Diagnostic accuracy of fractional exhaled nitric oxide measurement in predicting cough-variant asthma and eosinophilic bronchitis in adults with chronic cough: A systematic review and meta-analysis

Bibliometric Analysis of Cough Variant Asthma from 1993 to 2022

Purpose

Cough variant asthma (CVA) is a chronic inflammatory disease characterized by recurrent coughing, a prevalent cause of chronic cough in children and adults. As a unique form of asthma, researchers have recently become increasingly interested in developing effective diagnostic and treatment methods. Currently, there has been no bibliometric analysis in CVA. Therefore, this study aims to enrich this knowledge network by examining the current development status, research focal points, and emerging trends in this field.

Methods

Articles and reviews on CVA published between 1993 and 2022 were collected from the Web of Science Core Collection (WoSCC) database. Relevant data from the reports were extracted, and collaborative network analysis was performed using CiteSpace and VOSviewer software.

Results

772 articles were included in this study, indicating a significant increase since 2019. The countries with the highest output are China, Japan. The Journal of Asthma and Pulmonary Pharmacology Therapeutics emerged as the most prolific journals in this field. Keyword analysis revealed 22 clusters, highlighting airway inflammation, airway hyperresponsiveness, and eosinophil as the main focus and frontier of research on CVA.

Conclusion

From the visual analysis results, the research of CVA is still in the development stage, and there is no unified definition of pathogenesis, diagnostic criteria and treatment strategies. Therefore, researchers and teams should actively carry out cross-institutional and cross-regional cooperation, expand cooperation areas, and carry out high-quality clinical research in the future.

Cough Response to High-Dose Inhaled Corticosteroids in Patients with Chronic Cough and Fractional Exhaled Nitric Oxide Levels ≥ 25 ppb: A Prospective Study

This study aimed to investigate the effects of high-dose inhaled corticosteroids (ICS) on chronic cough patients with elevated fractional exhaled nitric oxide (FeNO) levels. In a prospective study, adults with chronic cough and FeNO ≥ 25 ppb, without any other apparent etiology, received fluticasone furoate (200 mcg) for three weeks. Outcomes were evaluated using FeNO levels, cough severity, and Leicester Cough Questionnaire (LCQ) before and after treatment. Of the fifty participants (average age: 58.4 years; 58% female), the treatment responder rate (≥ 1.3-point increase in LCQ) was 68%, with a significant improvement in cough and LCQ scores and FeNO levels post-treatment. However, improvements in cough did not significantly correlate with changes in FeNO levels. These findings support the guideline recommendations for a short-term ICS trial in adults with chronic cough and elevated FeNO levels, but the lack of correlations between FeNO levels and cough raises questions about their direct mechanistic link.

The diagnostic impact of fractional exhaled nitric oxide for asthmatic cough in nontuberculous mycobacterial pulmonary disease

BACKGROUND

Measurement of exhaled nitric oxide (FeNO) is a potentially useful diagnostic test for asthma. However, no study has explored the relationship between FeNO and respiratory symptoms of nontuberculous mycobacterial pulmonary disease (NTM-PD) complicated with asthma. The objective of this study was to assess the utility of measuring FeNO levels in patients with NTM-PD complicated by asthma.

METHODS

In this single-center retrospective cohort study, 140 NTM-PD patients with FeNO measured were enrolled. We selected NTM-PD patients who complicated with asthma as the NTM+BA group, defined using the following criteria: NTM patients with symptoms consistent with asthma, and NTM patients with symptomatic improvement after diagnostic therapy with ICS ± a long-acting beta 2-agonist (LABA). We then calculated a diagnostic cutoff point to distinguish between the NTM+BA groups and the NTM groups (all others). High-resolution computed tomography (HRCT) images were evaluated using the CT scoring system and their association with FeNO was examined.

RESULTS

A total of 89 patients were included in the study. (31 in the NTM+BA group and 58 in the NTM group). Compared with the NTM group, the NTM+BA group had higher rates of allergic disease (51.6% vs. 22.4%; p=0.0085) and higher FeNO values (median, 23 [interquartile range {IQR}, 15.0-43.0] ppb vs. median, 17 [IQR, 11.8-23.0] ppb; p=0.015). With diagnostic asthma care using mainly ICS/LABA with reference to the FeNO, most patients (91.0%, 20/22) in the NTM-preceding subgroup in the NTM+BA group demonstrated a prompt improvement of their symptoms and AFB culture findings did not worsen (Culture positive rate (%): Pre-treatment: 59.1% vs. Post-treatment: 40.9%, p=0.3660) at 6 months after starting diagnostic therapy. The optimal diagnostic cutoff point of FeNO to distinguish between the two groups was calculated as 21.5 ppb by the ROC curve (sensitivity 75%, specificity 71.93%, p<0.0001; area under the curve: 0.7989). No significant correlation was observed between FeNO and the severity of CT images in the patients.

CONCLUSIONS

A certain number of patients with NTM-PD showed exacerbated respiratory symptoms due to asthmatic complications. Elevated FeNO levels suggest asthma complications, even in patients with NTM.

Alveolar nitric oxide concentration plays an important role in identifying cough variant asthma and assessing asthma control in children

OBJECTIVE

To study the value of alveolar nitric oxide concentration (CaNO) in the identification and disease control of cough variant asthma.

METHODS

A retrospective study was conducted on cough variant asthma (CVA-Group), nonasthmatic cough (NAC-Group) and healthy control children (C-Group) aged 5-12 years. The exhaled nitric oxide and spirometry test results of the three groups were collected and compared.

RESULTS

A total of 410 children were included in this study, including 190 in the CVA-Group, 183 in the NAC-Group, and 37 in the C-Group. The CaNO values of the CVA-Group [11.40 ppb (8.48-14.25)] were significantly higher than those of the NAC-Group and C-Group (all p values <.05). The MMEF %pred values of the CVA-Group [63.65 (56.28-73.58)] were significantly lower than those of the NAC-Group and C-Group (all p values <.05). FeNO50, JawNO and other spirometry indices (FVC %pred, FEV1%pred, FEV1/FVC %pred) showed no significant difference among the three groups. ROC curve analysis showed that the optimal cutoff point value of CaNO was 9.45 ppb, corresponding to 0.816 sensitivity and 0.736 specificity. Spearman correlation analysis showed a significant negative correlation between the CaNO measurement and CVA control score.

CONCLUSIONS

CaNO can not only help identify CVA early in children aged 5-12 years with chronic cough but is also significantly negatively correlated with the CVA control score.

Cough in Children and Adults: Diagnosis, Assessment and Management (CICADA). Summary of an updated position statement on chronic cough in Australia

INTRODUCTION

Cough is the most common symptom leading to medical consultation. Chronic cough results in significant health care costs, impairs quality of life, and may indicate the presence of a serious underlying condition. Here, we present a summary of an updated position statement on cough management in the clinical consultation.

MAIN RECOMMENDATIONS

Assessment of children and adults requires a focused history of chronic cough to identify any red flag cough pointers that may indicate an underlying disease. Further assessment with examination should include a chest x-ray and spirometry (when age > 6 years). Separate paediatric and adult diagnostic management algorithms should be followed. Management of the underlying condition(s) should follow specific disease guidelines, as well as address adverse environmental exposures and patient/carer concerns. First Nations adults and children should be considered a high risk group. The full statement from the Thoracic Society of Australia and New Zealand and Lung Foundation Australia for managing chronic cough is available at https://lungfoundation.com.au/resources/cicada-full-position-statement.

CHANGES IN MANAGEMENT AS A RESULT OF THIS STATEMENT

Algorithms for assessment and diagnosis of adult and paediatric chronic cough are recommended. High quality evidence supports the use of child-specific chronic cough management algorithms to improve clinical outcomes, but none exist in adults. Red flags that indicate serious underlying conditions requiring investigation or referral should be identified. Early and effective treatment of chronic wet/productive cough in children is critical. Culturally specific strategies for facilitating the management of chronic cough in First Nations populations should be adopted. If the chronic cough does not resolve or is unexplained, the patient should be referred to a respiratory specialist or cough clinic.

The Saudi initiative for asthma - 2024 update: Guidelines for the diagnosis and management of asthma in adults and children

The Saudi Initiative for Asthma 2024 (SINA-2024) is the sixth version of asthma guidelines for the diagnosis and management of asthma for adults and children that was developed by the SINA group, a subsidiary of the Saudi Thoracic Society. The main objective of the SINA is to have guidelines that are up-to-date, simple to understand, and easy to use by healthcare workers dealing with asthma patients. To facilitate achieving the goals of asthma management, the SINA Panel approach is mainly based on the assessment of symptom control and risk for both adults and children. The approach to asthma management is aligned for age groups: adults, adolescents, children aged 5-12 years, and children aged <5 years. SINA guidelines have focused more on personalized approaches reflecting a better understanding of disease heterogeneity with the integration of recommendations related to biologic agents, evidence-based updates on treatment, and the role of immunotherapy in management. The medication appendix has also been updated with the addition of recent evidence, new indications for existing medication, and new medications. The guidelines are constructed based on the available evidence, local literature, and the current situation at national and regional levels. There is also an emphasis on patient-doctor partnership in the management that also includes a self-management plan.

Bronchoscopy for refractory/unexplained cough with mucus

INTRODUCTION

Refractory/unexplained cough (RUCC) is typically associated with throat symptoms and a dry cough. Some patients attending specialist cough clinics however, report sputum production (>1 tablespoon daily) and atypical sensations (urge-to-cough in chest). Bronchoscopy findings in this specific cohort have rarely been described.

AIMS

We aimed to evaluate bronchoscopy, bronchoalveolar lavage (BAL) cell differential and microbiology findings in RUCC with mucus production.

METHODS

We retrospectively reviewed case notes, procedure results and treatment of patients undergoing bronchoscopy for RUCC with more than a tablespoon of sputum daily.

RESULTS

Data were included from 54 patients with RUCC, normal or trivial findings on CT (Computerised Tomography) imaging and no response to guideline-directed treatment of their cough. Most (84%) patients had BAL neutrophilia and excessive dynamic airway collapse (EDAC) was seen in 31%. Treatment strategies in these patients differed to those adopted in typical RUCC associated with a dry cough. Management was influenced or changed in 48/54 (89%) of the patients undergoing bronchoscopy.

CONCLUSIONS

Bronchoscopy provides high diagnostic value in RUCC with mucus production (>1 tbsp daily), identifying specific treatable traits including neutrophilic airway inflammation and EDAC.

Validity of fractional exhaled nitric oxide and small airway lung function measured by IOS in the diagnosis of cough variant asthma in preschool children with chronic cough

BACKGROUND

To investigate the role of combined impulse oscillometry (IOS) and fractional exhaled nitric oxide (FeNO) in the diagnosis of cough variant asthma (CVA) in preschool children.

METHODS

A total of 197 preschool-aged children with chronic cough were selected from the paediatric outpatient clinic. Allergy histories were collected for all children along with IOS and FeNO. Paediatric respiratory specialists divided the children into a CVA group (n = 90) and a noncough variant asthma (nCVA) group (n = 107) according to the diagnostic criteria for CVA After diagnostic treatment, the correlation between the FeNO and IOS values and the diagnosis in the two groups was analysed, and the area under the curve (AUC) of each index was calculated.

RESULTS

(1) X5 was significantly different between the CVA group and the nCVA group (- 4.22 vs. - 3.64, p < 0.001), as was the FeNO value (29.07 vs. 16.64, p < 0.001). (2) Receiver operating characteristic (ROC) analysis showed that the AUCs of FeNO alone and X5 alone were 0.779 and 0.657, respectively, while the AUC of FeNO (cut-off value of 18 ppb) plus X5 (cut-off value of -4.15 cmH2O/(l/s)) reached 0.809.

CONCLUSIONS

Children with CVA may have small airway dysfunction at an early stage. For preschool children with chronic cough, the combination of FeNO and X5 can better identify those with CVA.

TRIAL REGISTRATION NUMBER

This trial was registered with and approved by the Chinese Clinical Trial Registry, with registration number ChiCTRcRRC-17011738, and was reviewed and approved by the Ethics Committee of Southwest Hospital.

Fractional nitric oxide measurement in exhaled air (FeNO): perspectives in the management of respiratory diseases

Exhaled nitric oxide (NO) production, upregulated by inflammatory cytokines and mediators in central and peripheral airways, can be easily and non-invasively detected in exhaled air in asthma and other respiratory conditions as a promising tool for disease monitoring. The American Thoracic Society and European Respiratory Society released recommendations that standardize the measurement of the fractional exhaled NO (FeNO). In asthma, increased FeNO reflects eosinophilic-mediated inflammatory pathways and, as a biomarker of T2 inflammation can be used to identify asthma T2 phenotype. In this setting its measurement has shown to be an important tool especially in the diagnostic process, in the assessment and evaluation of poor adherence or predicting positive response to inhaled corticosteroids treatment, in phenotyping severe asthma patients and as a biomarker to predict the response to biologic treatments. The discovery of the role of NO in the pathogenesis of different diseases affecting the airways and the possibility to estimate the predominant site of increased NO production has provided new insight on its regulatory role in the airways, making it suitable for a potential extended use in clinical practice for different pulmonary diseases, even though its role remains less clear than in asthma. Monitoring FeNO in pulmonary obstructive lung diseases including chronic bronchitis and emphysema, interstitial lung diseases, obstructive sleep apnea and other pulmonary diseases is still under debate but has opened up a window to the role NO may play in the management of these diseases. The use of FeNO is reliable, cost effective and recommendable in both adults and children, and should be implemented in the management of patients with asthma and other respiratory conditions.

Sex differences of small airway function and fractional exhaled nitric oxide in patients with mild asthma

BACKGROUND

Sex differences of small airway function (SAF) and fractional exhaled nitric oxide (FeNO) in patients with mild asthma remain unclear.

OBJECTIVE

To evaluate sex differences of SAF and FeNO in patients with mild asthma confirmed by positive methacholine challenge test (MCT) result.

METHODS

This cross-sectional, double-centered, observational study enrolled 1609 adult patients with forced expiratory volume in 1 second greater than or equal to 80% and suspected asthma symptoms. Data of spirometry, FeNO, impulse oscillometry measurements, and peripheral blood test result were compared between males and females. The receiver-operating characteristic curves of SAF parameters and FeNO in predicting positive MCT result were also calculated.

RESULTS

In patients with mild asthma matched by age, males had better SAF but higher FeNO levels than females (60 [29.27%] vs 187 [46.75%] for small airway dysfunction, 78.6% vs 72.0% for forced expiratory flow [FEF]_50%, 67.5% vs 60.1% for FEF_75%, 73.7% vs 67.4% for FEF_25%-75%, and 42.0 ppb vs 29.0 ppb for FeNO, respectively, all P ≤ .001). The FeNO levels in male current smokers were considerably lower than those of nonsmokers. SAF and FeNO values declined more rapidly with age among female than male patients with asthma. The optimal cutoff values of FEF_25%-75%, FEF_50%, and FeNO for predicting a positive MCT result were 81.5%, 86.4%, and 41.0 ppb in males vs 73.7%, 76.9%, and 35.0 ppb in females.

CONCLUSION

In patients with mild asthma, the female patients have worse SAF, lower FeNO levels, and a more prominent decline trend of those parameters with age than males. Sex-specific cutoff values should be considered when SAF parameters (FEF_25%-75%, FEF_50%), alone or combined with FeNO, are used to predict positive MCT result in asthma diagnosis.

Prediction of bronchodilation test in adults with chronic cough suspected of cough variant asthma

Background

Many patients with cough variant asthma (CVA) are underdiagnosed and undertreated due to the atypical symptoms, low diagnostic sensitivity of bronchodilator response (BDR), and limited application of bronchial challenge test.

Objective

To investigate whether airway reversibility in BDR can predict CVA diagnosis in patients with chronic cough and negative BDR.

Methods

This open-label, prospective cohort study included patients with chronic cough, nearly normal chest CT scan, and negative BDR results. Inhaled corticosteroids and long-acting β₂ agonists were given for 4 weeks. The confirmed diagnosis of CVA was defined as improved symptoms and an increase of forced expiratory volume in 1 s (FEV₁) by >12% and >200 mL after 4 weeks of treatment.

Results

Of 155 patients recruited, 140 completed the study. Patients in the CVA positive diagnosis group had greater absolute (Δ) and percent (Δ%) improvements in FEV₁ and forced expiratory flows (FEFs), and higher fractional exhaled nitric oxide (FENO) than in the CVA negative diagnosis group. The area under the receiver operating characteristic curves (AUCs) of ΔFEV₁%, FEF_25-75%pred (percentage of predicted forced expiratory flow at 25% to 75%) and FENO for CVA positive diagnosis was 0.825, 0.714, and 0.637, with cutoff values of 5.90%, 61.99% and 41.50 ppb, respectively. A joint model of ΔFEV₁% combined with FEF_25-75%pred or FENO increased the AUC to 0.848 and 0.847, respectively.

Conclusion

ΔFEV₁% in BDR can predict a CVA diagnosis and response to anti-asthma treatment in patients with chronic cough and negative BDR.

Clinical trial registration

[http://www.chictr.org.cn/index.aspx], identifier [ChiCTR2000029065].

Narrative Review of the Mechanisms and Treatment of Cough in Asthma, Cough Variant Asthma, and Non-asthmatic Eosinophilic Bronchitis

Chronic cough is a debilitating condition affecting 10-12% of the general population and is one of the leading causes for referral to secondary care. Many conditions have been associated with chronic cough, including asthma, gastro-esophageal reflux disease and upper airways cough syndrome. Inflammatory airway conditions including cough variant asthma (CVA) and non-asthmatic eosinophilic bronchitis (NAEB) contribute to a significant proportion of presentations with chronic cough, with differing diagnostic criteria and different responses to commonly used asthma therapy for their respective diagnoses. Mechanistic studies in both animal models and humans have identified increased neuronal sensitivity and subsequent central sensitization. These mechanisms include inflammatory-mediated nociceptor sensitization and alterations of afferent nerve terminal excitability, phenotypic changes in the vagal afferent neurons over time, and central neuroplasticity resulting from increased synaptic signalling from peripheral afferents. The aim of this review is to discuss the mechanisms, neurophysiology, and management approaches currently available for patients presenting with chronic cough with underlying asthma, CVA, and NAEB and to shed a light on areas of further research required to elucidate the mechanisms of cough in this patient population.

Exploration in the Mechanism of Zhisou San for the Treatment of Cough Variant Asthma Based on Network Pharmacology

Background

Cough variant asthma (CVA) has no definitive diagnosis or pathogenic causes, and there is currently no effective and safe treatment.

Methods

The network pharmacology was employed to investigate possible targets of Zhisou San (ZSS) in CVA treatment. The main chemical constituents of seven herbs in ZSS were collected based on the TCMSP. To explain the main mechanism, we sequentially screened the targets of each active ingredient and constructed the network of “herb-ingredient-target-disease.” The core targets of ZSS were further confirmed by the molecular docking analysis. Furthermore, pulmonary function, histopathology, and biochemical assays in mice were used to investigate the effect of ZSS on the treatment of CVA.

Results

A total of 137 active ingredients and 86 potential targets for the ZSS in the treatment of CVA were screened, which were connected with the regulation of inflammatory response and immune balance, such as IL-17 signaling pathway, Th17 cell differentiation, TNF signaling pathway, Toll-like receptor signaling pathway, MAPK signaling pathway, T-cell receptor signaling pathway, Th1 and Th2 cell differentiation, and other signaling pathways closely related to the pathogenesis of CVA. Thereinto, 29 core targets contained 8 of the highest scores and could evidently bind to components such as stigmasterol, quercetin, stemoninine B, luteolin, and β-sitosterol predicted by molecular docking. Furthermore, experiments in vivo were conducted for further validation that ZSS had essential effects on lung function and histopathology as well as the inflammatory state in CVA mice, which was significantly related to regulating the Th17/Treg immune balance to reduce inflammation as the important pharmacological mechanism.

Conclusion

This study revealed that ZSS has multicomponent and multipathway characteristics of ZSS in the treatment of CVA, which was primarily associated with inflammation and Th17/Treg immune balance. This study provides a scientific foundation for systematically elaborating the pharmacological activities and mechanism of ZSS, as well as explaining the reliability of the TCM compatibility theory.

WAO-ARIA consensus on chronic cough - Part III: Management strategies in primary and cough-specialty care. Updates in COVID-19

Background

Chronic cough management necessitates a clear integrated care pathway approach. Primary care physicians initially encounter the majority of chronic cough patients, yet their role in proper management can prove challenging due to limited access to advanced diagnostic testing. A multidisciplinary approach involving otolaryngologists and chest physicians, allergists, and gastroenterologists, among others, is central to the optimal diagnosis and treatment of conditions which underly or worsen cough. These include infectious and inflammatory, upper and lower airway pathologies, or gastro-esophageal reflux. Despite the wide armamentarium of ancillary testing conducted in cough multidisciplinary care, such management can improve cough but seldom resolves it completely. This can be due partly to the limited data on the role of tests (eg, spirometry, exhaled nitric oxide), as well as classical pharmacotherapy conducted in multidisciplinary specialties for chronic cough. Other important factors include presence of multiple concomitant cough trigger mechanisms and the central neuronal complexity of chronic cough. Subsequent management conducted by cough specialists aims at control of cough refractory to prior interventions and includes cough-specific behavioral counseling and pharmacotherapy with neuromodulators, among others. Preliminary data on the role of neuromodulators in a proof-of-concept manner are encouraging but lack strong evidence on efficacy and safety.

Objectives

The World Allergy Organization (WAO)/Allergic Rhinitis and its Impact on Asthma (ARIA) Joint Committee on Chronic Cough reviewed the recent literature on management of chronic cough in primary, multidisciplinary, and cough-specialty care. Knowledge gaps in diagnostic testing, classical and neuromodulator pharmacotherapy, in addition to behavioral therapy of chronic cough were also analyzed.

Outcomes

This third part of the WAO/ARIA consensus on chronic cough suggests a management algorithm of chronic cough in an integrated care pathway approach. Insights into the inherent limitations of multidisciplinary cough diagnostic testing, efficacy and safety of currently available antitussive pharmacotherapy, or the recently recognized behavioral therapy, can significantly improve the standards of care in patients with chronic cough.

Suhuang Antitussive Capsule Ameliorates Corticosteroid Insensitivity in Cough Variant Asthma Guinea Pigs by Inhibiting p38 MAPK Signal Pathway

Methods

The CVA guinea pig model was successfully established by use of ovalbumin (OVA) sensitization and cigarette smoke (CS) exposure. The guinea pigs were divided into 6 groups: a control group, an OVA model group, an OVA + CS model group, a Suhuang treatment group, a BUD treatment group, and a combination (Suhuang and BUD) treatment group. The effects of the treatment were determined by measuring lung function (RI/Cydn) and cough symptoms (coughs number/cough latency) as outcome criteria. The levels of inflammatory cytokines in bronchoalveolar lavage fluid (BALF) were determined by ELISA. Lung tissues were stained by hematoxylin and eosin (H&E). The expressions of GR/total p38 MAPK/p-p38 MAPK were detected by Western blot. The MKP-1 mRNA levels were detected by RT-PCR.

Results

Combination treatment significantly decreased RI/coughs numbers and increased Cydn/cough latency. Significantly, the results indicated that combination treatment decreased injury to pulmonary tissues. Results also revealed that levels of inflammatory cytokines were reduced in all treatment groups but most markedly in the combination treatment group. Moreover, Suhuang treatment significantly ameliorated corticosteroid insensitivity by improving the expression of glucocorticoid receptors (GR). The expressions of total p38 MAPK and p-p38 MAPK in lung tissue were significantly inhibited in the Suhuang and combination treatment groups. The MKP-1 mRNA levels in Suhuang and combination treatment groups were also increased significantly.

Conclusion

Suhuang was effective for reversing corticosteroid insensitivity by regulating the p38 MAPK signal pathway, and combining BUD and Suhuang treatment showed synergistic interactions in CVA guinea pigs. Our findings showed that this combination therapy might be a promising therapeutic agent for CVA and also clarified its underlying mechanism of action, providing a theoretical basis for clinical combination treatment with Suhuang and BUD in CVA patients.

A History of Recurrent Episodes of Prolonged Cough as a Predictive Value for Determining Cough Variant Asthma in a Primary Care Setting

Background

Many patients visit primary care clinics with a complaint of cough. General practitioners (GPs) developed a list of the causative diseases of cough that can produce a patient's symptoms and signs. Then, the patients' medical histories were evaluated to determine whether the diagnosis of cough variant asthma (CVA) or post-infectious cough (PIC) could have been predicted.

Methods

We retrospectively investigated 195 outpatients with a complaint of cough. Medical histories of "recurrent episodes of prolonged cough" and "upper respiratory infection" were obtained during the initial visit. The accuracy of medical histories in predicting CVA and PIC was calculated on the area under the curve (AUC).

Results

Among eligible patients with cough, PIC was diagnosed in 99 patients (50.8%), CVA in 40 patients (20.5%), upper airway cough syndrome in 28 patients (14.4%), and chronic obstructive pulmonary disease in 11 patients (5.6%). Among the patients with CVA and those with PIC, 93% and 12%, respectively, had a history of recurrent episodes of prolonged cough. For the diagnosis of CVA, having a history of recurrent episodes of prolonged cough showed a moderately accurate AUC (0.76, 95% CI: 0.71-0.82). On the other hand, for the diagnosis of PIC, having no history of recurrent episodes of prolonged cough also showed a moderately accurate AUC (0.87, 95% CI: 0.82-0.92).

Conclusion

The medical history of recurrent episodes of prolonged cough is useful for the prediction of CVA as well as PIC.

Use of Fractional Exhaled Nitric Oxide to Guide the Treatment of Asthma: An Official American Thoracic Society Clinical Practice Guideline

Background: The fractional exhaled nitric oxide (FE_NO) test is a point-of-care test that is used in the assessment of asthma.

Objective: To provide evidence-based clinical guidance on whether FE_NO testing is indicated to optimize asthma treatment in patients with asthma in whom treatment is being considered.

Methods: An international, multidisciplinary panel of experts was convened to form a consensus document regarding a single question relevant to the use of FE_NO. The question was selected from three potential questions based on the greatest perceived impact on clinical practice and the unmet need for evidence-based answers related to this question. The panel performed systematic reviews of published randomized controlled trials between 2004 and 2019 and followed the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) evidence-to-decision framework to develop recommendations. All panel members evaluated and approved the recommendations.

Main Results: After considering the overall low quality of the evidence, the panel made a conditional recommendation for FE_NO-based care. In patients with asthma in whom treatment is being considered, we suggest that FE_NO is beneficial and should be used in addition to usual care. This judgment is based on a balance of effects that probably favors the intervention; the moderate costs and availability of resources, which probably favors the intervention; and the perceived acceptability and feasibility of the intervention in daily practice.

Conclusions: Clinicians should consider this recommendation to measure FE_NO in patients with asthma in whom treatment is being considered based on current best available evidence.

Diagnostic Value of Fractional Exhaled Nitric Oxide and Small Airway Function in Differentiating Cough-Variant Asthma from Typical Asthma

Purpose

To explore the diagnostic value of fractional exhaled nitric oxide (FeNO), small airway function, and a combined of both in differentiating cough-variant asthma (CVA) from typical asthma (TA).

Methods

A total of 206 asthma subjects, including 104 CVA and 102 TA, were tested for pulmonary function, bronchial provocation test and FeNO. The correlation between FeNO, small airway function and other pulmonary indicators was analyzed by single correlation and multiple regression analysis. The receiver operating characteristic (ROC) curve was established to evaluate the diagnostic efficiency of FeNO, small airway function, and their combination and to predict the optimal cut-off point.

Results

All the respiratory function parameters and small airway function indicators in TA group were significantly different from those in CVA group, and FeNO value was significantly higher than that in CVA group. In addition, the area under the ROC curve (AUC) was estimated to be 0.660 for FeNO, 0.895 for MMEF_75%/25%, 0.873 for FEF_50%, 0.898 for FEF_25%, 0.695 for Fres, 0.650 for R5-R20, and 0.645 for X5. The optimal cut-off points of FeNO, MMEF_75%/25%, FEF_50%, FEF_25%, Fres, R5-R20 and X5, were 48.50 ppb, 60.02%, 63.46%, 45.26%, 16.63 Hz, 0.38 kPa·L⁻¹·s⁻¹, and −1.32, respectively. And the AUC of FeNO combined with small airway function indexes FEF_25%, Fres, R5-R20, and X5 were prior than single indicators.

Conclusion

FeNO and small airway function indexes might have great diagnostic value for differentiating CVA from TA. The combination of FeNO and FEF_25%, Fres, R5-R20, and X5 provided a significantly better prediction than either alone.

Narrative Review: how long should patients with cough variant asthma or non-asthmatic eosinophilic bronchitis be treated?

The causes of chronic cough can be categorized into eosinophilic and noneosinophilic disorders, and approximately 30% to 50% of people with chronic cough have eosinophilic airway inflammation, the presence of which can be confirmed by sputum eosinophilia or elevated exhaled nitric-oxide levels. Cough variant asthma (CVA) is a phenotype of asthma which lacks wheezing or dyspnea, and consistently one of the most common causes of chronic cough worldwide. CVA and non-asthmatic eosinophilic bronchitis (NAEB) shares common feature such as chronic dry cough, eosinophilic inflammation, and development of chronic airflow obstruction (CAO) and asthma in a subset of patients. The distinctive characteristic of these conditions is the presence of airway hyperresponsiveness in CVA but not in NAEB. Coughing is responsive to bronchodilators such as beta-agonists in CVA, but such feature has not been clarified in NAEB. Inhaled corticosteroids (ICSs) are the first-line treatment, and leukotriene receptor antagonists are also effective, in patients with both CVA and NAEB. This review will give an outline of clinical and physiological features, and prognosis and its determinants of CVA and EBNA. Further, the rationale and evidence, despite limited, for the need of long-term treatment will be discussed. The development of airway remodeling due to mechanical stress to the airways exerted by long-standing coughing will also be discussed.

Small-Airway Function Variables in Spirometry, Fractional Exhaled Nitric Oxide, and Circulating Eosinophils Predicted Airway Hyperresponsiveness in Patients with Mild Asthma

Purpose

Patients with variable symptoms suggestive of asthma but with normal forced expiratory volume in 1 second (FEV₁) often fail to be diagnosed without a bronchial provocation test, but the test is expensive, time-consuming, risky, and not readily available in all clinical settings.

Patients and Methods

A cross-sectional study was performed in 692 patients with FEV₁≥80% predicted; normal neutrophils and chest high-resolution computed tomography; and recurrent dyspnea, cough, wheeze, and chest tightness.

Results

Compared with subjects negative for AHR (n=522), subjects positive for AHR (n=170) showed increased FENO values, peripheral eosinophils (EOS), and R5-R20; decreased FEV₁, FEV₁/Forced vital capacity (FVC), and forced expiratory flow (FEFs) (P≤.001 for all). Small-airway dysfunction was identified in 104 AHR⁺ patients (61.17%), and 132 AHR⁻ patients (25.29%) (P<0.001). The areas under the curve (AUCs) of variables used singly for an AHR diagnosis were lower than 0.77. Using joint models of FEF_50%, FEF_75%, or FEF_25%-75% with FENO increased the AUCs to 0.845, 0.824, and 0.844, respectively, significantly higher than univariate AUCs (P <0.001 for all). Patients who reported chest tightness (n=75) had lower FEFs than patients who did not (P<0.001 for all). In subjects with chest tightness, the combination of FEF_50% or FEF_25%-75% with EOS also increased the AUCs substantially, to 0.815 and 0.816, respectively (P <0.001 for all versus the univariate AUCs).

Conclusion

FENO combined with FEF_50% and FEF_25%-75% predict AHR in patients with normal FEV₁. FEF_25%-75%, FEF_50%, or FEF_25%-75% together with EOS also can potentially suggest asthma in patients with chest tightness.

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.

Gastroesophageal reflux and asthma: when, how, and why

PURPOSE OF REVIEW

Gastro-esophageal reflux is a possible cause of uncontrolled symptoms of asthma and should be actively investigated and treated before severe asthma is diagnosed and biological therapy started.

RECENT FINDINGS

Recent investigations on esophageal function and tissue biomarkers in patients with asthma and associated GERD have established a relevant role for esophageal motility and neuronal sensory abnormalities in linking the two diseases. Characterization of the underpinning inflammatory substrate has showed mixed results as both neutrophilic and eosinophilic type 2 inflammatory changes have been described.

SUMMARY

New findings regarding inflammatory mechanisms in GERD-associated asthma as well as new diagnostic tools to investigate functional esophageal abnormalities and characterize asthma endotype have identified potential treatable traits that may improve the clinical management and outcome of asthmatic patients with GERD.

Characterization of Occupational Eosinophilic Bronchitis in a Multicenter Cohort of Subjects with Work-Related Asthma Symptoms

BACKGROUND

Occupational eosinophilic bronchitis (OEB) has been described only as anecdotal case reports.

OBJECTIVE

We investigated the clinical and inflammatory characteristics of subjects with OEB identified in a cohort of subjects who completed a specific inhalation challenge (SIC) with occupational agents.

METHODS

In this retrospective multicenter study, OEB was defined by (1) a fall in FEV1 less than 15% during the SIC and the absence of nonspecific bronchial hyperresponsiveness both before and after the SIC and (2) a postchallenge increase of 3% or more in sputum eosinophils. The subjects who fulfilled these criteria were compared with 226 subjects with a negative SIC and 30 subjects with a positive SIC who failed to show baseline nonspecific bronchial hyperresponsiveness.

RESULTS

An isolated increase in postchallenge sputum eosinophils was documented in 33 of 259 subjects (13%) with a negative SIC. These subjects reported significantly more often an isolated cough at work compared with the negative and positive SIC controls. When compared with positive SIC controls, the subjects with OEB experienced less frequently work-related wheezing and reported a shorter duration of symptoms at work. The sensitivity of the post-SIC increase in fractional exhaled nitric oxide in identifying OEB among subjects with a negative SIC was low, ranging from 43% to 24% using cutoff values of 8 ppb to 17.5 ppb, whereas the specificity was high (90%-97%).

CONCLUSIONS

This study highlights the relevance of induced sputum analysis in the investigation of work-related asthma symptoms to identify isolated increases in sputum eosinophils that are consistent with a diagnosis of OEB.

A snapshot of exhaled nitric oxide and asthma characteristics: experience from high to low income countries

Nitric oxide is a gas produced in the airways of asthmatic subjects and related to T2 inflammation. It can be measured as fractional nitric oxide (FeNO) in the exhaled air and used as a non-invasive, easy to evaluate, rapid marker. It is now widely used in many settings to determine airway inflammation. The aim of this narrative review is to report relationship between FeNO and the physiopathologic characteristics of asthmatic patients. Factors affecting FeNO levels have also been analysed as well as the impact of corticosteroid, target therapies and rehabilitation programs. Considering the availability of the test, spreading this methodology to low income countries has also been considered as a possibility for evaluating airway inflammation and monitoring adherence to inhaled corticosteroid therapy. PubMed data search has been performed restricted to English language papers. Research was limited to studies in adults unless studies in children were the only ones reported for a particular issue. This revision could be useful to summarize the role of FeNO in relation to asthma characteristics and help in the use of FeNO in different clinical settings particularly in low income countries.

Helicobacter pylori is associated with weakened pulmonary function and reduced incidence of allergic conditions in patients with chronic cough

The present study aimed to investigate the potential association between Helicobacter pylori (a H. pylori) positive state and chronic cough. A clinical observational study with systematic analysis was performed, including 278 patients with complaints of chronic cough and 148 healthy controls. a H. pylori positive state was present in 61.2% of the patients in the chronic cough group and 68.9% in the chronic refractory cough group, as opposed to 43.9% in the control group. There was a significant improvement in 65.5% of the patients with chronic refractory cough following successful a H. pylori eradication therapy. In addition, patients with chronic cough exposed to a H. pylori exhibited decreased pulmonary function with a decrease in forced expiratory volume in 1 sec by 84 ml, a decrease in the forced vital capacity by 53 ml and a decrease in maximal vital capacity by 46 ml. The difference was even more obvious in the chronic refractory cough group. The allergy status differed significantly according to age between a H. pylori-positive and -negative cases in the cough variant asthma and allergic cough groups. Among patients aged <40 years, a H. pylori-positive cases had a lower prevalence of atopy and lower total serum immunoglobin E levels compared with a H. pylori-negative cases. However, there was no significant association between a H. pylori status and C-reactive protein levels, erythrocyte sedimentation rate or eosinophil count in the peripheral blood. In conclusion, the present study demonstrated that a H. pylori infection may be a factor associated with chronic cough and it may be associated with a decline in pulmonary function and reduced incidence of allergic conditions. Thus, a H. pylori may represent a target for the treatment of chronic cough.

Perspectives on chronic cough in Korea

Chronic cough is a common condition, and generally affects about 3% of Korean adults with a significant influence on quality of life (QoL). Despite continued clinical and academic efforts, there are unmet needs for chronic cough prevention and management in Korea. Epidemiologically, there are two major challenges: an aging population and air pollution. Korea is one of the most rapidly aging countries, and the relative proportion of elderly to younger people is expected to double within the next two decades. Air pollution is a major concern, but there is very limited evidence on the effects of air pollutant on cough in Korean patients. Clinically, upper and lower airway diseases, such as rhinitis/rhinosinusitis and cough variant asthma/eosinophilic bronchitis, are reported to account for about 75% of chronic cough in Korean adults, which formed the basis in formulating clinical practice guidelines. However, further studies are warranted to resolve clinical uncertainty, particularly for the evaluation and treatment of upper airway conditions in chronic cough. The prevalence of gastroesophageal reflux disease (GERD) is increasing, thus its relevance to cough among Koreans may warrant re-evaluation. Infection-associated chronic cough, such as tuberculosis, is another continuing concern. The proportion of chronic refractory or unexplained cough is assumed to be 10–20% among patients visiting referral clinics for chronic cough. This review presents our perspectives on current epidemiological and clinical issues of chronic cough in Korea, and addresses major knowledge gaps and future research priorities.

Assessment of the role of fractional exhaled nitric oxide as a predictor of airway eosinophilia and corticosteroid responsiveness in patients with chronic cough

Background

Fractional exhaled nitric oxide (FeNO) can be used as a rapid indicator of eosinophilic airway inflammation and steroid responsiveness in patients with bronchial asthma, but this role in chronic cough is still questionable. So, this study was carried out to assess the role FeNO as a predictor of airway eosinophilia and inhaled steroids responsiveness in patients with chronic cough. This prospective study included 70 patients with undiagnosed chronic cough and 20 healthy non-smoker control group. Sputum eosinophils % and FeNO were measured before and after a 4-week treatment trial with high dose inhaled corticosteroids. The optimal cut-off value of FeNO to predict sputum eosinophilia and the responsiveness of cough for corticosteroids were determined.

Results

Forty-five patients (64.3%) of the studied 70 patients with chronic cough responded to the 4-week trial of inhaled steroids. In the steroid responder group, FeNO and sputum eosinophils % were significantly higher than in the non-responder group. There was a significant positive correlation between FeNO and sputum eosinophils %. The optimal cut-off value of FeNO to detect airway eosinophilia was 33 ppb (with 65% sensitivity and 80% specificity) The ROC AUC was 0.757 and the optimal cut-off value of FeNO to predict corticosteroids responsiveness was 34.5 ppb (with 85% sensitivity and 90% specificity). The ROC AUC was 0.835.

Conclusion

FeNO can be used as a rapid and non-invasive diagnostic tool of airway eosinophilic inflammation and as a predictor for steroid responsiveness in patients with chronic cough.

Recent progress in the management of chronic cough

Chronic cough is a common clinical condition with significant impact on quality of life and for which effective therapy remains an unmet clinical need. Over the past decade, there has been a major shift in how we approach this problem, driven by better appreciation of the clinical manifestation of chronic cough and an improved understanding of the associated neurobiology. "Cough hypersensitivity syndrome" has been proposed as a new diagnostic term for chronic cough, encompassing different phenotypes of the condition. Accumulating evidence suggests that this new concept is clinically relevant. However, while it is gaining widespread endorsement within the allergy and respiratory community, raising its profile in routine clinical practice is a priority. Thus, the present paper reviews recent progress in our understanding and management of chronic cough, with focus on mechanistic and clinical studies. It also provides detail on knowledge gaps and future research directions.

Establishment of a mouse model with all four clinical features of eosinophilic bronchitis

Eosinophilic bronchitis (EB) is a clinical disease characterized by chronic cough, airway eosinophil infiltration, and responsive to steroid therapy but with the absence of airway hyperreactivity (AHR). This study established an EB mouse model with all the above features. First, 42 mice were divided into 7 groups to investigate the optimal time interval between cough and AHR detections. Afterward, 28 mice were divided into the asthma, EB, normal saline (NS), and dexamethasone (DXM) groups. Mice were challenged using nasal drops of 200 µg ovalbumin (OVA), 10 µg OVA, NS, or intraperitoneal injections of 5 mg/kg of DXM one hour prior to 10 µg OVA challenge. Airway reactivity was measured 6 h after cough was observed. The frequency of coughs in the asthma and EB groups increased significantly compared to mice in the NS group. After DXM administration, frequency of coughs was significantly decreased compared to mice in the asthma and EB groups. Lung resistance in the asthma group was significantly higher compared to mice in the NS, EB, and DXM groups. Obvious airway eosinophilic inflammation in BALF and lung tissues were observed in the asthma and EB groups, while DXM administration could attenuate airway inflammatory infiltration. In summary, we developed a mouse EB model with all four clinical features of EB by the administration of 10 µg OVA nasal drops.

Efficacy and safety of Zihua Wenfei granules in treatment of postinfectious cough (wind-cold invading lungs syndrome): study protocol for a randomized controlled trial

Background

Postinfectious cough usually develops and persists following respiratory tract infection. The protracted cough is embarrassing and troublesome and significantly impairs daily life. However, the optimal treatment available for this condition is still not known. This study aims to investigate the efficacy and safety of a new Chinese herbal prescription, Zihua Wenfei granule (ZHWFG), in treatment of postinfectious cough (wind-cold invading lungs syndrome).

Methods

This study is a prospective, multi-center, randomized, double-blinded, parallel group, placebo-controlled trial. A total of 216 adult participants with postinfectious cough will be enrolled from six study centers across China. All participants are randomly allocated to one of three parallel treatment groups: (1) 15 g of active ZHWFG three times daily, (2) 10 g of active ZHWFG plus 5 g of ZHWFG-matched placebo three times daily, and (3) 15 g of ZHWFG-matched placebo three times daily. The treatment duration is 14 consecutive days. The primary outcomes are cough resolution rate and cough relief rate. Secondary outcomes include time to cough resolution, time to cough relief, change from baseline in cough symptom score, cough visual analog scale value, traditional Chinese medicine syndrome score at days 7 and 14, and change of CQLQ from baseline to post-treatment as well as adverse events.

Discussion

This trial may not only investigate the efficacy and safety of ZHWFG in the management of postinfectious cough (wind-cold invading lungs syndrome), but also add the evidence of Chinese herbal medicine in treatment of postinfectious cough and provide an alternative option for the management of postinfectious cough.

Trial registration

ChiCTR1900022078. Registered on 23 March 2019. http://www.chictr.org.cn/showproj.aspx?proj=36547.

Fractional Exhaled Nitric Oxide (FENO) in the management of asthma: a position paper of the Italian Respiratory Society (SIP/IRS) and Italian Society of Allergy, Asthma and Clinical Immunology (SIAAIC)

Asthma prevalence in Italy is on the rise and is estimated to be over 6% of the general population. The diagnosis of asthma can be challenging and elusive, especially in children and the last two decades has brought evidences that asthma is not a single disease but consists of various phenotypes. Symptoms can be underestimated by the patient or underreported to the clinician and physical signs can be scanty. Usual objective measures, like spirometry, are necessary but sometimes not significant. Despite proper treatment, asthma can be a very severe condition (even leading to death), however new drugs have recently become available which can be very effective in its control. Since asthma is currently thought to be caused by inflammation, a direct measure of the latter can be of paramount importance. For this purpose, the measurement of Fractional Exhaled Nitric Oxide (FE_NO) has been used since the early years of the current century as a non-invasive, easy-to-assess tool useful for diagnosing and managing asthma. This SIP-IRS/SIAAIC Position Paper is a narrative review which summarizes the evidence behind the usefulness of FE_NO in the diagnosis, management and phenotypization of asthma.

Exploring the clinical relevance of cough hypersensitivity syndrome

Introduction: Knowledge of the pathophysiology of cough has continued to advance over recent decades. Establishing anatomic-diagnostic protocols, based on the anatomy and distribution of vagus nerve pathways regulating the cough reflex, was the first breakthrough in modern clinical medicine for chronic cough. The unmet clinical need has prompted revised thinking regarding the pathophysiology of and the clinical approach to chronic cough.Areas covered: The paradigm of cough hypersensitivity syndrome (CHS) has been recently proposed, wherein aberrant neuro-pathophysiology is a common etiology. This review covers major findings on chronic cough and cough hypersensitivity, particularly focused on recently-published studies and explores the clinical relevance and applicability of CHS based on current knowledge and discuss knowledge gaps and future research directions.Expert opinion: This paradigm has provided new opportunities in managing chronic cough and evidence is accumulating to support the validity of CHS. It also warrants the re-appraisal of existing clinical evidence and investigation of how to refine our clinical strategy. While CHS highlights the importance of clinical thinking from the viewpoint of cough, the value of anatomic-diagnostic protocols should remain. Moreover, given the considerable heterogeneity in clinical presentation, cough-associated disease conditions, and treatment responses across different patients, precise molecular endotyping remains key to making further to advancing clinical practice .

ERS guidelines on the diagnosis and treatment of chronic cough in adults and children

These guidelines incorporate the recent advances in chronic cough pathophysiology, diagnosis and treatment. The concept of cough hypersensitivity has allowed an umbrella term that explains the exquisite sensitivity of patients to external stimuli such a cold air, perfumes, smoke and bleach. Thus, adults with chronic cough now have a firm physical explanation for their symptoms based on vagal afferent hypersensitivity. Different treatable traits exist with cough variant asthma (CVA)/eosinophilic bronchitis responding to anti-inflammatory treatment and non-acid reflux being treated with promotility agents rather the anti-acid drugs. An alternative antitussive strategy is to reduce hypersensitivity by neuromodulation. Low-dose morphine is highly effective in a subset of patients with cough resistant to other treatments. Gabapentin and pregabalin are also advocated, but in clinical experience they are limited by adverse events. Perhaps the most promising future developments in pharmacotherapy are drugs which tackle neuronal hypersensitivity by blocking excitability of afferent nerves by inhibiting targets such as the ATP receptor (P2X3). Finally, cough suppression therapy when performed by competent practitioners can be highly effective. Children are not small adults and a pursuit of an underlying cause for cough is advocated. Thus, in toddlers, inhalation of a foreign body is common. Persistent bacterial bronchitis is a common and previously unrecognised cause of wet cough in children. Antibiotics (drug, dose and duration need to be determined) can be curative. A paediatric-specific algorithm should be used.

Diagnostic value of FeNO and MMEF for predicting cough variant asthma in chronic cough patients with or without allergic rhinitis

OBJECTIVE

To evaluate the diagnostic value of fractional exhaled nitric oxide (FeNO) and maximum mid-expiratory flow (MMEF) for differentiating cough variant asthma (CVA) from chronic cough in patients with or without allergic rhinitis.

METHODS

In total, 328 patients with chronic cough who underwent spirometry and FeNO testing were consecutively included in the retrospective analysis. Patients were divided into the CVA (n = 125) or NCVA (n = 203) groups according to the diagnostic criteria of CVA. Receiver operating characteristic (ROC) curves were established to assess the diagnostic efficiency and optimal cutoff points of FeNO and MMEF for the prediction of CVA.

RESULTS

The optimal cutoff values of FeNO and MMEF to discriminate CVA from chronic cough were 24.5 ppb (AUC, 0.765; sensitivity, 69.60%; specificity 72.91%; PPV, 61.27%; NPV, 79.57%) and 66.2% (AUC, 0.771; sensitivity, 67.20%; specificity 78.33%; PPV, 65.63%; NPV, 79.50%). The optimal cutoff values of combining FeNO with MMEF to discriminate CVA from chronic cough were >22 ppb for FeNO and <62.6% for MMEF (AUC, 0.877). In patients with and without allergic rhinitis, the optimal cutoff point of FeNO to discriminate CVA from chronic cough was 24.5 ppb (AUC, 0.820) and 33.5 ppb (AUC, 0.707), respectively.

CONCLUSIONS

FeNO and MMEF might have greater value as negative parameters for differentiating CVA from chronic cough. Combining FeNO and MMEF provided a significantly better prediction than either alone. The diagnostic accuracy of FeNO for predicting CVA in chronic cough patients with allergic rhinitis was higher than in chronic cough patients without allergic rhinitis.

Combining spirometry and fractional exhaled nitric oxide improves diagnostic accuracy for childhood asthma

OBJECTIVES

There are insufficient evidences supporting the use of spirometric indices along with tests for airway inflammation to improve diagnostic accuracy for asthma. We aimed to study the utility of combination of spirometric indices and fractional exhaled nitric oxide (FeNO) measured at the initial visit in diagnosing asthma.

METHODS

Consecutive children aged 8-16 years who were referred for evaluation of possible asthma were included. At referral, all participants completed FeNO measurements and spirometry. The diagnosis of asthma was established with conventional criteria. Diagnostic performance of the spirometric indices and FeNO was determined using receiver-operator characteristic (ROC) curve analyses.

RESULTS

Of 275 participants, 191 children were diagnosed with asthma and showed lower spirometric indices and higher FeNO than non-asthmatics. In the ROC curve analyses, forced expiratory flow between 25% and 75% of vital capacity (FEF_25-75 ) percent predicted demonstrated diagnostic performance with the area under the ROC curve (AUC) value of 0.81 (95% CI: 0.76-0.87) which was significantly higher than those for forced expiratory volume in the first second (FEV₁ ) percent predicted and FEV₁ /forced vital capacity. The combined use of FEF_25-75 percent predicted and FeNO improved the AUC to 0.90 (95% CI: 0.86-0.93). In addition, compared to FEF_25-75 percent predicted or FeNO alone, this combination improved sensitivity with comparable specificity.

CONCLUSIONS

FEF_25-75 percent predicted had a better diagnostic value in detection of childhood asthma than other standard spirometric indices and its combination with FeNO improves the diagnostic accuracy for childhood asthma.

Factors influencing breath analysis results in patients with diabetes mellitus

Breath analysis is used to detect the composition of exhaled gas. As a quick and non-invasive detection method, breath analysis provides deep insights into the progression of various kinds of diseases, especially those with metabolism disorders. Abundant information on volatile compounds in diabetic patients has been studied in numerous articles in the literature. However, exhaled gas in diabetic patients can be altered by various complications. So far, little attention has been paid to this alteration. In our paper, we found that under air pollution conditions, diabetic patients exhale more nitric oxide. Diabetic patients with heart failure exhale more acetone than those without heart failure. After ¹³C-labeled glucose intake, patients infected with Helicobacter pylori exhaled more ¹³C and less ¹⁸O than those without infection. Exhalation with chronic kidney disease changes volatile organic compounds on a large scale. Diabetic patients with ketoacidosis exhale more acetone than those without ketoacidosis. Some specific volatile organic compounds also emanate from diabetic feet. By monitoring breath frequency, diabetic patients with obstructive sleep apnea syndrome exhibit a unique breath pattern and rhythm as compared with other diabetic patients, and sleep apnea is prevalent among diabetic patients. In addition to clinical findings, we analyzed the underlying mechanisms at the levels of molecules, cells and whole bodies, and provided suggestions for further studies.

Comparison of fractional exhaled nitric oxide levels measured by different analyzers produced by different manufacturers

Objective: Fractional exhaled nitric oxide (FeNO) is widely used as a biomarker of allergic airway inflammation. At present, both stationary chemiluminescence and portable electrochemical analyzers produced by different manufacturers are available. However, it remains debatable whether those analyzers are comparable to each other. We compare FeNO levels obtained by different analyzers.Methods: For the first study, 153 subjects were enrolled to compare differences in FeNO levels measured using three analyzers (NA623NP^®, NObreath^®, and NIOX MINO^®) which were produced by different manufacturers. For the second study, 30 subjects were recruited to compare FeNO levels obtained by the two analyzers (NIOX MINO^® and NIOX VERO^®) produced by the same manufacturer. FeNO was measured twice using each analyzer in random order.Results: FeNO levels obtained using the NIOX MINO^® and NObreath^® were more variable than those measured using the NA623NP^®. There were strong positive correlations in FeNO levels measured by the NA623NP^®, NIOX MINO^®, and NObreath^® (p < 0.001). The NA623NP^® and NIOX MINO^® provided the highest and lowest FeNO levels, respectively; whereas, those obtained by NObreath^® were intermediate. No significant differences were observed in FeNO levels obtained using the NIOX MINO^® and NIOX VERO^®.Conclusions: FeNO levels measured by the NIOX MINO^® and NIOX VERO^®, both of which were produced by the same manufacturer, have comparability. However, significant differences in FeNO levels exist when measured by analyzers manufactured by different manufacturers. This should be taken into account for FeNO measurement.

Fractional Exhaled Nitric Oxide (FeNO) Combined with Pulmonary Function Parameters Shows Increased Sensitivity and Specificity for the Diagnosis of Cough Variant Asthma in Children

Background

Cough variant asthma in children presents with a dry nonproductive cough. This study aimed to investigate the diagnostic value of fractional exhaled nitric oxide (FeNO) combined with small airway functional parameters in cough variant asthma.

Material/Methods

Children with asthma (n=136) were divided into a cough variant asthma (CVA) group (n=57; mean age, 8.03±2.1 years) and a non-cough variant asthma (nCVA) group (n=79; mean age, 8.61±1.7 years). In both groups, FeNO and other pulmonary function parameters were measured including forced expiratory volume in one second (FEV1), forced vital capacity (FVC), peak expiratory flow (PEF), maximum mid-expiratory flow (MMEF), forced expiratory flow (FEF), and maximum expiratory flow at 25%, 50%, and 75% expired volume (MEF25, MEF50, and MEF75). Receiver-operating characteristic (ROC) curve analysis compared the sensitivity and specificity between the diagnostic parameters.

Results

The FeNO values were significantly increased in the CVA group compared with the nCVA group (Z=6.890, p<0.001). The MMEF, MEF25, MEF50, and MEF75 values were significantly lower in the CVA group compared with the nCVA group (p=0.000, p=0.014, p=0.000, and p=0.000, respectively). The FeNO values were negatively correlated with MEF25, MEF50, and MMEF (r=−0.334, r=−0.257 and r=−0.276, respectively). FeNO was significantly more efficient diagnosing cough variant asthma comparing with pulmonary parameters (p<0.05), and was most sensitive and specific when combined with MMEF/MEF50 compared with single diagnostic parameters (p<0.05).

Conclusions

FeNO combined with pulmonary function parameters of MMEF/MEF50 showed increased sensitivity and specificity for the diagnosis of cough variant asthma.

Impaired cough suppression in chronic refractory cough

Functional brain imaging in individuals with chronic cough demonstrates reduced activation in cortical regions associated with voluntary cough suppression. Little is known about the ability of patients with chronic cough to suppress cough. This study aimed to compare the ability to voluntarily suppress cough during inhaled capsaicin challenge in participants with chronic refractory cough with that in healthy controls. In addition, this study aimed to assess the repeatability of capsaicin challenge test with voluntary cough suppression.

Participants with chronic refractory cough and healthy controls underwent inhaled capsaicin challenge tests while attempting to suppress their cough responses. After 5 days, either a conventional capsaicin challenge test with no cough suppression attempt, or a repeat test with an attempt at cough suppression was performed. Threshold capsaicin concentrations required to elicit one, two and five coughs were calculated by interpolation. Objective 24-h cough frequency was measured in individuals with chronic refractory cough.

Healthy controls were able to suppress capsaicin-evoked cough while participants with chronic refractory cough were not. Geometric mean±sd capsaicin dose thresholds for five coughs with (CS5) and without (C5) suppression attempts were 254.40±3.78 versus 45.89±3.95 µmol·L−1, respectively, in healthy controls (p=0.033) and 3.34±5.04 versus 3.86±5.13 µmol·L−1, respectively, in participants with chronic refractory cough (p=0.922). Capsaicin dose thresholds for triggering five coughs with self-attempted cough suppression were significantly lower in participants with chronic refractory cough than in healthy controls; geometric mean±sd 4.94±4.43 versus 261.10±4.34 µmol·L−1, respectively; mean difference (95% CI) 5.72 (4.54–6.91) doubling doses (p<0.001). Repeatability of cough suppression test in both patients and healthy controls was high; intraclass correlation coefficients of log(CS5) values 0.81 and 0.87, respectively. CS5 was associated with objective cough frequency (ρ=−0.514, p=0.029).

Participants with chronic refractory cough were less able to voluntarily suppress capsaicin-evoked cough compared to healthy controls. This may have important implications for the pathophysiology and treatment of chronic cough.

Chronic cough and obesity

With respective prevalence of 13% and 9.6%, obesity and chronic cough are two common conditions worldwide. The crucial role of obesity has been highlighted in the development and progression of many respiratory diseases. According to the results of epidemiological studies, obesity, particularly abdominal obesity, may also be associated with chronic cough (CC). CC seems to be more severe in obese patients compared to normal-weight subjects. The management of CC may differ slightly in obese patients compared to non-obese patients. Indeed, asthma and reflux diseases, which are considered key factors in the onset of CC, are characterised by more severe symptoms in obese patients. Asthma is associated with a resistance to usual treatments in obese patients but no data are available on the effect of inhaled therapies in obese subjects with cough variant asthma. Other emergent causes of CC have been reported in obese patients. Obstructive sleep apnoea and diabetes may also be involved in the development of CC and should be taken into account in obese patients with CC. The beneficial effect of weight loss on chronic cough has been suggested.

Cough in exercise and athletes

In the general population, particularly in individuals with asthma, cough is a common symptom, often reported after exertion, although regular exercise may be associated with a reduction in the prevalence of cough. In athletes, exercise-induced cough is also a particularly frequent symptom. The main etiologies of cough in athletes are somewhat similar to non-athletes, including asthma/airway hyperresponsiveness, upper airways disorders such as allergic or non-allergic rhinitis, and exercise-induced laryngeal obstruction, although these conditions are more frequently observed in athletes. In these last, this symptom can also be related to the high ventilation and heat exchange experienced during exercise, particularly during exposure to cold/dry air or pollutants. However, gastroesophageal reflux, a common cause of cough in the general population, despite being highly prevalent in athletes, has not been reported as a main cause of cough in athletes. Cough may impair quality of life, sleep and exercise performance in the general population and probably also in athletes, although there are few data on this. The causes of cough should be documented through a systematic evaluation, the treatment adapted according to identified or most probable cough etiology and pattern of presentation, while respecting sports anti-doping regulations. More research is needed on exercise-induced persistent cough in the athlete to determine its pathophysiology, optimal management and consequences.

Diagnostic value of fractional exhaled nitric oxide in cough-variant asthma: an updated meta-analysis

Objective: We aimed to evaluate the diagnostic value of fractional exhaled nitric oxide (FeNO) in cough-variant asthma (CVA) detection. Methods: Relevant studies on the FeNO test in patients with CVA were retrieved from electronic databases including PubMed, Medline, Springer, Elsevier Science Direct, the Cochrane Library, and Google Scholar, up to August 2018. Meta-analysis for sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), and diagnostic odds ratio (DOR) of the FeNO test were conducted after extracting related data from the included studies. Meta-DiSc 1.4 and Stata 12.0 software were applied to perform the meta-analysis. Results: In total, 12 studies involving 1968 participants were selected for the meta-analysis. The pooled results of the FeNO test for CVA diagnosis showed that the sensitivity was 0.74 (95% confidence interval [CI] = 0.70 to 0.77), specificity was 0.82 (95% CI = 0.80 to 0.84), PLR was 4.15 (95% CI = 3.04 to 5.65), NLR was 0.30 (95% CI = 0.22 to 0.41), and DOR was 15.33 (95% CI = 8.43 to 27.86). The area under the curve and Q* index were 0.87 and 0.80, respectively. Moreover, no significant publication bias was observed using Egger's linear regression test (P > 0.05). Conclusion: The FeNO test might be an appropriate diagnostic tool for CVA detection.

Value of Exhaled Nitric Oxide and FEF25-75 in Identifying Factors Associated With Chronic Cough in Allergic Rhinitis

Purpose

Chronic cough in allergic rhinitis (AR) patients is common with multiple etiologies including cough variant asthma (CVA), non-asthmatic eosinophilic bronchitis (NAEB), gastroesophageal reflux-related cough (GERC), and upper airway cough syndrome (UACS). Practical indicators that distinguish these categories are lacking. We aimed to explore the diagnostic value of the fraction of exhaled nitric oxide (FeNO) and forced expiratory flow at 25% and 75% of pulmonary volume (FEF_25–75) in specifically identifying CVA and NAEB in these patients.

Methods

Consecutive AR patients with chronic cough were screened and underwent induced sputum, FeNO, nasal nitric oxide, spirometry, and methacholine bronchial provocation testing. All patients also completed gastroesophageal reflux disease questionnaires.

Results

Among 1,680 AR patients, 324 (19.3%) were identified with chronic cough, of whom 316 (97.5%) underwent etiology analyses. Overall, 87 (27.5%) patients had chronic cough caused by NAEB, 78 (24.7%) by CVA, 16 (5.1%) by GERC, and 81 (25.6%) by UACS. Patients with either NAEB or CVA (n = 165, in total) were further assigned to a common group designated as CVA/NAEB, because they both responded to corticosteroid therapy. Receiver operating characteristic curves of FeNO revealed obvious differences among CVA, NAEB, and CVA/NAEB (area under the curve = 0.855, 0.699, and 0.923, respectively). The cutoff values of FeNO at 43.5 and 32.5 ppb were shown to best differentiate CVA and CVA/NAEB, respectively. FEF_25–75 was significantly lower in patients with CVA than in those with other causes. A FEF_25–75 value of 74.6% showed good sensitivity and specificity for identifying patients with CVA.

Conclusions

NAEB, CVA, and UACS are common causes of chronic cough in patients with AR. FeNO can first be used to discriminate patients with CVA/NAEB, then FEF_25–75 (or combined with FeNO) can further discriminate patients with CVA from those with CVA/NAEB.

Inhaled Corticosteroids and Placebo Treatment Effects in Adult Patients With Cough: A Systematic Review and Meta-analysis

PURPOSE

Inhaled corticosteroids (ICSs) are often considered an empirical therapy in the management of patients with cough. However, ICS responsiveness is difficult to interpret in daily clinical practice, as the improvements may include placebo effects or self-remission. We aimed to evaluate ICS and placebo treatment effects in adult patients with cough.

METHODS

Electronic databases were searched for studies published until June 2018, without language restriction. Randomized controlled trials reporting the effects of ICSs compared with placebo in adult patients with cough were included. Random effects meta-analyses were conducted to estimate the treatment effects. Therapeutic gain was calculated by subtracting the percentage change from baseline in the cough score in the ICS treatment group from that in the placebo treatment group.

RESULTS

A total of 9 studies were identified and 8 studies measuring cough severity outcomes were included for meta-analyses. Therapeutic gain from ICSs ranged from -5.0% to +94.6% across the studies included; however, it did not exceed +22%, except for an outlier reporting very high therapeutic gains (+45.6% to +94.6%, depending on outcomes). Overall ICS treatment effects in cough severity outcomes were small-to-moderate (standardized mean difference [SMD], -0.38; 95% confidence interval [CI], -0.54, -0.23), which were comparable between subacute and chronic coughs. However, pooled placebo treatment effects were very large in subacute cough (SMD, -2.58; 95% CI, -3.03, -2.1), and modest but significant in chronic cough (SMD, -0.46; 95% CI, -0.72, -0.21).

CONCLUSIONS

Overall therapeutic gain from ICSs is small-to-moderate. However, placebo treatment effects of ICS are large in subacute cough, and modest but still significant in chronic cough. These findings indicate the need for careful interpretation of ICS responsiveness in the management of cough patients in the clinic, and also for rigorous patient selection to identify ICS-responders.

The Saudi Initiative for Asthma - 2019 Update: Guidelines for the diagnosis and management of asthma in adults and children

This is the fourth version of the updated guidelines for the diagnosis and management of asthma, developed by the Saudi Initiative for Asthma (SINA) group, a subsidiary of the Saudi Thoracic Society. The main objective of the SINA is to have guidelines that are up to date, simple to understand, and easy to use by healthcare workers dealing with asthma patients. To facilitate achieving the goals of asthma management, the SINA panel approach is mainly based on the assessment of symptom control and risk for both adults and children. The approach to asthma management is now more aligned for different age groups. The guidelines have focused more on personalized approaches reflecting better understanding of disease heterogeneity with integration of recommendations related to biologic agents, evidence-based updates on treatment, and role of immunotherapy in management. The medication appendix has also been updated with the addition of recent evidence, new indications for existing medication, and new medications. The guidelines are constructed based on the available evidence, local literature, and current situation at national and regional levels. There is also an emphasis on patient–doctor partnership in the management that also includes a self-management plan.