Childhood asthma and return to school in Sydney, Australia

Prediction of Asthma Exacerbations in Children

Asthma exacerbations are common in asthmatic children, even among those with good disease control. Asthma attacks result in the children and their parents missing school and work days; limit the patient's social and physical activities; and lead to emergency department visits, hospital admissions, or even fatal events. Thus, the prompt identification of asthmatic children at risk for exacerbation is crucial, as it may allow for proactive measures that could prevent these episodes. Children prone to asthma exacerbation are a heterogeneous group; various demographic factors such as younger age, ethnic group, low family income, clinical parameters (history of an exacerbation in the past 12 months, poor asthma control, poor adherence to treatment, comorbidities), Th2 inflammation, and environmental exposures (pollutants, stress, viral and bacterial pathogens) determine the risk of a future exacerbation and should be carefully considered. This paper aims to review the existing evidence regarding the predictors of asthma exacerbations in children and offer practical monitoring guidance for promptly recognizing patients at risk.

Respiratory virus detection during the COVID-19 pandemic in Queensland, Australia

Objective: To determine if non‐pharmaceutical interventions (NPIs) impacted on respiratory virus detections in Queensland, Australia, during the COVID‐19 pandemic year of 2020.

Methods: We analysed weekly counts of influenza, human metapneumovirus, parainfluenza, respiratory syncytial virus, rhinovirus, and adenovirus available from a Queensland laboratory network for the year 2020. These were compared with averaged counts from 2015 to 2019.

Results: Overall, 686,199 tests were performed. The timing of NPI implementation was associated with a sharp and sustained decline in influenza, where during the typical annual influenza season (weeks 23–40) no cases were detected from 163,296 tests compared with an average of 26.1% (11,844/45,396) of tests positive in 2015–2019. Similar results were observed for human metapneumovirus and parainfluenza. Respiratory syncytial virus detections also declined but increased in weeks 48–52 (5.6%; 562/10,078) to exceed the 2015–2019 average (2.9%; 150/5,018). Rhinovirus detections increased after schools reopened, peaking in weeks 23–27 (57.4%; 36,228/63,115), exceeding the 2017–2019 detections during that period (21.9%; 8,365/38,072).

Conclusions: NPIs implemented to control COVID‐19 were associated with altered frequency and proportions of respiratory virus detections.

Implications for public health: NPIs derived from influenza pandemic plans were associated with profound decreases in influenza detections during 2020.

Models for estimating and projecting global, regional and national prevalence and disease burden of asthma: a systematic review

Background

Statistical models are increasingly being used to estimate and project the prevalence and burden of asthma. Given substantial variations in these estimates, there is a need to critically assess the properties of these models and assess their transparency and reproducibility. We aimed to critically appraise the strengths, limitations and reproducibility of existing models for estimating and projecting the global, regional and national prevalence and burden of asthma.

Methods

We undertook a systematic review, which involved searching Medline, Embase, World Health Organization Library and Information Services (WHOLIS) and Web of Science from 1980 to 2017 for modelling studies. Two reviewers independently assessed the eligibility of studies for inclusion and then assessed their strengths, limitations and reproducibility using pre-defined quality criteria. Data were descriptively and narratively synthesised.

Results

We identified 108 eligible studies, which employed a total of 51 models: 42 models were used to derive national level estimates, two models for regional estimates, four models for global and regional estimates and three models for global, regional and national estimates. Ten models were used to estimate the prevalence of asthma, 27 models estimated the burden of asthma – including, health care service utilisation, disability-adjusted life years, mortality and direct and indirect costs of asthma – and 14 models estimated both the prevalence and burden of asthma. Logistic and linear regression models were most widely used for national estimates. Different versions of the DisMod-MR- Bayesian meta-regression models and Cause Of Death Ensemble model (CODEm) were predominantly used for global, regional and national estimates. Most models suffered from a number of methodological limitations – in particular, poor reporting, insufficient quality and lack of reproducibility.

Conclusions

Whilst global, regional and national estimates of asthma prevalence and burden continue to inform health policy and investment decisions on asthma, most models used to derive these estimates lack the required reproducibility. There is a need for better-constructed models for estimating and projecting the prevalence and disease burden of asthma and a related need for better reporting of models, and making data and code available to facilitate replication.

Spatiotemporal characteristics of asthma emergency department presentations in diverse geographical and climatic regions, Queensland, Australia

OBJECTIVE

Sudden acute episodes of asthma exacerbation are often treated by hospital EDs. It is hypothesised that determinants of acute asthma would differ across geographic regions. The objective of the present study was to detail seasonality, trends and spatiotemporal patterns of asthma ED presentations across Queensland (QLD), Australia, a state covering 1.8 million square kilometres, spanning multiple climates.

METHODS

Six years of routinely collected data (2012 to 2017) from 28 major QLD public hospitals were extracted from Queensland Health's Emergency Data Collection. The dataset contained individual, episode-level asthma-like diagnoses of ED presentations. Seasonality and trends of acute asthma were assessed through multiplicative time-series analysis.

RESULTS

The study consisted of 2192 days with a total of 65 012 asthma ED presentations in QLD. The 6-year average daily incidence rate was 270 asthma ED presentations per 100 000 population. The highest morbidity of asthma ED presentations occurred during the southern hemisphere winter months. Children showed a higher incidence rate compared to adults with males experiencing a higher incidence compared to females up until the age of 13, after which an inversion was observed persisting through adulthood. Seasonality of asthma ED presentations differed with latitude across QLD.

CONCLUSION

Asthma-related ED presentations exhibit spatiotemporal variation across QLD, which appears to be related to climate. Furthermore, aeroallergens and respiratory viruses may be responsible for asthma ED peaks outside the winter period. Socioeconomic status may influence asthma ED presentation rates between regions. This knowledge can guide ongoing management and assist public health policy response.

Emergency department visits and hospitalisations for asthma, COPD and respiratory tract infections: what is the role of respiratory viruses, and return to school in September, January and March?

Background

Asthma exacerbations increase in September coinciding with children returning to school. The aim of this study was to investigate whether this occurs 1) for COPD and respiratory tract infections (RTIs); 2) after school resumes in January and March; and 3) identify which viruses may be responsible.

Methods

Emergency department (ED) visits and admissions for asthma, COPD and RTIs and the prevalence of viruses in Ontario, Canada were analysed daily between 2003 and 2013. ED visits and admissions were provided by the Canadian Institute for Health Information. Viral prevalence was obtained from the Centre for Immunisation and Respiratory Infectious Diseases.

Results

ED visits and admissions rates demonstrated a biphasic pattern. Lowest rates occurred in July and August and the highest rates in September for asthma, and after December for COPD and RTI. The increase in rates for 30 days before and after school return in September was greatest for children with asthma <15 years (2.4–2.6×). Event rates fell after school return in January for all three conditions ranging from 10–25%, and no change followed March break for asthma and COPD. Human rhinovirus was prevalent in summer with a modest relationship to asthma rates in September. The prevalence of respiratory syncytial virus, influenza A and coronavirus was associated with sustained event rates for COPD and RTIs.

Conclusions

Asthma, COPD and RTIs increase in September but do not occur after return to school in January and March. Human rhinovirus is associated with ED visits and admissions only in September.

Asthma, COPD and RTIs increase in September but do not occur after return to school in January and March. Human RV is associated with ED visits and admissions only in September.https://bit.ly/3jEy168

Asthma exacerbation prediction: recent insights

PURPOSE OF REVIEW

Asthma attacks are frequent in children with asthma and can lead to significant adverse outcomes including time off school, hospital admission and death. Identifying children at risk of an asthma attack affords the opportunity to prevent attacks and improve outcomes.

RECENT FINDINGS

Clinical features, patient behaviours and characteristics, physiological factors, environmental data and biomarkers are all associated with asthma attacks and can be used in asthma exacerbation prediction models. Recent studies have better characterized children at risk of an attack: history of a severe exacerbation in the previous 12 months, poor adherence and current poor control are important features which should alert healthcare professionals to the need for remedial action. There is increasing interest in the use of biomarkers. A number of novel biomarkers, including patterns of volatile organic compounds in exhaled breath, show promise. Biomarkers are likely to be of greatest utility if measured frequently and combined with other measures. To date, most prediction models are based on epidemiological data and population-based risk. The use of digital technology affords the opportunity to collect large amounts of real-time data, including clinical and physiological measurements and combine these with environmental data to develop personal risk scores. These developments need to be matched by changes in clinical guidelines away from a focus on current asthma control and stepwise escalation in drug therapy towards inclusion of personal risk scores and tailored management strategies including nonpharmacological approaches.

SUMMARY

There have been significant steps towards personalized prediction models of asthma attacks. The utility of such models needs to be tested in the ability not only to predict attacks but also to reduce them.

Evaluating the Risk of Epidemic Thunderstorm Asthma: Lessons from Australia

Epidemic thunderstorm asthma (ETA) is an emerging public health threat in Australia, highlighted by the 2016 event in Melbourne, Victoria, that overwhelmed health services and caused loss of life. However, there is limited understanding of the regional variations in risk. We evaluated the public health risk of ETA in the nearby state of Tasmania by quantifying the frequency of potential ETA episodes and applying a standardized natural disaster risk assessment framework. Using a case⁻control approach, we analyzed emergency presentations in Tasmania's public hospitals from 2002 to 2017. Cases were defined as days when asthma presentations exceeded four standard deviations from the mean, and controls as days when asthma presentations were less than one standard deviation from the mean. Four controls were randomly selected for each case. Independently, a meteorologist identified the dates of potential high-risk thunderstorm events. No case days coincided with thunderstorms during the study period. ETA was assessed as a very low risk to the Tasmanian population, with these findings informing risk prioritization and resource allocation. This approach may be scaled and applied in other settings to determine local ETA risk. Furthermore, the identification of hazards using this method allows for critical analysis of existing public health systems.

Retrospective observational study of emergency department syndromic surveillance data during air pollution episodes across London and Paris in 2014

INTRODUCTION

Poor air quality (AQ) is a global public health issue and AQ events can span across countries. Using emergency department (ED) syndromic surveillance from England and France, we describe changes in human health indicators during periods of particularly poor AQ in London and Paris during 2014.

METHODS

Using daily AQ data for 2014, we identified three periods of poor AQ affecting both London and Paris. Anonymised near real-time ED attendance syndromic surveillance data from EDs across England and France were used to monitor the health impact of poor AQ.Using the routine English syndromic surveillance detection methods, increases in selected ED syndromic indicators (asthma, difficulty breathing and myocardial ischaemia), in total and by age, were identified and compared with periods of poor AQ in each city. Retrospective Wilcoxon-Mann-Whitney tests were used to identify significant increases in ED attendance data on days with (and up to 3 days following) poor AQ.

RESULTS

Almost 1.5 million ED attendances were recorded during the study period (27 February 2014 to 1 October 2014). Significant increases in ED attendances for asthma were identified around periods of poor AQ in both cities, especially in children (aged 0-14 years). Some variation was seen in Paris with a rapid increase during the first AQ period in asthma attendances among children (aged 0-14 years), whereas during the second period the increase was greater in adults.

DISCUSSION

This work demonstrates the public health value of syndromic surveillance during air pollution incidents. There is potential for further cross-border harmonisation to provide Europe-wide early alerting to health impacts and improve future public health messaging to healthcare services to provide warning of increases in demand.

Seasonal asthma in Melbourne, Australia, and some observations on the occurrence of thunderstorm asthma and its predictability

We examine the seasonality of asthma-related hospital admissions in Melbourne, Australia, in particular the contribution and predictability of episodic thunderstorm asthma. Using a time-series ecological approach based on asthma admissions to Melbourne metropolitan hospitals, we identified seasonal peaks in asthma admissions that were centred in late February, June and mid-November. These peaks were most likely due to the return to school, winter viral infections and seasonal allergies, respectively. We performed non-linear statistical regression to predict daily admission rates as functions of the seasonal cycle, weather conditions, reported thunderstorms, pollen counts and air quality. Important predictor variables were the seasonal cycle and mean relative humidity in the preceding two weeks, with higher humidity associated with higher asthma admissions. Although various attempts were made to model asthma admissions, none of the models explained substantially more variation above that associated with the annual cycle. We also identified a list of high asthma admissions days (HAADs). Most HAADs fell in the late-February return-to-school peak and the November allergy peak, with the latter containing the greatest number of daily admissions. Many HAADs in the spring allergy peak may represent episodes of thunderstorm asthma, as they were associated with rainfall, thunderstorms, high ambient grass pollen levels and high humidity, a finding that suggests thunderstorm asthma is a recurrent phenomenon in Melbourne that occurs roughly once per five years. The rarity of thunderstorm asthma events makes prediction challenging, underscoring the importance of maintaining high standards of asthma management, both for patients and health professionals, especially during late spring and early summer.

Interventions for autumn exacerbations of asthma in children

BACKGROUND

Asthma exacerbations in school-aged children peak in autumn, shortly after children return to school following the summer holiday. This might reflect a combination of risk factors, including poor treatment adherence, increased allergen and viral exposure, and altered immune tolerance. Since this peak is predictable, interventions targeting modifiable risk factors might reduce exacerbation-associated morbidity and strain upon health resources. The peak occurs in September in the Northern Hemisphere and in February in the Southern Hemisphere.

OBJECTIVES

To assess the effects of pharmacotherapy and behavioural interventions enacted in anticipation of school return during autumn that are designed to reduce asthma exacerbations in children during this period.

SEARCH METHODS

We searched the Cochrane Airways Group Trials Register, ClinicalTrials.gov, the World Health Organization International Clinical Trials Registry Platform, reference lists of primary studies and existing reviews, and manufacturers' trial registries (Merck, Novartis and Ono Parmaceuticals). We searched databases from their inception to 1 December 2017, and imposed no restriction on language of publication.

SELECTION CRITERIA

We included all randomised controlled trials comparing interventions aimed specifically at reducing autumn exacerbations with usual care, (no systematic change in management in preparation for school return). We included studies providing data on children aged 18 years or younger.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane. Two review authors independently screened records identified by the search and then extracted data and assessed bias for trials meeting the inclusion criteria. A third review author checked for accuracy and mediated consensus on disagreements. The primary outcome was proportion of children experiencing one or more asthma exacerbations requiring hospitalisation or oral corticosteroids during the autumn period.

MAIN RESULTS

Our searches returned 546 trials, of which five met our inclusion criteria. These studies randomised 14,252 children to receive either an intervention or usual care. All studies were conducted in the Northern Hemisphere. Three interventions used a leukotriene receptor antagonist, one used omalizumab or a boost of inhaled corticosteroids, and the largest study, (12,179 children), used a medication reminder letter. Whilst the risk of bias within individual studies was generally low, we downgraded the evidence quality due to imprecision associated with low participant numbers, poor consistency between studies, and indirect outcome ascertainment.A US study of 513 children with mild/severe asthma and allergic sensitisation was the only study to provide data for our primary outcome. In this study, the proportion of participants experiencing an exacerbation requiring oral corticosteroids or hospital admission in the 90 days after school return was significantly reduced to 11.3% in those receiving omalizumab compared to 21.0% in those receiving placebo (odds ratio 0.48, 95% confidence interval 0.25 to 0.92, moderate-quality evidence). The remaining studies used alternative exacerbation definitions. When data from two leukotriene receptor antagonist studies with comparable outcomes were combined in a random-effects model, there was no evidence of an effect upon exacerbations. There was no evidence that a seasonal medication reminder letter decreased unscheduled contacts for a respiratory diagnosis between September and December.Four studies recorded adverse events. There was no evidence that the proportion of participants experiencing at least one adverse event differed between intervention and usual care groups. Lack of data prevented planned subgroup and sensitivity analyses.

AUTHORS' CONCLUSIONS

Seasonal omalizumab treatment from four to six weeks before school return might reduce autumn asthma exacerbations. We found no evidence that this strategy is associated with increased adverse effects other than injection site pain, but it is costly. There were no data upon which to judge the effect of this or other seasonal interventions on asthma control, quality of life, or asthma-related death. In future studies definitions of exacerbations should be provided, and standardised where possible. To investigate possible differential effects according to subgroup, participants in future trials should be well characterised with respect to baseline asthma severity and exacerbation history in addition to age and gender.

Asthma hospitalisation trends from 2010 to 2015: variation among rural and metropolitan Australians

Background

Asthma remains a leading cause of illness, where primary care can assist to reduce hospitalisations through prevention, controlling acute episodes, and overall management of asthma. In Victoria, Asthma hospitalisations were as high as 3.1 hospitalisations per 1000 population in 1993–94. The primary aims of this study are to: determine if changes in asthma hospitalisations have occurred between 2010 and 2015; determine the key factors that impact asthma hospitalisation over time; and verify whether rural and urban asthma hospitalisations are disparate. A secondary aim of the study is to compare 2010–2015 results with asthma data prior to 2010.

Methods

Hospital separation data from 1 July 2010 to 30 June 2015 were obtained through the Victorian Admitted Episodes Dataset and other agencies. Data included sex, age, Local Government Area, private or public patient, length of stay, and type of discharge. Asthma and predictor variables were analysed according to hospital separation rates after adjusting for smoking and sex. Hierarchical multiple regression examined the association between asthma and predictor variables.

Results

During the study period, 49,529 asthma hospital separations occurred, of which 77.5% were in metropolitan hospitals, 55.4% hospital separations were aged 0–14 years, and 21.7% were privately funded. State-wide hospital separations were 1.85 per 1000 population and were consistently higher in metropolitan compared to rural areas (1.93 vs 1.64 per 1000 population). When data among metropolitan adults aged 15 and over were analysed, an increase in the proportion of smokers in the population was reflected by an increase in the number of hospital separations (Adj OR 1.035). Further, among rural and metropolitan children aged 0–14 the only predictor of asthma hospital separations was sex, where metropolitan male children had higher odds of separation than metropolitan females of the same age (Adj OR 4.297). There was no statistically meaningful difference for separation rates between males and females in rural areas.

Conclusions

We demonstrated a higher overall hospital separation rate in metropolitan Victoria. For children in metropolitan areas, males were hospitalised at higher rates than females, while the inverse was demonstrated for children residing in rural areas. Therefore, optimising asthma management requires consideration of the patient’s age, gender and residential context. Primary health care may play a leading role in increasing health literacy for patients in order to improve self-management and health-seeking behaviour.

School attendance and daily respiratory symptoms in children: influence of moisture damage

We investigated the effect of weekends and school holidays on the daily frequency and severity of respiratory and other symptoms among children attending schools with (index) or without (reference) moisture damage in Spain, the Netherlands, and Finland. Throughout 1 year, parents of 419 children with a respiratory condition attending index (n=15) or reference (n=10) primary schools completed three symptom diaries. We assessed associations between lower respiratory tract, upper respiratory tract or allergy, and other symptom scores and school day, weekend, or summer holiday using mixed regression models stratified by country and moisture damage. We evaluated interactions between moisture damage and type of day. We combined country-specific estimates (incidence rate ratios [IRRs] and 95% confidence interval [CI]) in meta-analyses. Symptom scores were lower during weekends and holiday. Lower respiratory tract symptoms were statistically significantly less common during holiday with strongest effect in index schools (IRR=0.7; CI=0.6-0.8). Reporting of other symptoms was more reduced during holiday in index (IRR=0.6; CI=0.4-0.9) than in reference (IRR=0.95; CI=0.8-1.2) schools (interaction P<.01). In conclusion, symptoms were less frequent and/or severe during summer holiday and weekends. This pattern was stronger among children attending moisture-damaged schools, suggesting potential improvement in moisture damage-related symptoms during school breaks.

The Annual September Peak in Asthma Exacerbation Rates. Still a Reality?

RATIONALE

Recent research suggests that the asthma epidemic observed in the 1980s and 1990s has stabilized. Changing trends in asthma may have an impact on the well-reported global phenomenon of the "asthma September peak." The 38th week of the year has been identified as the peak time for asthma exacerbations among children.

OBJECTIVES

The purposes of this study were to examine the longitudinal trend of the September peak and to see if it changed over time, differed by age groups, or varied across different geographical regions.

METHODS

Monthly rates of asthma emergency department (ED) and physician outpatient visits were calculated using data provided by the Ontario Asthma Surveillance Information System from 2003 to 2013 for patients of all ages. The Ontario Asthma Surveillance Information System is a population-based surveillance system with over 2 million individuals with asthma. Age-specific rates were calculated using the prevalent asthma population-asthma individuals with at least one health service claim for asthma in the respective year-as the denominator. Rates were stratified by age group and region of residence. Spatial relationships within the province were tested to examine if the September peak was more prominent in certain regions of Ontario.

MEASUREMENTS AND MAIN RESULTS

The highest September peak in ED visits was observed in 2005 for children aged 0-4 years and 5-9 years (18.35 and 8.11 per 1,000 asthma prevalence, respectively). The rate of asthma ED visits of all children was consistently highest in September; however, the spike became marginally less pronounced over time. Since 2005, there has been a 51.7% decrease in the September asthma ED visit rate for all age groups. Monthly physician visits for all age groups usually peaked in October, roughly 4 weeks following the peak in ED visits. Analysis by residence showed that rates throughout Ontario were higher in September than in other months, suggesting that the spike was widespread rather than localized.

CONCLUSIONS

While the magnitude of the September peak has decreased over time, the asthma ED visit rate remains significantly higher in September than in other months. Physician visits are also highest in the fall. These findings stress the importance of empowering children and families to maintain good asthma control throughout the year, including hand washing, to minimize respiratory viral infections in September.

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

BACKGROUND

Asthma is a highly prevalent chronic inflammatory disease characterised by reversible airflow obstruction and hyperreactivity and inflammation of the airways. Factors that cause and/or trigger asthma attacks include host-related factors (genetic predisposition, obesity and sex) and environmental factors (allergens, infections, occupational sensitisation, smoking status, pollution and diet).

OBJECTIVE

To describe the epidemiology of asthma exacerbations (AEs) in the Basque Country and to explore its relationship with potentially associated environmental variables. We studied a total of 31,579 emergency department (ED) visits and 28,189 hospitalisations due to asthma. We describe the trends, incidence, seasonality and the influence of age and sex, as well as of exposure to NO2 , CO, PM, O3 , and pollen, temperature, relative humidity and flu status. We calculated the Pearson's R correlation coefficient for the study variables.

RESULTS

The incidence was 486 and 88.9 cases per 100,000 people for ED visits and hospitalisations, respectively. Slightly over half (53.5%) of the ED cases were male, while females represented 62.6% of the hospital admissions. Hospitalisations are tending to decrease in children and increase in over 64-year-olds. Peaks in cases occur at the beginning of autumn in children and in winter in adults. AEs were correlated positively with exposure to NO2 , CO and to the influenza virus and negatively with temperature and exposure to O3 . These relationships vary, however, with age and season.

CONCLUSIONS AND CLINICAL RELEVANCE

Rates of hospitalisation for AEs and trends in these rates over time are different in adults and children with the patterns varying by sex, season and environmental conditions.

The school environment and asthma in childhood

In this article, we discuss the relationship between environmental exposures within the school environment and pediatric asthma morbidity. This article will conclude by reviewing novel school based asthma education and therapeutic programs and environmental interventions designed to help mitigate pediatric asthma morbidity.

The association between seasonal asthma exacerbations and viral respiratory infections in a pediatric population receiving inhaled corticosteroid therapy with or without long-acting beta-adrenoceptor agonist: a randomized study

BACKGROUND

A seasonal peak in asthma exacerbations in the fall has previously been reported. The association between fall exacerbations and viral respiratory tract infections (RTI) remains uncertain.

OBJECTIVE

To investigate the number of fall exacerbations and the incidence of RTIs in a pediatric asthmatic population using an at-home mucus collection methodology.

METHODS

This was a 16-week, multicenter, randomized, double-blind, parallel-group exploratory study. Children, 4-11 years of age with a clinical diagnosis of asthma requiring use of an inhaled corticosteroid, a morning peak expiratory flow ≥70% predicted and a history of ≥1 asthma exacerbation during the previous respiratory viral season were eligible for enrollment. Subjects were randomized (1:1) to receive fluticasone propionate/salmeterol (FP/SAL) 100/50 mcg or FP 100 mcg prior to starting school. Subjects collected mucus samples using an at-home kit when they experienced respiratory symptoms. Mucus samples obtained during symptomatic periods were analyzed for common respiratory viruses by multiplex polymerase chain reaction. The number of exacerbations requiring systemic corticosteroids was recorded.

RESULTS

In total, 339 (FP/SAL, n = 171; FP, n = 168) subjects were randomized and included in the intent-to-treat population; 292 (86%) completed the study. Of the 537 mucus samples collected, 64% tested positive for viruses, but only 6% of positive samples were associated with an asthma exacerbation. Exacerbations were infrequent, with only 41 subjects reporting 49 exacerbations in total. Adverse events were reported in 66% of subjects.

CONCLUSIONS

In a susceptible population, the fall asthma exacerbation rates in children were low despite frequent detection of viral RTIs. NCT01192178; GSK ID: ADA113872.

Absence of back to school peaks in human rhinovirus detections and respiratory symptoms in a cohort of children with asthma

Much of what is known about the seasonality of human rhinovirus (hRV) infections has been learned from the study of acute asthma exacerbations presenting to emergency care, including those among children at the start of the school term. Much less is known about the patterns of hRVs in the community. In this study, viruses and day-to-day symptoms of asthma and colds were monitored twice weekly in 67 children with asthma aged 5-12 years, over a 15 month period in Sydney, Australia. Overall hRV was detected in 314/1232 (25.5%) of nasal wash samples and 142/1231 (11.5%) of exhaled breath samples; of these, 231 and 24 respectively were genotyped. HRVs were detected with similar prevalence rate throughout the year, including no peak in hRV prevalence following return to school. No peaks were seen in asthma and cold symptoms using twice-weekly diary records. However, over the same period in the community, there were peaks in asthma emergency visits both at a large local hospital and in state-wide hospitalizations, following both return to school (February) and in late autumn (May) in children of the same age. This study suggests that hRV infections are common throughout the year among children, and differences in virus prevalence alone may not account for peaks in asthma symptoms.

Air pollution events from forest fires and emergency department attendances in Sydney, Australia 1996-2007: a case-crossover analysis

BACKGROUND

Severe air pollution generated by forest fires is becoming an increasingly frequent public health management problem. We measured the association between forest fire smoke events and hospital emergency department (ED) attendances in Sydney from 1996-2007.

METHODS

A smoke event occurred when forest fires caused the daily citywide average concentration of particulate matter (PM10 or PM2.5) to exceed the 99th percentile of the entire study period. We used a time-stratified case-crossover design and conditional logistic regression models adjusted for meteorology, influenza epidemics, and holidays to estimate odds ratios (OR) and 95% confidence intervals (CI) for ED attendances on event days compared with non-event days for all non-trauma ED attendances and selected cardiorespiratory conditions.

RESULTS

The 46 validated fire smoke event days during the study period were associated with same day increases in ED attendances for all non-trauma conditions (1.03, 95% CI 1.02, 1.04), respiratory conditions (OR 1.07, 95% CI 1.04, 1.10), asthma (OR 1.23, 95% CI 1.15, 1.30), and chronic obstructive pulmonary disease (OR 1.12, 95% CI 1.02, 1.24). Positive associations persisted for one to three days after the event. Ischaemic heart disease ED attendances were increased at a lag of two days (OR 1.07, 95% CI 1.01, 1.15) while arrhythmias had an inverse association at a lag of two days (OR 0.91, 95% CI 0.83, 0.99). In age-specific analyses, no associations present in children less than 15 years of age for any outcome, although a non-significant trend towards a positive association was seen with childhood asthma. A further association between smoke event and heart failure attendances was present for the 15-65 year age group, but not older adults at a lag of two days (OR 1.37 95% CI 1.05, 1.78).

CONCLUSION

Smoke events were associated with an immediate increase in presentations for respiratory conditions and a lagged increase in attendances for ischaemic heart disease and heart failure. Respiratory impacts were either absent or considerably attenuated in those <15 years. Similar to previous studies we found inconsistent associations between fire smoke and cardiovascular diseases. Better characterisation of the spectrum of population health risks is needed to guide public heath responses to severe smoke events as this exposure becomes increasingly common with global climate change.

Seasonality of asthma: a retrospective population study

OBJECTIVES

Seasonal variations in asthma are widely recognized, with the highest incidence during September. This retrospective population study aimed to investigate whether this holds true in a large group of asthmatic children in primary care and to assess the impact of age, gender, urban/rural living, and population sector.

METHODS

The key study outcomes were the diagnosis of asthma exacerbations and asthma medication prescriptions, recorded by family physicians during 2005 to 2009. These were analyzed by "week of diagnosis" in Clalit Health Services' electronic medical record database. Regression models were built to assess relative strength of secular trends, seasonality, and age-group in explaining the incidence of asthma exacerbations.

RESULTS

A total of 919,873 children aged 2 to 15 years were identified. Of these, 82,234 (8.9%) were asthmatic, 61.6% boys and 38.4% girls; 49.1% aged 2 to 5 years, 24.1% 6 to 9 years, and 26.8% 10 to 15 years. We observed a 2.01-fold increase in pediatric asthma exacerbations and 2.28-fold increase in prescriptions of asthma bronchodilator medications during September (weeks 37-39 vs weeks 34-36) compared with August. The association between the opening of school and the incidence of asthma-related visits to the primary care physician was greatest in children aged 2 to 5 years (odds ratio, 2.15) and 6 to 11 years (1.90-fold). Adolescents (age 12-15 years) had a lesser peak (1.81-fold). In late fall there was a second rise, lasting with fluctuations throughout winter, with a trough in summer.

CONCLUSIONS

Returning to school after summer is strongly associated with an increased risk for asthma exacerbations and unscheduled visits to the primary care physician.

Air pollution from bushfires and their association with hospital admissions in Sydney, Newcastle and Wollongong, Australia 1994-2007

OBJECTIVE

We examined the association between validated bushfire smoke pollution events and hospital admissions in three eastern Australian cities from 1994 to 2007.

METHODS

Smoke events were defined as days on which bushfire smoke caused the 24-hour citywide average concentration of airborne particles to exceed the 99(th) percentile of the daily distribution for the study period. We used a time-stratified case-crossover design to assess the association between smoke events and hospital admissions. Odds ratios (OR) and 95% confidence intervals (CI) were estimated for cardiovascular and respiratory conditions on event days compared with non-event days. Models were adjusted for daily meteorology, influenza epidemics and holidays.

RESULTS

Smoke events occurred on 58 days in Sydney (population: 3,862,000), 33 days in Wollongong (population: 406,000) and 50 days in Newcastle (population: 278,000). In Sydney, events were associated with a 6% (OR=1.06, 95%CI=1.02-1.09) same day increase in respiratory hospital admissions. Same day chronic obstructive pulmonary disease admissions increased 13% (OR=1.13, 95%CI=1.05-1.22) and asthma admissions by 12% (OR=1.12, 95%CI=1.05-1.19). Events were also associated with increased admissions for respiratory conditions in Newcastle and Wollongong.

CONCLUSIONS

Smoke events were associated with increased hospital admissions for respiratory but not cardiovascular conditions. Large populations are needed to assess the impacts of brief exposures. Implications : Public health impacts from bushfire pollution events are likely to increase in association with a warming climate and more frequent severe fire weather.

The impact of heat on mortality and morbidity in the Greater Metropolitan Sydney Region: a case crossover analysis

BACKGROUND

This study examined the association between unusually high temperature and daily mortality (1997-2007) and hospital admissions (1997-2010) in the Sydney Greater Metropolitan Region (GMR) to assist in the development of targeted health programs designed to minimise the public health impact of extreme heat.

METHODS

Sydney GMR was categorized into five climate zones. Heat-events were defined as severe or extreme. Using a time-stratified case-crossover design with a conditional logistic regression model we adjusted for influenza epidemics, public holidays, and climate zone. Odds ratios (OR) and 95% confidence intervals were estimated for associations between daily mortality and hospital admissions with heat-event days compared to non-heat event days for single and three day heat-events.

RESULTS

All-cause mortality overall had similar magnitude associations with single day and three day extreme and severe events as did all cardiovascular mortality. Respiratory mortality was associated with single day and three day severe events (95th percentile, lag0: OR = 1.14; 95%CI: 1.04 to 1.24). Diabetes mortality had similar magnitude associations with single day and three day severe events (95th percentile, lag0: OR = 1.22; 95%CI: 1.03 to 1.46) but was not associated with extreme events. Hospital admissions for heat related injuries, dehydration, and other fluid disorders were associated with single day and three day extreme and severe events. Contrary to our findings for mortality, we found inconsistent and sometimes inverse associations for extreme and severe events with cardiovascular disease and respiratory disease hospital admissions. Controlling for air pollutants did not influence the mortality associations but reduced the magnitude of the associations with hospital admissions particularly for ozone and respiratory disease.

CONCLUSIONS

Single and three day events of unusually high temperatures in Sydney are associated with similar magnitude increases in mortality and hospital admissions. The trend towards an inverse association between cardio-vascular admissions and heat-events and the strong positive association between cardio-vascular mortality and heat-events suggests these events may lead to a rapid deterioration in persons with existing cardio-vascular disease resulting in death. To reduce the adverse effects of high temperatures over multiple days, and less extreme but more frequent temperatures over single days, targeted public health messages are critical.

The Christmas season as a risk factor for chronic obstructive pulmonary disease exacerbations

BACKGROUND

Epidemics of hospitalization for chronic obstructive pulmonary disease (COPD) occur annually during the Christmas holidays, and COPD exacerbations commonly coincide with respiratory viral infections.

OBJECTIVE

To compare the incidence and determinants of COPD exacerbations occurring between the Christmas holiday period and the remainder of the winter season.

METHODS

Seventy-one subjects with COPD of mixed severity faxed daily symptom diaries to a computer monitoring system from December 1, 2006, to April 30, 2007. Possible exacerbations prompted a home visit for assessment, spirometry and specimen collection for virological testing.

RESULTS

Study subjects submitted a total of 95.4% of possible daily symptom diary sheets by fax. Of 114 possible COPD exacerbations detected using the faxed diaries, 110 met the Anthonisen criteria for true exacerbations. A total of 47 exacerbations (mean 6.7/week) occurred during the Christmas holiday period, while 63 exacerbations (mean 4.3/week) occurred during the remainder of winter. Of the Christmas period exacerbations and of those in the balance of winter, 21 (44%) and 20 (32%), respectively, coincided with respiratory viral infections.

CONCLUSIONS

The incidence of COPD exacerbations during the Christmas period was greater than during the rest of winter in 2006/2007 and peaked immediately before Christmas - in contrast to hospital presentation for COPD, which peaked during the Christmas week. No clear role of respiratory viral infections in the increased rate of exacerbations during the Christmas period was established in the present study. COPD patients were highly compliant with daily symptom reporting using faxed daily diaries, which permitted nearly complete detection of all exacerbations that occurred at incidence.

A modern miasma hypothesis and back-to-school asthma exacerbations

A sudden increase in the rate of asthma exacerbations has been observed among young children in many countries 2-3 weeks after their return-to-school following the summer holidays. These exacerbations are frequently associated with human rhinovirus (hRV) infections, with possible interactions with allergen sensitisation, allergen exposure and medication use. It was originally proposed that the sudden increase resulted from new strains of respiratory viruses acquired during the holidays spreading rapidly on return to school. While there is compelling evidence implicating hRV in these exacerbations, recent observations on virus transmission, infection patterns and immune responses to both viruses and allergens have led us to propose an additional hypothesis for this increase in exacerbations. We propose that classrooms typically provide persistent exposure to a mixture of airborne viruses, viral proteins, endotoxin, community allergens and other human-derived aerosols - a modern miasma. During the preceding school term, this exposure establishes and maintains a level of immune tolerance and herd immunity, which then declines during the two-month holidays due to lack of such exposure, creating a transitory window of susceptibility to viral infections and asthma. The return to school re-establishes exposure to these aerosols resulting in an acceleration of exacerbations, until the tolerance and herd immunity are re-established. Thus, the peak in return-to-school asthma is more a function of a transitory increase in susceptibility due to a temporary lack of this complex exposure, than it is to novel, locally endemic strains of hRV.

The Back to School asthma study: the effect of montelukast on asthma burden when initiated prophylactically at the start of the school year

BACKGROUND

Pediatric asthma hospitalizations peak in early autumn.

OBJECTIVE

To determine the effectiveness of montelukast therapy in reducing the asthma burden in children when initiated prophylactically on school return.

METHODS

This was a randomized, multicenter, double-blind, placebo-controlled study of children with asthma aged 6 to 14 years. No minimum asthma symptoms were required, and patients could continue inhaled corticosteroid (ICS) use. Montelukast, 5 mg, chewable tablet (n = 580) or matching placebo (n = 582) was taken the night before the first day of school and nightly thereafter for 8 weeks. The primary end point was the percentage of days with worsening asthma, defined by one of the following: (1) increased beta-agonist use, (2) increased daytime symptoms, (3) awake "all night," (4) oral corticosteroid rescue or increased ICS use for worsening asthma, or (5) unanticipated health care utilization.

RESULTS

The reduction in the percentage of days with worsening asthma with montelukast use versus placebo use was not significant (24.3% vs 27.2%, P = .07). Prespecified subgroup analyses demonstrated nonsignificant trends favoring montelukast therapy in boys and older children but no effect by baseline ICS use or history of cold symptoms. Post hoc analysis showed a nonsignificant trend favoring montelukast therapy in reducing worsening asthma days for children commencing school after August 15 compared with earlier commencement.

CONCLUSIONS

Montelukast use was not significantly more effective than was placebo use in reducing the percentage of days with worsening asthma when initiated at the start of the school year. The effect of montelukast treatment on the fall peak in asthma burden may depend on sex, age, and the date of school return.

Effects of bushfire smoke on daily mortality and hospital admissions in Sydney, Australia

BACKGROUND

Little research has investigated the health effects of particulate exposure from bushfires (also called wildfires, biomass fires, or vegetation fires), and these exposures are likely to increase, for several reasons. We investigated associations of daily mortality and hospital admissions with bushfire-derived particulates, compared with particulates from urban sources in Sydney, Australia from 1994 through 2002.

METHODS

On days with the highest particulate matter (PM)10 concentrations, we assumed PM10 was due primarily to bushfires. We calculated the contribution of bushfire PM10 on these days by subtracting the background PM10 concentration estimated from surrounding days. We assumed PM10 on the remaining days was from usual urban sources. We implemented a Poisson model, with a bootstrap-based methodology, to select optimum smoothed covariate functions, and we estimated the effects of bushfire PM10 and urban PM10, lagged up to 3 days.

RESULTS

We identified 32 days with extreme PM10 concentrations due to bushfires or vegetation-reduction burns. Although bushfire PM10 was consistently associated with respiratory hospital admissions, we found no consistent associations with cardiovascular admissions or with mortality. A 10 microg/m increase in bushfire PM10 was associated with a 1.24% (95% confidence interval = 0.22% to 2.27%) increase in all respiratory disease admissions (at lag 0), a 3.80% (1.40% to 6.26%) increase in chronic obstructive pulmonary disease admissions (at lag 2), and a 5.02% (1.77% to 8.37%) increase in adult asthma admissions (at lag 0). Urban PM10 was associated with all-cause and cardiovascular mortality, as well as with cardiovascular and respiratory hospital admission, and these associations were not influenced by days with extreme PM10 concentrations.

CONCLUSIONS

PM10 from bushfires is associated primarily with respiratory morbidity, while PM10 from urban sources is associated with cardiorespiratory mortality and morbidity.

The September epidemic of asthma in Israel

BACKGROUND

The seasonality of asthma morbidity is well recognized. A peak in asthma exacerbations in September has been noted for years at our center.

OBJECTIVE

To examine the hypothesis that the increment in asthma exacerbations in September is influenced by the beginning of the kindergarten and school year.

METHODS

The monthly admission rate for asthma in patients of different ages was retrospectively evaluated in seven hospitals from various areas in Israel from January 2003 to December 2005.

RESULTS

Of the 408,242 hospital admissions during the study period, 8,011 were for asthma exacerbations: 4,091 in adults (1.3% of adult admissions) and 3,920 in children (3.8% of pediatric admissions). The asthma admission rates varied considerably throughout the year, with a peak of 4% of total admissions in the winter months and a nadir of 2% in the summer months. September was unique for its particularly high rate of admissions for asthma attacks in children (6% of total admissions), especially toddlers and the school-age group. In adults there was a progressive increase in asthma admissions from September through December without a unique peak in September.

CONCLUSIONS

There is a characteristic increase in asthma exacerbations and admissions in September in the pediatric age group. This phenomenon might be explained by the increased exposure to respiratory viruses, to new allergen exposure in school or kindergarten, increased emotional stress due to start of the new school year, or poor compliance and withdrawal of treatment during the summer. Clinicians should consider administering prophylactic treatment for asthma in children before onset of the school year.

Seasonal patterns in health care use and pharmaceutical claims for asthma prescriptions for preschool- and school-aged children

BACKGROUND

In children, hospitalization for asthma is reported to have a distinct seasonal pattern with peaks coincident with the start of school. Although guidelines indicate that asthma controller medications should be used daily, there is limited information on actual seasonal patterns of medication use.

OBJECTIVE

To describe seasonal patterns of asthma-related health care use and asthma controller and reliever medication claims in children.

METHODS

An ecological analysis was conducted of data collected from records for children aged 2 to 12 years from 2002 through 2004 from an automated research database of insurance claims from a large US health care plan. Seasonal patterns for health care use and estimates of prescription asthma controller and reliever use were determined for preschool-aged children (aged 2-5 years) and school-aged children (aged 6-12 years). Rates were constructed by week; deviations from annual mean rates were used to determine peaks in use. Results were confirmed using Poisson regression models, modeling for rates within age group, with factors for week, year, and regions.

RESULTS

Emergency department and outpatient visits and hospitalizations were lowest during summer; rates increased beginning in September, peaking in October or November. Asthma controller and reliever medication claims increased beginning in September, peaking in December. Rates also were elevated in February.

CONCLUSIONS

The data suggest that children who reduce their asthma medications during the summer do not resume taking medications until signs or symptoms of asthma worsen. The summer hiatus and other factors may contribute to seasonal increases in health care use and in asthma medication prescriptions, particularly in the fall.

Epidemiology of asthma exacerbations

Exacerbations of asthma sufficient to require urgent medical intervention are often, but not always, associated with viral infection, especially rhinovirus, with significant interaction with allergen sensitization and exposure. Seasonal patterns of exacerbations are seen especially in children, and may be aggravated by lack of adequate maintenance anti-inflammatory drug treatment during the high-risk viral season most well described in the Northern Hemisphere after school return in September. Age and sex differences in the epidemiology of exacerbations remain less than fully explained, but hormonal influences are demonstrable. Frequent exacerbations may be an indication of greater severity of disease, significant comorbidities, or poor compliance with therapy. Recognizing risk factors for exacerbations and implementing appropriate long-term management strategies coupled with improved compliance should reduce morbidity and mortality associated with asthma exacerbations.

Attenuation of the September epidemic of asthma exacerbations in children: a randomized, controlled trial of montelukast added to usual therapy

BACKGROUND

A recurring epidemic of asthma exacerbations in children occurs annually in September in North America when school resumes after summer vacation.

OBJECTIVE

Our goal was to determine whether montelukast, added to usual asthma therapy, would reduce days with worse asthma symptoms and unscheduled physician visits of children during the September epidemic.

PATIENTS AND METHODS

A total of 194 asthmatic children aged 2 to 14 years, stratified according to age group (2-5, 6-9, and 10-14 years) and gender, participated in a double-blind, randomized, placebo-controlled trial of the addition of montelukast to usual asthma therapy between September 1 and October 15, 2005.

RESULTS

Children randomly assigned to receive montelukast experienced a 53% reduction in days with worse asthma symptoms compared with placebo (3.9% vs 8.3%) and a 78% reduction in unscheduled physician visits for asthma (4 [montelukast] vs 18 [placebo] visits). The benefit of montelukast was seen both in those using and not using regular inhaled corticosteroids and among those reporting and not reporting colds during the trial. There were differences in efficacy according to age and gender. Boys aged 2 to 5 years showed greater benefit from montelukast (0.4% vs 8.8% days with worse asthma symptoms) than did older boys, whereas among girls the treatment effect was most evident in 10- to 14-year-olds (4.6% [montelukast] vs 17.0% [placebo]), with nonsignificant effects in younger girls.

CONCLUSIONS

Montelukast added to usual treatment reduced the risk of worsened asthma symptoms and unscheduled physician visits during the predictable annual September asthma epidemic. Treatment-effect differences observed between age and gender groups require additional investigation.

Increases in asthma hospital admissions associated with the end of the summer vacation for school-age children with asthma in two cities from England and Scotland

In school-age asthmatics, an increase in hospitalizations has been reported in early autumn. This increase in admissions is conjectured to be associated with the return back to school. In the UK schools in England complete their summer vacations 2 weeks later than in Scotland and so there should be a lag between the two countries in the increase in asthma episode. Daily hospital asthma admission data from Aberdeen (in Scotland) and Doncaster (in England) for the period July 23rd to October 8th for years 1999-2004 were included in the analysis. There are peaks in hospitalization after the return back to school for both Aberdeen and Doncaster with the peak for Doncaster appearing 2 weeks after Aberdeen. This study has demonstrated peaks in admissions in school-age children around the return back to school in two cities where different school return dates were reflected in a 2-week lag effect. These data therefore provide strong evidence that peaks in admissions are associated with the end of the summer holidays.