Epidemiology of asthma exacerbations and their relation with environmental factors in the Basque Country

Analysis of Patients Admitted for Asthma Exacerbation in a Tertiary Hospital in Spain

OBJECTIVES

To analyze the characteristics of adult patients admitted for asthma exacerbation and determine optimization, treatment adherence, and follow-up in clinics.

METHODS

Patients ≥ 18 years old admitted from May 2021 to June 2023 with a primary diagnosis of asthma exacerbation were included. Patients with a secondary diagnosis of asthma exacerbation and those without a confirmed diagnosis were excluded.

RESULTS

A total of 186 patients were analyzed, 63% were female, with a mean age of 49 ± 34 years, mean body mass index (BMI) of 26.4 ± 5 kg/m2, mean immunoglobulin E level of 132 ± 235 IU/mL (range: 25-2041), mean eosinophils count of 180 ± 443, and length of stay of 8.6 ± 5 days. Comparing patients with one admission to those with multiple admissions, differences were observed in age (39 ± 15 vs. 58 ± 20, p < 0.0001), BMI (25.2 ± 3 vs. 27.4 ± 4, p < 0.0003), comorbidity (15% vs. 60%, p < 0.0001), and length of stay (4.5 ± 2 vs. 11 ± 3, p < 0.0001). Of the patients, 15% had undiagnosed asthma, 28% had known asthma without maintenance therapy, 23% were managed by primary care, and 34% were followed by pneumology. The mean Test of Adherence to Inhalers (TAI) score was 42.5 ± 8 points, with 70% showing erratic non-adherence, 46% showing deliberate non-adherence, and 21% showing unconscious non-adherence.

CONCLUSIONS

The young population represents a significant percentage of admissions for asthma exacerbation due to poor follow-up in pulmonology clinics, inadequate treatment optimization, and low adherence. This study adds that it is necessary to improve the approach to asthma in primary care to optimize treatment, reduce under-diagnosis, and avoid hospital admissions.

Short-Term Nitrogen Dioxide Exposure and Emergency Hospital Admissions for Asthma in Children: A Case-Crossover Analysis in England

Background

There is an increasing body of evidence associating short-term ambient nitrogen dioxide (NO2) exposure with asthma-related hospital admissions in children. However, most studies have relied on temporally resolved exposure information, potentially ignoring the spatial variability of NO2. We aimed to investigate how daily NO2 estimates from a highly resolved spatio-temporal model are associated with the risk of emergency hospital admission for asthma in children in England.

Methods

We conducted a time-stratified case-crossover study including 111,766 emergency hospital admissions for asthma in children (aged 0-14 years) between 1st January 2011 and 31st December 2015 in England. Daily NO2 levels were predicted at the patients' place of residence using spatio-temporal models by combining land use data and chemical transport model estimates. Conditional logistic regression models were used to obtain the odds ratios (OR) and confidence intervals (CI) after adjusting for temperature, relative humidity, bank holidays, and influenza rates. The effect modifications by age, sex, season, area-level income deprivation, and region were explored in stratified analyses.

Results

For each 10 µg/m³ increase in NO2 exposure, we observed an 8% increase in asthma-related emergency admissions using a five-day moving NO2 average (mean lag 0-4) (OR 1.08, 95% CI 1.06-1.10). In the stratified analysis, we found larger effect sizes for male (OR 1.10, 95% CI 1.07-1.12) and during the cold season (OR 1.10, 95% CI 1.08-1.12). The effect estimates varied slightly by age group, area-level income deprivation, and region.

Significance

Short-term exposure to NO2 was significantly associated with an increased risk of asthma emergency admissions among children in England. Future guidance and policies need to consider reflecting certain proven modifications, such as using season-specific countermeasures for air pollution control, to protect the at-risk population.

Asthma triggered by extreme temperatures: From epidemiological evidence to biological plausibility

BACKGROUND

There is rapidly growing evidence indicating that extreme temperature is a crucial trigger and potential activator of asthma; however, the effects of extreme temperature on asthma are inconsistently reported and the its potential mechanisms remain undefined.

OBJECTIVES

This review aims to estimate the impacts of extreme heat, extreme cold, and temperature variations on asthma by systematically summarizing the existing studies from epidemiological evidence to biological plausibility.

METHODS

We conducted a systematic search in PubMed, Embase, and Web of Science from inception to June 30, 2022, and we retrieved articles of epidemiology and biological studies which assessed associations between extreme temperatures and asthma. This protocol was registered with PROSPERO (CRD42021273613).

RESULTS

From 12,435 identified records, 111 eligible studies were included in the qualitative synthesis, and 37 articles were included in the meta-analysis (20 for extreme heat, 16 for extreme cold, and 15 for temperature variations). For epidemiological evidence, we found that the synergistic effects of extreme temperatures, indoor/outdoor environments, and individual vulnerabilities are important triggers for asthma attacks, especially when there is extreme heat or cold. Meta-analysis further confirmed the associations, and the pooled relative risks for asthma attacks in extreme heat and extreme cold were 1.07 (95%CI: 1.03-1.12) and 1.20 (95%CI: 1.12-1.29), respectively. Additionally, this review discussed the potential inflammatory mechanisms behind the associations between extreme temperatures and asthma exacerbation, and highlighted the regulatory role of immunological pathways and transient receptor potential ion channels in asthma triggered by extreme temperatures.

CONCLUSIONS

We concluded that both extreme heat and cold could significantly increase the risk of asthma. Additionally, we proposed a potential mechanistic framework, which is important for understanding the disease pathogenesis that uncovers the complex mechanisms of asthma triggered by extreme temperatures and protects the sensitive individuals from impacts of extreme weather events and climate change.

Looking back on 50 years of literature to understand the potential impact of influenza on extrapulmonary medical outcomes

We conducted a scoping review of the epidemiological literature from the past 50 years to document the contribution of influenza virus infection to extrapulmonary clinical outcomes. We identified 99 publications reporting 243 associations using many study designs, exposure and outcome definitions, and methods. Laboratory confirmation of influenza was used in only 28 (12%) estimates, mostly in case-control and self-controlled case series study designs. We identified 50 individual clinical conditions associated with influenza. The most numerous estimates were of cardiocirculatory diseases, neurological/neuromuscular diseases, and fetal/newborn disorders, with myocardial infarction the most common individual outcome. Due to heterogeneity, we could not generate summary estimates of effect size, but of 130 relative effect estimates, 105 (81%) indicated an elevated risk of extrapulmonary outcome with influenza exposure. The literature is indicative of systemic complications of influenza virus infection, the requirement for more effective influenza control, and a need for robust confirmatory studies.

Extrafine triple therapy and asthma exacerbation seasonality: TRIMARAN and TRIGGER post hoc analyses

BACKGROUND

Previous studies have shown seasonal variation in asthma exacerbations, peaking over the winter months. A single-inhaler triple therapy containing extrafine formulations of the inhaled corticosteroid (ICS) beclomethasone dipropionate (BDP), long-acting β₂-agonist formoterol fumarate (FF), and long-acting muscarinic antagonist glycopyrronium (G) is in development for asthma.

OBJECTIVE

We sought to evaluate whether calendar season impacted the relative effect of BDP/FF/G versus BDP/FF on moderate and severe asthma exacerbations.

METHODS

TRIMARAN and TRIGGER were double-blind 52-week studies comparing BDP/FF/G with BDP/FF (TRIMARAN medium-dose ICS; TRIGGER high-dose) in adults with uncontrolled asthma (Asthma Control Questionnaire-7 score ≥1.5), prebronchodilator FEV₁ less than 80% predicted, history of 1 or more asthma exacerbation, who had been receiving ICS/long-acting β₂-agonist for at least 4 weeks before entry. Moderate and severe asthma exacerbations were captured throughout each study. In these post hoc analyses, the annual moderate and severe exacerbation rate was calculated for each month, with rate ratios determined from events grouped by season.

RESULTS

In patients who received BDP/FF alone, there was a marked seasonal effect on the occurrence of asthma exacerbations, with the rate highest in the winter months. However, the addition of the long-acting muscarinic antagonist component to BDP/FF reduced this seasonal variation, especially during the winter, such that the relative effect of BDP/FF/G versus BDP/FF was greatest in the winter (significant 20.3% reduction [P = .0008]). Reductions in the other seasons ranged between 8.6% and 12.0%.

CONCLUSIONS

These post hoc analyses indicate that inhaled triple therapy with extrafine BDP/FF/G reduces seasonal peaks in moderate and severe exacerbations, and confirm the overall utility of adding long-acting muscarinic antagonist to ICS/long-acting β₂-agonist in the management of asthma.

Short-term effects of air pollution on exacerbations of allergic asthma in Užice region, Serbia

Introduction

Many time-series studies have shown a positive association between air pollution and asthma exacerbation. However, till now only one study in Serbia has examined this relationship.

Aim

To examine the associations between air pollution and asthma emergency department (ED) visits in the Užice region, Serbia.

Material and methods

A time-stratified case-crossover design was applied to 424 ED visits for asthma exacerbation that occurred in the Užice region, Serbia, in 2012–2014. Data about ED visits were routinely collected in the Užice Health Centre. The daily average concentrations of particulate matter (PM_2.5 and PM₁₀), sulphur dioxide (SO₂), nitrogen dioxide (NO₂), and black carbon (BC) were measured by automatic ambient air quality monitoring stations. Odds ratios and their corresponding 95% confidence intervals were estimated using conditional logistic regression adjusted for the potential confounding influence of weather variables (temperature, humidity and air pressure).

Results

Statistically significant associations were observed between ED visits for asthma and 3-day lagged exposure to BC (OR = 3.23; 95% CI: 1.05–9.95), and between ED visits for asthma with coexisting allergic rhinitis and 0-day lag exposure to NO₂ (OR = 1.57; 95% CI: 0.94–2.65), 2-day lag exposure to SO₂ (OR = 1.97; 95% CI: 1.02–3.80), and 3-day lag exposure to PM₁₀ (OR = 2.38; 95% CI: 1.17–4.84).

Conclusions

Exposure to ambient air pollution in the Užice region increases the risk of ED visits for asthma, particularly during the heating season.

Ambient pollen concentrations and asthma hospitalization in children and adolescents: a systematic review and meta-analysis

ObjectiveWe aimed to conduct a systematic review examining the association between outdoor pollen and childhood asthma hospitalizations.Data SourceA systematic search of articles in MEDLINE, EMBASE, CINAHL, ProQuest Central, Web of Science and Google Scholar published to 18 July 2019.Study selection: Studies that presented data on pollen exposure and childhood asthma hospitalization were included and evaluated for potential risk of bias by two independent authors. Random effects meta-analysis was performed where possible.ResultsA total of 1048 records were identified, and twelve studies included in the review. The synthesis suggested possible associations between outdoor pollen, especially for grass and birch and childhood asthma hospitalization. However, the results varied widely across geographical areas and settings for other pollen taxa. The meta-analysis of the case-crossover studies showed a positive association between grass and childhood asthma hospitalization, an increase in 10 grass pollen grains/m³ was associated with a 3% increase in childhood asthma admission (OR = 1.03; 95%CI:1.01, 1.04), but the pooled estimate was not significant for timeseries studies. The meta-analysis of the timeseries studies for birch pollen showed an increase in 10 pollen grains/m³ being significantly associated with a Mean Percentage Change (MPC) in childhood asthma admissions (MPC= 0.85; 95%CI:0.40, 1.30).Conclusion: Globally, grass and birch pollen are important triggers of childhood asthma hospitalization, but the association could not be ascertained for other pollen taxa. Pollen is a major environmental trigger of asthma exacerbations and more focus on early interventions to reduce this burden needs to be considered.

Is nicotine exposure linked to cardiopulmonary vulnerability to COVID-19 in the general population?

The recent emergence of COVID‐19 has resulted in a worldwide crisis, with large populations locked down and transportation links severed. While approximately 80% of infected individuals have minimal symptoms, around 15–20% need to be hospitalized, greatly stressing global healthcare systems. As of March 10, the death rate appears to be about 3.4%, although this number is highly stratified among different populations. Here, we focus on those individuals who have been exposed to nicotine prior to their exposure to the virus. We predict that these individuals are ‘primed’ to be at higher risk because nicotine can directly impact the putative receptor for the virus (ACE2) and lead to deleterious signaling in lung epithelial cells.

The Short-Term Effects of Ambient Air Pollutants on Childhood Asthma Hospitalization in Taiwan: A National Study

This investigation determined the effects of air pollution on childhood asthma hospitalization in regions with differing air pollution levels in Taiwan over a long time period. Data of childhood hospital admissions for asthma in patients aged 0–18 years and air quality in eight regions for the period 2001–2012 in Taiwan were collected. Poisson generalized linear regression analysis was employed to identify the relative risks of hospitalization due to asthma in children associated with exposure to varying levels of air pollutants with a change in the interquartile range after adjusting for temperature and relative humidity. Particulate matter ≤2.5 μm (PM_2.5), particulate matter ≤10 μm (PM₁₀), ozone (O₃), sulfur dioxide (SO₂), and nitrogen dioxide (NO₂), were positively associated with childhood asthma hospitalization, while O₃ was negatively associated with childhood asthma hospitalization. SO₂ was identified as the most significant risk factor. The relative risks for asthma hospitalization associated with air pollutants were higher among children aged 0–5 years than aged 6–18 years and were higher among males than females. The effects of air pollution on childhood asthma were greater in the higher-level air pollution regions, while no association was observed in the lower-level air pollution regions. These findings may prove important for policymakers involved in implementing policies to reduce air pollution.

Important changes in the timing of influenza epidemics in the WHO European Region over the past 20 years: virological surveillance 1996 to 2016

The global epidemiology of many infectious diseases is changing, but little attention has been paid to whether the timing of seasonal influenza epidemics changed in recent years. This study investigated whether the timing of the peak of influenza epidemics has changed in countries of the World Health Organization (WHO) European Region between 1996 and 2016. 
Methods: Surveillance data were obtained from the WHO FluNet database. For each country and season (July to June of the next year), the peak was defined as the week with the highest 3-week moving average for reported cases. Linear regression models were used to test for temporal trends in the timing of the epidemic peak in each country and to determine whether this differed geographically. 
Results: More than 600,000 influenza cases were included from 38 countries of the WHO European Region. The timing of the epidemic peak changed according to a longitudinal gradient, occurring progressively later in Western Europe (e.g. by 2.8 days/season in Spain) and progressively earlier in Eastern Europe (e.g. by 3.5 days/season in the Russian Federation). 
Discussion: These results were confirmed in several sensitivity analyses. Our findings have implications for influenza control and prevention measures in the WHO European Region, for instance for the implementation of influenza vaccination campaigns.

Co-occurrence of Asthma and the Inflammatory Bowel Diseases: A Systematic Review and Meta-analysis

Background

Inflammatory bowel diseases (IBD) and asthma share genetic and environmental risk factors. Consequently, several observational studies have explored an association between IBD and asthma. We systematically reviewed and summarized the literature on the co-occurrence of asthma and IBD.

Methods

MEDLINE and EMBASE (to April 2017) were searched to identify observational studies on the association between asthma and IBD. Relative risks (RR) were pooled using random effects models. Heterogeneity was assessed using the I² and Cochran Q statistics. Meta-regression based on study design, source of patients (population-based vs. tertiary-care center) and study location was conducted to explain between-study heterogeneity.

Results

Eighteen studies were identified (15 Crohn’s disease, 15 ulcerative colitis (UC)). Asthma was associated with both Crohn’s disease (pooled RR 1.30, 95% confidence interval (CI) 1.16–1.47, I² = 88%) and UC (RR 1.34, 95% CI 1.24–1.44, I² = 93%). The study design and source of patients and study location explained between-study heterogeneity in Crohn’s disease, but not UC.

Conclusion

Asthma is associated with both Crohn’s disease and UC. Additional research is needed to determine if one disease influences the risk of developing the other or if the frequent co-occurrence of these diseases result from shared genetic, environmental, and microbial risk factors.

Association between air pollution and asthma exacerbations in Badalona, Barcelona (Spain), 2008-2016

INTRODUCTION AND OBJECTIVE

Air pollution has been widely associated with respiratory diseases. Nevertheless, association between air pollution and exacerbations of asthma in our area has been less studied. To analyse the effect of air pollution on exacerbations of asthma in Badalona.

MATERIAL AND METHODS

This was an observational study conducted in Badalona. The number of daily hospital admissions and accident and emergency visits related to exacerbation of asthma between 2008 and 2016 was obtained. We used simple Poisson regressions to test the effects of daily mean temperature, atmospheric pressure, relative humidity, and NO₂, SO₂ and CO levels on asthma-related emergencies and hospitalisations the same day and 1-4 days after. All p-values were corrected for multiple comparisons.

RESULTS

The number of hospitalisations was associated with low temperature (lags 0 to 4) and higher levels of NO₂ (lags 0, 1, 2 and 4) and atmospheric pressure (lags 2 and 3). The number of accident and emergency visits was associated with low temperature (lags 0 to 4) and higher levels of NO₂ (lags 2, 3 and 4).

CONCLUSIONS

The number of accident and emergency visits and hospitalisations for exacerbation of asthma is associated with higher levels of NO₂ and with lower temperatures.

[Climate-sensitive diseases in Brazil and the world: systematic reviewEnfermedades sensibles al clima en Brasil y el mundo: revisión sistemática]

OBJECTIVE

To survey the literature regarding climate-sensitive diseases (CSD) and the impacts of climate changes on health.

METHOD

This systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). The Lilacs, SciELO, Scopus, and PubMed databases were searched in July 2017 without temporal restrictions for articles published in in Portuguese, English and Spanish. The following search strategy was used in all databases: (climate) AND (disease) AND (sensitive).

RESULTS

The systematic review included 106 articles, most of which focused on dengue, malaria, and respiratory and cardiovascular diseases. The most commonly studied climate variables were temperature and precipitation. The studies revealed a relationship between the incidence of certain diseases, especially cardiovascular and respiratory diseases, dengue, malaria, and arboviral diseases, and climate conditions in different regions of the world. This relationship was analyzed considering both past data on the incidence of diseases and climate variables and projections regarding the future incidence of diseases according to expected climate variations. A greater number of studies was performed by authors originating from developed countries. The world regions most often studied were China, the United States, Australia, and Brazil.

CONCLUSIONS

Despite the increase in the number of published articles on this theme, a greater number of climate and environmental variables must be studied, with expansion of studies to additional regions in the world.

Application of a Time-Stratified Case-Crossover Design to Explore the Effects of Air Pollution and Season on Childhood Asthma Hospitalization in Cities of Differing Urban Patterns: Big Data Analytics of Government Open Data

Few studies have assessed the lagged effects of levels of different urban city air pollutants and seasons on asthma hospitalization in children. This study used big data analysis to explore the effects of daily changes in air pollution and season on childhood asthma hospitalization from 2001 to 2010 in Taipei and Kaohsiung City, Taiwan. A time-stratified case-crossover study and conditional logistic regression analysis were employed to identify associations between the risk of hospitalization due to asthma in children and the levels of air pollutants (PM_2.5, PM₁₀, O₃, SO₂, and NO₂) in the days preceding hospitalization. During the study period, 2900 children in Taipei and 1337 in Kaohsiung aged ≤15 years were hospitalized due to asthma for the first time. The results indicated that the levels of air pollutants were significantly associated with the risk of asthma hospitalization in children, and seasonal effects were observed. High levels of air pollution in Kaohsiung had greater effects than in Taipei after adjusting for seasonal variation. The most important factor was O₃ in spring in Taipei. In children aged 0-6 years, asthma was associated with O₃ in Taipei and SO₂ in Kaohsiung, after controlling for the daily mean temperature and relative humidity.

Therapeutic Effect of Omalizumab in Severe Asthma: A Real-World Study in Korea

Purpose

Omalizumab, an anti-immunoglobulin E (IgE) monoclonal antibody, has proved to be effective for the treatment of severe asthma. However, there is no direct evidence of effectiveness of omalizumab in Korean patients with severe asthma. We sought to evaluate the real-world effectiveness of omalizumab in Korean adult patients suffering from severe asthma and to identify predictors of favorable response.

Methods

A retrospective analysis of electrical medical records was performed on severe allergic asthmatic patients with omalizumab treatment group (OT group) for more than 6 months between March 2008 and February 2016. Propensity score matching was applied to define the standardized treatment control group (STC group) treated without omalizumab. Asthma-related outcomes were compared between the 2 groups, and analyzed before and after omalizumab use in the OT group. Responders to treatment were defined as patients showing >50% reduction in asthma exacerbations and/or systemic steroid requirement during the outcome period.

Results

One hundred twenty-four patients with severe asthma (62 in the OT group; 62 in the STC group) were enrolled in the study. Proportion of patients having the reduction of asthma exacerbation (53.2% vs 35.5%, P=0.015) and the rate of responders (67.7% vs 41.9%, P=0.007) were significantly higher in the OT group than in the STC group. Significant reductions were noted in asthma exacerbation (P=0.006), hospitalization (P=0.009), hospitalization days (P=0.006), systemic corticosteroid requirements (P=0.027), and sputum eosinophil count (P=0.031) in OT group compared with STC group. There were no significant differences in changes of forced expiratory volume in the 1 second (FEV1) levels between the 2 groups. No predictors of responders were found for omalizumab treatment.

Conclusions

Omalizumab can reduce exacerbations/hospitalization/systemic steroid burst in Korean adult patients with severe asthma.

Pollen exposure and hospitalization due to asthma exacerbations: daily time series in a European city

Exposure to pollen can contribute to increased hospital admissions for asthma exacerbation. This study applied an ecological time series analysis to examine associations between atmospheric concentrations of different pollen types and the risk of hospitalization for asthma in London from 2005 to 2011. The analysis examined short-term associations between daily pollen counts and hospital admissions in the presence of seasonal and long-term patterns, and allowed for time lags between exposure and admission. Models were adjusted for temperature, precipitation, humidity, day of week, and air pollutants. Analyses revealed an association between daily counts (continuous) of grass pollen and adult hospital admissions for asthma in London, with a 4-5-day lag. When grass pollen concentrations were categorized into Met Office pollen 'alert' levels, 'very high' days (vs. 'low') were associated with increased admissions 2-5 days later, peaking at an incidence rate ratio of 1.46 (95%, CI 1.20-1.78) at 3 days. Increased admissions were also associated with 'high' versus 'low' pollen days at a 3-day lag. Results from tree pollen models were inconclusive and likely to have been affected by the shorter pollen seasons and consequent limited number of observation days with higher tree pollen concentrations. Future reductions in asthma hospitalizations may be achieved by better understanding of environmental risks, informing improved alert systems and supporting patients to take preventive measures.

Respiratory medication sales and urban air pollution in Brussels (2005 to 2011)

BACKGROUND

We investigated the associations between daily sales of respiratory medication and air pollutants in the Brussels-Capital Region between 2005 and 2011.

METHODS

We used over-dispersed Poisson Generalized Linear Models to regress daily individual reimbursement data of prescribed asthma and COPD medication from the social security database against each subject's residential exposure to outdoor particulate matter (PM10) or NO2 estimated, by interpolation from monitoring stations. We calculated cumulative risk ratios (RR) and their 95% confidence intervals (CI) for interquartile ranges (IQR) of exposure for different windows of past exposure for the entire population and for seven age groups.

RESULTS

Median daily concentrations of PM10 and NO2 were 25μg/m(3) (IQR=17.1) and 38μg/m(3) (IQR=20.5), respectively. PM10 was associated with daily medication sales among individuals aged 13 to 64y. For NO2, significant associations were observed among all age groups except >84y. The highest RR were observed for NO2, among adolescents, including three weeks lags (RR=1.187 95%CI: 1.097-1.285).

CONCLUSION

The associations found between temporal changes in exposure to air pollutants and daily sales of respiratory medication in Brussels indicate that urban air pollution contributes to asthma and COPD morbidity in the general population.

[Seasonality in asthma: Impact and treatments]

The role of seasons should be taken into account in the management of asthma. The environment varies between seasons and it is well documented that asthma is modulated by environment. Viruses cause asthma exacerbations peak, in winter, in adults while the peak is present in September in children. Allergens are probably a less powerful source of asthma exacerbation than viruses but pollen involvement in spring and summer and dust mites in autumn are indisputable. Air pollutants, present in summer during the hottest periods, are also highly involved in asthma exacerbations. Indoor air pollution, in winter, is also implicated in asthma disease. All these environmental factors are synergistic and increase the risk of asthma exacerbation. Therapies should be adapted to each season depending on environmental factors potentially involved in the asthma disease.

Pollen concentration and asthma exacerbations in Wake County, North Carolina, 2006-2012

Pollen has been generally linked to an increased risk for asthma exacerbation. However, the delayed effect (lag), the length of effect duration, and the association heterogeneity by pollen types have not been well characterized. Short-term associations between ambient concentration of various pollen types (tree, grass, and weed) and emergency department (ED) visits for asthma were assessed using data in Wake County, North Carolina, during 2006-2012. Distributed lag nonlinear models (DLNM) were used to characterize the associations, while adjusting for air pollutants, meteorological, and temporal factors. A strong association between same-day tree pollen and asthma ED visits was detected. This association lasted four days, with a 4-day cumulative risk ratio (RR) up to 2.10 (3500 grains/m(3) vs. 0 grains/m(3), 95% confidence interval [CI]=1.21-3.65). The associations of asthma ED visits with weed pollen and grass pollen were weak, suggestively starting from lag 2 and lasting 3 days, with the strongest association a 3-day cumulative RR of 1.08 (32 grains/m(3) vs. 0 grains/m(3), 95% CI=1.01-1.15) and 1.05 (11 grains/m(3) vs. 0 grains/m(3), 95% CI=1.00-1.11). Our results indicate that the association of ambient pollen and asthma exacerbation vary by pollen type, both quantitatively and temporally. These findings have important implications for optimizing targeted allergic disease prevention and management, and helping understand the etiology of ambient exposure-induced allergic diseases.

Environmental factors affecting seasonality of ambulance emergency service visits for exacerbations of asthma and COPD

OBJECTIVE

The aim of this study was to assess the association of severe exacerbations of asthma and Chronic Obstructive Pulmonary Disease (COPD) requiring ambulance emergency service (AES) visits with meteorological parameters and influenza outbreaks.

METHODS

The records of patients calling the AES in 2007 and 2008 in the urban area of Lodz due to dyspnea were analyzed. Information on 25 daily reported meteorological parameters was obtained from the local meteorological service and data on influenza outbreaks obtained from the national surveillance service.

RESULTS

During the winter months, a significantly higher mean daily number of AES visits for both COPD and asthma were noticed when compared to the summer. Interestingly, the number of daily AES visits correlated with several weather parameters, and the multiple regression analysis confirmed a negative correlation with minimum temperature, mean temperature and the dew point for both diseases (R = 0.526; p < 0.01; R = 0.577; p < 0.01 and R = 0.589; p < 0.01). Furthermore, the increased number of AES visits also correlated with a new number of cases of influenza infections as reported by local influenza surveillance system (rs = 77.6%; p < 0.001 and rs = 80.8%; p < 0.001 for asthma and COPD, respectively).

CONCLUSION

Seasonality of AES visits for asthma and COPD are similar and seems to be related to specific weather conditions and to influenza outbreaks.