (forced expiratory volume in 1 s (FEV₁), mid forced expiratory flow (FEF_25-75)) and bronchial responsiveness were made at 7–9 years of age.

Results:

Six phenotypes were identified. The strongest associations with atopy and airway responsiveness were found for intermediate onset (18 months) wheezing (OR for atopy 8.36, 95% CI 5.2 to 13.4; mean difference in dose response to methacholine 1.76, 95% CI 1.41 to 2.12 %FEV₁ per μmol, compared with infrequent/never wheeze phenotype). Late onset wheezing (after 42 months) was also associated with atopy (OR 6.6, 95% CI 4.7 to 9.4) and airway responsiveness (mean difference 1.61, 95% CI 1.37 to 1.85 %FEV₁ per μmol). Transient and prolonged early wheeze were not associated with atopy but were weakly associated with increased airway responsiveness and persistent wheeze had intermediate associations with these outcomes.

Conclusions:

The wheezing phenotypes most strongly associated with atopy and airway responsiveness were characterised by onset after age 18 months. This has potential implications for the timing of environmental influences on the initiation of atopic wheezing in early childhood.

Prevalence of asthma and risk factors for asthma-like symptoms in Aboriginal and non-Aboriginal children in the northern territories of Canada

BACKGROUND

Few studies have investigated the prevalence and risk factors of asthma in Canadian Aboriginal children.

OBJECTIVE

To determine the prevalence of asthma and asthma-like symptoms, as well as the risk factors for asthma-like symptoms, in Aboriginal and non-Aboriginal children living in the northern territories of Canada.

METHODS

Data on 2404 children, aged between 0 and 11 years, who participated in the North component of the National Longitudinal Survey of Children and Youth were used in the present study. A child was considered to have an asthma-like symptom if there was a report of ever having had asthma, asthma attacks or wheeze in the past 12 months.

RESULTS

After excluding 59 children with missing information about race, 1399 children (59.7%) were of Aboriginal ancestry. The prevalence of asthma was significantly lower (P<0.05) in Aboriginal children (5.7%) than non-Aboriginal children (10.0%), while the prevalence of wheeze was similar between Aboriginal (15.0%) and non-Aboriginal (14.5%) children. In Aboriginal children, infants and toddlers had a significantly greater prevalence of asthma-like symptoms (30.0%) than preschool-aged children (21.5%) and school-aged children (11.5%). Childhood allergy and a mother's daily smoking habit were significant risk factors for asthma-like symptoms in both Aboriginal and non-Aboriginal children. In addition, infants and toddlers were at increased risk of asthma-like symptoms in Aboriginal children. In analyses restricted to specific outcomes, a mother's daily smoking habit was a significant risk factor for current wheeze in Aboriginal children and for ever having had asthma in non-Aboriginal children.

CONCLUSIONS

Asthma prevalence appears to be lower in Aboriginal children than in non-Aboriginal children. The association between daily maternal smoking and asthma-like symptoms, which has been mainly reported for children living in urban areas, was observed in Aboriginal and non-Aboriginal children living in northern and remote communities in Canada.

Perinatal factors and the risk of asthma in childhood--a population-based register study in Finland

The aim of the study was to assess whether perinatal factors are associated with the risk of asthma in childhood in a register-based, nested case-control study in Finland. All children born between January 1, 1996, and April 30, 2004, who were entitled to a special reimbursement for antiasthmatic drugs (i.e., had diagnosed asthma by 2006 and had purchased inhaled corticosteroids or montelukast at least once), were identified (n = 21,038). For each case, one matched control child was selected. The associations between perinatal factors, derived from the Finnish Medical Birth Register, and the risk of asthma were analyzed by conditional logistic regression. In the final multivariate model, maternal asthma, young age, smoking, previous miscarriages, and a high number of previous deliveries, as well as cesarean section, low gestational age, and low ponderal index, were associated with an increased risk of asthma in children diagnosed before the age of 3 years. Among children diagnosed at the age of 3 years or later, maternal asthma, low gestational age, and low ponderal index were associated with an increased risk, and a high number of previous deliveries was associated with a decreased risk of asthma. In conclusion, perinatal factors play a role in the development of asthma in childhood, but the etiology may differ in early and late-onset asthma.

Acute respiratory symptoms and general illness during the first year of life: a population-based birth cohort study

Respiratory symptoms are common in infancy. Most illnesses occurring among children are dealt with by parents and do not require medical attention. Nevertheless, few studies have prospectively and on a community-basis assessed the amount of respiratory symptoms and general illness in normal infants. In this population-based birth cohort study, 228 healthy infants from Copenhagen, Denmark were followed from birth to 1 year of age during 2004-2006. Symptoms were registered using daily diaries and monthly home visits. Interviews were performed at inclusion and every second month. Risk factor analysis was carried out by multiple logistic regression analysis. On average, children had general symptoms for 3.5 months during their first year of life, nasal discharge being most frequent followed by cough. Frequency of all symptoms increased steeply after 6 months of age. Each child had on average 6.3 episodes (median: 5.1, inter-quartile range (IQR): 3.3-7.8) of acute respiratory tract illness (ARTI) (nasal discharge and > or = 1 of the following symptoms: cough, fever, wheezing, tachypnea, malaise, or lost appetite) and 5.6 episodes (median: 4.3, IQR: 2.1-7.3) of simple rhinitis per 365 days at risk. Determinants for respiratory symptoms were increasing age, winter season, household size, size of residence, day-care attendance, and having siblings aged 1-3 years attending a day nursery. In conclusion, the present study provides detailed data on the occurrence of disease symptoms during the first year of life in a general population cohort and emphasizes the impact of increasing age, seasonality, and living conditions on the occurrence of ARTI.

Environmental tobacco smoke and interleukin 4 polymorphism (C-589T) gene: environment interaction increases risk of wheezing in African-American infants

OBJECTIVES

To determine whether infants exposed to environmental tobacco smoke (ETS) having the interleukin 4 (IL-4) or interleukin 13 (IL-13) gene polymorphisms were at increased risk of wheezing.

STUDY DESIGN

A birth cohort of 758 infants was evaluated annually by a questionnaire, physical examination, and skin prick testing. DNA samples from 560 children were genotyped for IL-4 C-589T and IL-13 C-1112T. The relationship of ETS exposure and genotype with the outcome of wheezing was analyzed.

RESULTS

At the time of evaluation, mean age was 13.4 +/- 2.2 months. The prevalence of sensitization was 29%, and wheezing without a cold was 26.2%. The interaction of ETS exposure and the CT/TT genotypes for IL-4 C-589T showed a significant association with wheezing (odds ratio: 10.84; 95% confidence interval: 1.12-104.64, P = .04) in African-American infants.

CONCLUSIONS

In African-American infants with a family history of atopy, the interaction of ETS and IL-4 C-589T demonstrated a 10-fold risk associated with wheezing without a cold.

Predictors for wheezing phenotypes in the first decade of life

BACKGROUND AND OBJECTIVE

This study examined prenatal, perinatal and early childhood predictors of wheezing phenotypes in the first decade of life.

METHODS

Information on current wheezing, was collected prospectively from five surveys conducted every 2 years over the first decade of life. Five wheezing phenotypes were defined: non-wheezers, preschool, primary-school, intermittent and persistent wheezers. Logistic regression with adjustment for survey design was used to determine the predictors of wheezing phenotypes.

RESULTS

Data on 2711 children were used in the analysis. Early respiratory infection, the child's allergy and parental asthma were significant risk factors for preschool, intermittent and persistent wheeze. The child's allergy and parental asthma had stronger associations with persistent wheeze than with preschool wheeze. Breastfeeding was a significant predictor of both preschool and intermittent wheezing. Daycare attendance was a risk factor for preschool wheeze but a protective factor for primary-school wheezing. Crowding at home was a protective factor for both preschool and primary-school wheeze. Parental smoking was a significant factor for preschool wheeze.

CONCLUSION

This study identified different predictors for each wheezing phenotype with some degree of overlap. The observed differential effects for these conditions raises the possibility that there are different aetiologies for asthma among children.

Predicting the development of early skin test sensitization in offspring of parents with asthma

BACKGROUND

The direct causal relationship between skin sensitization and asthma are controversial until now and remains to be further researched. Our aim is to analyse the role of parental asthma in the development of skin sensitization in offspring.

MATERIALS AND METHODS

This study was performed among nuclear families (determined by index of asthma patients), and subjects included parents and offspring. Parents were subdivided into four phenotypes on the basis of skin sensitization (SPT+ or SPT-) and asthma status (AST+ or AST-) and offspring were subdivided into three age groups: 3-8, 9-14 and 15-20 years. The main tests included a standard questionnaire and skin prick tests.

RESULTS

Offspring's skin sensitization differed among parental phenotypes at all ages (P < 0.05). In the SPT+/AST-, SPT-/AST+ and SPT+/AST+ groups, offspring were significantly more likely to be allergic than the ones in SPT-/AST- group at 3-8 years. Offspring with at least one parent with asthma were significantly more likely to have positive skin prick test response than those with non-asthmatic parents at age 3-8 years and 9-14 years, but not at 15-20 years among offspring with allergic parents. Results were independent of asthma in the children and of the characteristics of atopy in the parents.

CONCLUSION

Parent asthma history is an independent risk factor for allergic sensitization in their offspring in a Chinese population.

Young maternal age at delivery is associated with asthma in adult offspring

OBJECTIVE

Some studies have shown an association between lower maternal age at delivery and increased asthma in children and young adults. It is unclear whether this represents an effect of maternal ageing or a protective effect of siblings. In a North-European population based study, we investigated whether mother's age at delivery was associated with risk for asthma and hay fever in adult offspring, taking into account relevant confounders.

METHODS

A total of 16,190 subjects (74%) aged 23-54 yr answered a postal questionnaire in a follow-up of the European Community Respiratory Health Survey (ECRHS I).

RESULTS

The associations of maternal age at delivery with hay fever, respiratory symptoms and diagnosed asthma were analysed using logistic regression, adjusting for household size, dwelling, parental education, centre, gender, adult hay fever, smoking, age and body mass index (BMI). The adjusted odds ratios (95% CI) for wheeze with breathlessness, wheeze without a cold and asthma in the offspring were 0.94 (0.90-0.99), 0.89 (0.86-0.94) and 0.92 (0.88-0.97), respectively, per 5 yr increase in maternal age. No heterogeneity between centres was found (p=0.84). The estimates remained similar in sub-sample analyses when adjusting for siblings, maternal smoking (n=3109) and for birth weight (n=1686). Hay fever was more common among those with the youngest and oldest mothers.

CONCLUSIONS

In this large North-European multi-centre study, asthma was less common with increasing maternal age. This effect was consistent between centres and persisted with adjustment for several potential confounders, suggesting that the association may possibly be explained by biological changes related to maternal ageing.

Respiratory symptoms in the first 7 years of life and birth weight at term: the PIAMA Birth Cohort

RATIONALE

The relation between birth weight and respiratory symptoms and asthma in children remains unclear. Previous studies focused on a relation at separate ages. A longitudinal analysis may lead to a better understanding.

OBJECTIVES

To estimate the effect of birth weight on the development and course of respiratory symptoms and asthma in the first 7 years of life.

METHODS

In a prospective birth cohort study, 3,628 children with a gestational age 37 weeks or more were monitored for 7 years. Parental questionnaires were used to assess respiratory health yearly. Associations of birth weight with respiratory symptoms (wheezing, coughing, respiratory infections) and doctor's diagnosis of asthma were assessed in a repeated-event analysis.

MEASUREMENTS AND MAIN RESULTS

Lower birth weight was associated with more respiratory symptoms (odds ratio [OR] per kg decrease in birth weight, 1.21; 95% confidence interval [CI], 1.09-1.34). The effect of birth weight increased from age 1 to 5, but decreased thereafter and was no longer significant at the age of 7. The effect of birth weight on respiratory symptoms was significantly greater among children exposed to tobacco smoke in their home than among nonexposed children (OR at 5 yr: 1.21 [95% CI, 1.02-1.44] and 1.52 [95% CI, 1.23-1.87], respectively). Birth weight and a doctor's diagnosis of asthma were not related (OR, 1.06; 95% CI, 0.82-1.37).

CONCLUSIONS

A lower birth weight in children born at term is associated with a transiently increased risk of respiratory symptoms. This effect is enhanced by environmental tobacco smoke exposure.

The Paris prospective birth cohort study: Which design and who participates?

The Paris prospective birth cohort study was implemented in 2003 to assess environmental/behavioural factors associated with respiratory and allergic disorder occurrence in early childhood. This paper describes the design and sociodemographic features of eligible/enrolled families. Full-term newborns without any medical problem at birth were recruited in five Paris maternity hospitals. They resided in the Paris area and had French speaking mothers. Sample size is at least 3500 infants, and children are followed-up until their sixth birthday. Data collection is based on regular medical and environmental self-administered questionnaires to parents. Information on dwellings is gathered by means of phone questionnaires, and standardized medical examinations are carried out at 18 months and 6 years. Exposure to traffic-related pollution is modelled. At inclusion, some information concerning refusals is gathered in order to describe sociodemographic features of participating families as compared with eligible children. 4115 (63%) out of the 6493 eligible infants are now participating in this study. Participation rate is higher in parents with a high SES (socioeconomic status), for French and European parents, and for > or =25-year-old mothers, but decreases with sibship size. Similar determinants are associated with the distribution of reasons for non-participation. The participation rate in the Paris study is comparable with other similar studies. Finally, giving detailed explanation of the study aims at inclusion, establishing regular mailed and phoned contacts with families, offering free complete medical examinations for the participant child and re-sent missing questionnaires are very important to improve participation at inclusion and during follow-up.

Characteristics of early transient, persistent, and late onset wheezers at 9 to 11 years of age

STUDY OBJECTIVE

To investigate the early determinants and characteristics of different phenotypes of wheeze in children on the basis of questionnaire data, lung function, and prick tests.

DESIGN

Cross-sectional survey. Setting. Rome and Fiumicino municipalities in Lazio region, Italy, within the ISAAC phase II project.

SUBJECTS

Sample of 2107 9-11 year old schoolchildren (response rate 83.5%).

RESULTS

We divided children into four mutually exclusive groups according to onset of wheeze: 154 early transient (birth to age 2), 51 persistent (birth to age 2 and current), 66 late onset (current only), and 1,446 control subjects (no early or current wheeze). Logistic regression models have shown that a family history of asthma and allergies is strongly associated with persistent and late onset wheezing; exposure to parental smoking--both during pregnancy and during the child's first year of life--is related to persistent wheezing; all children with wheezing show a significantly greater risk to have current respiratory symptoms other than wheeze compared with control subjects; current allergic rhinoconjunctivitis symptoms and atopy are related with both persistent and late onset wheeze. Multiple linear regression models show that forced expiratory rates at 25% to 75% of vital capacity (FEF25-75) and the ratio between forced expiratory volume in 1 second and forced vital capacity (FEV1/FVC) are significantly lower both in early transient (-305 mL/s, -1.7%) and persistent (-298 mL/s, -3.2%) wheezers; FEV1/FVC is significantly reduced in late onset wheezers too (-2.0%).

CONCLUSIONS

The strength of the association of family history and exposure to parental smoking varies with the three wheezing phenotypes. Moreover, early, persistent and late onset wheezers have different clinical characteristics in terms of their respiratory health and atopic status.

Association of transient tachypnea of the newborn and childhood asthma

OBJECTIVE

To determine if transient tachypnea of the newborn (TTN) is independently associated with childhood asthma.

METHODS

The sampling frame was a computerized database on 18,379 term infants born between January 1, 1996 and December 31, 2000 in an urban tertiary care hospital. This was a case-control study nested in a cohort of all term newborns who were subsequently diagnosed with asthma (n = 2137) and a similar number of birthday-matched controls. The International Classification of Diseases, Ninth Revision code was used to identify the infants with TTN and those who developed asthma. Logistic regression was used to adjust for potentially confounding variables. Stratified multivariate analysis was undertaken on subgroups to assess possible effect modification by factors known to influence the incidence of asthma: race, gender, domicile, and maternal asthma.

RESULTS

After adjustment for potential confounding, TTN was significantly associated with the diagnosis of childhood asthma (adjusted OR = 1.50, 95% CI: 1.13-1.99; P = 0.0052). The association of TTN and asthma was statistically strongest among male infants, especially among males whose mothers lived at an urban address, males of non-white race, and males whose mothers did not have asthma. The pattern of association of TTN and asthma was similar for infants diagnosed with asthma once compared with those diagnosed with asthma recurrently.

CONCLUSION

TTN was independently and significantly associated with the subsequent diagnosis of childhood asthma, especially among male infants. TTN may be a marker of deficient pulmonary function reflecting inherited susceptibility to asthma.

Issues in design and implementation in an urban birth cohort study: the Syracuse AUDIT project

The Syracuse AUDIT (Assessment of Urban Dwellings for Indoor Toxics) project is a birth cohort study of wheezing in the first year of life in a low-income urban setting. Such studies are important because of the documented serious risks to children's health and the lack of attention and published work on asthma development and intervention in communities of this size. We studied 103 infants of mothers with asthma, living predominantly in inner-city households. Our study combines measurements of a large panel of indoor environmental agents, in-home infant assessments, and review of all prenatal and postnatal medical records through the first year of life. We found multiple environmental pollution sources and potential health risks in study homes including high infant exposure to tobacco smoke. The prevalence of maternal smoking during pregnancy was 54%; postnatal environmental tobacco smoke (ETS) exposure was nearly 90%. The majority (73%) of homes showed signs of dampness. Participants' lives were complicated by poverty, unemployment and single-parenthood. Thirty-three percent of fathers were not involved with their children, and 62% of subjects moved at least once during the study period. These socioeconomic issues had an impact on project implementation and led to modification of study eligibility criteria. Extensive outreach, follow up, and relationship-building were required in order to recruit and retain families and resulted in considerable work overload for study staff. Our experiences implementing the project will inform further studies on this and other similar populations. Future reports on this cohort will address the role of multiple environmental variables and their effects on wheezing outcome during the first year of life.

Risk factors of bronchial hyperresponsiveness in children with wheezing-associated respiratory infection

The objectives of this study were to identify possible risk factors of bronchial hyperesponsiveness (BHR) in children up to 5 years of age with wheezing-associated respiratory infection (WARI), and to study the prevalence of BHR. Children up to 5 years of age with WARI were enrolled in the study. The parents or caregivers of children were asked about their demographic data and clinical histories. Physical examination and clinical score assessment were performed. Pulmonary function tests, i.e., tidal breathing flow volume (TBFV), were performed to measure tidal breathing parameters before and after salbutamol nebulization. If volume at peak tidal expiratory flow/expiratory tidal volume and time to peak expiratory flow/total expiratory time increased > or = 20%, or tidal expiratory flow at 25% of tidal volume/peak tidal expiratory flow increased > or = 20% after nebulization therapy, BHR was diagnosed. The number in the positive BHR group was used to calculate the prevalence of BHR, and clinical features were compared with those of the negative BHR group. Categorical data were analyzed for statistical significance (P < 0.05) by chi-square test or Fisher's exact test, or Student's t-test, as appropriate. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated for those with statistical significance. One hundred and six wheezing children underwent pulmonary function tests before and after salbutamol nebulization. With the aforementioned criteria, 41 cases (38.7%) were diagnosed with BHR. History of reactive airway disease, (OR, 6.31; 95% CI, 1.68-25), maternal history of asthma (OR, 3.45; 95% CI, 1.34-9), breastfeeding less than 3 months (OR, 3.18; 95% CI, 1.26-8.12), and passive smoking (OR, 3; 95% CI, 1.15-7.62) were significant risk factors of BHR. The eosinophil count was significantly higher in the BHR (+) group particularly, in children 1-5 years of age (P < or = 0.01). Patchy infiltrates were more commonly found in patients with negative BHR but not statistically significant. In conclusion, a history of reactive airway disease, maternal history, breastfeeding less than 3 months, and passive smoking were significant risk factors for BHR.

Paternal history of asthma and airway responsiveness in children with asthma

RATIONALE

Little is known regarding the relationship between parental history of asthma and subsequent airway hyperresponsiveness (AHR) in children with asthma.

OBJECTIVES

We evaluated this relationship in 1,041 children with asthma participating in a randomized trial of antiinflammatory medications (the Childhood Asthma Management Program [CAMP]).

METHODS

Methacholine challenge testing was performed before treatment randomization and once per year over an average of 4.5 years postrandomization. Cross-sectional and longitudinal repeated measures analyses were performed to model the relationship between PC20 (the methacholine concentration causing a 20% fall in FEV1) with maternal, paternal, and joint parental histories of asthma. Models were adjusted for potential confounders.

MEASUREMENTS AND MAIN RESULTS

At baseline, AHR was strongly associated with a paternal history of asthma. Children with a paternal history of asthma demonstrated significantly greater AHR than those without such history (median log(e)PC20, 0.84 vs. 1.13; p = 0.006). Although maternal history of asthma was not associated with AHR, children with two parents with asthma had greater AHR than those with no parents with asthma (median log(e)PC20, 0.52 vs. 1.17; p = 0.0008). Longitudinal multivariate analysis of the relation between paternal history of asthma and AHR using repeated PC20 measurements over 44 months postrandomization confirmed a significant association between paternal history of asthma and AHR among children in CAMP.

CONCLUSIONS

Our findings suggest that the genetic contribution of the father is associated with AHR, an important determinant of disease severity among children with asthma.

Frequent use of chemical household products is associated with persistent wheezing in pre-school age children

BACKGROUND

In the UK and other developed countries the prevalence of asthma symptoms has increased in recent years. This is likely to be the result of increased exposure to environmental factors. A study was undertaken to investigate the association between maternal use of chemical based products in the prenatal period and patterns of wheeze in early childhood.

METHODS

In the population based Avon Longitudinal Study of Parents and Children (ALSPAC), the frequency of use of 11 chemical based domestic products was determined from questionnaires completed by women during pregnancy and a total chemical burden (TCB) score was derived. Four mutually exclusive wheezing patterns were defined for the period from birth to 42 months based on parental questionnaire responses (never wheezed, transient early wheeze, persistent wheeze, and late onset wheeze). Multinomial logistic regression models were used to assess the relationship between these wheezing outcomes and TCB exposure while accounting for numerous potential confounding variables. Complete data for analysis was available for 7019 of 13, 971 (50%) children.

RESULTS

The mean (SD) TCB score was 9.4 (4.1), range 0-30. Increased use of domestic chemical based products was associated with persistent wheezing during early childhood (adjusted odds ratio (OR) per unit increase of TCB 1.06 (95% confidence interval (CI) 1.03 to 1.09)) but not with transient early wheeze or late onset wheeze. Children whose mothers had high TCB scores (>90th centile) were more than twice as likely to wheeze persistently throughout early childhood than children whose mothers had a low TCB score (<10th centile) (adjusted OR 2.3 (95% CI 1.2 to 4.4)).

CONCLUSION

These findings suggest that frequent use of chemical based products in the prenatal period is associated with persistent wheezing in young children. Follow up of this cohort is underway to determine whether TCB is associated with wheezing, asthma, and atopy at later stages in childhood.

Artificial neural networks as statistical tools in epidemiological studies: analysis of risk factors for early infant wheeze

Artificial neural networks (ANNs) are being used increasingly for the prediction of clinical outcomes and classification of disease phenotypes. A lack of understanding of the statistical principles underlying ANNs has led to widespread misuse of these tools in the biomedical arena. In this paper, the authors compare the performance of ANNs with that of conventional linear logistic regression models in an epidemiological study of infant wheeze. Data on the putative risk factors for infant wheeze have been obtained from a sample of 7318 infants taking part in the Avon Longitudinal Study of Parents and Children (ALSPAC). The data were analysed using logistic regression models and ANNs, and performance based on misclassification rates of a validation data set were compared. Misclassification rates in the training data set decreased as the complexity of the ANN increased: h = 0: 17.9%; h = 2: 16.2%; h = 5: 14.9%, and h = 10: 9.2%. However, the more complex models did not generalise well to new data sets drawn from the same population: validation data set misclassification rates: h = 0: 17.9%; h = 2: 19.6%; h = 5: 20.2% and h = 10: 22.9%. There is no evidence from this study that ANNs outperform conventional methods of analysing epidemiological data. Increasing the complexity of the models serves only to overfit the model to the data. It is important that a validation or test data set is used to assess the performance of highly complex ANNs to avoid overfitting.

Parental smoking and airway reactivity in healthy infants

Parental tobacco smoking is associated with lower airway function and an increased incidence of wheezy respiratory illnesses in infants. We evaluated in 76 healthy infants whether exposure to parental tobacco smoking was associated with airway hyperreactivity, which could contribute to lower airway function and the increased wheezy illnesses. Airway function was measured using the raised-volume rapid thoracic compression technique, and airway reactivity was assessed by methacholine challenge (0.015-10 mg/ml), which was stopped for a more than 30% decrease in forced expiratory flow (FEF)(75) or the final dose with a less than 30% decrease. Parental tobacco smoking was associated with lower baseline airway function (FEF(50), 600 vs. 676 ml/second, p < 0.04; FEF(25-75), 531 vs. 597 ml/second, p < 0.05). Infants exposed to tobacco smoking were approximately half as likely to develop a more than 30% decline in FEF(75) at any given methacholine dose (hazard ratio = 0.4, p = 0.001). In addition, a history of asthma in an extended family member increased the likelihood that an infant would develop a more than 30% decline in FEF(75) (hazard ratio = 1.7, p = 0.04). We conclude that exposure to parental smoking is associated with lower airway function but not increased airway reactivity; however, family history of asthma is associated with heightened airway reactivity.

Low-normal gestational age as a predictor of asthma at 6 years of age

BACKGROUND

Perinatal factors, including gestational age and birth weight, influence the development of atopy in early life. However, the role of these factors in the development of asthma in later life among children who do not develop perinatal respiratory disease remains unclear.

METHODS

Four hundred fifty-four infants who had a history of allergy or asthma in at least 1 parent, were born in the 36th week of gestation or later, and did not develop perinatal respiratory distress were monitored for at least 6 years. Associations between predictor variables and asthma and wheeze were assessed with multivariate logistic regression and repeated-event analyses.

RESULTS

Although we previously observed a relationship between low birth weight and persistent wheeze in the first 1 year of life, we did not observe similar associations between low birth weight and asthma at 6 years of age (odds ratio [OR]: 1.05; 95% confidence interval [CI]: 0.40-2.73). However, a strong relationship was found between low-normal gestational age and asthma at 6 years of age (OR: 4.7; 95% CI: 2.1-10.5). The effects of low-normal gestational age were significantly greater among boys than among girls (boys: OR: 8.15; 95% CI: 2.98-22.3; girls: OR: 1.90; 95% CI: 0.38-13.83). Longitudinal analysis of the relationship between gestational age and wheeze during the 6 years of observation confirmed these gender differences.

CONCLUSIONS

Among children at high risk of developing atopic disease, late prematurity might be an important additional determinant of asthma later in life, and these effects are gender specific.

Difficult asthma in the pre-school child

The most important aspect of dealing with a pre-school child suspected of having difficult asthma, is to ensure that the diagnosis is correct, in order to avoid the inappropriate use of therapies such as inhaled corticosteroids. After exclusion of other diagnoses, if a pre-school child is thought to have asthma, difficult or otherwise, the corollary is, what sort of asthma? Is it a syndrome with airway inflammation susceptible to treatment, or one in which there is no inflammation and time alone will result in resolution of symptoms? Probably the most common mistake in this age group is to fail to recognise the latter and institute ever more aggressive and useless therapies. An approach to excluding other diagnoses, appropriate investigations to elicit the presence of airway inflammation and suggestions for subsequent management have been detailed in this review.

Development of atopy and wheezing symptoms in relation to heredity and early pet keeping in a Swedish birth cohort

The role of pet keeping during infancy for the development of allergy and asthma is still controversial. The objective of this population-based birth cohort study was to assess the development of atopy and different wheezing phenotypes during the first 4 yr of life in relation to heredity and early pet keeping. The cohort comprised all 1228 infants living in a Swedish county who were born over a 1-yr period. The parents replied to repeated questionnaires and 817 of the children were skin prick tested both at 1 and 4 yr. Cat keeping during the first year of life was associated with an increased risk of a positive skin prick test to cat at 1 yr of age [odds ratio (OR) 2.2, 95% confidence interval (CI) 0.9-5.6], but neither with sensitivity nor clinical symptoms of allergy at 4 yr. Dog keeping during the first year of life was associated with an increased risk of early-onset transient wheezing, but only in children with parental asthma (adjusted OR 4.3, 95% CI 1.5-12.1). In contrast, early dog keeping had an inverse association with sensitivity to pollen allergen at 4 yr (adjusted OR 0.3, 95% CI 0.1-0.9) and late-onset wheezing (adjusted OR 0.4, 95% CI 0.2-1.0). Thus, pet keeping during the first year of life was not associated with an increased risk of atopy at 4 yr, although a positive SPT to cat was more common at 1 yr. Our findings may even suggest that dog keeping during the first year of life might provide some protection from pollen allergy and late-onset wheezing and increase the risk of early-onset transient wheezing in children with heredity for asthma.

Reduced interferon gamma production and soluble CD14 levels in early life predict recurrent wheezing by 1 year of age

It is unknown whether reduced production of IFNgamma in early life, before any lower respiratory tract illness, is a risk factor for recurrent wheezing in infancy. We followed 238 infants prospectively from birth to 1 year of age. At birth and at 3 months of age, IFNgamma production from polyclonally stimulated peripheral blood mononuclear cells and soluble CD14 (sCD14) levels in plasma were measured. The odds of developing recurrent wheezing (assessed by questionnaire) in the first year of life were up to 4.5 times higher for children in the lowest quartile of IFNgamma production at 3 months (p = 0.0005) and 3.2 times higher for children in the lowest quartile of sCD14 levels at birth (p = 0.004) as compared with children in the other 3 combined quartiles of IFNgamma and sCD14, respectively. Findings were confirmed in the multivariate analysis. IFNgamma production at 3 months and sCD14 levels at birth were correlated (r = 0.188, p = 0.031). Our findings from a longitudinal cohort suggest that impaired IFNgamma production at 3 months and reduced plasma-sCD14 levels at birth significantly increase the risk of developing recurrent wheezing in the first year of life.

A retrospective population based trend analysis on hospital admissions for lower respiratory illness among Swedish children from 1987 to 2000

BACKGROUND

Data relating to hospital admissions of very young children for wheezing illness have been conflicting. Our primary aim was to assess whether a previous increase in hospital admissions for lower respiratory illness had continued in young Swedish children. We have included re-admissions in our analyses in order to evaluate the burden of lower respiratory illness in very young children. We have also assessed whether changes in the labelling of symptoms have affected the time trend.

METHODS

A retrospective, population based study was conducted to assess the time trend in admissions and re-admissions for lower respiratory illness. Data were obtained from the Swedish Hospital Discharge Register for all children with a first hospital admission before nine years of age, a total of 109,176 children. The register covers more than 98% of all hospital admissions in Sweden. The coding of diagnoses was based on ICD-9 from 1987 to 1996 and ICD-10 from 1997.

RESULTS

The first admission rates declined significantly in children with a first admission after two years of age. However, an increasing admission trend was observed in children aged less than one year and 35% of first admissions occurred in this age group. The annual increase was 3.8% (95% CI 1.3-6.3) in boys and 5.0% (95% CI 2.4-7.6) in girls. A diagnostic shift appeared to occur when ICD-10 was introduced in 1997. The asthma and pneumonia admission rate in children aged less than one year levelled off, whereas the increase in admissions for bronchitis continued. The re-admission rates for asthma decreased and the probability of re-admission was higher in boys. National drug statistics demonstrated a substantial increase in the delivery of inhaled steroids to all age groups but most prescriptions occurred to children aged one year or more.

CONCLUSION

Hospital admissions for lower respiratory illness are still increasing in children aged <1 year. Our findings are in line with other recent studies suggesting a change in the responsiveness to viral infections in very young children, but changes in admission criteria cannot be excluded. An increased use of inhaled steroids may have contributed to decreasing re-admission rates.

Eighteen-month outcomes of house dust mite avoidance and dietary fatty acid modification in the Childhood Asthma Prevention Study (CAPS)

BACKGROUND

Observational studies have linked house dust mite (HDM) exposure and dietary fatty acid intake with asthma in childhood. However, definitive evidence of their role in the etiology of asthma requires a randomized controlled trial.

OBJECTIVE

We hypothesized that the incidence of asthma and allergy in high-risk children would be reduced by avoidance of HDM allergens, supplementation with omega-3 fatty acids, or the combination of these strategies. We present the results of an interim analysis reporting outcomes assessed at 18 months.

METHODS

A total of 616 pregnant women were randomized to an HDM avoidance intervention, comprising the use of impermeable mattress covers and an acaricide or control and the use of an oil supplement, margarines, and cooking oils containing high levels of omega-3 fatty acids or control. Atopic status was measured by skin prick testing. Symptoms, diagnoses, and medication histories were elicited by means of parental interviews.

RESULTS

The diet intervention resulted in a 9.8% absolute reduction (95% CI, 1.5-18.1; P =.02) in the prevalence of any wheeze and a 7.8% absolute reduction (95% CI, 0.5-15.1, P =.04) in prevalence of wheeze of >1 week, but it had no effect on serum IgE, atopy, or doctors' diagnosis of asthma. The HDM avoidance intervention did not affect these outcomes but was associated with a lower use of oral steroids.

CONCLUSION

Increasing dietary omega-3 fatty acids might have a beneficial effect on the prevalence of wheeze during the first 18 months of life. Follow-up to age 5 years, when the effect of the interventions on asthma risk will be assessed, is underway.

Paracetamol use in pregnancy and wheezing in early childhood

BACKGROUND

We recently reported links between frequent paracetamol (acetaminophen) use and wheezing and asthma in adults and children, but data are lacking on possible effects of prenatal exposure on wheezing in early childhood.

METHODS

In the population based Avon Longitudinal Study of Parents and Children (ALSPAC) women were asked twice during pregnancy (at 18-20 weeks and 32 weeks) about their usage of paracetamol and aspirin. Six months after birth, and at yearly intervals thereafter, mothers were asked about wheezing and eczema symptoms in their child. The effects of paracetamol and aspirin use in pregnancy on the risk in the offspring of wheezing at 30-42 months (n=9,400) and eczema at 18-30 months (n=10,216) and on their risk of different wheezing patterns (defined by presence or absence of wheezing at <6 months and at 30-42 months) were examined.

RESULTS

Paracetamol was taken frequently (most days/daily) by only 1% of women. After controlling for potential confounders, frequent paracetamol use in late pregnancy (20-32 weeks), but not in early pregnancy (<18-20 weeks), was associated with an increased risk of wheezing in the offspring at 30-42 months (adjusted odds ratio (OR) compared with no use 2.10 (95% CI 1.30 to 3.41); p=0.003), particularly if wheezing started before 6 months (OR 2.34 (95% CI 1.24 to 4.40); p=0.008). Assuming a causal relation, only about 1% of wheezing at 30-42 months was attributable to this exposure. Frequent paracetamol use in pregnancy was not associated with an increased risk of eczema. Frequent aspirin use in pregnancy was associated with an increased risk of wheezing only at <6 months.

CONCLUSIONS

Frequent use of paracetamol in late pregnancy may increase the risk of wheezing in the offspring, although such an effect could explain only about 1% of the population prevalence of wheezing in early childhood.