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Background: The level of pollen in Korea has increased over recent decades. Research suggests that oral allergy syndrome (OAS) may be more frequent in childhood than previously recognized. We aimed to investigate the prevalence and characteristics of OAS in children aged 6–10 years from a general‐population‐based birth cohort. Methods: We analyzed 930 children from the cohort for childhood origin of asthma and allergic diseases (COCOA). Allergic diseases were diagnosed annually by pediatric allergists. The skin prick tests were performed with 14 common inhalant allergens and four food allergens for the general population of children aged 3 and 7 years. Results: Of the 930 eligible children, 44 (4.7%) aged 6–10 years were diagnosed with OAS. The mean age at onset was 6.74 years. OAS prevalence was 7.2% among children with allergic rhinitis (AR) and 19.1% among those with pollinosis, depending on comorbidity. OAS was more prevalent in schoolchildren with atopic dermatitis, food allergy, and sensitization to food allergens and grass pollen in early childhood. In schoolchildren with AR, only a history of food allergy until the age of 3 years increased the risk of OAS (aOR 2.971, 95% CI: 1.159–7.615). Conclusion: Food allergy and food sensitization in early childhood were associated with OAS in schoolchildren with AR. Further study is required to elucidate the mechanism by which food allergy in early childhood affects the development of OAS. [ABSTRACT FROM AUTHOR]

Rationale: Exposure to humidifier disinfectants (HDs) can increase the risk of asthma, but the characteristics of HD-related asthma are currently unclear. Polyhexamethylene guanidine (PHMG)-containing HD was the most commonly used and the most frequently associated with HD-associated lung injury. Objectives: To investigate the characteristics of PHMG-induced asthma. Methods: This general population-based birth cohort study used data from the Panel Study of Korean Children from 2008 (n = 846). Spirometry, bronchial provocation tests, detailed history recording, and physical examinations were performed on 7-year-old patients (n = 362). Exploratory analysis of plasma proteomics was performed. Results: Compared with the healthy control group, forced expiratory volume in 1 second was the lowest in PHMG-exposed asthma group (z-score = -0.806; 95% confidence interval, -1.492 to -0.119). The positive rate of bronchial hyperresponsiveness was lower in children with PHMG-exposed asthma compared with children with asthma without HD exposure (13.3% vs. 47.4%). Long-term exposure to low-intensity PHMG before the age of 3 years was associated with asthma symptoms. Periostin was higher in subjects with asthma without HD exposure compared with the healthy control subjects. The inducible T-cell costimulator ligand and hepatocyte growth factor activator were lower in PHMG-exposed asthma compared with asthma without exposure. Hepatocyte growth factor activator had a positive correlation with forced vital capacity (z-score) in asthma with PHMG exposure (r = 0.78; P < 0.01). Conclusions: The asthma associated with low-intensity exposure to PHMG is characterized by lower lung function, lower positive rates of bronchial hyperresponsiveness, and varied distributions of plasma proteins. These findings suggest that asthma related to PHMG exposure may constitute a different mechanism of asthma pathophysiology. [ABSTRACT FROM AUTHOR]

Background: The effect of diet on allergic rhinitis (AR), its severity in children, and whether it modifies AR depending on genetic susceptibility are unknown. We investigated the association between dietary patterns and AR in school children and the influence of diet on AR according to a genetic risk score (GRS). Methods: Totally, 435 7‐year‐old school children were recruited from the Panel Study on Korean Children. We used dietary patterns (vegetable, sugar, and meat) and dietary inflammatory index (DII) as dietary parameters. AR and its severity were defined by questionnaires about treatment in the previous 12 months and the Allergic Rhinitis and its Impact on Asthma (ARIA) guideline, respectively. A GRS was calculated using 6 single nucleotide polymorphisms for allergic diseases. Results: A vegetable diet containing a lot of anti‐inflammatory nutrients and higher vitamin D level in blood were negatively correlated, while DII was positively correlated with triglyceride level and triglyceride/HDL cholesterol. Vegetable diet (aOR, 95% CI = 0.73, 0.58‐0.94) and DII (1.13, 1.01‐1.28) were associated with AR risk. In particular, a high‐vegetable diet resulted in a lower risk of mild and persistent AR (aOR, 95% CI = 0.24, 0.10‐0.56) while a high DII represented a higher risk (2.33, 1.06‐5.10). The protective effect of vegetable diet on AR appeared only among children with a lower GRS (adjusted P =.018). Conclusions: A vegetable dietary pattern characterized by high intake of anti‐inflammatory nutrients and higher vitamin D level in blood might be associated with a lower risk of mild and persistent AR. This beneficial effect is modified by a genetic factor. [ABSTRACT FROM AUTHOR]

Background: The most relevant time of PM10 exposure to affect airway hyperresponsiveness (AHR) and new development of asthma in school‐aged children is unclear. The aims of this study were to investigate the most critical time of PM10 exposure to affect AHR and new diagnosis of asthma from AHR in school‐aged children. Methods: Elementary schoolchildren (n = 3570) have been enrolled in a nationwide prospective 4‐year follow‐up survey in Korea from 2005 to 2006. Individual annual PM10 exposure was estimated by using an ordinary kriging method from the prenatal period to 7 years of age. AHR at 7 years was defined by a methacholine PC20 ≤8 mg/mL. Results: PM10 exposure during pregnancy and at 1 year of age showed significant effects on AHR (aOR: 1.694, 95% CI: 1.298‐2.209; and aOR: 1.750, 95% CI: 1.343‐2.282, respectively). PM10 exposure during pregnancy was associated with the risk of a new diagnosis of asthma (aOR: 2.056, 95% CI: 1.240‐3.409), with the highest risk in children with AHR at age 7 (aOR: 6.080, 95% CI: 2.150‐17.195). PM10 exposure in the second trimester was associated with the highest risk of a new diagnosis of asthma in children with AHR at age 7 (aOR: 4.136, 95% CI: 1.657‐10.326). Conclusions: Prenatal PM10 exposure in the second trimester is associated with an increased risk of a new diagnosis of asthma in school‐aged children with AHR at 7 years. This study suggests that PM10 exposure during a specific trimester in utero may affect the onset of childhood asthma via AHR. Higher PM10* exposure in the second trimester and AHR# at 7 years showed combined effect on the new diagnosis of asthma at school age (aOR 4.136).PM10* exposure in the second trimester may affect the development of childhood asthma via AHR#. *PM10: Particulate matter with an aerodynamic diameter of less than 10 μm. #AHR: Airway hyperresponsiveness. [ABSTRACT FROM AUTHOR]

In South Korea, a cluster of humidifier disinfectant-induced lung injury (HDLI) cases developed between 2006 and 2011. There are no existing reports regarding the rate of humidifier disinfectant (HD) usage in the general population of Korean children. The purpose of this study was to investigate the rate of humidifier and HD usage in the general population of Korean children. This is a general population-based birth cohort multicenter study, Panel Study of Korean Children (PSKC) from 2008, a humidifier and HD-related questionnaire administered to 1577 subjects (809 male, 768 female) in 2015 (n=1577). The questionnaire consisted of four categories (humidifier usage, HD usage, exposure duration, and type of HD brands). A total of 75.6% (1192/1577) had used a humidifier, and the rate of HD usage was found to be 31.1% (409/1316). Polyhexamethylene guanidine (PHMG), used as a disinfectant, was found to have the highest usage rate (62.0%). HD was used for less than 3 months of the entire lifetime of most of the subjects. In conclusion, approximately 30% of young Korean children were exposed to HD. PHMG-containing HD was the most commonly used. These results suggest that a nationwide epidemiologic investigation is needed urgently, and children exposed to HD should be investigated regarding their status of lung injury, including a pulmonary function test. Moreover, a long-term follow-up period may be required to evaluate HD usage-associated lung injury. [ABSTRACT FROM AUTHOR]

Background: Children who were only exposed to a mixture of chloromethylisothiazolinone (CMIT) and methylisothiazolinone (MIT) as humidifier disinfectant (HD) components were evaluated for humidifier disinfectant-associated lung injury (HDLI) from 2012. This study was to evaluate the pulmonary function using, impulse oscillometry (IOS) for children exposed to a mixture of CMIT/MIT from HD. Methods: Twenty-four children who were only exposed to a mixture of CMIT/MIT, with no previous underlying disease, were assessed by IOS. Diagnostic criteria for HDLI were categorized as definite, probable, possible, or unlikely. Home visits and administration of a standardized questionnaire were arranged to assess exposure characteristics. Results: Definite and probable cases showed higher airborne disinfectant exposure intensity during sleep (32.4 ± 8.7 μg/m3) and younger age at initial exposure (3.5 ± 3.3 months) compared with unlikely cases (17.3 ± 11.0 μg/m3, p = 0.026; 22.5 ± 26.2 months, p = 0.039, respectively). Reactance at 5 Hz was significantly more negative in those with high-density exposure during sleep (mean, -0.463 kPa/L/s vs. low density, -0.296, p = 0.001). The reactance area was also higher with high-density exposure during sleep (mean, 3.240 kPa/L vs. low density, 1.922, p = 0.039). The mean bronchodilator response with high-density exposure was within the normal range for reactance. Conclusions: Significant peripheral airway dysfunction were found in children with high levels of inhalation exposure to a mixture of CMIT/MIT during sleep. Strict regulation of a mixture of CMIT/MIT exposure were associated with positive effects on lung function of children. [ABSTRACT FROM AUTHOR]

Background: Treatment guidelines for asthma have been established based on asthma severity; there are limitations in the identification of underlying pathophysiology and prediction of prognosis in heterogeneous phenotypes of asthma. Although the complex interactions between environmental and genetic factors affect the development and progression of asthma, studies on asthma phenotypes considering environmental factors are limited. This study aimed to identify asthma phenotypes using latent class analysis including environmental factors in school-age children.Methods: We included 235 children (6-8 years) with parent-reported, physician-diagnosed asthma from the Children's HEalth and Environmental Research (CHEER) study, which is a 4-year prospective follow-up study with 2-year intervals. At every survey, pulmonary function tests, methacholine challenge tests and blood tests with questionnaire were conducted.Results: Four asthma phenotypes were identified. Cluster 1 (22% of children) was characterized by high prevalence of atopy and mild symptoms; subjects in cluster 2 (17%) consisted of less atopy and normal lung function, but intermittent troublesome; cluster 3 (29%) experienced late-onset atopic troublesome asthma with decreased lung function in combination with low socioeconomic status; and cluster 4 was associated with early-onset and less-atopic infrequent asthma.Conclusions: Late-onset, high atopy, and low socioeconomic status are associated with troublesome persistent asthma phenotype in school-age children. Environmental factors might be implicated in the clinical heterogeneity of asthma. Asthma phenotypes considering diverse factors might be more helpful in the identification of asthma pathogenesis and its prevention. [ABSTRACT FROM AUTHOR]

Background A key therapeutic approach to asthma, which is characterized by chronic airway inflammation, is inhaled corticosteroid (ICS). This study evaluated the association of symptom control with changes in lung function, bronchial hyperresponsiveness (BHR), and exhaled nitric oxide (eNO) after ICS treatment in asthmatic children. Methods A total of 33 children aged between 5 and 12 years with mild to moderate persistent asthma were treated with 160 μg ciclesonide per day for 3 months. At days 0 and 90, the following parameters were assessed: asthma symptom scores; lung function, including forced expiratory volume in one second (FEV 1 ), forced vital capacity (FVC), and forced expiratory flow at 25–75% of forced vital capacity (FEF 25–75% ); BHR to methacholine and adenosine 5-monophosphate (AMP); and eNO. Results Asthma symptom scores, lung function parameters, BHR to methacholine and AMP, and eNO levels at day 90 were significantly improved versus day 0 (all p < 0.001). Symptom scores at day 90 were not correlated with changes in lung function and BHR to methacholine during the follow-up period, whereas those at day 90 were more closely correlated with changes in BHR to AMP ( r = 0.511, p = 0.003) than with eNO ( r = −0.373, p = 0.035). Additionally, changes in PC 20 AMP were correlated with changes in PC 20 methacholine ( r = 0.451, p = 0.011) and eNO ( r = −0.474, p = 0.006). Conclusions Changes in the BHR to AMP, and to a lesser extent eNO, correlate with asthma symptom control after ICS treatment. BHR to AMP may better reflect the relationship between improved airway inflammation due to ICS treatment and asthma symptoms. [ABSTRACT FROM AUTHOR]