Population Of Asthma Patients Research Articles

Granular Insights: Neutrophil Predominance and Elastase Release in Severe Asthma Exacerbations in a Pediatric Cohort.

The chronic inflammatory component of asthma is propagated by granulocytes, including neutrophils and eosinophils, in the peripheral circulation and airway. Previous studies have suggested that these cells have an altered expression of adhesion-related molecules and a propensity for the release of granule contents that may contribute to tissue damage and enhance inflammatory complications in patients with status asthmaticus. The goal of this prospective cohort study at a tertiary care pediatric hospital with a large population of asthma patients was to assess the role of granulocyte-based inflammation in the development of asthma exacerbation. Subjects were enrolled from two patient populations: those with mild-to-moderate asthma exacerbations seen in the emergency department and those with severe asthma admitted to the intensive care unit (PICU). Clinical data were collected, and blood was drawn. Granulocytes were immediately purified, and the phenotype was assessed, including the expression of cell surface markers, elastase release, and cytokine production. Severe asthmatics admitted to the PICU displayed a significantly higher total neutrophil count when compared with healthy donors. Moreover, little to no eosinophils were found in granulocyte preparations from severe asthmatics. Circulating neutrophils from severe asthmatics admitted to the PICU displayed significantly increased elastase release ex vivo when compared with the PMN from healthy donors. These data suggest that the neutrophil-based activation and release of inflammatory products displayed by severe asthmatics may contribute to the propagation of asthma exacerbations.

Post-COVID-19 Symptoms in Adults with Asthma-Systematic Review.

Research on the longer-term sequelae of COVID-19 in patients with asthma is limited. To assess the frequency and severity of long-term symptoms of COVID-19 in the population of asthma patients. A systematic review of the published literature was conducted in accordance with the recommendations of the PRISMA statement. EMBASE, MEDLINE/PubMed, Web of Science, CINAHL, and Scopus Scholar were searched for terms related to asthma and post or long COVID-19, and for systematic reviews related to specific questions within our review, up to June 2022. Data from 9 references publications included in the review were extracted. A total of 1466 adult asthmatic patients with COVID-19 infection were described in all the publications mentioned above. Of the long-term symptoms reported after COVID-19, patients indicated: lower respiratory symptoms, fatigue, cognitive symptoms, psychological problems, and other such as skin rashes, gastrointestinal disorders, tachycardia, palpitations, ocular disorders, ageusia/hypogeusia, anosmia/hyposmia, and poor sleep quality. These symptoms in similar intensity were observed in the comparison groups without a diagnosis of asthma. The published data neither confirm nor deny that long-term COVID-19 symptoms in patients with asthma diagnosis are different in strength and frequency from patients without asthma diagnosis. To indicate associations between asthma and COVID-19 infection and severity, as well as the frequency of long-term symptoms of COVID-19, more longitudinal research is needed in chronic asthma patients with different phenotypes, intensity of treatment, and degree of asthma control.

Assessing Inhaler Techniques of Asthma Patients Using Aerosol Inhalation Monitors (AIM): A Cross-Sectional Study.

A high percentage of asthma patients have symptoms that are not well controlled, despite effective drugs being available. One potential reason for this may be that poor inhaler technique limits the dose delivered to the lungs, thereby reducing the therapeutic efficacy. The aim of this study was to assess the prevalence of poor inhaler technique in an asthma patient population and to probe the impact of various demographic parameters on technique quality. This study was conducted at community pharmacies across Wales, UK. Patients diagnosed with asthma and 12 years or older were invited to participate. An aerosol inhalation monitor (AIM, Vitalograph®) was used to measure the quality of patient inhaler technique. A total of 295 AIM assessments were carried out. There were significant differences in the quality of inhaler technique across the different inhaler types (p < 0.001, Chi squared). The best technique was associated with dry-powder inhalers (DPI devices, 58% of 72 having good technique), compared with pressurized metered-dose inhalers (pMDI) or pMDIs with a spacer device (18% of 174 and 47% of 49 AIM assessments, respectively). There were some significant associations between gender, age, and quality of inhaler technique, as determined with adjusted odds ratios. It seems that the majority of asthmatic patients were not using their inhalers appropriately. We recommend that healthcare professionals place more emphasis on assessing and correcting inhaler technique, as poor inhaler technique might be responsible for the observed lack of symptom control in the asthma patient population.

Prevalence of asthma in Catalonia (Spain): a retrospective, large-scale population-based study.

Asthma epidemiology reports an estimated global prevalence of about 4.3-8.6% in adults, with last differences among geographical regions. This study analyses a more significant population of asthma patients (473,737 individuals).To study the prevalence of medical diagnosis of asthma, overall and by age, gender, and disease severity, as well as comorbidities and type 2 biomarkers, and undergo medical treatments of a retrospective population-based asthma cohort from Catalonia (Spain). Individuals with a diagnosis of asthma established by medical records at different healthcare levels (primary, hospital, and emergency) from the Catalan Health System (CHS) were included. Socio-demographic characteristics, prevalence, overall and by age and gender, disease severity, comorbidities, and biomarkers of type-2 inflammation were evaluated, together with appropriate medical treatment. The overall diagnosed asthma prevalence in the population of Catalonia was 6.3%, where patients mainly had mild asthma (5.3%) and were significantly higher in females (6.8%) than males (5.7%). By age groups, asthma was more prevalent in boys and young men adults; however, being more prevalent in females above the age of 30y. The prevalence of severe asthma was 0.4%, 42.6% had uncontrolled asthma, and a high proportion (84.2%) were under systemic corticosteroid prescription. As expected, SABAs were the most prescribed drug (62.6%), followed by systemic corticosteroids (43.3%). More than half (53.8%) of patients showed type 2 inflammation. Asthma prevalence in Catalonia is similar to other areas studied in Spain, with a high prevalence in women and of T2 asthma.

Stratification of asthma by lipidomic profiling of induced sputum supernatant

Asthma is a chronic respiratory disease with significant heterogeneity in its clinical presentation and pathobiology. There is need for improved understanding of respiratory lipid metabolism in asthma patients and its relation to observable clinical features. We performed a comprehensive, prospective, cross-sectional analysis of the lipid composition of induced sputum supernatant obtained from asthma patients with a range of disease severities, as well as from healthy controls. Induced sputum supernatant was collected from 211 adults with asthma and 41 healthy individuals enrolled onto the U-BIOPRED (Unbiased Biomarkers for the Prediction of Respiratory Disease Outcomes) study. Sputum lipidomes were characterized by semiquantitative shotgun mass spectrometry and clustered using topologic data analysis to identify lipid phenotypes. Shotgun lipidomics of induced sputum supernatant revealed a spectrum of 9 molecular phenotypes, highlighting not just significant differences between the sputum lipidomes of asthma patients and healthy controls, but also within the asthma patient population. Matching clinical, pathobiologic, proteomic, and transcriptomic data helped inform the underlying disease processes. Sputum lipid phenotypes with higher levels of nonendogenous, cell-derived lipids were associated with significantly worse asthma severity, worse lung function, and elevated granulocyte counts. We propose a novel mechanism of increased lipid loading in the epithelial lining fluid of asthma patients resulting from the secretion of extracellular vesicles by granulocytic inflammatory cells, which could reduce the ability of pulmonary surfactant to lower surface tension in asthmatic small airways,as well as compromise its role as an immune regulator.

Predicting asthma patients' total cost using neural networks and linear regression

In this paper, we analyze a population of asthma patients trying to predict the total cost of their treatment based on various demographic, clinical, and pharmacological data. We are comparing a neural network architecture with a simple linear regression using data from a healthcare insurance provider based in Louisiana. Our first focus was to explore the factors associated with the total cost of asthma treatment. Then we identified a sufficient threshold of data for which the neural networks outperform the linear regression models in terms of predictive accuracy. We showed that even with a simple Neural Network architecture, after approximately 6,000 randomly selected data points Neural Networks outperform Linear Regression almost always.

Characteristics of Oral Corticosteroid Users Among Persons with Asthma on GINA Step 3 Therapy and Above: A Cross-Sectional Study in Portuguese Community Pharmacies.

Oral corticosteroids (OCS) are frequently used in asthma management but have an important risk-profile. The aim of the study is to characterize and compare the sociodemographic and clinical characteristics, treatment regimen and asthma control between OCS users and non-users among the population of asthma patients (≥18 years) at GINA step 3 and above treated with a fixed combination of an inhaled corticosteroid and a long-acting beta-agonist (ICS/LABA). Cross-sectional study in Portuguese community pharmacies. Data was collected via paper-based interview delivered at the pharmacy (sociodemographic characteristics and asthma treatment regimen, namely ICS/LABA and OCS utilization), followed by a telephonic interview collecting smoking history, comorbidities, body mass index (BMI), history of exacerbations and asthma-related healthcare resource utilization (HCRU) in the previous 12 months, as well as asthma control using the Control of Allergic Rhinitis and Asthma Test (CARAT®). A total of 347 patients recruited in 98 pharmacies were included in the analysis. Of those, 328 had completed both questionnaires. A quarter of the individuals reported OCS use in the previous 12 months (OCS users), either as add-on therapy (6%) or exacerbation treatment (19%). Patients were mostly females (72%), with an average age of 59.5 years (SD=15.4). OCS users were significantly older and reported more frequently having conjunctivitis (25.9% vs 15.0%), osteoporosis (25.9% vs 13.4%), arthritis (14.6% vs 6.9%), and gastrointestinal disease (16.1% vs 8.1%). OCS users also reported greater urgent HCRU: unscheduled consultations (33.3% vs 9.3%) and emergency department (ED) visits (32.1% vs 12.1%). Both groups presented poor disease control (85.2% of OCS users vs 72.9% of non-OCS users). These results highlight the burden of OCS therapy to asthma patients and the need to improve asthma management, by adopting OCS sparing strategies in this subgroup of patients.

Asthma exacerbations are associated with a decline in lung function: a longitudinal population-based study

RationaleProgressive lung function (LF) decline in patients with asthma contributes to worse outcomes. Asthma exacerbations are thought to contribute to this decline; however, evidence is limited with mixed results.MethodsThis historical...

Effect of combination treatment with Lactobacillus rhamnosus and corticosteroid in reducing airway inflammation in a mouse asthma model.

Asthma is a complex multifactorial chronic airway inflammatory disease with diverse phenotypes and levels of severity and is associated with significant health and economic burden. In a certain population of asthma patients, the symptoms cannot be well controlled with steroid. There has been long standing interest in the use of probiotics for treating allergic diseases. The purpose of this study is to investigate whether the combination of Lactobacillus rhamnosus GG (LGG) with prednisolone could reduce the dosage of glucocorticoid in controlling airway inflammation in a murine model for allergic asthma. We used Der p 2-sensitized asthma model in female BALB/c mice. The animals were treated with 75μl or 50μl oral prednisolone or combination treatment of these two doses of oral prednisolone with LGG. Airway hyperresponsiveness, serum specific IgE/IgG1/IgG2a, infiltrating inflammatory cells in lung and cytokines were assessed. Compared to 75μl prednisolone, a lower dose of prednisolone with 50μl was less satisfactory in suppressing airway hyperresponsives, serum IgE and IgG1, Th2 cytokines and inflammatory cytokines such as IL-6, IL-8 and IL-17 as well as infiltrating inflammatory cells. However, combination of 50μl prednisolone and LGG decreased airway resistance and serum IgE and IgG1, inhibited the production of IL-4, IL-5, IL-6, IL-8, IL-13 and IL-17, upregulated serum IgG2a and enhanced Th1 immune response. LGG may reduce the dosage of prednisolone and thus may be beneficial in the treatment of asthma.

Codonopsis laceolata Water Extract Ameliorates Asthma Severity by Inducing Th2 Cells’ and Pulmonary Epithelial Cells’ Apoptosis via NF-κB/COX-2 Pathway

Asthma is an incurable pulmonary disease with several symptoms, including abnormal breathing, coughing, and sleep apnea, which can lead to death, and the population of asthma patients has been increasing worldwide. There are many adverse effects in current drugs, and thus, we have tried to develop anti-asthmatic agents from natural products such as Codonopsis laceolata. To define the anti-asthmatic effect and the mechanism of Codonopsis laceolata, an animal study was conducted considering different cell counts of BALF, serum IgE levels, morphological changes in the pulmonary system, the Th2 cell transcription factor (GATA-3), and the apoptotic pathway (NF-κB/COX-2). Codonopsis laceolata significantly suppressed the representative asthmatic changes, such as airway remodeling, mucous hypersecretion, epithelial hyperplasia, and inflammatory cell infiltration, in the respiratory system. It suppressed the levels of GATA-3, IL-4, and IL-13. The down-regulation of Th2-related factors, such as GATA-3, IL-4, and IL-13, results from the stimulated apoptosis of Th2 cells and epithelial cells via a decrease in the levels of NF-κB and COX-2. We concluded that Codonopsis laceolata might be a promising anti-asthmatic drug.

Role of Th17 Cytokines in Airway Remodeling in Asthma and Therapy Perspectives.

Airway remodeling is a frequent pathological feature of severe asthma leading to permanent airway obstruction in up to 50% of cases and to respiratory disability. Although structural changes related to airway remodeling are well-characterized, immunological processes triggering and maintaining this phenomenon are still poorly understood. As a consequence, no biotherapy targeting cytokines are currently efficient to treat airway remodeling and only bronchial thermoplasty may have an effect on bronchial nerves and smooth muscles with uncertain clinical relevance. Th17 cytokines, including interleukin (IL)-17 and IL-22, play a role in neutrophilic inflammation in severe asthma and may be involved in airway remodeling. Indeed, IL-17 is increased in sputum from severe asthmatic patients, induces the expression of “profibrotic” cytokines by epithelial, endothelial cells and fibroblasts, and provokes human airway smooth muscle cell migration in in vitro studies. IL-22 is also increased in asthmatic samples, promotes myofibroblast differentiation, epithelial-mesenchymal transition and proliferation and migration of smooth muscle cells in vitro. Accordingly, we also found high levels of IL-17 and IL-22 in a mouse model of dog-allergen induced asthma characterized by a strong airway remodeling. Clinical trials found no effect of therapy targeting IL-17 in an unselected population of asthmatic patients but showed a potential benefit in a sub-population of patients exhibiting a high level of airway reversibility, suggesting a potential role on airway remodeling. Anti-IL-22 therapies have not been evaluated in asthma yet but were demonstrated efficient in severe atopic dermatitis including an effect on skin remodeling. In this review, we will address the role of Th17 cytokines in airway remodeling through data from in vitro, in vivo and translational studies, and examine the potential place of Th17-targeting therapies in the treatment of asthma with airway remodeling.

Pathogenic changes in group 2 innate lymphoid cells (ILC2s) in a steroid-insensitive asthma model of mice

A certain population of asthma patients is resistant to steroid therapy, whereas the mechanisms remain unclear. One of characteristic features of steroid-resistant asthma patients is severe airway eosinophilia based on type-2 inflammation. Aims of this study were: 1) to develop a murine model of steroid-resistant asthma, 2) to elucidate that predominant cellular source of a type-2 cytokine, IL-5 was group 2 innate lymphoid cells (ILC2s), 3) to analyze pathogenic alteration of ILC2s in the severe asthma, and 4) to evaluate therapeutic potential of anti-IL-5 monoclonal antibody (mAb) on the steroid-resistant asthma. Ovalbumin (OVA)-sensitized BALB/c mice were intratracheally challenged with OVA at 5 or 500 μg/animal 4 times. Development of airway eosinophilia and remodeling in 5-μg OVA model were significantly suppressed by 1 mg/kg dexamethasone, whereas those in 500-μg OVA model were relatively insensitive to the dose of dexamethasone. ILC2s isolated from the lung of the steroid-insensitive model (500-μg OVA) produced significantly larger amounts of IL-5 in response to IL-33/TSLP than ILC2s from the steroid-sensitive model (5-μg OVA). Interestingly, TSLP receptor expression on ILC2s was up-regulated in the steroid-insensitive model. Treatment with anti-IL-5 mAb in combination with dexamethasone significantly suppressed the airway remodeling of the steroid-insensitive model. In conclusion, multiple intratracheal administration of a high dose of antigen induced steroid-insensitive asthma in sensitized mice. IL-5 was mainly produced from ILC2s, phenotype of which had been pathogenically altered probably through the up-regulation of TSLP receptors. IL-5 blockage could be a useful therapeutic strategy for steroid-resistant asthma.

The Impact of Tobacco Smoking on Adult Asthma Outcomes.

Background: Tobacco smoking is associated with more severe asthma symptoms, an accelerated decline in lung function, and reduced responses to corticosteroids. Our objective was to compare asthma outcomes in terms of disease control, exacerbation rates, and lung function in a population of asthmatic patients according to their smoking status. Methods: We compared patients’ demographics, disease characteristics, and lung-function parameters in current-smokers (CS, n = 48), former-smokers (FS, n = 38), and never-smokers (NS, n = 90), and identified predictive factors for asthma control. Results: CS had a higher prevalence of family asthma/atopy, a lower rate of controlled asthma, impaired perception of dyspnea, an increased number of exacerbations, and poorer lung function compared to NS. The mean asthma control questionnaire’s (ACQ) score was higher in CS vs. NS and FS (1.9 vs. 1.2, p = 0.02). Compared to CS, FS had a lower rate of exacerbations, a better ACQ score (similar to NS), a higher prevalence of dyspnea, and greater lung-diffusion capacity. Non-smoking status, the absence of dyspnea and exacerbations, and a forced expiratory volume in one second ≥80% of predicted were associated with controlled asthma. Conclusions: CS with asthma exhibit worse clinical and functional respiratory outcomes compared to NS and FS, supporting the importance of smoking cessation in this population.

Modified BuShenYiQi formula alleviates experimental allergic asthma in mice by negative regulation of type 2 innate lymphoid cells and CD4+ type 9 helper T cells and the VIP–VPAC2 signalling pathway

Context Modified BuShenYiQi formula (M-BYF) is derived from BuShenYiQi formula, used for the treatment of allergic asthma. The exact effect and mechanism of M-BYF on the improvement of asthma remain unclear. Objective We investigated the mechanism underlying the therapeutic effect of M-BYF on allergic asthma. Materials and methods The asthma model was established in female BALB/c mice that were sensitized and challenged with ovalbumin (OVA). Mice in the treated groups were orally treated once a day with M-BYF (7, 14 and 28 g/kg/d) or dexamethasone before OVA challenge. Control and Model group received saline. Pathophysiological abnormalities and percentages of lung type 2 innate lymphoid cells (ILC2s) and Th9 cells were measured. Expression levels of type 2 cytokines and transcription factors required for these cells function and differentiation were analysed. Expression of vasoactive intestinal polypeptide (VIP)–VPAC2 signalling pathway-related proteins, and percentages of VIP expressing (VIP+) cells and VPAC2, CD90 co-expressing (VPAC2+CD90+) cells were detected. Results M-BYF alleviated airway hyperresponsiveness, inflammation, mucus hypersecretion and collagen deposition in asthmatic mice. M-BYF down-regulated percentages of ILC2s and Th9 cells with lower expression of GATA3, PU.1 and IRF4, reduced IL-5, IL-13, IL-9 and VIP production. The decrease in the expression of VIP–VPAC2 signalling pathway and percentages of VIP+ cells, VPAC2+CD90+ cells were observed after M-BYF treatment. The LD50 value of M-BYF was higher than 90 g/kg. Discussion and conclusions M-BYF alleviated experimental asthma by negatively regulating ILC2s and Th9 cells and the VIP–VPAC2 signalling pathway. These findings provide the theoretical basis for future research of M-BYF in asthma patient population.

Effectiveness of the Air Purification Strategies for the Treatment of Allergic Asthma: A Meta-Analysis

FE van Boven, NW de Jong, GJ Braunstahl, LR Arends, R Gerth van Wijk. Int Arch Allergy Immunol . 2020;181(5):395–402 To update an existing systematic review by McDonald et al, which was conducted 20 years ago, by reviewing the clinical effectiveness of the air purification strategy for the treatment of allergic asthma. Participants included children and adults with physician-diagnosed bronchial allergic asthma with positive testing to house dust mite, dog, cat, or cockroach. A meta-analysis of trials evaluating the impact of housing or mobile ventilation systems, including HEPA filters but not vacuum cleaners, on allergic asthma. Studies were included only if they documented …

PRS7 Economic Savings Driven By the Coupled Use of Inhalers with Apps for Asthma in Portugal

Asthma places a considerable burden on healthcare systems, particularly when uncontrolled. It is estimated that 43% of asthma patients in Portugal have their disease uncontrolled. Common causes for uncontrolled asthma are sub optimal compliance and inadequate inhaler technique. The objective of this study is to evaluate the potential economic savings achieved through the use of inhalers coupled with apps to improve the inhaler technique and compliance of asthma patients. This analysis considered the Portuguese societal perspective. Direct costs (consultations, emergency, hospitalizations, exams/tests, and transportation) and indirect costs (absenteeism) related with asthma were derived from a previous Portuguese cost-of-illness study and inflated to 2020 EUR prices. The willingness to use apps for asthma control is based on reported literature from Portugal. According to previous studies, it is assumed that up to 72% of users of apps having uncontrolled asthma will reach proper control. Asthma accounts for a total annual burden of direct healthcare resources (excluding treatments) of € 274 million and of € 15.2 million in indirect costs. The uncontrolled asthma patient population accounts for 69% of the overall burden. Under assumptions on the willingness to use an app for asthma control daily, it is considered that 20.6% of the uncontrolled asthma patients would adopt it to improve medication compliance and inhaler technique, leading to 14.8% of the uncontrolled patient population achieving control. This would lead to a reduction of the overall annual direct medical costs by €17.5 million (-6%) and of €1.8 million (-12%) in indirect costs. The adherence/adoption of interventions by asthma patients to improve disease control will potentially have a significant impact in reducing the healthcare and societal burden of asthma in Portugal. The inclusion of additional technologies, such as sensors in inhalers coupled with apps, could further improve asthma control and economic outcomes.

Effect of Ambient Air Pollution on Hospital Readmissions among the Pediatric Asthma Patient Population in South Texas: A Case-Crossover Study.

Few studies have evaluated the association between ambient air pollution and hospital readmissions among children with asthma, especially in low-income communities. This study examined the short-term effects of ambient air pollutants on hospital readmissions for pediatric asthma in South Texas. A time-stratified case-crossover study was conducted using the hospitalization data from a children’s hospital and the air pollution data, including particulate matter 2.5 (PM2.5) and ozone concentrations, from the Centers for Disease Control and Prevention between 2010 and 2014. A conditional logistic regression analysis was performed to investigate the association between ambient air pollution and hospital readmissions, controlling for outdoor temperature. We identified 111 pediatric asthma patients readmitted to the hospital between 2010 and 2014. The single-pollutant models showed that PM2.5 concentration had a significant positive effect on risk for hospital readmissions (OR = 1.082, 95% CI = 1.008–1.162, p = 0.030). In the two-pollutant models, the increased risk of pediatric readmissions for asthma was significantly associated with both elevated ozone (OR = 1.023, 95% CI = 1.001–1.045, p = 0.042) and PM2.5 concentrations (OR = 1.080, 95% CI = 1.005–1.161, p = 0.036). The effects of ambient air pollutants on hospital readmissions varied by age and season. Our findings suggest that short-term (4 days) exposure to air pollutants might increase the risk of preventable hospital readmissions for pediatric asthma patients.

Retrospective Analysis to Describe Patient Profiles, Current Treatment Patterns and Economic Burden for Asthma Patients in UAE. A Descriptive Analysis of the Asthma Patient Population in the Emirate of Dubai With Respect to Healthcare Resource Utilization, Costs, and Asthma-related Treatment Pattern

Retrospective Analysis to Describe Patient Profiles, Current Treatment Patterns and Economic Burden for Asthma Patients in UAE. A Descriptive Analysis of the Asthma Patient Population in the Emirate of Dubai With Respect to Healthcare Resource Utilization, Costs, and Asthma-related Treatment Pattern

The Salford Lung Study is a way to improve asthma control in real clinical practice (a review)

The Salford Lung Study in asthma (SLS-Asthma) is the first prospective, randomized, controlled clinical trial conducted in conditions and in population that were very close to real clinical practice. The study demonstrated that treatment of a large heterogeneous population of asthma patients using combination of vilanterol (VI) and fluticasone furoate (FF) (22/92 mg q.d. or 22/184 mg q.d.) via Ellipta dry powder inhaler provided better control of the disease than the conventional therapy administered by an attendant physician. The level of asthma control in VI/FF group was consistently maintained for 12 months with no identified change in risk of development of serious adverse events. Results were similar in patients receiving ICS or ICS/LABA combinations and did not depend on smoking status or number of exacerbations over the previous year.

What are the characteristics of asthma patients with elevated serum IgG4 levels?

IntroductionIgG4 has recently been a subject of great interest in human pathology. No data are available about the characteristics of asthma patients with elevated IgG4 levels. Population and methodsAn observational study was conducted from January 2006 to March 2015 in a difficult-to-treat population of asthma patients. Twenty-six difficult-to-treat asthma patients with elevated serum IgG4 levels (IgG4/IgG ratio up to 10%) were compared with a control population of 98 difficult-to-treat asthma patients with normal serum IgG4. Blood eosinophilia, total IgE and FeNO were compared between groups to better characterize asthma patients with elevated serum IgG4 levels. ResultsMedian IgG4 concentrations were 1.72 g/l [1.19–2.36] and 0.22 g/l [0.10–0.49] in the elevated IgG4 group and normal Ig4 group, respectively. Median blood eosinophilia was more than three times higher in patients with elevated serum IgG4 levels than in controls (0.75 109/L [IQR 0.54–1.78] vs 0.22 109/L [IQR 0.09–0.54] respectively, p < 0.0001). Total IgE was twice as high (264.5 kUI/l [IQR 166.3–779] vs 126 kUI/l [IQR 26–350] respectively; p < 0.05) and FeNO was nearly twice as high (61 [IQR 41–111] ppb vs 35 [IQR 23–51] ppb, p < 0.001). Allergic broncho-pulmonary aspergillosis (ABPA) and eosinophilic granulomatosis with polyangiitis (EGPA) were observed in the asthma patients with elevated serum IgG4. Ten patients had unexplained increased blood eosinophilia. ConclusionAsthma patients with elevated IgG4 levels have significantly higher blood eosinophilia, total IgE and FeNO. ABPA and EGPA are observed in patients with elevated serum IgG4.