Exhaled nitric oxide may predict bronchial hyperreactivity in patients with allergic rhinitis

European Respiratory Society Guidelines for the Diagnosis of Asthma in Adults

Although asthma is very common affecting 5-10% of the population, the diagnosis of asthma in adults remains a challenge in the real world that results in both over- and under-diagnosis. A task force (TF) was set up by the European Respiratory Society to systematically review the literature on the diagnostic accuracy of tests used to diagnose asthma in adult patients and provide recommendation for clinical practice.The TF defined eight PICO (Population, Index, Comparator, and Outcome) questions that were assessed using the GRADE (Grading of Recommendations, Assessment, Development and Evaluation) approach, The TF utilised the outcomes to develop an evidenced-based diagnostic algorithm, with recommendations for a pragmatic guideline for everyday practice that was directed by real-life patient experiences.The TF support the initial use of spirometry followed, and if airway obstruction is present, by bronchodilator reversibility testing. If initial spirometry fails to show obstruction, further tests should be performed in the following order: FeNO, PEF variability or in secondary care, bronchial challenge. We present the thresholds for each test that are compatible with a diagnosis of asthma in the presence of current symptoms.The TF reinforce the priority to undertake spirometry and recognise the value of measuring blood eosinophils and serum IgE to phenotype the patient. Measuring gas trapping by body plethysmography in patients with preserved FEV1/FVC ratio deserves further attention. The TF draw attention on the difficulty of making a correct diagnosis in patients already receiving inhaled corticosteroids, the comorbidities that may obscure the diagnosis, the importance of phenotyping, and the necessity to consider the patient experience in the diagnostic process.

Predictive Markers of Bronchial Hyperreactivity in a Large Cohort of Young Adults With Cough Variant Asthma

Cough variant asthma (CVA), a common asthma phenotype characterized by nonproductive cough and bronchial hyperreactivity (BHR), is usually detected by bronchial provocation tests (BPTs) which are time-consuming, expensive, and unsafe. The primary study objective was to provide proof of concept for the use of fractional exhaled nitric oxide (F_ENO), eosinophil count percentage in induced sputum (sEOS%), forced expiratory flow between 25 and 75% of forced vital capacity (FEF_25–75%) % predicted value, and FEF_25–75% z-scores as surrogate markers predicting BHR in young adults with suspected CVA; the secondary objective was to compare the diagnostic performance of the various techniques. Three hundred and ten subjects (median age 24 years) were included in a cross-sectional study. Subjects were characterized as BHR positive (POS) (n = 147) or BHR negative (NEG) (n = 163) according to methacholine BPT. Classification accuracies were expressed as areas under the receiver operator characteristic curves (AUC). Compared with BHR NEG, FEF_25–75% % predicted value and FEF_25–75% z-scores were lower in the BHR POS group (p < 0.001), whereas F_ENO (p < 0.001) and sEOS% were higher (p < 0.001). AUC values for detecting BHR were as follows: F_ENO, 0.98 (SD = 0.02); sEOS%, 0.98 (SD = 0.02); FEF_25–75% % pred, 0.93 (SD = 0.05); FEF_25–75% z scores, 0.92 (SD = 0.05). Optimal cutoff values (OCV) for BHR prediction were as follows: F_ENO, 32.7 ppb (sensitivity = 0.93, specificity = 0.96), sEOS%, 3.80% (sensitivity = 0.94, specificity = 0.94), FEF_25–75% % predicted value, 80.0% (sensitivity = 0.90, specificity = 0.87), and FEF_25–75% z-score, −0.87 (sensitivity = 0.89, specificity = 0.87). Non-invasive/semi-invasive airway inflammatory or small airway functional measures might be used as surrogate markers predicting BHR in young adults with suspected CVA.

House dust mites-driven allergic rhinitis: could its natural history be modified?

INTRODUCTION

Allergic rhinitis (AR) is the most common IgE-mediated disease. House dust mites (HDMs)-sensitization is the main cause of AR. HDM-driven AR is characterized by a typical natural history consisting of possible progression to asthma. Allergen Immunotherapy (AIT) is, at present, a unique treatment to modify the natural history of allergic diseases. Tablets AIT (TAIT) represents a new era in AIT. There is evidence that TAIT could prevent asthma in AR patients.

AREAS COVERED

The literature search methodology was based on the articles cited by PubMed from 1980 to 2020. AIT's rationale is to restore an immunological and, consequently, clinical tolerance toward the causal allergen. The progression from rhinitis to asthma may be influenced by a relevant risk factor, such as the persistent type 2 inflammation of airways. HDMs are perennial allergens and allergen exposure is the condicio sine qua non to maintain inflammation. AIT could modify the progression toward asthma restoring physiologic immune response to the causal allergen and consequently dampening type 2 inflammation.

EXPERT OPINION

Patients with HDM-driven AR are susceptible to develop asthma over time. Many studies explored this topic. Cross-sectional and longitudinal studies identified some markers which predict the risk of developing asthma. They include bronchial airflow limitation, bronchial hyperresponsiveness, type 2 inflammation, and rhinitis duration. TAIT could block this progression by acting on this vicious circle. Future studies should explore this issue using adequate methodology.

Usefulness of extended nitric oxide analysis in children with allergic rhinitis

OBJECTIVE

Evaluation of airway inflammation and dysfunction is important in management of allergic rhinitis (AR) since AR is a risk factor for developing asthma. Theoretical nonlinear modeling of exhaled nitric oxide (NO) has revealed extended flow-independent NO parameters that could explain where or how NO metabolism was altered. We aimed to evaluate the association between extended NO parameters and bronchial hyperresponsiveness (BHR) in children with AR.

METHODS

Exhaled NO was measured in 74 children with AR on the same day they underwent the provocholine challenge test (PCT). Extended NO was measured in three different exhaled flow rates (30, 100, 200 mL/s) and calculated using the Högman-Meriläinen model. We compared the extended NO parameters including bronchial NO (JawNO), airway tissue NO (CawNO), alveolar tissue NO (CaNO), and diffusing capacity of NO (DawNO) between AR with and without BHR groups, and analyzed the correlation between extended NO parameters and the response-dose ratio (RDR) of the PCT. We additionally evaluated 49 respiratory healthy controls.

RESULTS

Among the 74 children with AR, nine showed BHR. JawNO increased more in children with AR than the control group. In children with AR, JawNO was higher in the AR with BHR than without BHR group, and was correlated positively with log RDR (r = 0.373, p = .001).

CONCLUSIONS

Extended NO analysis including JawNO can be a useful tool for assessing BHR in AR.

Factors associated with exhaled nitric oxide in children with asthma and allergic rhinitis

BACKGROUND

Factors attributable to the level of fraction of exhaled nitric oxide (FeNO) in different age groups of asthmatic children are still lack of report.

OBJECTIVE

To evaluate factors associated with FeNO and the response of FeNO to inhaled steroid in different age groups of asthmatic children with allergic rhinitis.

METHODS

Asthmatic children aged 5 to 12 years were recruited. FeNO, lung function and bronchial hyperresponsiveness (BHR) to methacholine, skin prick testing to a panel of aeroallergens, total immunoglobulin E (T-IgE) in serum and eosinophils in blood were tested. Correlations between FeNO and the measured parameters were assessed. FeNO was measured again after the treatment of combined inhaled corticosteroid and long-acting beta-agonist (ICS/LABA) for 4 weeks. Changes in FeNO between different age groups were compared.

RESULTS

A total of 121 eligible subjects were enrolled in and completed this study. Asthmatic children aged 10 to 12 years old had significantly higher FeNO than those between 8 and 9 years and 5 to 7 years of children (both P < 0.01). Greater height/age (P < 0.01) and higher level of total allergen IgE (P < 0.01) are associated with a higher value of FeNO. After 4 weeks of treatment with ICS/LABA, asthma control test scores were significantly increased in all age groups (P < 0.01), while the level of FeNO significantly decreased in the elder age group only (P < 0.01).

CONCLUSIONS

Height and T-IgE are well correlated with FeNO in asthmatic children aged 5 to 12 years. Measurement of FeNO is more suitable for evaluating the efficacy of ICS/LABA in elder asthmatic children.

Treatment of Allergic Rhinitis as a Strategy for Preventing Asthma

PURPOSE OF REVIEW

To evaluate the impact of allergic rhinitis (AR) on the development of asthma and to update readers on recent literature suggesting that early treatment of allergic subjects with immunotherapy may prevent asthma onset.

RECENT FINDINGS

AR is frequently associated with asthma, leading to the concept that these two conditions are different aspects of the same disease. There is increasing evidence that AR precedes the onset of asthmatic symptoms and current treatment strategies are beneficial in symptom control with no impact prevention. There is limited knowledge about the risk factors responsible for the progression of AR to asthma, though recent data supports the notion that it is possible to prevent asthma onset by allergen immunotherapy. Despite significant advances in specific immunotherapy (SIT) therapy strengthening its efficacy in AR and possible prevention of progression to asthma, the adoption of this therapeutic strategy is still restricted in comparison to therapies directed towards treatment of AR symptoms. Unlike corticosteroids and other symptomatic therapies, the benefit of SIT treatment in allergic individuals has been shown to prevent the development of allergic conditions. Hence, large well-conducted randomized clinical trials with long-term efficacy of SIT are required to confirm or refute the concept that SIT may abrogate the progression of AR to asthma in patients.

Relationship between upper airway diseases, exhaled nitric oxide, and bronchial hyperresponsiveness to methacholine

OBJECTIVE

The "united airway disease" concept is based on the bidirectional interaction between asthma and rhinitis. The aim of this study was to determine the relationship between upper airway diseases and bronchial hyperresponsiveness (BHR), as well as their association with the fractional concentration of exhaled nitric oxide (FeNO) and atopy in patients with persistent symptoms suggestive of asthma requiring methacholine challenge testing (MCT) to confirm asthma diagnosis.

METHODS

A cross-sectional prospective study was carried out in adult patients with persistent asthma-like symptoms and negative bronchodilator testing. FeNO and MCT were performed in all patients. Asthma was confirmed based on the presence of suggestive symptoms and MCT results. Associated upper airway diseases included allergic rhinitis, nonallergic rhinitis, chronic rhinosinusitis with nasal polyps (CRSwNP), and aspirin-exacerbated respiratory disease (AERD).

RESULTS

The study included 575 patients; asthma was confirmed in 32.3%, and FeNO values ≥ 50 ppb were found in 27% of the patients. Elevated FeNO was significantly associated to AERD. The prevalence of atopy in asthma patients was 86.6%. Atopy was present in 90.4% of patients with asthma and FeNO levels ≥ 50 ppb. A significant association was found between AERD, asthma, and FeNO ≥ 50 ppb.

CONCLUSIONS

Patients with symptoms suggestive of asthma but negative bronchodilator testing are commonly seen in usual practice. In this population, the association of high FeNO levels and BHR to atopy, as well as to AERD, suggests the presence eosinophilic inflammation in both the upper and lower airways and supports the "one airway" hypothesis.

Fractional Exhaled Nitric Oxide: A Potential Biomarker in Allergic Rhinitis?

BACKGROUND

The fractional concentration of exhaled nitric oxide (FeNO) is a surrogate biomarker for Th2-dependent bronchial inflammation. The present study investigated whether FeNO may characterize allergic rhinitis (AR) patients.

METHODS

A total of 553 AR patients (497 males, mean age 28.8 years) were evaluated. Those patients with a high FeNO underwent a 2-year follow-up.

RESULTS

Increased FeNO was associated with a significantly longer AR duration, impaired lung function, more severe symptoms, and more frequent bronchial hyperresponsiveness (BHR). At follow-up, 22 out of 82 patients (26.8%) with high FeNO levels (>50 ppb) developed asthma.

CONCLUSIONS

AR patients may frequently have high FeNO values, exceeding 50 ppb. This might be associated with an initial impaired lung function, BHR, a perceived worsening of respiratory symptoms, and potential progression to asthma.

Comorbidities of asthma and the unified airway

BACKGROUND

Asthma is a comorbid condition that may be seen by otolaryngic allergists when treating their patients with allergic rhinitis (AR). Often asthma is overlooked when aggressive treatment could prevent the development or progression of early disease.

METHODS

This article is a retrospective review of the current literature on asthma as a comorbidity of the unified airway. The unified airway and asthma are clearly defined. The epidemiology, morbidity, mortality, pathophysiologic mechanisms, and the chronicity of asthma are reviewed.

RESULTS

The otolaryngic allergist will become familiar the unified airway concept and the close relationships between AR, chronic rhinosinusitis, and asthma.

CONCLUSION

Otolaryngologists should be aware of the unified airway in order to most effectively treat their patients with AR. Knowledge of the close relationships between asthma and AR will help prevent progression of disease, identify early asthma, and improve the outcomes and quality of life for our patients.

Association of FEF25-75% Impairment with Bronchial Hyperresponsiveness and Airway Inflammation in Subjects with Asthma-Like Symptoms

BACKGROUND

Forced expiratory flow at 25 and 75% of the pulmonary volume (FEF25-75%) might be considered as a marker of early airway obstruction. FEF25-75% impairment might suggest earlier asthma recognition in symptomatic subjects even in the absence of other abnormal spirometry values.

OBJECTIVES

The study was designed in order to verify whether FEF25-75% impairment in a cohort of subjects with asthma-like symptoms could be associated with the risk of bronchial hyperresponsiveness (BHR) and with airway inflammation expressed as fractional exhaled nitric oxide (FeNO) and eosinophil counts in induced sputum.

METHODS

Four hundred adults with a history of asthma-like symptoms (10.5% allergic) underwent spirometry, determination of BHR to methacholine (PD20FEV1), FeNO analysis and sputum induction. FEF25-75% <65% of predicted or <-1.64 z-score was considered abnormal.

RESULTS

All subjects had normal FVC, FEV1 and FEV1/FVC, while FEF25-75% was abnormal in 27.5% of them. FEF25-75% (z-score) was associated with PD20FEV1 (p < 0.001), FeNO (p < 0.001) and sputum eosinophils (p < 0.001). Patients with abnormal FEF25-75% showed higher levels of FeNO and eosinophils in induced sputum than did patients with normal FEF25-75% (p < 0.01 and p < 0.01, respectively). Subjects with abnormal FEF25-75% had an increased probability of being BHR positive (OR = 13.38; 95% CI: 6.7-26.7; p < 0.001).

CONCLUSIONS

Our data show that abnormal FEF25-75% might be considered an early marker of airflow limitation associated with eosinophilic inflammation and BHR in subjects with asthma-like symptoms, indicating a role for FEF25-75% as a predictive marker of newly diagnosed asthma.

Lower airway inflammation and hyperresponsiveness in non-asthmatic patients with non-allergic rhinitis

BACKGROUND

Potential associations between non-allergic rhinitis (NAR) and asthma have been verified epidemiologically, but these associations remain not very clear. It is necessary to further explore the possible implication of lower airway abnormities in NAR patients but without asthma. This study aims to determine lower airway hyperresponsiveness (AHR), inflammation and lung function in non-asthmatic patients with NAR.

METHODS

We recruited 262 non-asthmatic patients with NAR, 377 with AR and 264 healthy subjects. All subjects were non-smokers who underwent meticulous history taking, nasal examination, allergen skin prick test (SPT), blood routine test, measurement of fractional exhaled nitric oxide (FeNO), methacholine bronchial challenge test and induced sputum eosinophil count, in this order.

RESULTS

Compared with healthy subjects, non-asthmatic patients with NAR yielded markedly lower FEV1/FVC, maximal mid-expiratory flow (MMEF), mid-expiratory flow when 50% of FVC has been expired (MEF50%) and mid-expiratory flow when 75% of FVC has been expired (MEF25%) (P<0.05). Differences in spirometry between group AR and NAR were unremarkable (P>0.05). Patients with NAR yielded higher rate of AHR and higher FeNO levels than healthy subjects but lower than those with AR. The proportion of lower airways disorders (sputum eosinophilia, high FeNO levels or AHR) was highest in group AR (70.8%), followed by NAR (53.4%) and healthy subjects (24.2%) (P<0.01). However, sputum eosinophils in NAR patients were not higher compared with healthy subjects (P>0.05). Sputum eosinophils and FeNO had significant correlation with positive AHR and MMEF in group AR but not in NAR.

CONCLUSIONS

Non-asthmatic patients with NAR harbor lower AHR, small airways dysfunction and inflammation, despite being less significant than those with AR. This offers clues to unravel the link between NAR and asthma.

A pathophysiological approach for FeNO: A biomarker for asthma

The present review is focused on literature concerning the relevance of fractional exhaled nitric oxide (FeNO) in clinical practice from a pathophysiological point of view. There is increasing evidence that asthma is a heterogeneous pathological condition characterised by different phenotypes/endotypes related to specific biomarkers, including FeNO, helpful to predict therapeutic response in selected asthmatic populations. Nowadays FeNO, a non-invasive biomarker, appears to be useful to foresee asthma developing, to recognise specific asthma phenotypes, like the eosinophilic, to ameliorate asthma diagnosis and management in selected populations and to predict standard corticosteroid and biologic therapy efficacy. In addition, FeNO assessment may also be useful in patients with allergic rhinitis in order to detect the potential involvement of eosinophilic bronchial inflammation in "case finding" subjects at risk of asthma diagnosis. Therefore, it is possible to hypothesise a future with an appropriate use of FeNO by physicians dealing with worrisome clinical issues in specific asthma phenotypes.

Allergic rhinitis phenotypes based on bronchial hyperreactivity to methacholine

BACKGROUND

Allergic rhinitis (AR) and asthma may be associated, bronchial hyperreactivity (BHR) is quite common in AR patients. Methacholine (MCH) is a stimulus able to elicit BHR, as many other ones. Phenotyping AR is an up-to-date issue.

OBJECTIVE

The aim of this study was to evaluate whether MCH bronchial challenge is able to differentiate patients with AR.

METHODS

A total of 298 patients (277 males, mean age 28.9 years), suffering from AR were evaluated. Sensitization, rhinitis duration, values for bronchial function (forced vital capacity [FVC], forced expiratory volume [FEV]1, forced expiratory flow [FEF]25-75, and FEV1/FVC ratio), MCH bronchial challenge, visual analog scale (VAS) for nasal and bronchial symptoms perception, and fractioned exhaled nitric oxide (FeNO) were evaluated.

RESULTS

BHR-positive patients (22.8%) had significantly more frequent mite allergy (p = 0.025), longer AR duration (p < 0.001), lower FEV1 (p = 0.003), FEV1/FVC (p < 0.001), FEF25-75 (p < 0.001), higher (p < 0.001), and higher VAS values for both nasal and bronchial symptoms (p < 0.001 for both) in comparison with BHR-negative patients. FeNO can be considered a good predictor for BHR in AR patients (area under the curve, 0.90) with 27.0 ppb as cutoff.

CONCLUSIONS

The present study demonstrates that BHR to MCH could define two distinct phenotypes in AR patients. It could be clinically relevant as BHR-positive patients have initial impairment of lung function, impaired FeNO values, and worsening of respiratory symptoms perception.

Revisiting the role of exhaled nitric oxide in asthma

PURPOSE OF REVIEW

This review focuses on the most recent studies investigating fractional nitric oxide concentration in exhaled breath (FeNO) as a useful biomarker for identifying specific phenotypes in asthma and as a tool for asthma diagnosis, monitoring and clinical decision-making.

RECENT FINDINGS

On the basis of the current literature, it has been highlighted that FeNO is a clinically relevant marker in various clinical aspects of asthma: FeNO is a predictor for developing asthma in persistent rhinitis or in infants with respiratory symptoms; FeNO contributes to identification of asthma phenotypes in both children and adults, also in relation to severity; FeNO is useful in monitoring the effectiveness of inhaled corticosteroids (including compliance) and biologic treatments like omalizumab; FeNO, in conjunction with symptom registration and lung function measurements, contributes to asthma diagnosis and optimizes asthma management.

SUMMARY

FeNO provides further information in distinguishing different phenotypes in asthma, allowing a much more appropriate control of the disease, especially in patients with difficult/severe asthma. In the future, it would be interesting to shed light on the hidden biological mechanisms responsible for low or normal FeNO values in symptomatic asthmatic patients.

Nasal nitric oxide is associated with exhaled NO, bronchial responsiveness and poor asthma control

The fraction of exhaled nitric oxide (FeNO) is an established marker of airway inflammation in asthma. Nasal nitric oxide (nNO) has initially been regarded as a promising marker of inflammation of nasal mucosa. However, due to its dual origins, paranasal sinuses and nasal mucosa, the clinical use of nNO is controversial. There is an inflammatory link between inflammation in the upper and lower airways within the united airways' paradigm, but the study of the clinical value of nNO in asthma has been limited. The objective of this study is to analyse nNO in asthmatics and its relationship to FeNO, bronchial hyperresponsiveness, allergic sensitization and asthma control. A total of 371 children and young adults from an asthma cohort were included in this study, which performed measurements of nNO (through aspiration at 5 mL s(-1)), FeNO, bronchial responsiveness to methacholine, blood eosinophil count (B-Eos) and IgE sensitization. The asthma control test (ACT) and a questionnaire regarding medical treatment, symptoms of asthma, rhinitis and chronic rhinosinusitis were completed by all subjects. An association was found between higher nNO levels and increased bronchial responsiveness (p < 0.001), FeNO (p < 0.001) and B-Eos (p = 0.002). Sensitization to furry animals related to higher levels of nNO (p < 0.001). Subjects with poorly controlled asthma (ACT < 15) had lower levels of nNO than subjects with a higher ACT score (619 ± 278 ppb, versus 807 ± 274 ppb, p = 0.002). Loss of smell showed the strongest association with lower nNO levels among the upper airway symptoms recorded. In patients with asthma, nNO was positively correlated with exhaled NO, bronchial responsiveness and asthma control. This study suggests clinical utility of nNO in subjects with asthma, but in order to get better understanding of the nNO determinants, simultaneous mapping of upper airway comorbidities by clinical examination is appropriate.

Preventing progression of allergic rhinitis to asthma

The prevalence of allergic rhinitis (AR) is on the increase and this condition is frequently associated with asthma, thus leading to the concept that these two conditions are different aspects of the same disease. There is now accumulating evidence that AR often precedes the onset of asthmatic symptoms. This notion has important implications, not only for the diagnosis and management of these common allergic conditions but also for the potential progression of disease. Very little is known about the risk factors responsible for the progression of AR to asthma; current treatment options can control symptoms but do not prevent or cure the disease. However, there are recent data supporting the notion that it is possible to prevent new asthma cases by modifying the immune response and clinical outcome with allergen immunotherapy. This review article evaluates the impact of AR on the development of asthma, examines putative predictors for the progression of AR to asthma, and reviews recent, promising literature suggesting that early treatment of allergic individuals with immunotherapy may aid in asthma prevention.