Anne DyBuncio

Traffic-related air pollution and incident asthma in a high-risk birth cohort

Objectives The risk of incident asthma and bronchial hyper-reactivity associated with early life exposure to traffic-related air pollution has not been fully elucidated. We aimed to evaluate the hypothesis that the risk of new onset asthma is positively associated with early exposure to traffic-related air pollution in a well-characterised high-risk birth cohort. Methods Infants at high-risk for asthma were recruited for an intervention study. Birth year exposures to NO, NO2, black carbon and PM2.5 were estimated by land use regression. At 7 years of age, asthma was assessed by a paediatric allergist and bronchial hyper-reactivity was measured by methacholine challenge. Associations between exposures and outcomes were analysed by stepwise multiple logistic regression, adjusted for potential confounding variables. Results Exposure estimates were available for 184 children; 23 were diagnosed with asthma and 68 with bronchial hyper-reactivity. The IQR (4.1 μg/m3) of birth year PM2.5 was associated with a significantly increased risk of asthma (OR 3.1, 95% CI 1.3 to 7.4) and with a trend to increased risk of bronchial hyper-reactivity. Similar findings were noted in association with NO and NO2, while black carbon did not appear to confer increased risk. Conclusion Modest elevations in exposure to some traffic-related air pollutants during the year of birth are associated with new onset asthma assessed at age 7. That significant associations were revealed in spite of a limited sample size emphasises the strengths of a high-risk birth cohort model, along with individual air pollution exposure estimates and well-characterised data on covariates and outcomes.

Atopic dermatitis in a high-risk cohort: natural history, associated allergic outcomes, and risk factors.

BACKGROUND Atopic dermatitis (AD) is commonly associated with asthma and other atopic disorders in childhood. OBJECTIVE To evaluate the natural history of AD and its association with other allergic outcomes in a high-risk cohort through the age of 7 years. METHODS A total of 373 high-risk infants, who had undergone a randomized controlled trial with intervention measures for primary prevention of asthma applied during the first year of life, were assessed for asthma, AD, and allergic sensitization at 1, 2, and 7 years. RESULTS The multifaceted intervention program did not reduce AD despite reducing the prevalence of asthma significantly. Sixty-two children (16.6%) had AD during the first 2 years (early-onset AD); of these, 26 continue to have AD at the age of 7 years (persistent), whereas 36 no longer had the disease (nonpersistent) at the age of 7 years. Twenty-three children (6.2%) developed AD only after the age of 2 years (late-onset AD). Early-onset AD, persistent or nonpersistent, was associated with increased risk of allergic sensitization to food allergens within the first 2 years of life and asthma diagnosis at year 7. However, only persistent AD was associated with an increased risk of other atopic diseases and allergic sensitization to food and aeroallergens at year 7. Late-onset AD was not associated with atopic diseases or allergic sensitization at year 7 with the exception of Alternaria alternans. CONCLUSION In this cohort of infants at high risk of asthma, early-onset persistent AD, which was highly associated with atopic sensitization, increased the risk of atopic diseases in later childhood and thus appears to be part of the atopic march.

Respiratory abnormalities among workers in an iron and steel foundry.

A study of the health of 78 workers in an iron and steel foundry in Vancouver, British Columbia, was carried out and the results compared with those found in 372 railway repair yard workers who were not significantly exposed to air contaminants at work. The foundry workers were exposed to PepSet, which consists of diphenyl methane diisocyanate (MDI) and phenol formaldehyde and their decomposition products as well as to silica containing particulates. A questionnaire was administered by trained interviewers, and chest radiography, allergy skin tests, pulmonary function tests, and methacholine inhalation tests were carried out as well as measurement levels of dust and MDI. Compared with the controls, the foundry workers had more respiratory symptoms and a significantly lower mean FEV1 and FEF25-75% after adjustments had been made for differences in age, height, and smoking habit. Three workers (4.8%) had radiographic evidence of pneumoconiosis and 12 (18.2%) had asthma defined as presence of bronchial hyperreactivity, cough, and additional respiratory symptoms such as wheeze, chest tightness, or breathlessness. Sensitisation to MDI is probably the cause of asthma in these workers.

Indoor allergen exposure, sensitization, and development of asthma in a high-risk birth cohort.

Carlsten C, Dimich‐Ward H, Becker AB, Ferguson A, Chan HW, DyBuncio A, Chan‐Yeung M. Indoor allergen exposure, sensitization, and development of asthma in a high‐risk birth cohort.
Pediatr Allergy Immunol 2010: 21: e740–e746.
© 2010 John Wiley & Sons A/S

Elevated cord blood IgE is associated with recurrent wheeze and atopy at 7 yrs in a high risk cohort

There is considerable interest in identifying children at high risk for developing atopic diseases for primary prevention. This study evaluates risk factors for detectable cord blood IgE and assesses CB‐IgE in predicting asthma and other IgE‐mediated allergic diseases in children at high risk because of family history. Cord blood was obtained as part of a randomized controlled trial assessing the efficacy of an intervention program in the primary prevention of IgE‐mediated allergic diseases. CB‐IgE was measured and the degree to which this was associated with perinatal risk factors was assessed. The cohort was then evaluated for atopic disorders at 7 yrs of age to assess the predictive value of CB‐IgE. Fifty‐five (19.3%) of infants had detectable CB‐IgE (≥0.5 kU/l). Maternal atopy and birth in winter months were risk factors associated with detectable CB‐IgE. CB‐IgE was found to be significantly associated with allergic sensitization (OR 2.22; 95% CI 1.11, 4.41) and recurrent wheeze at 7 yrs (OR 2.51, 95% CI 1.09, 5.76) but not with other outcomes. CB‐IgE may be a useful measure for identifying children at high risk of atopic diseases for the purpose of primary prevention.

Combined exposure to dog and indoor pollution: incident asthma in a high-risk birth cohort

The impact of single exposures on asthma development is better understood than the effect of multiple exposures. The objective of the present study was to evaluate the effect of combined early exposure to dog allergen (Can-f1) plus indoor nitrogen dioxide (NO2) or environmental tobacco smoke (ETS) on asthma and bronchial hyperreactivity (BHR) in a high-risk birth cohort. We also aimed to assess atopys impact on the effects of these exposures. Peri-birth ETS exposure was measured using cord blood cotinine (CCot). During year 1, atopy, NO2, Can-f1, and urinary cotinine (UCot) were measured. At 7 yrs of age, 380 children were assessed for asthma and BHR. Exposure effects were determined using stepwise multiple linear regression. Co-exposure to elevated Can-f1 and NO2, or Can-f1 and ETS (CCot), increased risk for asthma, relative to having neither such exposure (OR 4.8 (95% CI 1.1–21.5) and 2.7 (1.1–7.1), respectively); similar risks resulted when substituting dog ownership for allergen. Atopy increased asthma and BHR risk associated with several exposures; notably, atopy with elevated UCot, relative to atopy without such exposure, increased risk of BHR (OR 3.1 (95% CI 1.1–8.6)). In a high-risk birth cohort, early co-exposure to Can-f1 and NO2 or ETS increased the risk of incident asthma. Atopy increased the risk of asthma and BHR associated with ETS.

Association between endotoxin and mite allergen exposure with asthma and specific sensitization at age 7 in high-risk children

To cite this article: Carlsten C, Ferguson A, Dimich‐Ward H, Chan H, DyBuncio A, Rousseau R, Becker A, Chan‐Yeung M. Association between endotoxin and mite allergen exposure with asthma and specific sensitization at age 7 years in high‐risk children. Pediatr Allergy Immunol 2011; 22: 320–326.

Respiratory health at a pulpmill in British Columbia

The respiratory parameters of 392 white male pulpmill workers were measured by standardized procedures and compared with those of 310 white male rail yard workers. The pulpmill workers complained more frequently of wheezing and chest tightness and missed work more commonly because of chest illness as compared with the rail yard workers. Significant airflow obstruction was noted in nonsmokers who worked in the bleach plant, and it was most striking in the younger members of this group. The principal environmental contaminant in this area was chlorine at levels generally below current permissible concentrations. Members of the maintenance group--especially older members--demonstrated significantly lower forced vital capacity compared to the rail yard workers.

Cotinine versus questionnaire: early-life environmental tobacco smoke exposure and incident asthma

BackgroundThe use of biomarkers has expanded considerably, as an alternative to questionnaire-based metrics of environmental tobacco smoke (ETS); few studies have assessed the affect of such alternative metrics on diverse respiratory outcomes in children, and we aimed to do so.MethodsWe evaluated various measures of birth-year ETS, in association with multiple respiratory endpoints early years of life, in the novel context of a birth cohort at high risk for asthma. We administered questionnaires to parents, both at the end of pregnancy and at one year of life, and measured cotinine in cord blood (CCot; in 275 children) and in urine (UCot; obtained at 12 months in 365 children), each by radioimmunoassay. Multiple logistic regression was used to assess the association of the various metrics with recurrent wheeze at age 2 and with bronchial hyperresponsiveness (BHR) and asthma at age 7.ResultsSelf-reported 3rd trimester maternal smoking was associated with significantly increased risk for recurrent wheeze at age 2 (odds ratio 3.5 [95% confidence interval = 1.2,10.7]); the risks associated with CCot and 3rd trimester smoking in any family member were similar (OR 2.9 [1.2,7.0] and 2.6 [1.0,6.5], respectively). No metric of maternal smoking at 12 months appeared to significantly influence the risk of recurrent wheeze at age 2, and no metric of ETS at any time appeared to significantly influence risk of asthma or BHR at age 7.ConclusionsBiomarker- and questionnaire-based assessment of ETS in early life lead to similar estimates of ETS-associated risk of recurrent wheeze and asthma.

Airway hyperresponsiveness to methacholine in 7-year-old children: sensitivity and specificity for pediatric allergist-diagnosed asthma

The operating characteristics of PC20 values used as cut‐offs to define airway hyperresponsiveness, as it informs the diagnosis of asthma in children, are poorly understood. We examine data from a unique cohort to inform this concern.