Phenotyping chronic respiratory diseases with airways obstruction.

Given the high prevalence of asthma-chronic obstructive pulmonary disease overlap (ACO) in Vietnam, there is an urgent need to establish a simplified strategy for categorising patients as either having asthma or chronic obstructive pulmonary disease (COPD). This classification would streamline the application of treatment recommendations outlined by the Global Initiative for Asthma (GINA) and the Global Initiative for Chronic Obstructive Lung Disease (GOLD).Patients with obstructive lung function were classified as having COPD, asthma, or ACO based on GINA/GOLD guidelines. We hypothesised that ACO-like asthma (ACO-A) would present with positive skin prick tests (SPTs) or early onset of symptoms without a history of tuberculosis (TB), while those with ACO-like COPD (ACO-B) would exhibit negative SPTs and late onset of symptoms and/or a history of TB.Among 235 patients, the prevalence of asthma, ACO-A, ACO-B, and COPD was respectively 21%, 22%, 17%, and 40%. Allergic history, rhinitis, and childhood asthma were associated with ACO-A, while high cumulative smoking was correlated with ACO-B. Socio-economic and demographic parameters, medical history, clinical features, smoking habits, lung function, and para-clinical investigations significantly differed between "all asthma" (i.e., individuals with asthma combined with ACO-A) and "all COPD" (i.e., individuals with COPD combined with ACO-B).Based on SPTs, history of TB, and onset age, ACO patients may be defined as people with asthma or COPD..

Prevalence and Severity of COVID-19 among Pediatric Patients with Atopy: A Cross-sectional Study in Kerman, Southeast Iran.

The tragic COVID-19 pandemic affected many children worldwide. Among the factors that may influence the course of viral infections including COVID-19, it is still uncertain whether atopy has a protective or predisposing role. The study aims to address the knowledge gap by investigating the prevalence and severity of COVID-19 among atopic children in Kerman, in 2022. A descriptive-analytical cross-sectional study on children with a history of atopy was performed in Kerman Medical University. Demographic information, type of atopy (including allergic rhinitis, Hyper-Reactive Airway Disease (HRAD) or asthma, eczema, urticaria, anaphylaxis, and food allergy), history of COVID-19 infection, and disease severity were recorded. A total of 1007 children and adolescents, (boys: 56.4%, girls: 43.6%, age:5.61±2.64 years) were included in the study. History of COVID-19 infection was positive in 53.5%, with 75.9% of the cases exhibiting mild disease severity. The frequency of atopies was HRAD or asthma (67.2%), allergic rhinitis (42.6%), and food allergy (27.4%). The frequency of COVID-19 cases was significantly higher among patients with HRAD or asthma, whereas it was significantly lower among those with food allergies, anaphylaxis, and eczema. Among atopic individuals, COVID-19 severity was significantly lower in those with allergic rhinitis, while the opposite trend was observed among food-allergic individuals. This study sheds light on the relationship between atopy and COVID-19 among pediatric patients. It seems specific types of atopies may influence the risk and severity of COVID-19 infection differently. A better understanding of these associations can inform clinical management and preventive measures for vulnerable pediatric populations.

Referral Pathways for Children with Atopic Diseases in Denmark.

Atopic diseases such as atopic dermatitis, food allergy, allergic rhinoconjunctivitis, and/or asthma are common. In Denmark, however, there are multiple referral pathways for these diseases in the healthcare system and they are poorly understood. To describe how children with atopic diseases navigate their way through the Danish healthcare system, a questionnaire was distributed to children aged ≤ 17 years, who were being treated for atopic diseases between August 2020 and June 2021, either by a practising specialist or a hospital department, in the Capital Region of Denmark. A total of 279 children completed the questionnaire and most were referred to a specialist or to a hospital by their general practitioner. No "common track" to hospital existed for patients with ≥ 3 atopic diseases. These patients were more often referred to a hospital compared with children with 2 atopic diseases or fewer (odds ratio [OR] 3.79; 95% CI 2.07-7.24). The primary determinants for hospital treatment were food allergy (OR 4.69; 95% CI 2.07-10.61) and asthma (OR 2.58; 95% CI 1.18-5.63). In conclusion, children with multiple atopic diseases were more likely to be referred to hospital departments than to practising specialists, mainly due to food allergies.

Environmental and structural factors associated with bacterial diversity in household dust across the Arizona-Sonora border.

We previously reported that asthma prevalence was higher in the United States (US) compared to Mexico (MX) (25.8% vs. 8.4%). This investigation assessed differences in microbial dust composition in relation to demographic and housing characteristics on both sides of the US-MX Border. Forty homes were recruited in the US and MX. Home visits collected floor dust and documented occupants' demographics, asthma prevalence, housing structure, and use characteristics. US households were more likely to have inhabitants who reported asthma when compared with MX households (30% vs. 5%) and had significantly different flooring types. The percentage of households on paved roads, with flushing toilets, with piped water and with air conditioning was higher in the US, while dust load was higher in MX. Significant differences exist between countries in the microbial composition of the floor dust. Dust from Mexican homes was enriched with Alishewanella, Paracoccus, Rheinheimera genera and Intrasporangiaceae family. A predictive metagenomics analysis identified 68 significantly differentially abundant functional pathways between US and MX. This study documented multiple structural, environmental, and demographic differences between homes in the US and MX that may contribute to significantly different microbial composition of dust observed in these two countries.

The Impact of Air Pollution on Asthma Severity among Residents Living near the Main Industrial Complex in Oman: A Cross-Sectional Study.

BACKGROUND: Asthma is a widespread chronic respiratory disease that poses a significant public health challenge. The current study investigated the associations between air pollution and asthma severity among individuals residing near the Sohar industrial port (SIP) in Oman. Despite the presence of multiple major industrial complexes in Oman, limited knowledge regarding their impact on respiratory health is accredited. Hence, the primary objective of this study is to offer valuable insights into the respiratory health consequences of industrial air pollution in Al Batinah North. METHODS: The state health clinics' records for patient visits related to asthma were collected for the timeframe spanning 2014 to 2022. Exposure was defined as the distance from the SIP, Majan Industerial Area (MIA), and Sohar Industerial Zone (SIZ) to determine high-, intermediate-, and low-exposure zones (<6 km, 6-12 km and >12 km, respectively). Exposure effect modifications by age, gender, and smoking status were also examined. RESULTS: The conducted cross-sectional study of 410 patients (46.1% males and 53.9% females) living in over 17 areas around SIP revealed that 73.2% of asthmatics were under 50 years old, with severity significantly associated with closeness to the port. Risk ratios were estimated to be (RR:2.42; CI95%: 1.01-5.78), (RR:1.91; CI95%: 1.01-3.6), and (RR:1.68; CI95%: 0.92-3.09) for SIP, MIP, and SIZ areas, respectively, compared to the control area. Falaj Al Qabail (6.4 km) and Majees (6 km) had the highest number of asthma patients (N 69 and N 72) and highest percentages of severe asthma cases among these patients (28% and 24%) with significant risk ratios (RR:2.97; CI95%: 1.19-7.45 and RR:2.55; CI95%: 1.00-6.48), correspondingly. Moreover, severe asthma prevalence peaked in the 25-50 age group (RR:2.05; CI95%: 1.26-3.33), and this linkage between asthma and age was much more pronounced in males than females. Smoking and exposure to certain contaminants (dust and smoke) also increased the risk of severe asthma symptoms, but their effects were less important in the high-risk zone, suggesting much more important risk factors. A neural network model accurately predicted asthma risk (94.8% accuracy), with proximity to SIP as the most influential predictor. CONCLUSIONS: This study highlights the high asthma burden near SIP, linked to port proximity, smoking, and wind direction as major risk factors. These findings inform vital public health policies to reduce air pollution and improve respiratory health in the region, prompting national policy review.

Contribution of Obstructive Sleep Apnea to Asthmatic Airway Inflammation and Impact of Its Treatment on the Course of Asthma.

Asthma and obstructive sleep apnea (OSA) are very common respiratory disorders in the general population. Beyond their high prevalence, shared risk factors, and genetic linkages, bidirectional relationships between asthma and OSA exist, each disorder affecting the other's presence and severity. The author reviews here some of the salient links between constituents of the alternative overlap syndrome, that is, OSA comorbid with asthma, with an emphasis on the effects of OSA or its treatment on inflammation in asthma. In the directional relationship from OSA toward asthma, beyond direct influences, multiple factors and comorbidities seem to contribute.

Asthma in the Brazilian Unified Health Care System: an epidemiological analysis from 2008 to 2021.

OBJECTIVE: To analyze the number of hospitalizations, the length of hospital stay, and mortality due to asthma, as well as the costs to the Unified Health Care System in Brazil between 2008 and 2021. METHODS: This was a cross-sectional epidemiological study using data from the Information Technology Department of the Brazilian Unified Health Care System. Proportional hospitalization and death rates were estimated per 100,000 population by age, microregion, and year. RESULTS: The number of hospitalizations and deaths due to asthma decreased from 2008 to 2021 (205,392 vs. 55,009 and 822 vs. 327, respectively). In addition, a between-sex difference was observed in asthma-related hospitalizations in 2008, and more men were hospitalized in 2021 (51.8%). Asthma mortality rates were similar for both sexes (50.0% each) in 2008, and a slight increase was observed in women's deaths in 2021 (52.9%). Even so, approximately one death/day and more than 55,000 hospitalizations were observed yearly, with a mean length of hospital stay of three days. Additionally, the Southeast region allocated more financial resources to asthma-related hospitalizations. CONCLUSIONS: Our results showed that the number of deaths and hospitalizations due to asthma substantially declined during the study period.

Childhood atopic disorders in relation to placental changes-A systematic review and meta-analysis.

Fetal programming may arise from prenatal exposure and increase the risk of diseases later in life, potentially mediated by the placenta. The objective of this systematic review was to summarize and critically evaluate publications describing associations between human placental changes and risk of atopic disorders during childhood. The review adhered to the Preferred Reporting Items for Systematic Reviews and Meta-analysis guidelines. The inclusion criteria were original research articles or case reports written in English describing a human placental change in relation to disease occurring in offspring during childhood. The MEDLINE and EMBASE databases were searched for eligible studies. Risk of bias (RoB) was assessed using the ROBINS-I tool. The results were pooled both in a narrative way and by a meta-analysis. Nineteen studies were included (n = 12,997 participants). All studies had an overall serious RoB, and publication bias could not be completely ruled out. However, five studies showed that histological chorioamnionitis in preterm-born children was associated with asthma-related problems (pooled odds ratio = 3.25 (95% confidence interval = 2.22-4.75)). In term-born children, a large placenta (≥750 g) increased the risk of being prescribed anti-asthma medications during the first year of life. Placental histone acetylation, DNA methylation, and gene expression differences were found to be associated with different atopic disorders in term-born children. There is some evidence supporting the idea that the placenta can mediate an increased risk of atopic disorders in children. However, further studies are needed to validate the findings, properly control for confounders, and examine potential mechanisms.

Objective monitoring tools for improved management of childhood asthma.

Asthma is a common chronic disease amongst children. Epidemiological studies showed that the mortality rate of asthma in children is still high worldwide. Asthma control is therefore essential to minimize asthma exacerbations, which can be fatal if the condition is poorly controlled. Frequent monitoring could help to detect asthma progression and ensure treatment effectiveness. Although subjective asthma monitoring tools are available, the results vary as they rely on patients' self-perception. Emerging evidence suggests several objective tools could have the potential for monitoring purposes. However, there is no consensus to standardise the use of objective monitoring tools. In this review, we start with the prevalence and severity of childhood asthma worldwide. Then, we detail the latest available objective monitoring tools, focusing on their effectiveness in paediatric asthma management. Publications of spirometry, fractional exhaled nitric oxide (FeNO), hyperresponsiveness tests and electronic monitoring devices (EMDs) between 2016 and 2023 were included. The potential advantages and limitations of each tool were also discussed. Overall, this review provides a summary for researchers dedicated to further improving objective paediatric asthma monitoring and provides insights for clinicians to incorporate different objective monitoring tools in clinical practices.

[Burden and management of severe asthma in Russia: results from international observational study].

AIM: To assess clinical and demographic characteristics of severe asthma (SA) patients and their management in Russian Federation. MATERIALS AND METHODS: This publication provides data for Russian part of population of the international observational study. In Phase I, retrospective analysis of medical records of patients with SA was performed with assessment of clinical and demographic data, medical history, comorbidities, treatment approaches and healthcare utilization. Phase II was a cross-sectional collection of patient-reported outcomes: level of asthma control assessed by ACT (Asthma Control Test) and health-related quality of life (HRQoL) measured using the EQ-5D-5L questionnaire. Phase I patients were enrolled into Phase II if they signed a written consent form. RESULTS: A total of 315 patients were included in Phase I of the study, 106 (33.6%) of them entered Phase II. Majority of study participants were either obese (n=103; 39.8%) or overweight (n=94; 36.3%). The most common comorbidities were cardiovascular diseases (n=217; 71.4%), followed by chronic respiratory diseases (n=198; 68.8%). There were 268 (85.1%) patients who had at least one exacerbation during last 12 months. Data for blood eosinophil count were available in 176 patients; 81.3% of them (n=143) had only one test in the last 12 months. The mean (SD) last available blood eosinophil count was 161.2 (181.2) cells/mm3. Serum Immunoglobulin E (IgE) value was known for 88 patients, and the mean (SD) last measured IgE value was 254.3 (249.7) ng/mL. Only 4.7% of Phase II participants had ACT scores indicative of controlled asthma (>20). As much as 74.5% had scores ≤15 suggesting uncontrolled disease. Most patients also had impaired HRQoL. CONCLUSION: Most SA patients had poor disease control with frequent exacerbations and high number of comorbidities. Blood eosinophils and IgE level measurements were not evaluated routinely which might be a barrier for appropriate phenotyping and treatment selection.

Birth weight and asthma in young adults of a Brazilian birth cohort.

This article aims to evaluate the association between birth weight and asthma in adulthood, estimated by employing structural equation modeling. Cohort study with 1,958 participants aged 23-25 years from Ribeirão Preto, São Paulo, Brazil. Standardized questionnaires were applied and pulmonary function evaluated, including bronchial reactivity with methacholine. A theoretical model was proposed to explore the effects of birth weight and asthma in adulthood. Asthma, socioeconomic status at birth (Birth SES), and current socioeconomic status (Adult SES) were obtained by constructs. Maternal age, sex, skin color, body mass index (BMI), smoking, parental asthma history, history of respiratory infection before five years old, history of hospitalization for lung disease before two years old, and atopy were the studied variables. 14.1% of participants were diagnosed with asthma. Birth weight was associated with asthma (Standardized Coefficient - SCtotal=-0.110; p=0.030), and an indirect effect was also observed (SCindirect=-0.220; p=0.037), mediated by hospitalization before two years and respiratory infection before five years. Lower birth weight showed an increased risk of asthma in adulthood and the SES Birth and Adult SES variables underlie this association.

Tobacco control policies and respiratory conditions among children presenting in primary care.

Tobacco control policies can protect child health. We hypothesised that the parallel introduction in 2008 of smoke-free restaurants and bars in the Netherlands, a tobacco tax increase and mass media campaign, would be associated with decreases in childhood wheezing/asthma, respiratory tract infections (RTIs), and otitis media with effusion (OME) presenting in primary care. We conducted an interrupted time series study using electronic medical records from the Dutch Integrated Primary Care Information database (2000-2016). We estimated step and slope changes in the incidence of each outcome with negative binomial regression analyses, adjusting for underlying time-trends, seasonality, age, sex, electronic medical record system, urbanisation, and social deprivation. Analysing 1,295,124 person-years among children aged 0-12 years, we found positive step changes immediately after the policies (incidence rate ratio (IRR): 1.07, 95% CI: 1.01-1.14 for wheezing/asthma; IRR: 1.16, 95% CI: 1.13-1.19 for RTIs; and IRR: 1.24, 95% CI: 1.14-1.36 for OME). These were followed by slope decreases for wheezing/asthma (IRR: 0.95/year, 95% CI: 0.93-0.97) and RTIs (IRR: 0.97/year, 95% CI: 0.96-0.98), but a slope increase in OME (IRR: 1.05/year, 95% CI: 1.01-1.09). We found no clear evidence of benefit of changes in tobacco control policies in the Netherlands for the outcomes of interest. Our findings need to be interpreted with caution due to substantial uncertainty in the pre-legislation outcome trends.

Evaluation of sinonasal involvement in patients with asthma and chronic obstructive pulmonary disease.

Background: Asthma and chronic obstructive pulmonary disease (COPD) are the most common obstructive diseases. Based on the similarities, we aimed to evaluate sinonasal symptoms in patients with asthma or COPD, and compare the two diseases with regard to upper-airway involvement. Methods: Patients with asthma or with COPD who were followed up at Ankara University Immunology and Allergy or Chest Diseases Departments were included in the study. The participants went through pulmonary function tests, skin-prick tests, and disease severity assessment of either disease. Nasal endoscopic evaluations of all the patients were performed in the Department of Otorhinolaryngology. Lund-Mackay scoring was performed on the computed tomography of the paranasal sinus. Chronic rinosinusitis (CRS) diagnosis was made as recent guidelines. Results: A total of 112 subjects (number of women/men: n = 67/45; median age, 49 years [The range for IQR was 22 years]) were included in the study. Fifty-five patients had asthma, 33 had COPD, and 24 were healthy controls. Nasal symptoms were more frequent in the patients with asthma (patients with asthma, n = 52 [98%]; patients with COPD, n = 17 [52%]; controls, n = 9 [38%]) (p < 0.001). The median (IQR) 22-item Sino-Nasal Outcome Test (SNOT-22) questionnaire score was higher in the patients with asthma (33 [20-50]) than in the patients with COPD (8 [1.5-18.7]) and the control group (3.5 [0-18.7]) (p < 0.01). Patients with asthma had significantly higher prevalence rates of rhinosinusitis than did those in the COPD and the control groups (36%, 15.6%, 8.3%, respectively; p < 0.01). The SNOT-22 optimal cutoff score was calculated as ≥11 to detect the score limit for CRS prediction with the best sensitivity and specificity. Conclusion: As a result, patients with both asthma and COPD may have upper-airway symptoms. CRS, was primarily seen in the patients with asthma. Accordingly, SNOT-22 scores were higher in the patients with asthma than in those in the COPD and the control groups. A referral to the Ear Nose Throat department for further evaluation with nasal endoscopy and computed tomography of the paranasal may be required in a subgroup of patients.

Allergen skin test responses in broad U.S. asthma population in those with and without rhinitis.

Background: Asthma and allergic rhinitis are pathologically interlinked conditions. Despite skin testing (ST) being pivotal for evaluating allergic sensitization, U.S. data that date back to 1960s on ST reactivity patterns in subjects with asthma remain sparse. Objective: The purpose of this study was to elucidate seasonal, perennial ST responses, and their relationship with asthma severity, early versus late onset disease, and immunoglobulin E (IgE) levels. Methods: Five hundred patients with asthma were randomly selected from the National Jewish Health electronic medical record over a 3-year span. Demographic, clinical, and allergen ST reactivity data for a battery of seasonal and perennial allergens were procured, including total IgE levels, asthma onset, and severity, by using t-tests, χ² tests, and Analysis of Variance (ANOVA), patterns of reactivity were assessed for overall, seasonal, and perennial allergens in relation to IgE levels, asthma onset, and severity. Results: Of the 500 patients, 398 were analyzed. 63.3% were women, 50.1% had adult-onset asthma, and 86.1% had rhinitis; 75.3% tested positive to one or more allergens, with men demonstrating higher overall (p = 0.039) and perennial (p = 0.035) sensitization. ST reactivity varied based on the presence of rhinitis for seasonal (p = 0.028) but not perennial (p = 0.733) allergens. Asthma severity was not significantly associated with ST reactivity (p > 0.10). ST positivity for perennial (p < 0.001) but not seasonal (p = 0.128) allergens was higher in childhood-onset asthma versus adult-onset asthma despite both groups having a large percentage of reactors. Elevated IgE levels correlated with ST reactivity (p < 0.01). Conclusion: Our study represents a unique comprehensive evaluation of ST reactivity in a U.S. asthma population, which is lacking in the literature, when factoring in asthma onset, severity, and IgE levels. Our findings underscore the importance of allergen sensitization in asthma, regardless of severity, concurrent rhinitis symptoms, or asthma onset, which challenge some of the prevailing assumptions about the relationship between allergen sensitization and asthma onset.

Inflammatory bowel disease and allergic diseases: A Mendelian randomization study.

BACKGROUND: Inflammatory bowel disease (IBD) and allergic diseases possess similar genetic backgrounds and pathogenesis. Observational studies have shown a correlation, but the exact direction of cause and effect remains unclear. The aim of this Mendelian randomization (MR) study is to assess bidirectional causality between inflammatory bowel disease and allergic diseases. METHOD: We comprehensively analyzed the causal relationship between inflammatory bowel disease (IBD), Crohn's disease (CD), ulcerative colitis (UC) and allergic disease (asthma, Hay fever, and eczema) as a whole, allergic conjunctivitis (AC), atopic dermatitis (AD), allergic asthma (AAS), and allergic rhinitis (AR) by performing a bidirectional Mendelian randomization study using summary-level data from genome-wide association studies. The analysis results mainly came from the random-effects model of inverse variance weighted (IVW-RE). In addition, multivariate Mendelian randomization (MVMR) analysis was conducted to adjust the effect of body mass index (BMI) on the instrumental variables. RESULTS: The IVW-RE method revealed that IBD genetically increased the risk of allergic disease as a whole (OR = 1.03, 95% CI = 1.01-1.04, fdr.p = .015), AC (OR = 1.04, 95% CI = 1.01-1.06, fdr.p = .011), and AD (OR = 1.06, 95% CI = 1.02-1.09, fdr.p = .004). Subgroup analysis further confirmed that CD increased the risk of allergic disease as a whole (OR = 1.02, 95% CI = 1.00-1.03, fdr.p = .031), AC (OR = 1.03, 95% CI = 1.01-1.05, fdr.p = .012), AD (OR = 1.06, 95% CI = 1.02-1.09, fdr.p = 2E-05), AAS (OR = 1.05, 95% CI = 1.02-1.08, fdr.p = .002) and AR (OR = 1.03, 95% CI = 1.00-1.07, fdr.p = .025), UC increased the risk of AAS (OR = 1.02, 95% CI = 0.98-1.07, fdr.p = .038). MVMR results showed that after taking BMI as secondary exposure, the causal effects of IBD on AC, IBD on AD, CD on allergic disease as a whole, CD on AC, CD on AD, CD on AAS, and CD on AR were still statistically significant. No significant association was observed in the reverse MR analysis. CONCLUSION: This Mendelian randomized study demonstrated that IBD is a risk factor for allergic diseases, which is largely attributed to its subtype CD increasing the risk of AC, AD, ASS, and AR. Further investigations are needed to explore the causal relationship between allergic diseases and IBD.

Thunderstorm asthma: a paediatric emergency department experience in London.

The aim of this study was to characterise paediatric emergency department presentations during the 2023 thunderstorm asthma (TA) epidemic, characterised by a sudden surge in wheeze presentations, with analysis of environmental factors.Wheeze presentations totalled 50 (28%) on 12 June and 18 (19%) 13 June. There was no prior asthma in 39 (57%) and no atopic disorders in 30 (44%). There was neither asthma nor atopic disorders in 8 (12%). 44 (65%) were severe or life-threatening. There were no endotracheal intubations and no deaths. High pollen and air pollution warnings were issued.TA poses a significant, sudden health threat, often in children without asthma. A surge strategy is required.

Lack of association of atopic dermatitis severity and morphology with asthma onset and control.

BACKGROUND: Asthma is one of the most well-recognized comorbidities of atopic dermatitis (AD). However, the relationship of AD severity and morphology with asthma characteristics in adults is not well defined. OBJECTIVES: To understand associations of AD severity and morphology with comorbid asthma age-of-onset and control in adults with AD. METHODS: A cross-sectional, dermatology practice-based study was performed in adults (≥ 18 years) with AD and history of asthma (N = 252). Self-administered electronic questionnaires were completed by patients, including demographics, patient-reported outcomes measures of AD severity, history of asthma, age-of-onset, and Asthma Control Test (ACT). Multivariable logistic regression models were constructed to examine relationships between AD severity and morphology with asthma age-of-onset and control. RESULTS: The mean ± standard deviation ACT score was 21.7 ± 4.3 (range 5-25), with 55 (21.8%) having ACT scores ≤ 19 indicating poorly controlled asthma. AD severity and morphology were not associated with adult-onset asthma or poor asthma control. CONCLUSIONS: AD severity and morphology were not consistently associated with comorbid asthma age-of-onset or control in adults with AD.

Age-related effects of Mycoplasma pneumoniae infection and subsequent asthma exacerbation in children.

BACKGROUND: Mycoplasma pneumoniae causes community-acquired pneumonia in children and increases asthma risk, but large studies are lacking. OBJECTIVE: To assess the link between M. pneumoniae infection and to asthma exacerbation, in children with allergies, and age of infection impact. METHODS: This retrospective cohort study analyzed medical records of South Korean children between January 2002 and December 2017. The study's exposure was hospitalization with an M. pneumoniae-related diagnosis, and the outcome was defined as asthma exacerbation, confirmed by hospitalization at least 6 months after M. pneumoniae infection, with alternative validation using asthma diagnosis and systemic steroid prescription records. Hazard ratios (HRs) for asthma exacerbation risk were estimated for the matched cohort using a Cox proportional hazards model stratified by allergic comorbidities. Time-dependent covariates and age-stratified exposure groups were used to calculate odds ratios. RESULTS: The study included 84,074 children with M. pneumoniae infection and 336,296 unexposed children. Follow-up for 12.2 ± 2.3 years found the exposed group had a significant risk of asthma exacerbation (HR 2.86, 95% confidence interval [CI] 2.67-3.06) regardless of allergic comorbidities. The risk was highest (over threefold) in children infected between 24 and 71 months. Sensitivity analysis using an alternative definition of the outcome showed an HR of 1.38 (95% CI 1.35-1.42), further supporting the association between M. pneumoniae infection and asthma exacerbation. CONCLUSION: M. pneumoniae infection was significantly associated with an increased risk of subsequent asthma exacerbation regardless of allergic comorbidities. Further research needed for understanding and confirmation.