Dataset Information

Severe and Moderate Asthma Exacerbations in Asthmatic Children and Exposure to Ambient Air Pollutants.

ABSTRACT:

Background

It is well established that short-term exposure to ambient air pollutants can exacerbate asthma, the role of early life or long-term exposure is less clear. We assessed the association between severe asthma exacerbations with both birth and annual exposure to outdoor air pollutants with a population-based cohort of asthmatic children in the province of Quebec (Canada).

Method

Exacerbations of asthma occurring between 1 April 1996 and 31 March 2011 were defined as one hospitalization or emergency room visit with a diagnosis of asthma for children (<13 years old) already diagnosed with asthma. Annual daily average concentrations of ozone (O?) and nitrogen dioxide (NO?) were estimated at the child's residential postal code. Satellite based levels of fine particulate (PM2.5) estimated for a grid of 10 km by 10 km were also assigned to postal codes of residence for the whole province. Hazard ratios (HRs) were estimated from Cox models with a gap time approach for both birth and time-dependant exposure.

Results

Of the 162,752 asthmatic children followed (1,020,280 person-years), 35,229 had at least one asthma exacerbation. The HRs stratified by age groups and adjusted for the year of birth, the ordinal number of exacerbations, sex, as well as material and social deprivation, showed an interquartile range increase in the time-dependant exposure to NO? (4.95 ppb), O? (3.85 ppb), and PM2.5 (1.82 ?g/m³) of 1.095 (95% CI 1.058-1.131), 1.052 (95% CI 1.037-1.066) and 1.025 (95% CI 1.017-1.031), respectively. While a positive association was found to PM2.5, no associations were found between exposure at birth to NO? or O?.

Conclusions

Our results support the conclusion, within the limitation of this study, that asthma exacerbations in asthmatic children are mainly associated with time dependent residential exposures less with exposure at birth.

SUBMITTER: Tetreault LF

PROVIDER: S-EPMC4997457 | biostudies-literature | 2016 Aug

REPOSITORIES: biostudies-literature

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Publications

Severe and Moderate Asthma Exacerbations in Asthmatic Children and Exposure to Ambient Air Pollutants.

Tétreault Louis-Francois LF Doucet Marieve M Gamache Philippe P Fournier Michel M Brand Allan A Kosatsky Tom T Smargiassi Audrey A

International journal of environmental research and public health 20160801 8

<h4>Background</h4>It is well established that short-term exposure to ambient air pollutants can exacerbate asthma, the role of early life or long-term exposure is less clear. We assessed the association between severe asthma exacerbations with both birth and annual exposure to outdoor air pollutants with a population-based cohort of asthmatic children in the province of Quebec (Canada).<h4>Method</h4>Exacerbations of asthma occurring between 1 April 1996 and 31 March 2011 were defined as one ho ...[more]

PMID: 27490556

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Project description:BackgroundAlthough it is well established that air pollutants can exacerbate asthma, the link with new asthma onset in children is less clear.ObjectiveWe assessed the association between the onset of childhood asthma with both time of birth and time-varying exposures to outdoor air pollutants.MethodAn open cohort of children born in the province of Québec, Canada, was created using linked medical-administrative databases. New cases of asthma were defined as one hospital discharge with a diagnosis of asthma or two physician claims for asthma within a 2 year period. Annual ozone (O3) levels were estimated at the child's residence for all births 1999-2010, and nitrogen dioxide (NO2) levels during 1996-2006 were estimated for births on the Montreal Island. Satellite based concentrations of fine particles (PM2.5) were estimated at a 10 km × 10 km resolution and assigned to residential postal codes throughout the province (1996-2011). Hazard ratios (HRs) were assessed with Cox models for the exposure at the birth address and for the time-dependent exposure. We performed an indirect adjustment for secondhand smoke (SHS).ResultsWe followed 1,183,865 children (7,752,083 person-years), of whom 162,752 became asthmatic. After controlling for sex and material and social deprivation, HRs for an interquartile range increase in exposure at the birth address to NO2 (5.45 ppb), O3 (3.22 ppb), and PM2.5 (6.50 ?g/m3) were 1.04 (95% CI: 1.02, 1.05), 1.11 (95% CI: 1.10, 1.12), and 1.31 (95% CI: 1.28, 1.33), respectively. Effects of O3 and PM2.5 estimated with time-varying Cox models were similar to those estimated using exposure at birth, whereas the effect of NO2 was slightly stronger (HR = 1.07; 95% CI: 1.05, 1.09).ConclusionsAsthma onset in children appears to be associated with residential exposure to PM2.5, O3 and NO2.CitationTétreault LF, Doucet M, Gamache P, Fournier M, Brand A, Kosatsky T, Smargiassi A. 2016. Childhood exposure to ambient air pollutants and the onset of asthma: an administrative cohort study in Québec. Environ Health Perspect 124:1276-1282;?http://dx.doi.org/10.1289/ehp.1509838.

Project description:Oral corticosteroids are the cornerstone of acute asthma management in the emergency department. Recent evidence has raised doubts about the efficacy of this treatment in preschool-aged children with viral-induced wheezing and in smoking adults. The aims of the study were to: (1) document the magnitude of response to oral corticosteroids in children presenting to the emergency department with moderate or severe asthma; (2) quantify potential determinants of response to corticosteroids and (3) explore the role of gene polymorphisms associated with the responsiveness to corticosteroids.The design is a prospective cohort study of 1008 children aged 1-17 years meeting a strict definition of asthma and presenting with a clinical score of ?4 on the validated Pediatric Respiratory Assessment Measure. All children will receive standardised severity-specific treatment with prednisone/prednisolone and cointerventions (salbutamol with/without ipratropium bromide). Determinants, namely viral aetiology, environmental tobacco smoke and single nucleotide polymorphism, will be objectively documented. The primary efficacy endpoint is the failure of emergency department (ED) management within 72 h of the ED visit. Secondary endpoints include other measures of asthma severity and time to recovery within 7 days of the index visit. The study has 80% power for detecting a risk difference of 7.5% associated with each determinant from a baseline risk of 21%, at an ? of 0.05.Ethical approval has been obtained from all participating institutions. An impaired response to systemic steroids in certain subgroups will challenge the current standard of practice and call for the immediate search for better approaches. A potential host-environment interaction will broaden our understanding of corticosteroid responsiveness in children. Documentation of similar effectiveness of corticosteroids across determinants will provide the needed reassurance regarding current treatment recommendations.Results will be disseminated at international conferences and manuscripts targeted at emergency physicians, paediatricians, geneticists and respirologists.This study is registered at Clinicaltrials.gov (NCT02013076).

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Dataset Information

Severe and Moderate Asthma Exacerbations in Asthmatic Children and Exposure to Ambient Air Pollutants.

Background

Method

Results

Conclusions

Publications

Severe and Moderate Asthma Exacerbations in Asthmatic Children and Exposure to Ambient Air Pollutants.

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