Tree Pollen and Hospitalization for Asthma in Urban Canada

Dales, Robert; Cakmak, Sabit; Judek, Stan; Coates, Frances

doi:10.1159/000116360

Cited by 94 publications

(56 citation statements)

References 34 publications

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“…Environmental factors, including pollutants, allergen exposure, psychological stress and weather conditions, may increase the risk of developing an acute asthma exacerbation in both children and adults [24][25][26][27][28][29][30]. The multiplicity of precipitating factors points towards a multifactorial cause, as well as potential interactions, which have been shown for some combinations of factors, such as pollutants [31,32].…”

Section: Infection Among Factors Precipitating Asthma Exacerbationsmentioning

confidence: 99%

Childhood asthma and infection: virus-induced exacerbations as determinants and modifiers: Figure 1–

Xepapadaki¹,

Papadopoulos²

2010

Eur Respir J

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Respiratory infections have been implicated in the origin and exacerbation of asthma in a variety of ways; however, systemisation of this knowledge in a way helpful for disease management remains suboptimal.Several conceptual issues need to be taken into account: the fact that the effects of an infection may vary according to genetic background, the current immune status of the host, and parallel environmental stimuli, in addition to the particular infectious agent itself. Moreover, childhood is a very special period because of the continuous processes taking place, such as neural, immune and respiratory maturation.Epidemiological studies have convincingly demonstrated that the majority of asthma exacerbations, in both adults and children, follow viral upper respiratory tract infections. Asthma exacerbations are still often unresponsive to current asthma treatment, and new therapeutic approaches are required.This review presents current knowledge on the associations between infection and exacerbation of established asthma with respect to definitions, epidemiology, mechanisms and treatment.

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Section: Infection Among Factors Precipitating Asthma Exacerbationsmentioning

confidence: 99%

Childhood asthma and infection: virus-induced exacerbations as determinants and modifiers: Figure 1–

Xepapadaki¹,

Papadopoulos²

2010

Eur Respir J

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“…Some ecological studies have investigated the association between the short-term effects of birch pollen exposure and hospital admission for asthma [9], emergency visits for rhinitis or conjunctivitis [10], antiallergic drug consumption [11,12], or mortality [13]. A few panel studies have examined the relationship between tree pollens and nasal symptoms [14,15] and asthma [16,17,18].…”

Section: Introductionmentioning

confidence: 99%

Effects of Airborne Birch Pollen Levels on Clinical Symptoms of Seasonal Allergic Rhinoconjunctivitis

Caillaud¹,

Martin²,

Ségala³

et al. 2013

Int Arch Allergy Immunol

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Background: Most panel studies focusing on rhinitis and conjunctivitis symptoms and birch pollen have been performed on a linear basis and have not included air pollution and meteorological variables as potential confounders. The objective of this panel study was to assess the relationship between symptoms of seasonal allergic rhinoconjunctivitis and daily airborne birch pollen concentrations, checking with adequate statistical tools the shapes of concentration-response curves and controlling for confounders. Methods: The severity of rhinitis, conjunctivitis, and bronchial symptoms was recorded daily in March and April 2010 (3,311 person-days) in 61 seasonal allergic rhinoconjunctivitis patients sensitized to birch. Data were analyzed with generalized additive and generalized estimating equation models to quantify the effects of birch pollens. Results: The relationship between birch pollen and the percentage of patients with nasal, ocular and bronchial symptoms was linear until birch daily average concentrations of, respectively, 110, 70, and 70 grains/m³; it reached a plateau thereafter. For an increase of 10 grains/m³, the OR (95% CI) for nasal, ocular, and bronchial symptoms were, respectively, 1.07 (1.03-1.12), 1.17 (1.08-1.27), and 1.12 (1.03-1.21). At the beginning of the season, no nasal or ocular symptoms were observed below a threshold of 30 grains/m³. Conclusions: Adequate modeling regression shows that the clinical response to natural exposure to birch pollen in sensitized patients varies during Betula pollen season, with a threshold at the beginning of the season, while over the whole season the relationship is linear for nasal, ocular, and bronchial symptoms up to a saturation point, followed by a plateau.

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“…Some studies have demonstrated specifically that the airborne pollens or fungal spores influence exacerbation of asthma, particularly in younger age groups [7,8,9]. A recent study has reported asthma exacerbations requiring hospital admissions to be associated with various tree pollen types [10]. There is also a recent and growing body of evidence indicating that the hornbeam is an important tree pollen allergen [11,12], however, its role in exacerbating asthma has not been evaluated.…”

Section: Introductionmentioning

confidence: 99%

Effects of Traffic Air Pollution and Hornbeam Pollen on Adult Asthma Hospitalizations in Zagreb

Krmpotić

Lužar-Stiffler

Rakušić

et al. 2011

Int Arch Allergy Immunol

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Background: Environmental factors play an important role in asthma morbidity, although the contribution of individual pollutants or pollens in exacerbating asthma is not completely elucidated. Despite the evidence of importance of the hornbeam pollen in inducing allergic sensitization, its role in provoking asthma exacerbation has not been evaluated. The aim of the present study was to investigate effects of traffic pollutants on adult asthma hospitalization adjusting for pollens including hornbeam. Methods: During a 3-year period, health and environmental data were collected and analyzed. Daily asthma hospitalizations were regressed on pollutants and potential confounding variables using an autoregressive Poisson model. Results: The risk of asthma hospitalization was associated significantly with the 95th to 99th percentile increase in levels of nitrogen dioxide (RR = 1.22; 95% CI: 1.05–1.40), carbon monoxide (RR = 1.25; 95% CI: 1.01–1.55) and hornbeam pollen (RR = 1.21; 95% CI: 1.11–1.30). The effect of nitrogen dioxide was delayed by 5 days. No statistically significant increase in the risk of asthma hospitalization was found for PM₁₀ particles. A comparison among the standardized regression coefficients and their respective p values indicates that the most important risk factor for asthma hospitalization is associated with hornbeam pollen levels. No statistically significant interactions between pollutants and pollens were detected. Conclusions: The current results suggest that traffic-related air pollution is associated with increased risk of adult asthma hospitalization. Nonetheless, the most significant risk for asthma hospitalization is associated with hornbeam pollen levels in the city of Zagreb.

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Tree Pollen and Hospitalization for Asthma in Urban Canada

Cited by 94 publications

References 34 publications

Childhood asthma and infection: virus-induced exacerbations as determinants and modifiers: Figure 1–

Childhood asthma and infection: virus-induced exacerbations as determinants and modifiers: Figure 1–

Effects of Airborne Birch Pollen Levels on Clinical Symptoms of Seasonal Allergic Rhinoconjunctivitis

Effects of Traffic Air Pollution and Hornbeam Pollen on Adult Asthma Hospitalizations in Zagreb

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