Cough variant asthma and atopic cough

Prevalence of chronic cough, its risk factors and population attributable risk in the Burden of Obstructive Lung Disease (BOLD) study: a multinational cross-sectional study

Background

Chronic cough is a common respiratory symptom with an impact on daily activities and quality of life. Global prevalence data are scarce and derive mainly from European and Asian countries and studies with outcomes other than chronic cough. In this study, we aimed to estimate the prevalence of chronic cough across a large number of study sites as well as to identify its main risk factors using a standardised protocol and definition.

Methods

We analysed cross-sectional data from 33,983 adults (≥40 years), recruited between Jan 2, 2003 and Dec 26, 2016, in 41 sites (34 countries) from the Burden of Obstructive Lung Disease (BOLD) study. We estimated the prevalence of chronic cough for each site accounting for sampling design. To identify risk factors, we conducted multivariable logistic regression analysis within each site and then pooled estimates using random-effects meta-analysis. We also calculated the population attributable risk (PAR) associated with each of the identifed risk factors.

Findings

The prevalence of chronic cough varied from 3% in India (rural Pune) to 24% in the United States of America (Lexington,KY). Chronic cough was more common among females, both current and passive smokers, those working in a dusty job, those with a history of tuberculosis, those who were obese, those with a low level of education and those with hypertension or airflow limitation. The most influential risk factors were current smoking and working in a dusty job.

Interpretation

Our findings suggested that the prevalence of chronic cough varies widely across sites in different world regions. Cigarette smoking and exposure to dust in the workplace are its major risk factors.

Funding

Wellcome Trust.

Patient response to the management during the acute presentation of cough variant Asthma: Retrospective cohort study

The clinical improvement after assessing patients with cough variant asthma in outpatient clinics, and therapy success varied depending on the subjective improvement. Cough could be controlled within appropriate time and subsequent management can consist of inhaled corticosteroids. In this study we used the cough improvement, the only available clinical response, as a predictable factor to determine the effect of different modalities of treatment among patients with cough variant asthma. Retrospective observational analysis was performed in Saudi Arabia's King Saud University Medical City, on the presentation, diagnosis, course of therapy, and responsiveness to oral and inhaled steroids in patients with cough variant asthma. All patients who visited the clinic on multiple occasions with persistent, acute coughing without being pre-screened between September 2021 and September 2022 included based on medical records. Cough resembles cough variant asthma is the term used to describe a cough without a diagnosed etiology. To identify patients eligible for CVA treatment, iindividuals having GERD-associated cough, allergic rhinitis, bronchial asthma, smokers and atopic cough was excluded. For the examination of these findings, IBM SPSS version 28 (Armonk, NY, USA) was employed. As a result of using budesonide-formoterol inhaler, most patients (86.3 %) showed improvement in their cough symptoms (with 95 %CI: 78.3 to 94.9). There was a significant yet weak positive correlation between the frequency of cough symptoms before and after using budesonide-formoterol (r = 0.318, P value < 0.001). The understanding of treatment response and patient selection for budesonide-formoterol inhaler therapy, providing clinicians with valuable information to optimize patient care.

CT airway remodelling and chronic cough

RATIONALE

Structural airway changes related to chronic cough (CC) are described in the literature, but so far reported data are rare and non-conclusive. Furthermore, they derive mainly from cohorts with small sample sizes. Advanced CT imaging not only allows airway abnormalities to be quantified, but also to count the number of visible airways. The current study evaluates these airway abnormalities in CC and assesses the contribution of CC in addition to CT findings on the progression of airflow limitation, defined as a decline in forced expiratory volume in 1 s (FEV1) over time.

METHODS

A total of 1183 males and females aged ≥40 years with thoracic CT scans and valid spirometry from Canadian Obstructive Lung Disease, a Canadian multicentre, population-based study has been included in this analysis. Participants were stratified into 286 never-smokers, 297 ever-smokers with normal lung function and 600 with chronic obstructive pulmonary disease (COPD) of different severity grades. Imaging parameters analyses included total airway count (TAC), airway wall thickness, emphysema as well as parameters for functional small airway disease quantification.

RESULTS

Irrespective of COPD presence, CC was not related to specific airway and lung structure features. Independent of TAC and emphysema score, CC was highly associated with FEV1 decline over time in the entire study population, particularly in ever-smokers (p<0.0001).

CONCLUSION

The absence of specific structural CT features independently from COPD presence indicate that other underlying mechanisms are contributing to the symptomatology of CC. On top of derived CT parameters, CC seems to be independently associated with FEV1 decline.

TRIAL REGISTRATION NUMBER

NCT00920348.

Application of a Cold Dry Air Provocation Test in Pediatric Patients with Asthma

Asthma is a chronic inflammatory airway disease characterized by reversible airway obstruction and airway hyperreactivity. We proposed a cold dry air (CDA) provocation test and investigated its application in pediatric patients with asthma. We enrolled 72 children and adolescents older than 5 years who presented to our hospital with chronic cough, shortness of breath, and wheezing. We analyzed the results of allergy, pulmonary function, methacholine provocation, and CDA provocation tests. The FEV1 change 5 min after the provocation was recorded as CDA5 dFEV1; that after 15 min was recorded as CDA15 dFEV1. PT10 was the provocation time causing a 10% decrease in FEV1; a decrease of >10% in dFEV1 was considered a positive CDA test. Among the 72 subjects, 51 were diagnosed with asthma. A positive CDA test in patients with asthma correlated with non-eosinophilic asthma. In patients with asthma, sputum eosinophils and eosinophil cationic protein (ECP) levels of the patients with a positive CDA test were significantly lower than those of patients with a negative test. CDA5 dFEV1 correlated with PC20 and total immunoglobulin E. CDA15 dFEV1 correlated with PC20, sputum eosinophils, and ECP. PT10 became shorter as the peripheral blood eosinophil, FVC, FEV1, FEV1/FVC, and FEF25-75 decreased. The CDA provocation test showed airway hyperreactivity to non-specific stimuli, a high correlation with non-eosinophilic asthma, and the possibility of assessing asthma severity via PT10.

Distribution of chronic cough phenotypes in the general population: A cross-sectional analysis of the LEAD cohort in Austria

RATIONALE

Recent guidelines consider chronic cough to be a unique clinical entity with different phenotypes. We aimed to investigate them in a general population and to describe prevalence, distribution, and characteristics of these phenotypes within the Austrian general population.

METHODS

From the LEAD study, a longitudinal observational population-based cohort, data from questionnaires and spirometry of 10,057 adult participants was analysed. Chronic cough was defined as coughing nearly every day during the last 12 months for at least 3 months (>12 weeks).

RESULTS

The prevalence of chronic cough was 9% and increased with age. We found no sex predominance but a female preponderance (68%) in never smokers. A presumable cause was identified in 85% of which more than half (53.9%) had two phenotypes, 36.9% belonged to one only and 9.2% to three or more. Regarding the distribution of phenotypes, 40.8% were current smokers, 32.6% had an ACE inhibitor intake, 18.2% GERD, 17.6% asthmatic cough, 9.7% UACS and 28.3% other diseases associated with chronic cough. 15% had unexplained chronic cough with no identifiable phenotype. Current smoking, low socioeconomic status, obesity, COPD and obstructive sleep apnea were associated factors with chronic cough.

CONCLUSION

Chronic cough is common among adults in Austria and highly prevalent in the older population. Most participants can be phenotyped with simple questionnaire-based assessment and can therefore potentially receive specific treatment without intensive clinical workup.

WAO-ARIA consensus on chronic cough - Part II: Phenotypes and mechanisms of abnormal cough presentation - Updates in COVID-19

BACKGROUND

Chronic cough can be triggered by respiratory and non-respiratory tract illnesses originating mainly from the upper and lower airways, and the GI tract (ie, reflux). Recent findings suggest it can also be a prominent feature in obstructive sleep apnea (OSA), laryngeal hyperresponsiveness, and COVID-19. The classification of chronic cough is constantly updated but lacks clear definition. Epidemiological data on the prevalence of chronic cough are informative but highly variable. The underlying mechanism of chronic cough is a neurogenic inflammation of the cough reflex which becomes hypersensitive, thus the term hypersensitive cough reflex (HCR). A current challenge is to decipher how various infectious and inflammatory airway diseases and esophageal reflux, among others, modulate HCR.

OBJECTIVES

The World Allergy Organization/Allergic Rhinitis and its Impact on Asthma (WAO/ARIA) Joint Committee on Chronic Cough reviewed the current literature on classification, epidemiology, presenting features, and mechanistic pathways of chronic cough in airway- and reflux-related cough phenotypes, OSA, and COVID-19. The interplay of cough reflex sensitivity with other pathogenic mechanisms inherent to airway and reflux-related inflammatory conditions was also analyzed.

OUTCOMES

Currently, it is difficult to clearly ascertain true prevalence rates in epidemiological studies of chronic cough phenotypes. This is likely due to lack of standardized objective measures needed for cough classification and frequent coexistence of multi-organ cough origins. Notwithstanding, we emphasize the important role of HCR as a mechanistic trigger in airway- and reflux-related cough phenotypes. Other concomitant mechanisms can also modulate HCR, including type2/Th1/Th2 inflammation, presence or absence of deep inspiration-bronchoprotective reflex (lower airways), tissue remodeling, and likely cough plasticity, among others.

[The cough variant asthma]

Cough variant asthma (CVA) was first described by W. Corrao. CVA was described as the isolated chronic cough as the only presenting symptom responsive to bronchodilator therapy.This phenotype of asthma is present with airway hyperresponsiveness, eosinophilic inflammation airways and bronchodilator responsive coughing without typical manifestation of asthma such as wheezing or dyspnea. CVA shares common features with classic asthma such as eosinophilic inflammation and airway remodeling. Because of that, CVA is clinically considered as a variant type of asthma.

Naringin and Naringenin Relax Rat Tracheal Smooth by Regulating BKCa Activation

Naringin and its aglycone, naringenin, occur naturally in our regular diet and traditional Chinese medicines. This study aimed to detect an effective therapeutic approach for cough variant asthma (CVA) through evaluating the relaxant effect of these two bioactive herbal monomers as antitussive and antiasthmatic on rat tracheal smooth muscle. The relaxant effect was determined by measuring muscular tension with a mechanical recording system in rat tracheal rings. Cytosolic Ca²⁺ concentration was measured using a confocal imaging system in primary cultured tracheal smooth muscle cells. In rat tracheal rings, addition of both naringin and naringenin could concentration dependently relax carbachol (CCh)-evoked tonic contraction. This epithelium-independent relaxation could be suppressed by BaCl₂, tetraethylammonium, and iberiotoxin (IbTX), but not by glibenclamide. After stimulating primary cultured tracheal smooth muscle cells by CCh or high KCl, the intracellular Ca²⁺ increase could be inhibited by both naringin and naringenin, respectively. This reaction was also suppressed by IbTX. These results demonstrate that both naringin and naringenin can relax tracheal smooth muscle through opening big conductance Ca²⁺-activated K⁺ channel, which mediates plasma membrane hyperpolarization and reduces Ca²⁺ influx. Our data indicate a potentially effective therapeutic approach of naringin and naringenin for CVA.

Phenotyping patients with chronic cough: Evaluating the ability to predict the response to anti-inflammatory therapy

BACKGROUND

Whether the fraction of exhaled nitric oxide (FeNO) measurement can predict the response to anti-inflammatory treatment in chronic cough is unknown.

OBJECTIVE

To explore whether the effectiveness of treatment with 10 mg of montelukast or 20 mg of prednisolone in patients with chronic cough is predicted by FeNO level.

METHODS

In this randomized, open-label, controlled pilot study conducted in the Clinical Trial Unit in Castle Hospital in the United Kingdom, 50 nonsmoking patients with a cough that lasted more than 8 weeks were sequentially enrolled in the study. Thirty patients with high FeNO levels (≥30 ppb) were randomized in a 1:1 ratio to receive 10 mg of montelukast or 20 mg of prednisolone for 2 weeks followed by 10 mg of montelukast for 2 weeks. Twenty patients with a low FeNO level (≤20 ppb) received 10 mg of montelukast. The primary objective was to determine the effectiveness of treatment on 24-hour cough counts.

RESULTS

The 24-hour cough counts decreased in both groups by approximately 50% (P < .005), indicating that FeNO did not predict treatment response. However, it was a good marker for eosinophilic inflammation with a high degree of correlation with blood and sputum eosinophilia (P < .001).

CONCLUSION

These results suggest that prior investigation may not predict response to anti-inflammatory treatment, which may be consequent on localized leukotriene-mediated inflammation.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02479074.

The Emerging Role of The Eosinophil and Its Measurement in Chronic Cough

Although the aetiology of chronic cough in guidelines is clearly stated as asthma and related syndromes, gastro-oesophageal reflux disease (GORD), and upper airways disease, the inflammatory mechanisms underlying these conditions differ. Recent studies on asthma have increasingly focused on its molecular phenotypes instead of clinical characteristics. Here, we proposed the hypothesis that divides cough into two groups; the eosinophilic and neutrophilic. This division will enhance our ability to recognise the type of airway inflammation which, as a consequence will lead us to more targeted and personalized treatment approaches.

A Case of Chronic Cough in a Winemaker

BACKGROUND

Fungi have been known to cause a variety of respiratory conditions, ranging from mold- associated asthma to allergic bronchopulmonary mycosis and invasive disease. More recently some fungal species have been implicated in a non-asthmatic chronic cough syndrome.

CASE PRESENTATION

A 59-year-old male presented to the pulmonary clinic with chronic nonproductive cough. Workup included pulmonary function tests with methacholine challenge, sputum cultures, CT scans of the chest and therapeutic trial with proton pump inhibitors. Sputum cultures repeatedly showed Saccharomyces cerevisiae and patient had elevated specific IgA and IgG. Bronchoscopy was unremarkable, except for tracheal mucosa biopsies revealing acute and chronic inflammation. A one-month course of steroids provided temporary relief of chronic cough, but symptoms returned once steroids were discontinued. He also experienced temporary relief away from home. Upon further evaluation, the patient described his hobby of wine making which was believed to be the source of Saccharomyces cerevisiae. Once he stopped wine making at home and cleared his cellar, his symptoms stopped and have not returned since.

CONCLUSION

We describe a rare presentation of non-asthmatic chronic cough associated with exposure to Saccharomyces cerevisiae. This is the first report of fungi associated chronic cough without asthmatic features outside of Japan and the first one associated with Saccharomyces cerevisiae. This report provides further evidence linking fungi with chronic cough syndrome without the features of asthma or allergic bronchopulmonary mycosis.

Therapeutic effects of naringin in a guinea pig model of ovalbumin-induced cough-variant asthma

Naringin, a well known component isolated from Exocarpium Citri Grandis, has significant antitussive effects. Recently, Naringin exhibited novel anti-inflammatory effect in chronic inflammatory diseases. In this work, we firstly evaluated the effects of naringin on enhanced cough, airway hyper-responsiveness (AHR), and airway inflammation in an ovalbumin-induced experimental cough-variant asthma (CVA) model in guinea pigs. We investigated the effect of naringin (18.4 mg/kg, per os, single dose or consecutively) on cough to inhaled capsaicin after challenge with an aerosolized antigen in actively sensitized guinea pigs. The effect of naringin on AHR to inhaled methacholine was evaluated 24 h after cough determination. Airway inflammation was assessed via bronchoalveolar lavage fluid (BALF) cytology and lung histopathology. Naringin, given consecutively, significantly reduced ovalbumin-induced enhanced cough and AHR, inhibited the increases in the leukocytes, interleukin-4 (IL-4), IL-5, and IL-13 in BALF compared with the model group. Moreover, the pathologic changes in lung tissues were clearly ameliorated by naringin treatment. These results suggest that naringin may be a beneficial agent for CVA treatment.

Cough variant asthma patients are more depressed and anxious than classic asthma patients

OBJECTIVE

Many recent studies have indicated that depression and anxiety are more common in asthmatic patients than in the general population and psychological stress can lead to asthma exacerbations, but no study specifically targets cough variant asthma (CVA) patients. The purpose of this study was to evaluate depression and anxiety levels in CVA patients compared with classic asthma patients and to identify the psychological features of CVA patients.

METHODS

Fifty-nine outpatients with CVA and 128 outpatients with classic asthma were interviewed about psychosomatic and psychiatric symptoms, and they underwent three psychological tests: Self-rating Depression Scale (SDS), State-Trait Anxiety Inventory (STAI), and Comprehensive Asthma Inventory (CAI). They were ultimately screened for major and minor depression, dysthymia, panic disorder, generalized anxiety disorder, social anxiety disorder, and other anxiety disorders.

RESULTS

CVA patients showed higher SDS and STAI scores than classic asthma patients, and mood disorders and anxiety disorders were more common than in classic asthma outpatients. The psychological factors 'frustration', 'fright into illness', and 'distorted lifestyle' were more prominent in CVA patients than in classic asthma patients.

CONCLUSION

CVA patients are on average more depressed and anxious than classic asthma outpatients. Though CVA appears pathologically to be just an early stage of typical asthma, the psychological stress may often be more serious than in asthma controlled by medication, which may explain why CVA cannot be controlled by a bronchodilator alone and patients often require no less intense therapy than for severe asthma.

Frequent cough in unsatisfactory controlled asthma--results from the population-based West Sweden Asthma study

BACKGROUND

Asthma is a complex disease presenting with variable symptoms which are sometimes hard to control. The purpose of the study was to describe the prevalence of asthma symptoms, use of asthma medications and allergic sensitization in subjects with asthma. We also related those indices to the level of asthma control, lung function and in particular, cough.

METHODS

An extensive questionnaire was sent to randomly selected adults from the West Sweden region. Clinical examinations and interview were performed in a subset. Of the participants, 744 were defined as having an ongoing asthma - reported ever having asthma or physician diagnosed asthma and one of the following - use of asthma medications, recurrent wheeze or attacks of shortness of breath with or without wheeze in the last 12 months. A respiratory disease-free control group of 847 subjects was also described.

RESULTS

According to GINA guidelines, 40.6% of the asthmatics had partly controlled and 17.8% had uncontrolled asthma. Asthmatic subjects reported significantly more symptoms in the last 12 months than the control group - wheezing (79.4 vs 9.2%), shortness of breath (36.1 vs 2.5%), wheezing with shortness of breath (58.7 vs 1.3%). Important complaints were morning cough (42.5 vs 15.5%), cough with sputum production (36.1 vs 6.8%) and longstanding cough (32.5 vs 11.1%), which bothered two thirds of the uncontrolled and one third of partly controlled subjects. Asthma medications were used by 87.5% of the asthmatics, although around 30% of them who had insufficiently controlled disease used only short-acting beta-agonists. Asthmatics also had lower lung function, reacted to lower doses of methacholine that the controls and 13.6% of them had a FEV1/FVC ratio below 0.7. Allergic rhinitis was reported by 73.8% of the asthmatics and they were more frequently sensitized to several common allergens.

CONCLUSIONS

Approximately 60% of asthmatics from this population-based study had insufficiently controlled asthma and persistent complaints, despite a high use of asthma medications. These self-reported symptoms were supported by clinical examination data. Increased cough frequency is an indicator of a more severe and difficult to control disease and should be considered when asthma is characterized.

Anatomy and neuro-pathophysiology of the cough reflex arc

Coughing is an important defensive reflex that occurs through the stimulation of a complex reflex arc. It accounts for a significant number of consultations both at the level of general practitioner and of respiratory specialists. In this review we first analyze the cough reflex under normal conditions; then we analyze the anatomy and the neuro-pathophysiology of the cough reflex arc. The aim of this review is to provide the anatomic and pathophysiologic elements of evaluation of the complex and multiple etiologies of cough.