Seasonal Patterns of Asthma in Children and Adolescents Presenting at Emergency Departments in Korea

Comparison and review of international guidelines for treating asthma in children

Asthma, the most common chronic disease, is characterized by airway inflammation and airflow obstruction. The World Health Organization estimates that approximately 300 million people worldwide have asthma, 30% of whom are pediatric patients. Asthma is a major cause of morbidity that can lead to hospitalization or death in severe pediatric cases. Therefore, it is necessary to provide children with objective and reliable treatment according to consistent guidelines. Several institutes, such as the Global Institute for Asthma, National Heart, Lung, and Blood Institute, British Thoracic Society, Japanese Society of Pediatric Allergy and Clinical Immunology, and Korean Academy of Asthma, Allergy, and Clinical Immunology have published and revised asthma guidelines. However, since recommendations differ among them, confusion persists regarding drug therapy for pediatric asthma patients. Additionally, some guidelines have changed significantly in recent years. This review investigated the latest changes in each guideline, compared and analyzed the recommendations, and identified the international trends in pediatric asthma drug therapy. The findings of this review may aid determinations of the future direction of the Korean guidelines for childhood asthma.

Analysis of exacerbating factors of pediatric asthma before and after the COVID-19 pandemic

Purpose

The incidence of the existing respiratory virus and air pollutants had disappeared or decreased due to social distancing during the coronavirus disease 2019 (COVID-19) pandemic. Therefore, there was no increase in asthma exacerbations in 2020. This study aimed to analyze the emergency department (ED) visits of children and adolescent patients with asthma before and after the COVID-19 outbreak and examine the effects of respiratory virus infection and air pollutants.

Methods

This study included pediatric and adolescent patients with asthma aged 2-18 years who visited 419 EDs nationwide during February to December in 2018, 2019, and 2020. The patients who were diagnosed with asthma, ie, J45 or J46 (International Classification of Diseases, 10th revision) in the ED medical history, diagnosis history at discharge, and diagnosis at discharge after hospitalization through the ED were included using the National Emergency Department Information System. Data were analyzed by dividing the period as follows: pre-COVID-19 (from February to December 2018 and 2019) and COVID-19 pandemic (from February to December 2020).

Results

The monthly average of 673 visiting patients (95% confidence interval [CI], 474-872) during the pre-COVID-19 period decreased to 176 (95% CI, 113-239) during the COVID-19 pandemic, which is a 73.8% decrease (p < 0.001).In the pre-COVID-19 period, peaks were observed in spring and autumn. Meanwhile, during the COVID-19 pandemic, a peak was observed only during autumn. During the COVID-19 pandemic, no relationship was found between the rhinovirus infection and asthma exacerbations (p < 0.001).

Conclusions

Respiratory virus infections are strongly associated with asthma exacerbations in children and adolescents. In this study, air pollution is not a major factor for ER visits due to asthma exacerbations. Even though the prevalence of respiratory viruses is decreasing, ED visits due to worsening asthma are trending in the fall. This phenomenon may indicate that asthma has worsened due to other causes such as pollen or fluctuations in temperature and air pressure.

Effect of the COVID-19 Lockdown on Asthma Biological Rhythms

Asthma has a striking temporal character, in which time-of-day, patient age, and season each influence disease activity. The extent to which rhythms in asthma activity reflect exposure to specific disease triggers remains unclear. In this study, we examined how virus mitigation strategies enacted during the COVID-19 pandemic ("lockdown measures") affected rhythms in asthma clinical activity in children. To this end, we retrospectively analyzed asthma clinical presentations in children aged <18 years to our regional academic medical center, comparing 4 years of medical records prior to COVID-19 lockdown measures with the 12 months immediately after the institution of such measures. We correlated these data to positive viral test results, febrile seizures, and allergic clinical surrogates (allergic reaction visits and Emergency Department [ED] antihistamine prescriptions, respectively) over the same time frame. In the 12 months following the institution of the COVID-19 lockdown, positivity rates for common respiratory viruses dropped by 70.2% and ED visits for asthma among children dropped by 62% compared to pre-COVID years. Lockdown suppressed seasonal variation in positive viral tests and asthma ED visits, while diurnal rhythms in asthma visits were unchanged. Asthma seasonality correlated most strongly with rhinovirus positivity both before and after the institution of COVID lockdown measures. Altogether, our data support a causal role for viruses in driving seasonal variability in asthma exacerbations in children.

Seasonal and monthly variation in peak expiratory flow rate in children with asthma

Background

Although understanding the seasonal patterns of asthma deterioration is important to prevent asthma exacerbation, previous approaches have limitations in evaluating the actual trend of asthma exacerbation.

Objective

This study aimed to evaluate the seasonal and monthly variations in the peak expiratory flow rate (PEFR) among children with asthma.

Methods

A total of 89 patients with asthma were enrolled between December 2012 and March 2015. The PEFR in the morning and evening was recorded daily, and the percentage change in PEFR from baseline was calculated. Generalized estimating equation models were constructed after adjusting for age, sex, body mass index, and sensitization to house dust mites or pollen.

Results

The PEFR records of 11,222 person-days showed a significant decrease in the morning and evening in autumn than in winter by -1.9% (95% confidence interval [CI], -3.73 to -0.15) and -2.1% (95% CI, -3.80 to -0.37), respectively. The morning PEFR was significantly lower in April, August, October, and December than in January with changes of -4.2% (95% CI, -7.08 to -1.23) in April, -3.1% (95% CI, -5.79 to -0.47) in August, -3.7% (95% CI, -6.09 to -1.21) in October, and -1.9% (95% CI, -3.62 to -0.12) in December. The percentage change of evening PEFR significantly decreased by -3.3% (95% CI, -6.38 to -0.25) in April and by -3.3% (95% CI, -5.56 to -1.07) in October.

Conclusion

The PEFR in children with asthma was lower in autumn than in winter. In terms of monthly patterns, the PEFR was significantly reduced in April and October than in January. These results can serve as a basis for preventing asthma exacerbations by developing seasonal or monthly management strategies for children with asthma.

Seasonality of allergic diseases: Real-world evidence from a nationwide population-based study

INTRODUCTION

Seasonal variations of allergic diseases have been of great interest in clinical practice, but large-scale epidemiological data in the real world is lacking.

METHODS

We conducted a nationwide, population-based, cross-sectional study using the Korean National Health Insurance claims database to examine the seasonalities of allergic rhinitis (AR), asthma, allergic conjunctivitis (AC), and atopic dermatitis (AD). In addition, we investigated the correlations between the monthly patient numbers of each disease and climate factors such as daytime length, temperature, daily temperature range, humidity, solar radiation, rainfall, UVA dose, UVB dose, and PM10.

RESULTS

The highest seasonal variation was identified in AC, followed by AR, asthma, and AD. AR was most prevalent in September and least prevalent in July and was positively correlated with a daily temperature range. Asthma had peaked in the winter and spring and was negatively correlated with both temperature and humidity. AC had dual peaks in May and September and the valley in winter. AD was prevalent between May and August with the lowest visits in winter and positively correlated with temperature.

CONCLUSIONS

We demonstrated a clear seasonality of four allergic diseases. Korea is located in a temperate region with four distinct seasons, with 50 million people all having a single health insurance system. Therefore, our data reflects all hospital visits in Korea with the least chance for selection bias.

Effects of air pollution on moderate and severe asthma exacerbations

Background: Few studies have evaluated the impact of air pollution levels on the severity of exacerbations. Thus, we compared the relative risks posed by air pollutant levels on moderate and severe exacerbations.Methods: Exacerbation episodes of 618 from 143 adult asthmatics were retrospectively collected between 2005 and 2015 in a tertiary hospital of Korea. Air pollution GPS data for the location closest to each patient's home were obtained from the national ambient monitoring station. The relative impacts of air pollutants on asthma exacerbations were evaluated via a time-trend controlled symmetrical, bidirectional, case-crossover design using conditional logistic regression models on the day of the exacerbation (T-0) and up to 3 days before the exacerbation (T-1-T-3).Results: Overall asthma exacerbation were associated with O₃ levels in summer and winter (OR: 1.012[1.003-1.02] and 1.009[1.003-1.016]), SO₂ levels in spring and summer (OR: 1.009[1-1.018] and 1.02[1.006-1.035]) and NO₂ levels in winter (OR: 1.007[1.003-1.011]). Analyses of the temporal relationship between O₃ concentrations and exacerbations demonstrated that 63.2% of episodes in the summer occurred when the O₃ concentrations on T-1 were significantly higher than those on control days, while 51% of exacerbation episodes in the winter occurred. Severe and moderate exacerbations were similarly associated with O₃ levels in winter (OR: 1.012 [1.003-1.02] vs. 1.01 [0.999-1.021], p > 0.05) and in summer (OR: 1.006 [1.002-1.009] vs. 1.009 [1.003-1.016], p > 0.05).Conclusions: Asthma exacerbations may be associated with the seasonal elevation of O₃, SO₂ and NO₂ levels in summer and winter with the similar relative risk between moderate and severe exacerbations.

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.

Dyspnea Perception During Induced Bronchoconstriction Is Complicated by the Inhaled Methacholine in Children With Clinical Asthma

Purpose

Dyspnea is not widely utilized as an indicator of asthma provocation despite its universal presentation. We hypothesized that dyspnea severity was proportionate with the lung function decline, methacholine dose-step, and the degree of bronchial hyperresponsiveness (BHR).

Methods

We retrospectively analyzed 73 children's bronchial provocation test data with an assessment of dyspnea at every dose-step. Dyspnea severity was scored using a modified Borg (mBorg) scale. A linear mixed effect analysis was performed to evaluate the relationship between the mBorg scale, the percentage fall in the forced expiratory volume in 1 second (FEV1) (ΔFEV1%), the methacholine dose-step, and the degree of BHR (BHR grade).

Results

Subjects were divided into 5 BHR groups based on their last methacholine dose-steps. The mBorg scores did not differ significantly among BHR groups (P=0.596, Kruskal-Wallis test). The linear mixed effect analysis showed that ΔFEV1% was affected by the methacholine dose-step (P<0.001) and BHR grade (P<0.001). The mBorg score was affected by the dose-step (P<0.001) and BHR grade (P=0.019). We developed a model to predict the mBorg score and found that it was affected by the methacholine dose-step and ΔFEV1%, elevating it by a score of 0.039 (χ² [1]=21.06, P<0.001) and 0.327 (χ² [1]=47.45, P<0.001), respectively. A significant interaction was observed between the methacholine dose-step and ΔFEV1% (χ² [1]=16.20, P<0.001).

Conclusions

In asthmatic children, inhaled methacholine, as well as the degree of BHR and lung function decline, may affect dyspnea perception during the bronchial provocation test. If we wish to draw meaningful information from dyspnea perception, we have to consider various complicating factors underlying it.

Admission predictability of children with acute asthma

OBJECTIVES

We aimed to evaluate the seasonal variations of acute asthma presentation in children and the utility of the pediatric asthma score (PAS) and its components in early admission prediction.

METHODS

As part of a randomized controlled trial addressing the clinical efficacy of budesonide nebulization in the treatment of acute asthma in children, the PAS was measured at baseline, 1^st, 2^nd, 3^rd, and 4^th h from the start of medications. Decision of admission was taken at or beyond the 2^nd h.

RESULTS

Out of a total 906 emergency department (ED) visits with moderate-to-severe acute asthma, 157 children were admitted. June to September had the lowest number of visits. The admission-to-discharge ratio varied throughout the year. During the ED stay, between baseline and 3^rd h, admission predictability of the total score improved progressively with a small difference between the 2^nd and 3^rd h. The total score remained the strongest predictor of admission at every time point compared to its individual components. The drop of PAS from baseline to the 2^nd h was not a good predictor of admission. Oxygen saturation (OS) and respiratory rate (RR) had relatively higher predictability than other components.

CONCLUSIONS

Decision of admission could be made to many children with moderate-to-severe acute asthma at the 2^nd h of ED stay based on their total PAS. OS and RR should be part of any scoring system to evaluate acute asthma in children.

Effect of enterovirus infections on asthma in young children: A national cohort study

BACKGROUND

We conducted a cohort study to determine the relationship between enterovirus (EV) infection and asthma.

MATERIALS AND METHODS

From the National Health Insurance Research Database of Taiwan, we identified patients who received a new diagnosis of asthma and concurrent treatment between January 2000 and December 2011 (EV cohort: n = 208 213; non-EV cohort: n = 208 213). Cox proportional hazards regression analysis was performed to determine and compare the adjusted hazard ratios (aHRs) of asthma between these 2 cohorts. Kaplan-Meier analysis was conducted to assess the differences in the cumulative incidence curves of asthma between the 2 cohorts.

RESULTS

The overall aHR of asthma was 1.48-fold higher in the EV cohort than in the non-EV cohort (95% confidence interval = 1.45-1.50). The aHR of asthma was higher in the EV cohort than in the non-EV cohort, comprising children aged ≤5 years, regardless of sex, sociodemographic factors (urbanization level and parental occupation) or comorbidities. The risk of asthma was higher in 1-3, 4-6, 7-9 and 10-12 months (all P < .001), particularly in those with a higher frequency of admission (>5 per year).

CONCLUSION

The incidence of asthma was higher in the EV cohort than in the non-EV cohort, comprising children aged ≤5 years, regardless of sex, urbanization level, parental occupation or season. In particular, the risk of asthma was higher in children with a higher frequency of admission, even in the absence of atopy or other respiratory infections.

Seasonal Cycle and Relationship of Seasonal Rhino- and Influenza Virus Epidemics With Episodes of Asthma Exacerbation in Different Age Groups

Purpose

Seasonal variations in asthma exacerbation (AE) are associated with respiratory virus outbreaks and the return of children to school after vacation. This study aims to elucidate the period, phase, and amplitude of seasonal cycles of AE in 5 different age groups with regard to rhino- and influenza virus epidemics in Korea.

Methods

The number of daily emergency department (ED) visits for AE in all age groups of Korea and the nationwide weekly incidence of rhino- and influenza virus, were obtained for 2008-2012. Fourier regression was used to model rhythmicity, and the Cosinor method was used to determine the amplitude and phase of the cycles in each age group. The cross-correlation function (CCF) between AE and the rhino- and influenza virus epidemics was also calculated.

Results

There were 157,559 events of AE (0.62 events/1,000 individuals/year) during the study period. There were spring and fall peaks of AE in children and adults, but only 1 winter peak in the elderly. The amplitude of the AE peak in infants was higher in spring than in fall (9.16 vs 3.04, P<0.010), and the fall peak was approximately 1 month later in infants than in school children (October 11 vs November 13, P<0.010). The association between AE and rhinovirus was greatest in school children (rho=0.331), and the association between AE and influenza virus was greatest in those aged ≥60 years (rho=0.682).

Conclusions

The rhythmicity, amplitude, and phase of the annual cycle of AE differed among different age groups. The patterns of AE were related to the annual rhino- and influenza virus epidemics.