Exhaled nitric oxide levels and blood eosinophil counts independently associate with wheeze and asthma events in National Health and Nutrition Examination Survey subjects

Blood eosinophil reference values and determinants in a representative adult population

Background

The use of blood eosinophil count (BEC) as a prognostic biomarker in the management of conditions such as asthma and chronic obstructive pulmonary disease (COPD) may be complicated by factors such as atopy, age, sex, smoking, and comorbidities.

Objective

We sought to produce reference values for BEC, considering age, asthma, COPD, and clinical allergy for the general adult population.

Methods

The West Sweden Asthma Study constitutes a population-representative clinical epidemiological cohort of randomly selected adults in Western Sweden. From this cohort, 1145 individuals took part in clinical examinations, including skin prick testing, specific IgE, and BEC.

Results

The upper limit (95th percentile) of BEC varied by age. It ranged from 400 to 500 cells/μL in the full sample and from 300 to 400 cells/μL in subjects without asthma, COPD, and clinical allergy (n = 710). Sex, smoking, atopy, clinical allergy, obesity, asthma, COPD, diabetes, and hypertension were statistically significantly associated with higher BEC levels. However, only asthma and clinical allergy in the full sample, and obesity and diabetes in those without asthma, COPD, or clinical allergy, remained statistically significant with higher BEC levels in multivariable regression analyses.

Conclusions

In a population-representative sample, the upper limit of BEC in healthy adults ranged between 300 and 400 cells/μL, varying by age. Age, smoking, obesity, asthma, COPD, and clinical allergy influence BEC levels and should be considered in clinical interpretation.

Guidance for type 2 inflammatory biomarkers

Type 2 inflammation in the airways and lungs is inflammation induced by type 2 cytokines such as IL-4, IL-5, and IL-13, produced primarily by type 2 helper T cells and type 2 innate lymphoid cells, and causes changes in the physiology and structure of the airways. Type 2 inflammation is currently in the spotlight because of its direct link to the treatment of several airway and lung diseases. Abundant evidences have accumulated that inflammatory biomarkers such as blood eosinophils, fractional exhaled nitric oxide, and IgE are essential clinical tools in the diagnosis and management of asthma and COPD. It is well known that asthma and COPD have diverse inflammatory phenotypes even when clinical features are similar, and it has been demonstrated that assessment of airway inflammation with biomarkers can improve diagnostic accuracy, determine safer and more effective treatment strategies, and predict future risks such as exacerbations and lung function decline. The Japanese Respiratory Society has published clinical practice guidelines for the evaluation of type 2 inflammation in the airways and lungs. In addition to asthma and COPD, the guide covers a wide range of airway and lung diseases, including interstitial lung disease, allergic bronchopulmonary mycosis, allergic rhinitis, and eosinophilic chronic rhinosinusitis. It also provides comprehensive guidelines covering a variety of clinical biomarkers. The purpose of this guidance is to provide evidences for the interpretation of type 2 inflammation measurements and to promote the widespread use of inflammation assessment to further improve the efficiency of airway and respiratory disease management.

Mitochondrial DNA copy number variation in asthma risk, severity, and exacerbations

BACKGROUND

Asthma pathophysiology is associated with mitochondrial dysfunction. Mitochondrial DNA copy number (mtDNA-CN) has been used as a proxy of mitochondrial function, with lower levels indicating mitochondrial dysfunction in population studies of cardiovascular diseases and cancers.

OBJECTIVES

We investigated whether lower levels of mtDNA-CN are associated with asthma diagnosis, severity, and exacerbations.

METHODS

mtDNA-CN is evaluated in blood from 2 cohorts: UK Biobank (UKB) (asthma, n = 39,147; no asthma, n = 302,302) and Severe Asthma Research Program (SARP) (asthma, n = 1283; nonsevere asthma, n = 703).

RESULTS

Individuals with asthma have lower mtDNA-CN compared to individuals without asthma in UKB (beta, -0.006 [95% confidence interval, -0.008 to -0.003], P = 6.23 × 10-6). Lower mtDNA-CN is associated with asthma prevalence, but not severity in UKB or SARP. mtDNA-CN declines with age but is lower in individuals with asthma than in individuals without asthma at all ages. In a 1-year longitudinal study in SARP, mtDNA-CN was associated with risk of exacerbation; those with highest mtDNA-CN had the lowest risk of exacerbation (odds ratio 0.333 [95% confidence interval, 0.173 to 0.542], P = .001). Biomarkers of inflammation and oxidative stress are higher in individuals with asthma than without asthma, but the lower mtDNA-CN in asthma is independent of general inflammation or oxidative stress. Mendelian randomization studies suggest a potential causal relationship between asthma-associated genetic variants and mtDNA-CN.

CONCLUSION

mtDNA-CN is lower in asthma than in no asthma and is associated with exacerbations. Low mtDNA-CN in asthma is not mediated through inflammation but is associated with a genetic predisposition to asthma.

Assessing the Impact of Metalworking Exposures on Respiratory Health: The Role of Fractional Exhaled Nitric Oxide Levels

OBJECTIVE

The significance of measuring Fractional Exhaled Nitric Oxide (FeNO) has grown, particularly in monitoring respiratory diseases like asthma. FeNO levels indicate inflammation and a rise in response to respiratory irritants. This study investigates whether repeated exposure to irritants in metal casting and coating leads to respiratory inflammation and assesses the benefits of including FeNO measurement in periodic occupational health screenings.

METHODS

This cross-sectional study involved 99 workers aged 18-65 in the foundry and metal coating sectors in the İkitelli Organized Industrial Zone. The study group included 54 workers exposed to metal dust and fumes, while the control group comprised 45 workers in non-exposure roles (e.g., secretarial, assembly, packaging). Data were collected through face-to-face interviews, recording demographics, smoking habits, symptoms. FeNO levels were measured and analyzed with pulmonary function test parameters.

RESULTS

FeNO levels were significantly higher in the study group compared to the control group (p = 0.02). No significant relationships were found between FeNO levels and age, height, weight, BMI, waist circumference, years of work, or symptom presence, but a significant negative correlation was observed between FeNO levels and FEV1/FVC. Additionally, current smokers had significantly lower FeNO levels compared to those who had quit or never smoked (study, p = 0.014; control, p = 0.011).

CONCLUSION

Monitoring FeNO levels in occupational health assessments may facilitate early intervention and preventive measures, protecting worker health. Incorporating FeNO measurement into periodic screenings could enhance occupational health practices.

The association between peripheral eosinophil count and chronic kidney disease: evidence from NHANES 1999-2018

BACKGROUND

Renal impairment has been previously linked to peripheral eosinophil count (PEC), prompting an investigation into its potential relationship with chronic kidney disease (CKD). This cross-sectional study utilized data from the National Health and Nutrition Examination Survey (NHANES 1999-2018) to comprehensively explore the association between PEC and CKD.

METHODS

Survey-weighted generalized multivariate linear regression was employed to evaluate the associations between PEC, urinary albumin-to-creatinine ratio (UACR), and estimated glomerular filtration rate (eGFR), with meticulous adjustment for potential covariates. To assess non-linear correlations, a restricted cubic spline analysis was conducted. Sensitivity analysis was performed to test the stability of results.

RESULTS

The study included a total of 9224 participants with non-dialysis CKD. In the multivariate linear regression model, after comprehensive adjustment for potential covariates, PEC showed a negative association with eGFR (β per 100 cells/uL increase in PEC, -0.71; 95% CI, -1.04, -0.37), while demonstrating a positive trend with UACR (β per 100 cells/uL increase in PEC, 10.21; 95% CI, 1.37, 19.06). The restrictive cubic spline curve analysis suggested that these associations occurred within the range of 0 to 400 cells/uL for PEC. Sensitivity analysis supported the stability of the observed results.

CONCLUSIONS

Circulating eosinophil levels are negatively correlated with eGFR and demonstrate a positive trend with UACR, when PEC falls within the range of less than 400 cells/uL among adults with CKD. Further research is warranted to validate these findings.

Type-2 Inflammation in Health and Disease: Prevalence, Risk Factors and Multimorbidity

Background: In patients with airflow obstruction, the levels of biomarkers of Type-2 (T2) inflammation serve to predict the effectiveness of inhaled corticosteroid and biological therapies. Elevated biomarkers of T2 inflammation, including fractional exhaled nitric oxide (FeNO, ≥20 ppb) and blood eosinophil counts (BEC, ≥300 cells/µL), were investigated in a population-based cohort of the Austrian LEAD study. Methods: A total of 4976 individuals (aged 18-82 years) were categorised into four groups based on their FeNO and BEC levels: normal with FeNO < 20 ppb and BEC < 300 cells/µL (n = 2634); FeNO ≥ 20 ppb only (n = 1623); BEC ≥ 300 cells/µL only (n = 340); and FeNO ≥ 20 ppb and BEC ≥ 300 cells/µL (n = 379). Results: In age- and sex-adjusted regression models, individuals with elevated BEC only were most associated with chronic cough and sputum production (odds ratios [95% CI]: 1.22 [0.78, 1.84] and 1.37 [1.13, 2.62], respectively), whilst individuals with both elevated T2 biomarkers were most associated with wheezing, dyspnoea and asthma (odds ratios [95% CI]: 2.27 [1.56, 3.26], 1.32 [0.64, 2.50] and 3.63 [2.69, 4.88] respectively). Elevated levels of both FeNO and BEC presented an additive effect in extrapulmonary conditions, particularly in allergy, eczema and rhino conjunctivitis (odds ratios [95% CI]: 2.30 [1.84, 2.88], 1.37 [1.03, 1.81] and 2.95 [2.34, 3.70], respectively). Conclusions: T2 inflammation marked by elevated levels of FeNO and/or BEC is not only associated with respiratory conditions but also extends to extrapulmonary characteristics, with an additive effect.

High blood eosinophils predict the risk of COPD exacerbation: A systematic review and meta-analysis

BACKGROUND

The association between blood eosinophils and COPD exacerbation has been controversial. This study aims to investigate whether high blood eosinophils predict the risk of COPD exacerbation across different thresholds and subgroups.

METHODS

PubMed, Embase and Web of science were searched for randomized controlled trial (RCT) and observational studies regarding the relationship between blood eosinophils and COPD exacerbation. Pooled risk ratio (RR) for COPD exacerbation was calculated using the Mantel-Haenszel method with a random-effects model.

RESULTS

A total of 21 studies (1 RCT and 20 observational studies) with 79868 participants were included. Thresholds of high blood eosinophils including absolute counts (200, 300 and 400 cell/μL) and percentages (2%, 3% and 4%) were analyzed respectively. Pooled analyses suggested that high blood eosinophils were significantly associated with increased risk of COPD exacerbation when using the thresholds of 300 cells/μL (RR 1.21, 95%CI 1.12-1.30, P <0.001, 16 studies), 400 cells/μL (RR 1.79, 95%CI 1.41-2.28, P <0.001, 3 studies), 2% (RR 1.26, 95%CI 1.02-1.55, P = 0.030, 10 studies) and 4% (RR 1.44, 95%CI 1.05-1.96, P = 0.022, 4 studies), but not 200 cells/μL and 3% (P>0.05). Moreover, high blood eosinophils contributed to moderate-severe exacerbation of COPD by the cutoffs of 300 cells/μL (RR 1.30, 95%CI 1.16-1.45, P<0.001, 11 studies) and 2% (RR 1.33, 95%CI 1.02-1.76, P = 0.037, 8 studies). In subgroup analyses, the pooled results further showed a significant association between high blood eosinophils (especially over 300 cells/μL) and risk of COPD exacerbation among patients from Europe and Asia, and whether with stable or exacerbation phase at baseline, and regardless of the follow-up time (≤ or > 1year).

CONCLUSIONS

This study demonstrates that high blood eosinophils (over 300 cells/μL or 2%) could predict the risk of moderate-severe exacerbation of COPD in specific subgroups. However, large sample-sized, prospective, and well-designed studies are required to validate the present findings.

Clinical and Economic Burden of Severe Asthma With Low Blood Eosinophil Counts

BACKGROUND

Type 2 low-severe asthma phenotype is often a result of corticosteroid-overtreated type 2 disease owing to persistent symptoms, often unrelated to asthma and unlikely to respond to high-dose corticosteroid treatment.

OBJECTIVE

This study aimed to characterize patients with severe asthma with low eosinophil counts (<300 cells/μL) and describe their disease burden and treatment across health care settings in the United Kingdom.

METHODS

A retrospective cohort study of patients with severe asthma using linked Clinical Practice Research Datalink (CPRD) Aurum-Hospital Episode Statistics (HES) and UK Severe Asthma Registry (UKSAR) data indexed patients according to the latest blood eosinophil count (BEC). Clinical characteristics, treatment patterns, outcomes, and health care resource use were described by baseline BEC (≤150 and >150 to <300 cells/μL).

RESULTS

Analysis included 701 (CPRD-HES) and 1,546 (UKSAR) patients; 60.5% and 59.4% had BECs 150 cells/μL or less at baseline, respectively. Across BEC groups, the proportion with uncontrolled asthma (two or more exacerbations) at follow-up (12 months after the index) was 5.4% in CPRD-HES and 45.2% in UKSAR. Maintenance oral corticosteroid use remained high across BEC groups (CPRD-HES: 29.4%; UKSAR: 51.7%), symptom control remained poor (>200 μg short-acting β2 agonist or >500 μg terbutaline/d in CPRD-HES: 48.8%; median Asthma Control Questionnaire-6 score in UKSAR: 2.0 [range, 1.0-3.3]). Health care resource use was similar across BEC groups.

CONCLUSIONS

Most patients managed in primary care experienced infrequent exacerbations, whereas UKSAR patients had frequent exacerbations. Large proportions of both patient groups had poor symptom control and continued to receive high levels of maintenance oral corticosteroids, increasing the risk of corticosteroid-induced morbidity. These data highlight the need for rigorous assessment of underlying disease pathology to guide appropriate treatment.

Respiratory failure in a patient with exhaled nitric oxide >300 ppb and subsequent response to dupilumab

Multiple biologic agents are approved for the treatment of severe persistent asthma not controlled by inhaled corticosteroid/beta-agonist therapy. Appropriate phenotyping can aid in picking the right biologic for the right patient. Here is a unique case of a patient with severe asthma and respiratory arrest, with fraction of exhaled nitric oxide >300 ppb whose asthma became completely controlled with dupilumab.

An observational analysis on the influence of parental allergic rhinitis, asthma and smoking on exhaled nitric oxide in offspring

BACKGROUND

Parental allergic diseases and smoking influence respiratory disease in the offspring but it is not known whether they influence fractional exhaled nitric oxide (FeNO) in the offspring. We investigated whether parental allergic diseases, parental smoking and FeNO levels in parents were associated with FeNO levels in their offspring.

METHODS

We studied 609 offspring aged 16-47 years from the Respiratory Health in Northern Europe, Spain and Australia generation (RHINESSA) study with parental information from the Respiratory Health in Northern Europe (RHINE) III study and the European Community Respiratory Health Survey (ECRHS) III. Linear regression models were used to assess the association between offspring FeNO and parental FeNO, allergic rhinitis, asthma and smoking, while adjusting for potential confounding factors.

RESULTS

Parental allergic rhinitis was significantly associated with higher FeNO in the offspring, both on the paternal and maternal side (percent change: 20.3 % [95%CI 5.0-37.7], p = 0.008, and 13.8 % [0.4-28.9], p = 0.043, respectively). Parental allergic rhinitis with asthma in any parent was also significantly associated with higher offspring FeNO (16.2 % [0.9-33.9], p = 0.037). However, parental asthma alone and smoking were not associated with offspring FeNO. Parental FeNO was not associated with offspring FeNO after full adjustments for offspring and parental factors.

CONCLUSIONS

Parental allergic rhinitis but not parental asthma was associated with higher levels of FeNO in offspring. These findings suggest that parental allergic rhinitis status should be considered when interpreting FeNO levels in offspring beyond childhood.

Mepolizumab in children and adolescents with severe eosinophilic asthma not eligible for omalizumab: a single Center experience

BACKGROUND

Mepolizumab is an anti-interleukin-5 monoclonal antibody shown to reduce asthma exacerbations in adults and adolescents with severe eosinophilic asthma.

AIM

To assess the impact of mepolizumab on children and adolescents over 12 months by examining steroid usage, asthma-related hospitalizations, Asthma Control Test (ACT) scores, fractional exhaled nitric oxide concentration (FeNO), forced expiratory volume in 1 s (FEV1), mid expiratory flow (FEF25-75%), and blood eosinophil count.

METHODS

Retrospective analysis performed between October 2015 and December 2022. Data was reviewed 12 months before and after commencing mepolizumab. Mepolizumab was offered if the patient had severe eosinophilic asthma and were unresponsive to or ineligible for omalizumab.

RESULTS

Sixteen participants (age 7-17, 8 males, 8 females) received subcutaneous mepolizumab monthly with no serious adverse reactions. Incidence of hospital admissions fell significantly (IRR 0.33, p = 0.007). Among the 11 patients receiving daily oral corticosteroids, 3 were weaned off daily oral steroids and 3 patients' daily dose was significantly reduced (mean Δ-0.095 ± 0.071 mg/kg, p = 0.0012). Eosinophil count was decreased (mean Δ-0.85 x 109/L, p < 0.001). There was no significant change in mean overall steroid burden per patient (mean Δ-1445.63 ± 1603.18 mg, p = 0.10), ACT scores (mean Δ2.88 ± 6.71, p = 0.17), FEV1 z-scores (mean Δ-0.99 ± 1.88, p = 0.053), FEF25-75% z-scores (mean Δ-0.65 ± 1.61, p = 0.13), FeNO (mean Δ-20.09 ± 80.86, p = 0.34), or number of courses of oral steroids given for asthma attacks (IRR 0.71, p = 0.09).

CONCLUSION

Among children and adolescents with severe eosinophilic asthma ineligible for or not responsive to omalizumab, mepolizumab therapy exhibited significant reduction in rate of asthma-related hospitalizations and significant decrease in daily steroid dosage.

Lack of Association between Inhaled Corticosteroid Use Based on the Exhaled Nitric Oxide and Acute Exacerbation of Chronic Obstructive Pulmonary Disease

BACKGROUND

Fractional exhaled nitric oxide (FeNO) is known to useful biomarker for detecting eosinophilic airway inflammation. However, there is a lack of evidence regarding the role of FeNO in chronic obstructive pulmonary disease (COPD). We aimed to assess whether elevated FeNO and its impact on treatment change into an inhaled corticosteroid (ICS)-containing regimen and association with acute exacerbation (AE) in patients with COPD.

METHODS

We retrospectively analyzed 107 COPD patients without a history of asthma from March 2016 to December 2019. The patients whose FeNO value was more than 50 parts per billion (ppb) were defined into the high FeNO group. Multivariable analysis with logistic regression was used to identify factors associated with AE in COPD.

RESULTS

The median FeNO value was 32 ppb (interquartile range, 19 to 45) and 34 (20.0%) patients were classified as high FeNO group (median 74 ppb). In the high FeNO group, changes in inhaler treatment into an ICS-containing regimen occurred in 23 of 34 patients after the measurement of FeNO. In multivariate analysis, high FeNO was not a contributing factor for AE, but only the high blood eosinophil count (≥300 cells/μL) was associated with AE (adjusted odds ratio, 2.63; 95% confidence interval, 1.01 to 6.91; p=0.049).

CONCLUSION

High FeNO value had a significant impact on the prescription of ICSs in COPD patients, but it did not show a significant association with AE either on its own or with changes in treatment.

The Fractional exhaled Nitric Oxide (FeNO)- test as add-on test in the diagnostic work-up of asthma: a study protocol

BACKGROUND

Asthma is a common disease characterized by chronic inflammation of the lower airways, bronchial hyperactivity, and (reversible) airway obstruction. The Global Initiative of Asthma Guideline recommends a flowchart to diagnose asthma with first-step spirometry with reversibility and a bronchial challenge test (BPT) with histamine or methacholine as a second step [1]. The BPT is considered burdensome, time-consuming for patients and staff, can cause side effects, and is expensive. In addition, this test strongly encumbers lung function capacity. Elevated Nitric Oxide (NO) is associated with airway eosinophilic inflammation in asthma patients and can be measured in exhaled air with the Fractional exhaled (Fe) NO-test. This low-burden FeNO-test could be used as an 'add-on' test in asthma diagnostics [2, 3].

METHODS AND ANALYSIS

This multi-center prospective study (Trial number: NCT06230458) compares the 'standard asthma diagnostic work-up' (spirometry with reversibility and BPT) to the 'new asthma diagnostics work-up' (FeNO-test as an intermediate step between the spirometry with reversibility and the BPT), intending to determine the impact of the FeNO-based strategy, in terms of the number of avoided BPTs, cost-effectiveness and reduced burden to the patient and health care. The cost reduction of incorporating the FeNO-test in the new diagnostic algorithm will be established by the number of theoretically avoided BPT. The decrease in burden will be studied by calculating differences in the Visual Analogue Scale (VAS) -score and Asthma Quality of Life Questionnaire (AQLQ) -score after the BPT and FeNO-test with an independent T-test. The accuracy of the FeNO-test will be calculated by comparing the FeNO-test outcomes to the (gold standard) BPTs outcomes in terms of sensitivity and specificity. The intention is to include 171 patients.

ETHICS AND DISSEMINATION

The local medical ethics committee approved the proposed study and is considered a low-burden and risk-low study. The local medical ethics committee registration number: R23.005.

STRENGTHS AND LIMITATIONS OF THIS STUDY

Strengths: This is the first study that investigates the value of the FeNO-test (cut off ≥ 50 ppb) as an add-on test, to determine the impact of the FeNO-based strategy, in terms of the number of avoided BPTs, cost-effectiveness, and reduced burden on the patient and health care.

LIMITATIONS

High FeNO levels may also be observed in other diseases such as eosinophilic chronic bronchitis and allergic rhinitis. The FeNO-test can be used to rule in a diagnosis of asthma with confidence, however, due to the poor sensitivity it is not suitable to rule out asthma.

Type-2 inflammation and lung function decline in chronic airway disease in the general population

BACKGROUND

It is unclear if type-2 inflammation is associated with accelerated lung function decline in individuals with asthma and chronic obstructive pulmonary disease (COPD). We tested the hypothesis that type-2 inflammation indicated by elevated blood eosinophils (BE) and fraction of exhaled nitric oxide (FeNO) is associated with accelerated lung function decline in the general population.

METHODS

We included adults from the Copenhagen General Population Study with measurements of BE (N=15 605) and FeNO (N=2583) from a follow-up examination and assessed forced expiratory volume in 1 s (FEV1) decline in the preceding 10 years. Based on pre- and post-bronchodilator lung function, smoking history and asthma at follow-up examination, participants were assigned as not having airway disease, asthma with full reversibility (AR), asthma with persistent obstruction (APO), COPD, and not classifiable airflow limitation (NAL).

RESULTS

FEV1 decline in mL/year increased with 1.0 (95% CI 0.6 to 1.4, p<0.0001) per 100 cells/µL higher BE and with 3.2 (95% CI 2.0 to 4.5, p<0.0001) per 10 ppb higher FeNO. Adjusted FEV1 decline in mL/year was 18 (95% CI 17 to 20) in those with BE<300 cells/µL and FeNO<20 ppb, 22 (19-25) in BE≥300 cells/µL or FeNO≥20 ppb, and 27 (21-33) in those with BE≥300 cells/µL and FeNO≥20 ppb (p for trend<0.0001). Corresponding FEV1 declines were 24 (19-29), 33 (25-40) and 44 (31-56) in AR (0.002), 26 (14-37), 36 (12-60) and 56 (24-89) in APO (0.07), 32 (27-36), 31 (24-38) and 44 (24-65) in COPD (0.46), and 27 (21-33), 35 (26-45), and 37 (25-49) in NAL (0.10), respectively.

CONCLUSIONS

Type-2 inflammation indicated by elevated BE and FeNO is associated with accelerated FEV1 decline in individuals with chronic airway disease in the general population, and this association was most pronounced in an asthma-like phenotype.

A systematic review and meta-analysis on absolute eosinophil counts and the risk of asthma in preschool children with wheezing: An EAACI Task Force Report

Preschool children with wheezing disorders pose diagnostic and therapeutic challenges and consume substantial healthcare resources. Peripheral eosinophil blood count (EBC) has been proposed as a potential indicator for future asthma development. This review by the European Academy of Allergy and Clinical Immunology (EAACI) Preschool Wheeze Task Force aimed to provide systematic evidence for the association between increased EBC and the risk of future asthma, as well as to identify potential cutoff values. In February 2023, a search of PubMed, EMBASE, and Cochrane Library databases was conducted to identify studies comparing EBCs in preschool children with wheezing who continued to wheeze later in life and those who did not. Included observational studies focused on children aged <6 years with a wheezing disorder, assessment of their EBCs, and subsequent asthma status. No language or publication date restrictions were applied. Among the initial 3394 studies screened, 10 were included in the final analysis, involving 1225 patients. The data from these studies demonstrated that high EBC in preschool children with wheezing is associated with future asthma development, with odds ratios of 1.90 (95% CI: 0.45-7.98, p = .38), 2.87 (95% CI: 1.38-5.95, p < .05), and 3.38 (95% CI: 1.72-6.64, p < .05) for cutoff values in the <300, 300-449, and ≥450 cells/μL ranges, respectively. Defining a specific cutoff point for an elevated EBC lacks consistency, but children with EBC >300 cells/μL are at increased risk of asthma. However, further research is needed due to the limitations of the included studies. Future investigations are necessary to fully elucidate the discussed association.

Clinical Remission in Patients Affected by Severe Eosinophilic Asthma on Dupilumab Therapy: A Long-Term Real-Life Study

Background. Nowadays, highly selective biological drugs offer the possibility of treating severe type 2 asthma. However, in the real-life setting, it is crucial to confirm the validity of the chosen biological treatment by evaluating the achievement of clinical remission. Study purpose. The main aims of this real-life study were to evaluate the efficacy of dupilumab in terms of clinical, functional, and inflammatory outcomes at 6, 12, 18, and 24 months of treatment and to estimate the percentage of patients achieving partial or complete clinical remission at 12 and 24 months of treatment. In addition, we attempted to identify whether baseline clinical characteristics of patients could be associated with clinical remission at 24 months of treatment. Materials and methods. In this observational prospective study, 20 outpatients with severe uncontrolled eosinophilic asthma were prescribed dupilumab and followed-up after 6, 12, 18, and 24 months of treatment. At each patient visit, the need for oral corticosteroids (OCS) and corticosteroid required dose, number of exacerbations during the previous year or from the previous visit, asthma control test (ACT) score, pre-bronchodilator forced expiratory volume in the 1st second (FEV1), fractional exhaled nitric oxide at a flow rate of 50 mL/s (FeNO50), and blood eosinophil count were assessed. Results. The number of OCS-dependent patients was reduced from 10 (50%) at baseline to 5 (25%) at one year (T12) and 2 years (T24). The average dose of OCS required by patients demonstrated a significant reduction at T12 (12.5 ± 13.75 mg vs. 2.63 ± 3.94 mg, p = 0.015), remaining significant even at T24 (12.5 ± 13.75 mg vs. 2.63 ± 3.94 mg, p = 0.016). The number of exacerbators showed a statistically significant decrease at T24 (10 patients, 50% vs. 3 patients, 15%, p = 0.03). The mean number of exacerbations demonstrated a statistically significant reduction at T24 (1.45 ± 1.58 vs. 0.25 ± 0.43, p = 0.02). The ACT score improved in a statistically significant manner at T12 (15.30 ± 4.16 vs. 21.40 ± 2.35, p < 0.0001), improving further at T24 (15.30 ± 4.16 vs. 22.10 ± 2.59, p < 0.0001). The improvement in pre-bronchodilator FEV1 values reached statistical significance at T24 (79.5 ± 14.4 vs. 87.7 ± 13.8, p = 0.03). The reduction in flow at the level of the small airways (FEF25-75%) also demonstrated an improvement, although it did not reach statistical significance either at T12 or T24. A total of 11 patients (55%) showed clinical remission at T12 (6 complete + 5 partial) and 12 patients (60%) reached clinical remission at T24 (9 complete + 3 partial). Only obesity was associated with a negative odds ratio (OR) for achieving clinical remission at T24 (OR: 0.03, 95% CI: 0.002-0.41, p = 0.004). No other statistically significant differences in baseline characteristics emerged between patients who reached clinical remission at T24 and the group of patients who did not achieve this outcome. Conclusion. Dupilumab appears to be an effective drug in promoting achievement of clinical remission in patients with severe uncontrolled eosinophilic asthma. The achievement of clinical remission should be continuously evaluated during treatment. Further studies are needed to clarify whether certain baseline clinical characteristics can help predict dupilumab favorable outcomes.

The Impact of Airway Obstruction on Feno Values in Asthma Patients

BACKGROUND

Exhaled nitric oxide (Feno) is used as a marker of type-2 airway inflammation in asthma management. Studies with airway challenges demonstrated that a reduction in airway caliber decreases Feno levels.

OBJECTIVE

To evaluate the impact of airway caliber reduction occurring spontaneously in patients with asthma on Feno values in daily clinical practice.

METHODS

In this post hoc analysis, Feno, FEV1, and asthma control questionnaire scores were recorded on each visit for 120 (1073 visits) adult patients with asthma. Blood eosinophils were measured intermittently. The intraindividual relationship between Feno and FEV1 was evaluated via a linear mixed model. The determinants of the individual mean Feno were measured by a stepwise multivariate linear model including individual mean FEV1, inhaled corticosteroid dose, asthma control questionnaire score, and blood eosinophils.

RESULTS

Variations in the negative Feno-FEV1 relationship within individuals at different times were significantly determined by the individual's mean FEV1. This relationship did not hold for individuals above the 75th and below the 25th quartiles. The best explanatory variables for individual mean Feno were FEV1 (+4.3 parts per billion/10%pred) and blood eosinophil count (+1 part per billion per 100 cells/mm3).

DISCUSSION

In the presence of variable degrees of heterogeneous patterns of airway inflammation, airway caliber is shown to be an independent and significant determinant of Feno when measured in patients with asthma. We would propose a +4-parts-per-billion correction factor to the measured Feno value for each 10% reduction below 100% predicted FEV1. Doing this should improve the rigor of interpretation of Feno as an indicator of type-2 inflammation in patients with low FEV1.

Prediction of Asthma Exacerbations in Children

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

Mitochondrial DNA Copy Number Variation in Asthma Risk, Severity, and Exacerbations

Rationale

Although airway oxidative stress and inflammation are central to asthma pathogenesis, there is limited knowledge of the relationship of asthma risk, severity, or exacerbations to mitochondrial dysfunction, which is pivotal to oxidant generation and inflammation.

Objectives

We investigated whether mitochondrial DNA copy number (mtDNA-CN) as a measure of mitochondrial function is associated with asthma diagnosis, severity, oxidative stress, and exacerbations.

Methods

We measured mtDNA-CN in blood in two cohorts. In the UK Biobank (UKB), we compared mtDNA-CN in mild and moderate-severe asthmatics to non-asthmatics. In the Severe Asthma Research Program (SARP), we evaluated mtDNA-CN in relation to asthma severity, biomarkers of oxidative stress and inflammation, and exacerbations.

Measures and Main Results

In UK Biobank, asthmatics (n = 29,768) have lower mtDNA-CN compared to non-asthmatics (n = 239,158) (beta, -0.026 [95% CI, -0.038 to -0.014], P = 2.46×10-5). While lower mtDNA-CN is associated with asthma, mtDNA-CN did not differ by asthma severity in either UKB or SARP. Biomarkers of inflammation show that asthmatics have higher white blood cells (WBC), neutrophils, eosinophils, fraction exhaled nitric oxide (FENO), and lower superoxide dismutase (SOD) than non-asthmatics, confirming greater oxidative stress in asthma. In one year follow-up in SARP, higher mtDNA-CN is associated with reduced risk of three or more exacerbations in the subsequent year (OR 0.352 [95% CI, 0.164 to 0.753], P = 0.007).

Conclusions

Asthma is characterized by mitochondrial dysfunction. Higher mtDNA-CN identifies an exacerbation-resistant asthma phenotype, suggesting mitochondrial function is important in exacerbation risk.

A cross-sectional analysis of medical conditions and environmental factors associated with fractional exhaled nitric oxide (FeNO) in women and children from the ISA birth cohort, Costa Rica

BACKGROUND

Fractional exhaled nitric oxide (FeNO) is a marker of airway inflammation. Elevated FeNO has been associated with environmental exposures, however, studies from tropical countries are limited. Using data from the Infants' Environmental Health Study (ISA) birth cohort, we evaluated medical conditions and environmental exposures' association with elevated FeNO.

METHODS

We performed a cross-sectional analysis of 277 women and 293 8-year old children who participated in the 8-year post-partum visit in 2019. We measured FeNO and collected information on medical conditions and environmental exposures including smoke from waste burning, work in banana plantations, and home pesticide use. We defined elevated FeNO as >25 ppb for women and >20 ppb for children. To evaluate factors associated with elevated FeNO, we used logistic regression models adjusted for obesity in women and unadjusted in children.

RESULTS

Overall elevated FeNO was common (20% of women, 13% of children). Rhinitis diagnosis was significantly associated with elevated FeNO in both women (odds ratio (OR): 3.67 95% Confidence Interval (CI): 1.81,7.35) and children (OR: 8.18 95%CI: 3.15, 21.22); wheeze was associated with elevated FeNO in women (OR: 4.50 95% CI: 2.25, 8.99). Environmental exposures were associated with elevated FeNO, but not significantly. Waste burning was associated with elevated FeNO in both women (OR: 1.58 95%CI 0.68, 4.15) and children (OR: 2.49 95%CI:0.82, 10.79). Para-occupational pesticide exposures were associated with elevated FeNO in women and children. For women, having a partner working in agriculture was associated with elevated FeNO (OR: 1.61 95%CI:0.77, 3.58) and for children, maternal work in agriculture was associated with elevated FeNO. (OR 2.08 95%CI 0.86, 4.67) CONCLUSION: Rhinitis and wheeze were associated with elevated FeNO in this rural, agricultural population. Smoke from waste burning as well as para-occupational pesticide exposure may contribute to elevated FeNO in rural communities.

1-Year Prospective Study of the Relationship of Serial Exhaled Nitric Oxide Level and Asthma Control

Background and Objective

Previous studies found that the fractional nitric oxide concentration in exhaled breath (FeNO) levels in healthy Chinese adults was higher than in White adults. More understanding of serial changes of FeNO levels with asthma control in a real-life clinical setting would be important to explore the utility of this biomarker in routine asthma management. This study assessed the FeNO levels of Chinese asthma subjects with different levels of asthma control and the serial changes with respect to the changes in asthma control over 1 year.

Methods

A 12-month prospective study (subjects recruited between November 2019 and January 2021) with serial measurement of FeNO levels at baseline, 4, 8 and 12 months. Asthma control was assessed by the Global Initiative for Asthma classification, Asthma Control Test (ACT) and Asthma Control Questionnaire (ACQ).

Results

Altogether, 136 subjects (mean age 51.51±15.09 years, 46[33.8%] male) had successful baseline FeNO measurements. At baseline, the FeNO levels did not show a statistically significant difference for controlled, partly controlled and uncontrolled asthma according to GINA classification, ACT and ACQ. FeNO levels decreased with improving asthma control and stayed at similar levels with unchanged or worsening asthma control for all subjects. For subjects with baseline blood eosinophil levels ≥300 cells/µL(n=59), FeNO levels decreased with improving asthma control, stayed similar without change for asthma control and increased with worsening asthma control. Receiver operating characteristic (ROC) analysis with the highest area under curve (AUC) for changes in FeNO levels for improving asthma control was between ≤ -10 to -25 ppb at various time points in the 12-month study.

Conclusion

Changes in FeNO levels over time were associated with changes in clinical asthma control, particularly in those with higher blood eosinophil count and are likely more useful than a single time point measurement in managing asthma.

Eosinophilic Airway Diseases: From Pathophysiological Mechanisms to Clinical Practice

Eosinophils play a key role in airway inflammation in many diseases, such as allergic and non-allergic asthma, chronic rhinosinusitis with nasal polyps, and chronic obstructive pulmonary disease. In these chronic disabling conditions, eosinophils contribute to tissue damage, repair, remodeling, and disease persistence through the production a variety of mediators. With the introduction of biological drugs for the treatment of these respiratory diseases, the classification of patients based on clinical characteristics (phenotype) and pathobiological mechanisms (endotype) has become mandatory. This need is particularly evident in severe asthma, where, despite the great scientific efforts to understand the immunological pathways underlying clinical phenotypes, the identification of specific biomarkers defining endotypes or predicting pharmacological response remains unsatisfied. In addition, a significant heterogeneity also exists among patients with other airway diseases. In this review, we describe some of the immunological differences in eosinophilic airway inflammation associated with severe asthma and other airway diseases and how these factors might influence the clinical presentation, with the aim of clarifying when eosinophils play a key pathogenic role and, therefore, represent the preferred therapeutic target.

The clinical efficacy of type 2 monoclonal antibodies in eosinophil-associated chronic airway diseases: a meta-analysis

Background

Anti-type 2 inflammation therapy has been proposed as a treatment strategy for eosinophil-associated chronic airway disorders that could reduce exacerbations and improve lung function. We performed a meta-analysis of randomized controlled trials to assess the effectiveness of type 2 monoclonal antibodies (anti-T2s) for eosinophil-associated chronic airway disorders.

Methods

PubMed, Embase, Web of Science, and Cochrane Library were searched from their inception to 21 August 2022. Randomized clinical trials evaluating the effectiveness of anti-T2s versus placebo in the treatment of chronic airway diseases were selected. The outcomes were exacerbation rate and change in pre-bronchodilator forced expiratory volume in 1 s (FEV1) from baseline. The Cochrane Risk of Bias Assessment Tool 1.0 was used to evaluate the risk of bias, and the random-effects or fixed-effect model were used to pool the data.

Results

Thirty-eight articles concerning forty-one randomized clinical trials with 17,115 patients were included. Compared with placebo, anti-T2s therapy yielded a significant reduction in exacerbation rate in COPD and asthma (Rate Ratio (RR)=0.89, 95%CI, 0.83-0.95, I2 = 29.4%; RR= 0.59, 95%CI, 0.52-0.68, I2 = 83.9%, respectively) and improvement in FEV1 in asthma (Standard Mean Difference (SMD)=0.09, 95%CI, 0.08-0.11, I2 = 42.6%). Anti-T2s therapy had no effect on FEV1 improvement in COPD (SMD=0.05, 95%CI, -0.01-0.10, I2 = 69.8%).

Conclusion

Despite inconsistent findings across trials, anti-T2s had a positive overall impact on patients' exacerbation rate in asthma and COPD and FEV1 in asthma. Anti-T2s may be effective in treating chronic airway illnesses related to eosinophils.

Systematic Review Registration

https://www.crd.york.ac.uk/PROSPERO/, identifier CRD42022362280.

Asthma medication adherence and exacerbations and lung function in children managed in Leicester primary care

Poor adherence to asthma preventer medication is associated with life-threatening asthma attacks. The quality and outcomes framework mandated primary care annual asthma review does not include adherence monitoring and the effect of poor adherence on lung function in paediatric primary care patients is unknown. The aim was to investigate the link between inhaled corticosteroid (ICS) adherence and spirometry, fraction of exhaled nitric oxide (FeNO) and asthma control in asthmatic school-age children in this cross-sectional observational study involving three Leicestershire general practices. Children 5-16 years on the practice's asthma registers, were invited for a routine annual asthma review between August 2018 and August 2019. Prescription and clinical data were extracted from practice databases. Spirometry, bronchodilator reversibility (BDR) and FeNO testing were performed as part of the review. 130 of 205 eligible children (63.4%) attended their review. Mean adherence to ICS was 36.2% (SEM 2.1%) and only 14.6% of children had good adherence (≥75% prescriptions issued). We found no differences in asthma exacerbations in the preceding 12 months between the adherence quartiles. 28.6% of children in the lowest and 5.6% in the highest adherence quartile had BDR ≥ 12% but this was not statistically significant (p = 0.55). A single high FeNO value did not predict adherence to ICS. Adherence to ICS in children with asthma in primary care is poor. The link between adherence to ICS and asthma exacerbations, spirometry and FeNO is complex but knowledge of adherence to ICS is critical in the management of children with asthma.

Distribution of type 2 biomarkers and association with severity, clinical characteristics and comorbidities in the BREATHE real-life asthma population

Background

Type 2 (T2) high asthma is recognised as a heterogenous entity consisting of several endotypes; however, the prevalence and distribution of the T2 biomarkers in the general asthma population, across asthma severity, and across compartments is largely unknown. The objective of the present study was to describe expression and overlaps of airway and systemic T2 biomarkers in a clinically representative asthma population.

Methods

Patients with asthma from the real-life BREATHE cohort referred to a specialist centre were included and grouped according to T2 biomarkers: blood and sputum eosinophilia (≥0.3×10⁹ cells·L^-1 and 3% respectively), total IgE (≥150 U·mL^-1), and fractional exhaled nitric oxide (≥25 ppb).

Results

Patients with mild-to-moderate asthma were younger (41 versus 49 years, p<0.001), had lower body mass index (25.9 versus 28.0 kg·m^-2, p=0.002) and less atopy (47% versus 58%, p=0.05), higher forced expiratory volume in 1 s (3.2 versus 2.8 L, p<0.001) and forced vital capacity (4.3 versus 3.9 L, p<0.001) compared with patients with severe asthma, who had higher blood (0.22×10⁹ versus 0.17×10⁹ cells·L^-1, p=0.01) and sputum (3.0% versus 1.5%, p=0.01) eosinophils. Co-expression of all T2 biomarkers was a particular characteristic of severe asthma (p<0.001). In patients with eosinophilia, sputum eosinophilia without blood eosinophilia was present in 45% of patients with mild-to-moderate asthma and 35% with severe asthma.

Conclusion

Severe asthma is more commonly associated with activation of several T2 pathways, indicating that treatments targeting severe asthma may need to act more broadly on T2 inflammatory pathways. Implementation of airway inflammometry in clinical care is of paramount importance, as the best treatable trait is otherwise is overlooked in a large proportion of patients irrespective of disease severity.

Clinical Potential of Eosinophil-Derived Neurotoxin in Asthma Management

The assessment and management of patients with asthma is challenging because of the complexity of the underlying inflammatory mechanisms and heterogeneity of their clinical presentation. Optimizing disease management requires therapy individualization that should rely on reliable biomarkers to unravel the phenotypes and endotypes of asthma. The secretory activity and turnover of eosinophils, as assessed by measuring eosinophil-derived proteins, may provide an accurate and complementary tool that mirrors the eosinophil activation status. Emerging evidence suggests that eosinophil-derived neurotoxin has considerable potential as a precision medicine biomarker. In this review, we explore the suitability of eosinophil-derived neurotoxin as a biomarker in asthma management, with particular emphasis on its clinical significance in the management of both pediatric and adult populations.

Association between Exposure to Selected Heavy Metals and Blood Eosinophil Counts in Asthmatic Adults: Results from NHANES 2011-2018

(1) Background: Heavy metals are widely used and dispersed in the environment and people's daily routines. Many studies have reported an association between heavy metal exposure and asthma. Blood eosinophils play a crucial role in the occurrence, progression, and treatment of asthma. However, there have thus far been few studies that aimed to explore the effects of heavy metal exposure on blood eosinophil counts in adults with asthma. Our study aims to discuss the association between metal exposure and blood eosinophil counts among asthmatic adults. (2) Methods: A total of 2026 asthmatic individuals were involved in our research from NHANES with metal exposure, blood eosinophils, and other covariates among the American population. A regression model, the XGBoost algorithm, and a generalized linear model (GAM) were used to explore the potential correlation. Furthermore, we conducted a stratified analysis to determine high-risk populations. (3) Results: The multivariate regression analysis indicated that concentrations of blood Pb (log per 1 mg/L; coefficient β, 25.39; p = 0.010) were positively associated with blood eosinophil counts. However, the associations between blood cadmium, mercury, selenium, manganese, and blood eosinophil counts were not statistically significant. We used stratified analysis to determine the high-risk group regarding Pb exposure. Pb was identified as the most vital variable influencing blood eosinophils through the XGBoost algorithm. We also used GAM to observe the linear relationship between the blood Pb concentrations and blood eosinophil counts. (4) Conclusions: The study demonstrated that blood Pb was positively correlated with blood eosinophil counts among asthmatic adults. We suggested that long-time Pb exposure as a risk factor might be correlated with the immune system disorder of asthmatic adults and affect the development, exacerbation, and treatment of asthma.

A smartphone-based algorithm comprising cough analysis and patient-reported symptoms identifies acute exacerbations of asthma: a prospective, double blind, diagnostic accuracy study

Objective: Early and accurate recognition of asthma exacerbations reduces the duration and risk of hospitalization. Current diagnostic methods depend upon patient recognition of symptoms, expert clinical examination, or measures of lung function. Here, we aimed to develop and test the accuracy of a smartphone-based diagnostic algorithm that analyses five cough events and five patient-reported features (age, fever, acute or productive cough and wheeze) to detect asthma exacerbations.Methods: We conducted a double-blind, prospective, diagnostic accuracy study comparing the algorithm with expert clinical opinion and formal lung function testing. Results: One hundred nineteen participants >12 years with a physician-diagnosed history of asthma were recruited from a hospital in Perth, Western Australia: 46 with clinically confirmed asthma exacerbations, 73 with controlled asthma. The groups were similar in median age (54yr versus 60yr, p=0.72) and sex (female 76% versus 70%, p=0.5). The algorithm's positive percent agreement (PPA) with the expert clinical diagnosis of asthma exacerbations was 89% [95% CI: 76%, 96%]. The negative percent agreement (NPA) was 84% [95% CI: 73%, 91%]. The algorithm's performance for asthma exacerbations diagnosis exceeded its performance as a detector of patient-reported wheeze (sensitivity, 63.7%). Patient-reported wheeze in isolation was an insensitive marker of asthma exacerbations (PPA=53.8%, NPA=49%). Conclusions: Our diagnostic algorithm accurately detected the presence of an asthma exacerbation as a point-of-care test without requiring clinical examination or lung function testing. This method could improve the accuracy of telehealth consultations and might be helpful in Asthma Action Plans and patient-initiated therapy.

In 'real world' patients with COPD, exacerbation history, and not blood eosinophils, is the most reliable predictor of future exacerbations

INTRODUCTION

There is an interest in the role of blood eosinophils for predicting inhaled corticosteroid (ICS) response in chronic obstructive pulmonary disease (COPD). Most data are from interventional clinical studies; data from unselected real-world populations may help better inform treatment decisions. DACCORD is a non-interventional real-world study. Cohort 3 recruited patients with COPD who had received triple therapy for ≥ 6 months; prior to entry patients either continued triple therapy, or switched to a long-acting muscarinic antagonist/long-acting beta₂-agonist (LABA/LAMA), and were followed for 12 months.

METHODS

For these post-hoc analyses, patients were divided into four groups based on exacerbation history and baseline blood eosinophil count (< 100 vs. > 300 cells/µL). Exacerbation rates were calculated overall and for the two treatments.

RESULTS

Among the 430 patients in the current analyses, the largest groups had low exacerbation history with high (44.2%) or low eosinophils (36.7%). Most patients did not exacerbate during follow-up (68.8% overall; 83.2% and 63.7% with LABA/LAMA and triple therapy). The highest exacerbation rates were in groups with high exacerbation history, differing significantly in the overall analyses from those with low exacerbation history (matched by eosinophil count); rates did not differ when grouped by eosinophil count (matched by exacerbation history).

CONCLUSIONS

Although most patients in these analyses did not exacerbate during follow-up, whereas exacerbation history is a predictor of future exacerbations, blood eosinophil count is not. This suggests that although eosinophil count may help to guide ICS initiation, this is less of a consideration when 'stepping-down' from triple therapy to a LABA/LAMA.

Heterogeneity of asthma-chronic obstructive pulmonary disease (COPD) overlap from a cohort of patients with severe asthma and COPD

BACKGROUND

A considerable proportion of patients have features of both asthma and chronic obstructive pulmonary disease (COPD) simultaneously, called asthma-COPD overlap (ACO).

OBJECTIVES

The aim of this study was to identify heterogeneity of ACO from a cohort of patients with severe asthma and COPD using the same diagnostic criteria.

DESIGN

We used the International Severe Asthma Registry (ISAR) and the Korean COPD Subgroup Study (KOCOSS) to evaluate clinical characteristics of ACO from each cohort.

METHODS

We classified subjects into four groups: (1) pure severe asthma, (2) ACO from the severe asthma cohort, (3) ACO from the COPD cohort, and (4) pure COPD. ACO was defined by satisfying extreme bronchodilator response (BDR) >15% and 400 ml and/or blood eosinophil count ⩾300 /µL in patients aged 40 years or older and post-BD forced expiratory volume in 1 s (FEV1)/forced vital capacity (FVC) ratio <0.7.

RESULTS

The ACO group had 25 (23%) of 111 in the ISAR cohort and 403 (23%) of 1781 in the KOCOSS cohort. The ACO from the COPD cohort was older with more males and more smokers, but had similar degree of airflow limitation compared with the ACO from the severe asthma cohort. ICS-containing inhaler treatment was prescribed for all severe asthma subjects, but only for 43.9% of ACO subjects from the COPD cohort. Compared with patients having pure severe asthma, the risk for exacerbation was comparable in ACO either from severe asthma or COPD cohort [adjusted odds ratio (aOR): 1.54, 95% CI: 0.22-10.95 or aOR: 2.15, 95% CI: 0.59-7.85].

CONCLUSION

The prevalence of ACO was similar in severe asthma and COPD cohorts applying identical diagnostic criteria. ACO from the severe asthma cohort was similar to ACO from the COPD cohort in terms of lung function and exacerbation risk.

Baseline FeNO Independently Predicts the Dupilumab Response in Patients With Moderate-to-Severe Asthma

BACKGROUND

FeNO may have a role as both a prognostic and predictive biomarker in combination with eosinophils for assessing responsiveness to some biological therapies.

OBJECTIVE

We evaluated the value of baseline FeNO, adjusted for baseline blood eosinophil levels and other clinical characteristics, as an independent predictor of treatment response to dupilumab in patients with uncontrolled moderate-to-severe asthma.

METHODS

We performed a post hoc analysis of LIBERTY ASTHMA QUEST (NCT02414854), a phase 3, double-blind study in patients aged 12 years and older with uncontrolled moderate-to-severe asthma, who received dupilumab 200 or 300 mg, or placebo every 2 weeks up to 52 weeks. We assessed the annualized event rate of severe exacerbations and least-squares mean change from baseline in prebronchodilator FEV₁ at weeks 12 and 52 in relationship to baseline FeNO, adjusted for eosinophils and other clinical characteristics.

RESULTS

The annualized event rate increased with increasing baseline FeNO in placebo and decreased in dupilumab groups. The relative risk of severe exacerbations was 22·7%, 58·3%, and 69·3% lower for dupilumab versus placebo for the FeNO less than 25, 25 to less than 50, and 50 and greater parts per billion subgroups. The magnitude of FEV₁ improvement increased with higher baseline FeNO for dupilumab and was consistent across the continuum of FeNO levels in placebo. Both findings were independent of blood eosinophil levels. Significant differences were observed between FeNO subgroups.

CONCLUSIONS

Increased baseline FeNO was associated with greater clinical effects in dupilumab versus placebo independently of eosinophil levels and other clinical characteristics.

Comparison between clinical trials and real-world evidence studies on biologics for severe asthma

In recent years, the more widespread availability of biological drugs with specific mechanisms of action has led to significant breakthroughs in the management of severe asthma. Over time, numerous randomised clinical trials have been conducted to evaluate the efficacy and safety of these biologics and define the eligibility criteria of patients suitable for various therapeutic options. These studies were conducted under controlled conditions not always applicable to real life. For this and other reasons, real-world evidence and pragmatic studies are required to provide useful information on the effectiveness of biological drugs and their safety, even in the long term. Because differences in outcomes have sometimes emerged between clinical trials and real-life studies, it is important to clarify the causes of these discrepancies and define the significance of the results of studies conducted in the course of daily clinical practice. Thus, a scientific debate is ongoing, and no consensus has been reached. The purpose of this narrative review is to analyse the differences between randomised trials and real-world evidence studies, focusing on their roles in guiding clinicians among different therapeutic options and understanding the reasons for the large discrepancies often found in the results obtained.

Phenotyping, Precision Medicine, and Asthma

The traditional one-size-fits all approach based on asthma severity is archaic. Asthma is a heterogenous syndrome rather than a single disease entity. Studies evaluating observable characteristics called phenotypes have elucidated this heterogeneity. Asthma clusters demonstrate overlapping features, are generally stable over time and are reproducible. What the identification of clusters may have failed to do, is move the needle of precision medicine meaningfully in asthma. This may be related to the lack of a straightforward and clinically meaningful way to apply what we have learned about asthma clusters. Clusters are based on both clinical factors and biomarkers. The use of biomarkers is slowly gaining popularity, but phenotyping based on biomarkers is generally greatly underutilized even in subspecialty care. Biomarkers are more often used to evaluate type 2 (T2) inflammatory signatures and eosinophils (sputum and blood), fractional exhaled nitric oxide (FeNO) and serum total and specific immunoglobulin (Ig) E reliably characterize the underlying inflammatory pathways. Biomarkers perform variably and clinicians must be familiar with their advantages and disadvantages to accurately apply them in clinical care. In addition, it is increasingly clear that clinical features are critical in understanding not only phenotypic characterization but in predicting response to therapy and future risk of poor outcomes. Strategies for asthma management will need to leverage our knowledge of biomarkers and clinical features to create composite scores and risk prediction tools that are clinically applicable. Despite significant progress, many questions remain, and more work is required to accurately identify non-T2 biomarkers. Adoption of phenotyping and more consistent use of biomarkers is needed, and we should continue to encourage this incorporation into practice.

Exacerbation Profile and Risk Factors in a Type-2-Low Enriched Severe Asthma Cohort: A Clinical Trial to Assess Asthma Exacerbation Phenotypes

Rationale: The past 25 years have seen huge progress in understanding of the pathobiology of type-2 (T2) asthma, identification of measurable biomarkers, and the emergence of novel monoclonal antibody treatments. Although present in a minority of patients with severe asthma, very little is known about the mechanisms underlying T2-low asthma, making it a significant unmet need in asthma research. Objectives: The objective of this study was to explore the differences between study exacerbators and nonexacerbators, to describe physiological changes at exacerbation in those who are T2^HIGH and T2^LOW at the time of exacerbation, and to evaluate the stability of inflammatory phenotypes when stable and at exacerbation. Methods: Exacerbation assessment was a prespecified secondary analysis of data from a 48-week, multicenter, randomized controlled clinical study comparing the use of biomarkers and symptoms to adjust steroid treatment in a T2-low severe asthma-enriched cohort. Participants were phenotyped as T2^LOW (fractional exhaled nitric oxide ⩽ 20 ppb and blood eosinophil count ⩽ 150 cells/µl) or T2^HIGH (fractional exhaled nitric oxide > 20 or blood eosinophil count > 150) at study enrollment and at each exacerbation. Here, we report the findings of the exacerbation analyses, including comparison of exacerbators and nonexacerbators, the physiological changes at exacerbation in those who had evidence of T2 biology at exacerbation versus those that did not, and the stability of inflammatory phenotypes when stable and at exacerbation. Measurements and Main Results: Of the 301 participants, 60.8% (183) had one or more self-reported exacerbations (total of 390). Exacerbators were more likely to be female, have a higher body mass index, and have more exacerbations requiring oral corticosteroid and unscheduled primary care attendances for exacerbations. At enrollment, 23.6% (71) were T2^LOW and 76.4% (230) T2^HIGH. The T2^LOW group had more asthma primary care attendances, were more likely to have a previous admission to HDU (high dependency unit)/ICU and to be receiving maintenance oral corticosteroids. At exacerbation, the T2^LOW events were indistinguishable from T2^HIGH exacerbations in terms of lung function (mean fall in T2^LOW FEV_1, 200 [400] ml vs. T2^HIGH 200 [300] ml; P = 0.93) and symptom increase (ACQ5: T2^LOW, 1.4 [0.8] vs. T2^HIGH, 1.3 [0.8]; P = 0.72), with no increase in T2 biomarkers from stable to exacerbation state in the T2^LOW exacerbations. The inflammatory phenotype within individual patients was dynamic; inflammatory phenotype at study entry did not have a significant association with exacerbation phenotype. Conclusions: Asthma exacerbations demonstrating a T2^LOW phenotype were physiologically and symptomatically similar to T2^HIGH exacerbations. T2^LOW asthma was an unstable phenotype, suggesting that exacerbation phenotyping should occur at the time of exacerbation. The clinically significant exacerbations in participants without evidence of T2 biology at the time of exacerbation highlight the unmet and pressing need to further understand the mechanisms at play in non-T2 asthma. Clinical trial registered with www.clinicaltrials.gov (NCT02717689).

The Effect of Short Sleep Duration on the Development of Asthma

Asthma is regarded as a heterogeneous disease with chronic airway inflammation and reversible airway limitation. Asthma itself and recurrent attacks of asthma can decrease sleep duration and increase the prevalence of short sleep duration. Systemic low-grade inflammation and obesity caused by short sleep duration have been known for a long time, which potentially affect the development of asthma. It would be interesting to study the interaction between short sleep duration and asthma. However, there are relatively few studies and no review about the association between short sleep duration and asthma. This article performed a review about the relationships between short sleep duration and asthmatic phenotype, laboratory tests, comorbidity, and clinical outcomes. Pooled studies about short sleep duration and asthma provided following four results: (1) compared with healthy sleep duration, short sleep duration seemingly increased the risk of central obesity in asthmatics; (2) short sleep duration potentially reduced the level of FeNO and increased lung function impairment in patients with asthma; (3) asthmatic comorbidities, mainly obesity and depression, were negatively associated with short sleep duration among asthmatics; (4) short sleep duration potentially increased the risks of asthma-related hospitalization and emergency care. However, almost all studies are based on subjective but not objective sleep duration. In addition, the study on sleep duration and cause-specific mortality in patients with asthma is relatively scant. Considering the effect of short sleep duration on the development of asthma, we recommend that periodic sleep monitoring for asthmatic management is very necessary.

Treatment Resistance in Severe Asthma Patients With a Combination of High Fraction of Exhaled Nitric Oxide and Low Blood Eosinophil Counts

Background: Combining a fraction of exhaled nitric oxide (FeNO) and blood eosinophil count (B-EOS) may be a useful strategy for administration of biologics such as anti-IgE or anti-IL-5 to patients with type 2 inflammatory-predominant severe asthma and is important to be elucidated considering the increasing use of biologics.

Methods: This cross-sectional study analyzed the clinical data from 114 adult patients with severe asthma, who were treated at Saitama Medical University Hospital. The eligible patients were stratified into four subgroups defined by thresholds of FeNO and blood eosinophil (B-EOS) counts to detect sputum eosinophilia, using the receiver operating characteristic curve analysis. A total of 75 patients with optimal samples were stratified into four subtypes defined by thresholds of sputum eosinophilia and neutrophilia. Clinical characteristics, pattern of biologics, and distribution of sputum subtypes were analyzed in the stratified subclasses according to the FeNO and B-EOS thresholds. The asthma exacerbation (AE)-free time of the FeNO/B-EOS subgroups and any biologics treatment including anti-IgE or anti-IL-5 use were examined using the Kaplan–Meier method. The hazard ratios (HRs) for AE-free time were examined using the Cox proportional hazard model.

Results: The optimal cutoff values for prediction of sputum eosinophilia were defined as ≥2.7% wherein for FeNO as ≥27 ppb and B-EOS as ≥265/µL were considered. The high-FeNO subgroups showed significant high total IgE, compared with the low FeNO. The high-FeNO/high-B-EOS and the high-FeNO/low-B-EOS subgroups showed the largest prevalence of mepolizumab and benralizumab use among the other FeNO/B-EOS, respectively. The high-FeNO/low-B-EOS showed the largest frequency of AEs, high HR, and the shortest AE-free time, among the other FeNO/B-EOS. The sputum eosinophil-predominant subtype was the great majority in the high FeNO/high B-EOS. A diverse distribution of sputum leukocyte-predominant subtype was observed in the other FeNO/B-EOS. The subsequent AE-free time and its HR were comparable among the biologics use groups.

Conclusion: The strategy of classifying severe asthma based on the combination of FeNO and B-EOS proposes particular refractory type 2 severe asthma and underlying airway inflammation as a feasible trait for optimal biologics use.

Qualitative study on perceptions of use of Fractional Exhaled Nitric Oxide (FeNO) in asthma reviews

Current methods to assess asthma and guide inhaled corticosteroid (ICS) dose titration mainly centre on patient-reported symptoms and lung function assessments. However, these methods correlate only weakly with airway inflammation making them unreliable predictors of future exacerbations and ICS requirement. Fractional Exhaled Nitric Oxide (FeNO) is a simple non-invasive objective measure of airways inflammation used predominantly in specialist clinics. Previous qualitative studies have mainly focused on the acceptability of FeNO in secondary care and there is limited insight to support clinicians and patients using FeNO in primary care asthma reviews. This study aimed to explore adult patient with asthma and primary care health care professional (HCP) views on introducing FeNO as part of routine asthma reviews. Twenty-three health care professionals and 22 patients were interviewed over the phone or online. Both groups reported that current asthma reviews are often seen as tick-box exercises and that introducing the FeNO test would make reviews more tailored to the individual patient, rather than relying on subjective patient reports of asthma control. Adults with asthma also highlighted support more open communication and their understanding of asthma, as they desired to feel more engaged in decisions and conversations about their asthma. HCPs reported valuing patient education and empowerment over a paternalistic approach, when time and resources allow. They also recognised FeNO to provide an objective measure of inflammation that could support them in the education and empowerment of patients. FeNO was seen by both groups as a potentially valuable addition to current asthma reviews mainly led by nurses, both for increasing their understanding of current risk of exacerbation and also to provide more tailored and personalised asthma management to patients. Our findings highlighted the need for open and clear communication about how to interpret FeNO results.

FeNO in Asthma

Asthma is a common disease affecting 350 million people worldwide, which is characterized by airways inflammation and hyperreactivity. Historically diagnosis and treatment have been mainly based on symptoms, which have the potential to result in misdiagnosis and inappropriate treatment. Nitric oxide (NO) is exhaled in human breath and is a marker of airways inflammation. Levels of NO are increased in the exhaled breath of patients with type 2 asthma and fractional exhaled nitric oxide (FeNO) provides an objective biomarker of airway inflammation. FeNO testing is an accessible, noninvasive, and easy-to-use test. Cut-off values have been established by the American Thoracic Society (ATS), the Global Initiative for Asthma (GINA), and the National Institute for Health and Care Excellence (NICE) but vary between guidance. FeNO levels have been shown to be predictive of blood and sputum eosinophil levels but should not be used in isolation and current guidance emphasizes the importance of incorporating clinical symptoms and testing when utilizing FeNO results. The inclusion of FeNO testing can increase diagnostic accuracy of asthma, while high levels in asthmatic patients can help predict response to inhaled corticosteroids (ICS) and suppression of levels with ICS to monitor adherence. FeNO levels are also a predictor of asthma risk with increased exacerbation rates and accelerated decline in lung function associated with high levels as well as having an emerging role in predicting response to some biologic therapies in severe asthma. FeNO testing is cost-effective and has been shown, when combined with clinical assessment, to improve asthma management.

The German severe asthma patient: Baseline characteristics of patients in the German Severe Asthma Registry, and relationship with exacerbations and control

INTRODUCTION

The German Asthma Net Severe Asthma Registry is collecting long-term data from a large cohort of patients aged ≥6 years with severe asthma. This manuscript presents their baseline characteristics, and identifies relationships with exacerbations and/or poor asthma control.

METHODS

The registry is collecting routine clinical parameters including: demographics and medical history; disease characteristics (Asthma Control Questionnaire [ACQ]-5, forced expiratory volume in 1 s [FEV1]); exacerbations; and biomarkers (eosinophils, immunoglobulin E [IgE], fractional exhaled nitric oxide [FeNO]).

RESULTS

These analyses include data from 2011 patients at 72 sites (91.9% adult). Children (6-17 years) were more likely to be male, whereas more adults were female (males: children/adults 62%/41%). Most were receiving inhaled corticosteroid/long-acting β2-agonist combinations (78%/81%); 38.0% of adults were receiving systemic steroids. Asthma control was suboptimal in both groups: 21.5%/13.3% were controlled; 10.4%/49.1% were symptomatic; 33.1%/37.2% received emergency asthma treatment in the previous year. Median blood eosinophil (400/238 cells/μL) and IgE levels (494/186 IU/mL) were higher in children; FeNO was lower (19/35 ppb). Patients with ≥2 exacerbations in the previous year had lower FEV1 (absolute and % predicted) and IgE, and higher ACQ-5, FeNO and blood eosinophil levels (all p < 0.05). There was a weak, negative correlation between ACQ-5 and FEV1% predicted in adults (p < 0.001).

CONCLUSIONS

These analyses characterise the typical German patient with severe asthma, and provide information on their overall care. Their planned long-term follow-up will assess whether asthma control can be optimised, how best to do so, and most importantly how such optimisation can benefit patients.

T-high asthma phenotypes across life span

RATIONALE

In adults, personalised asthma treatment targets patients with T2-high and eosinophilic asthma phenotypes. It is unclear whether such classification is achievable in children.

OBJECTIVES

To define T2-high asthma with easily accessible biomarkers and compare resulting phenotypes across all ages.

METHODS

In the multicenter clinical ALL Age Asthma Cohort (ALLIANCE), 1125 participants (n=776 asthmatics, n=349 controls) were recruited and followed for 2 years (1 year in adults). Extensive clinical characterisation (questionnaires, blood differential count, allergy testing, lung function and sputum induction (in adults) was performed at baseline and follow-ups. Interleukin (IL)-4, IL-5 and IL-13 were measured after stimulation of whole blood with LPS or anti-CD3/CD28.

MEASUREMENTS AND MAIN RESULTS

Based on blood eosinophil counts and allergen-specific serum IgE antibodies (sIgE), patients were categorised into four mutually exclusive phenotypes: "Atopy-only", "Eosinophils-only", "T2-high" (eosinophilia+atopy) and "T2-low" (neither eosinophilia nor atopy). The T2-high phenotype was found across all ages, even in very young children in whom it persisted to a large degree even after 2 years of follow-up. T2-high asthma in adults was associated with childhood onset suggesting early origins of this asthma phenotype. In both children and adults, the T2-high phenotype was characterised by excessive production of specific IgE to allergens (p<0.0001) and, from school age onwards, by increased production of IL-5 after anti-CD3/CD28 stimulation of whole blood.

CONCLUSIONS

Using easily accessible biomarkers, patients with T2-high asthma can be identified across all ages delineating a distinct phenotype. These patients may benefit from therapy with biologicals even at younger age.

Improved prediction of asthma exacerbations by measuring distal airway inflammation

Introduction

Partitioning parameters measured from exhaled nitric oxide, such as the alveolar concentration of nitric oxide (CalvNO), may provide better predictors of future asthma exacerbation than exhaled nitric oxide fraction at an expiratory flow rate of 50 mL·s−1 (FENO50). We aimed to determine whether any partitioned nitric oxide parameters were more closely associated than FENO50 with subsequent asthma exacerbations.

Methods

68 asthmatic children (mean±sd age 9.0±2.4 years) were followed prospectively (134 visits) and exacerbations were recorded. Childhood Asthma Control Test (cACT), spirometry, FENO50, CalvNO, bronchial flux of nitric oxide (JawNO), transfer factor of nitric oxide (DawNO) and airway wall concentration of nitric oxide (CawNO) were measured.

Results

No exacerbation was recorded in 99 visits (Group 1) and an exacerbation was recorded in 35 visits (Group 2). The median (range) FENO50, JawNO, CalvNO, DawNO and CawNO of Group 1 versus Group 2: 12.7 (4–209) versus 13.5 (3.8–149.9) ppb, 715 (10–12 799) versus 438 (40–7457) pL·s−1, 3.4 (0.2–10.8) versus 5.2 (1.7–23.6) ppb, 38.3 (0.2–113.3) versus 38 (1.3–144.5) pL·s−1·ppb−1 and 26.8 (4.1–2163) versus 29.9 (5.5–3054) ppb, respectively. Other than for CalvNO (p<0.001), there was no difference between the two groups. CalvNO >7 ppb predicted asthma exacerbation with specificity 90.9% and positive likelihood ratio (LR) 3.1. Conversely, CalvNO <4 ppb excluded an exacerbation with sensitivity 71.4% and negative LR 0.48. An increase of CalvNO by 0.5 ppb between visits could also predict an exacerbation with sensitivity 92%, specificity 92%, positive LR 11.8 and negative LR 0.08.

Conclusions

Assessment of CalvNO improved prediction of subsequent exacerbation, highlighting the importance of distal inflammation in asthma outcomes in children.

Long-term predictors of loss of asthma control in school-aged well-controlled children with mild to moderate asthma: A 5-year follow-up

BACKGROUND

Long-term follow-up studies establishing risk factors for loss of asthma control in well-controlled children with mild to moderate disease are lacking and are of importance for improving patient quality of life and utilization of health-care resources.

METHODS

Loss of asthma control was assessed in 146 school-aged children with well-controlled mild to moderate asthma from a Danish pediatric asthma outpatient clinic based on hospital admissions, emergency department (ED), or outpatient management of exacerbations, oral corticosteroid (OCS) use, or step-up of regular asthma treatment according to Global Initiative for Asthma (GINA) guidelines through a 5-year follow-up period. Risk factors included sex, ethnicity, age, body mass index (BMI), atopic comorbidity and predisposition, lung function, fractional exhaled nitric oxide (FeNO) level, exercise challenge test results, regular physical activity, GINA treatment step at baseline, and adherence to controller therapy.

RESULTS

A total of 27 (18%) children experienced 56 acute events defined by hospital admission, ED, or outpatient management. Risk of experiencing any acute event was increased with female sex (adjusted odds ratio, aOR = 2.4 (1.0-5.9), p = 0.047) and higher baseline GINA treatment step (aOR = 1.6 (1.1-2.5), p = 0.03). Furthermore, female sex (aOR = 6.1 (1.4-42.2), p = 0.01) and higher FeNO (aOR = 1.8 (1.0-3.2), p = 0.04) were associated with OCS prescriptions, whereas no risk factors were identified for GINA treatment step-up during the 5-year follow-up.

CONCLUSIONS

Female sex, higher FeNO, and higher baseline GINA treatment step increase the risk of long-term loss of control including acute events and OCS use in well-controlled children with mild to moderate asthma. These findings are important for primary physicians and clinicians in asthma outpatient clinics to identify seemingly well-controlled children at risk to plan more frequent follow-ups.

Blood eosinophil counts in the general population and airways disease: a comprehensive review and meta-analysis

BACKGROUND

The clinical context for using blood eosinophil (EOS) counts as treatment-response biomarkers in asthma and COPD requires better understanding of EOS distributions and ranges. We describe EOS distributions and ranges published in asthma, COPD, control (non-asthma/COPD) and general populations.

METHODS

We conducted a comprehensive literature review and meta-analysis of observational studies (January 2008 to November 2018) that included EOS counts in asthma, severe asthma, COPD, control and general populations. Excluded studies had total sample sizes <200, EOS as inclusion criterion, hospitalised population only and exclusively paediatric participants.

RESULTS

Overall, 91 eligible studies were identified, most had total-population-level data available: asthma (39 studies), severe asthma (12 studies), COPD (23 studies), control (seven studies) and general populations (14 studies); some articles reported data for multiple populations. Reported EOS distributions were right-skewed (seven studies). Reported median EOS counts ranged from 157-280 cells·µL-1 (asthma, 22 studies); 200-400 cells·µL-1 (severe asthma, eight studies); 150-183 cells·µL-1 (COPD, six studies); and 100-160 cells·µL-1 (controls, three studies); and 100-200 cells·µL-1 (general populations, six studies). The meta-analysis showed that observed variability was mostly between studies rather than within studies. Factors reportedly associated with higher blood EOS counts included current smoking, positive skin-prick test, elevated total IgE, comorbid allergic rhinitis, age ≤18 years, male sex, spirometric asthma/COPD diagnosis, metabolic syndrome and adiposity.

CONCLUSION

EOS distribution and range varied by study population, and were affected by clinical factors including age, smoking history and comorbidities, which, regardless of severity, should be considered during treatment decision-making.

Ethnic Differences in Severe Asthma Clinical Care and Outcomes: An Analysis of United Kingdom Primary and Specialist Care

BACKGROUND

Understanding the effects of ethnicity in severe asthma is important for optimal personalized patient care.

OBJECTIVE

To assess ethnic differences in disease control, exacerbations, biological phenotype, and treatment in severe asthma in the United Kingdom.

METHODS

We compared demographics, type 2 biomarkers, lung function, asthma control, medications, and health care use between White and underrepresented ethnic group patients in the UK Severe Asthma Registry (UKSAR) and Optimum Patient Care Research Database (OPCRD).

RESULTS

A total of 3637 patients (665 from the underrepresented ethnic group) were included from UKSAR and 10,549 (577 from the underrepresented ethnic group) from OPCRD. Patients in the underrepresented ethnic group had higher levels of uncontrolled disease when measurements were made using the asthma control questionnaire in UKSAR (odds ratio [OR] = 1.47; 95% confidence interval [CI], 1.12-1.93) and the Royal College of Physicians 3 Questions in OPCRD (OR = 1.82; 95% CI, 1.27-2.60). Although exacerbation rates were similar, patients in the underrepresented ethnic group were more likely to have recently attended the emergency department (OR = 1.55; 95% CI, 1.26-1.92) or to have been hospitalized (OR = 1.31; 95% CI, 1.07-1.59) owing to asthma. Inflammatory biomarkers were consistently higher in the underrepresented ethnic group, including blood eosinophils in OPCRD (ratio = 1.12; 95% CI, 1.05-1.20) and in UKSAR blood eosinophils (ratio = 1.16; 95% CI, 1.06-1.27), FeNO (ratio = 1.14; 95% CI, 1.04-1.26), and IgE (ratio = 1.70; 95% CI, 1.47-1.97). Patients in the underrepresented ethnic group were more likely to be atopic in the UKSAR (OR = 1.32; 95% CI, 1.07-1.63) and OPCRD (OR = 1.67; 95% CI, 1.26-2.21), and less likely to be using maintenance oral corticosteroids at referral (OR = 0.75; 95% CI, 0.61-0.92).

CONCLUSIONS

Severe asthma patients from underrepresented ethnic groups presented with a higher disease burden and were more likely to attend the emergency department. They had a distinct phenotypic presentation and differences in medicine use, with higher levels of type 2 biomarkers.

Importance of type and degree of IgE sensitisation for defining fractional exhaled nitric oxide reference values

BACKGROUND

Fractional exhaled nitric oxide (FE_NO) is a marker of type 2 airway inflammation used in clinical practice in asthma. However, reference values are needed to broaden the clinical use of FE_NO and this is within the scope of a newly started Global Lung Function Initiative task force. We aim to study FE_NO levels with special emphasis on the upper limit of normal (ULN) in relation to the type and degree of IgE sensitisation.

METHODS

FE_NO was measured in 1855 non-smoking, respiratory healthy subjects from the Swedish CArdioPulmonary bioImage Study (SCAPIS). Atopic subjects (n = 424), defined as being IgE-sensitised to aeroallergens (ImmunoCAP Phadiatop™, ≥0.35 PAU/l) were compared to non-atopic subjects (<0.35 PAU/l, n = 1431). Atopic subjects were further characterised according to their grade of IgE sensitisation (IgE antibody tertiles: (T1<1.16, T2 1.16-3.72 and T3 >3.72 PAU/l) and sensitisation to perennial (cat or mite) or seasonal (birch) allergens.

RESULTS

Subjects IgE-sensitised to cat or mite had higher FE_NO compared to non-atopic subjects (FE_NO (ppb): median 20.0 vs. 15.0, and ULN 50.4 vs. 33.0, p < 0.001). This was seen to a lesser extent for subjects IgE-sensitised to birch only (median 18.0 vs. 15.0, and ULN 38.0 vs. 33.0, p = 0.048). Atopic subjects with a high degree of IgE sensitisation (Phadiatop: >3.72 PAU/l) had the highest FE_NO compared to non-atopic subjects (median 20.0 vs. 15.0, and ULN 56.0 vs. 33.0, p < 0.001).

CONCLUSIONS

The type and degree of IgE sensitisation should be considered in generating FE_NO reference values.

Diagnostic possibility of the combination of exhaled nitric oxide and blood eosinophil count for eosinophilic asthma

BACKGROUND

Tests to identify reversible airflow limitation are important in asthma diagnosis, but they are time-consuming and it may be difficult for patients to cooperate. We aimed to evaluate whether the combination of fractional exhaled nitric oxide (FeNO) and blood eosinophil (B-Eos) can be used to distinguish some asthma patients who could avoid objective tests.

METHODS

We conducted a retrospective cohort study on 7463 suspected asthma cases between January 2014 and December 2019 in Chongqing, China, and identified 2349 patients with complete FeNO, B-Eos count, and spirometry data. Asthma was diagnosed by clinicians by the criteria of recurrent respiratory symptoms and a positive bronchial-provocation or bronchodilation test (BPT, BPD). We evaluated the diagnostic accuracy of FeNO or B-Eos alone or both in combination for asthma using receiver operating characteristic (ROC) curve analysis.

RESULTS

In this study, 824 patients were diagnosed with asthma. When FeNO and B-Eos counts were used in combination, the area under the ROC curve (AUC) for diagnosing asthma increased slightly (0.768 vs. 0.745 [FeNO] or 0.728 [B-Eos]; both P < 0.001). The odds ratio for having asthma increased progressively with a gradual increase in FeNO or B-Eos count (both P < 0.001; assessed using the Cochran-Armitage trend test). Further analysis of in-series combinations of different threshold values for these biomarkers indicated that moderately elevated biomarker levels (FeNO > 40 ppb and B-Eos > 300 cells/μl) support a diagnosis of asthma because diagnostic specificity was > 95% and the positive likelihood ratio (PLR) was > 10. This conclusion was verified when selecting the 2017-2019 data as the internal validation dataset.

CONCLUSION

FeNO or B-Eos count alone is insufficient to accurately diagnose asthma. Patients with moderately elevated biomarkers (FeNO > 40 ppb and B-Eos > 300 cells/μl) could be diagnosed with asthma and avoid objective tests when such tests are not feasible.