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

Canadian Association of Radiologists Pediatric Imaging Referral Guideline

The Canadian Association of Radiologists (CAR) Pediatric Expert Panel is made up of pediatric physicians from the disciplines of radiology, emergency medicine, endocrinology, gastroenterology, general surgery, neurology, neurosurgery, respirology, orthopaedic surgery, otolaryngology, urology, a patient advisor, and an epidemiologist/guideline methodologist. After developing a list of 50 clinical/diagnostic scenarios, a rapid scoping review was undertaken to identify systematically produced referral guidelines that provide recommendations for one or more of these clinical/diagnostic scenarios. Recommendations from 32 guidelines and contextualization criteria in the Grading of Recommendations, Assessment, Development, and Evaluations (GRADE) for guidelines framework were used to develop 133 recommendation statements across the 50 scenarios. This guideline presents the methods of development and the referral recommendations for head, neck, spine, hip, chest, abdomen, genitourinary, and non-accidental trauma clinical scenarios.

Efficacy and Safety of Fexuprazan Versus Esomeprazole for Gastroesophageal Reflux Disease-Related Chronic Cough: A Randomized, Double-Blind, Active-Controlled Exploratory Trial

PURPOSE

Potassium-competitive acid blockers (P-CABs) are a newer class of acid suppressants with convenient dosing and a rapid onset of action, while showing efficacy comparable to proton pump inhibitors (PPIs) in treating peptic symptoms of gastroesophageal reflux disease (GERD). This study aimed to assess the effect of P-CABs on GERD-related chronic cough.

METHODS

This randomized, double-blind, active-controlled, exploratory trial evaluated adults with chronic cough (≥ 8 weeks) and a recent physician diagnosis of GERD or peptic symptoms (< 1 month). Participants were randomized (1:1) to receive either fexuprazan 40 mg or esomeprazole 40 mg (PPI) once daily for eight weeks, along with matched placebos. The primary endpoint was the change in Leicester Cough Questionnaire (LCQ) score from baseline. Secondary endpoints included changes in the cough severity Numerical Rating Scale (NRS) and Reflux Disease Questionnaire (RDQ) scores. Safety was evaluated through monitoring adverse events.

RESULTS

Of the 190 subjects recruited, 161 met the selection criteria and were randomized, and 146 completed the trial. The participants were predominantly female (74.3%, mean age 39 ± 12 years). After 8 weeks of treatment, cough-related quality of life improved significantly, with comparable LCQ scores change between the groups (fexuprazan: 4.9 ± 4.0 vs. esomeprazole: 5.3 ± 3.8, p = 0.558). Changes in cough severity NRS and RDQ scores were also similar between the groups. Adverse events were comparable and consisted mostly of mild symptoms.

CONCLUSION

These findings support the potential of P-CABs as a promising alternative to PPIs for patients with chronic cough requiring acid-suppressive therapy.

Unmet needs and future directions of treatment options for chronic cough

INTRODUCTION

Chronic cough is a persistent condition that significantly affects patients' quality of life and poses diagnostic and therapeutic challenges. Traditional anatomical diagnostic approaches often fail to address the underlying mechanisms, leading to suboptimal treatment outcomes.

AREA COVERED

This review aims to summarize the challenges of the management of chronic cough and highlights recent advances of several promising drug candidates in cough trials. PUBMED/CINAHL/Web of Science/Scopus were searched (February 2025).

EXPERT OPINION

Over the past 40 years, chronic cough has evolved from a mere symptom to a recognized disease. A key observation is that hypersensitivity of the afferent vagus and its central projections cause the state of cough hypersensitivity leading to the urge to cough being precipitated by otherwise innocuous stimuli. Clinical trial designs have also advanced, incorporating placebo run-in periods to reduce placebo effects and refining patient-reported outcomes to modern standards. Additionally, the realization that the variability in chronic cough, both diurnal and day-to-day, has highlighted the need for continuous cough monitoring, which has only recently been available consequence to the revolution in electronic applications. However, progress is hindered by a widespread lack of awareness among healthcare professionals and patients, underscoring the urgent need for education on this condition.

Channel synapse mediates neurotransmission of airway protective chemoreflexes

Neural reflexes to chemicals in the throat protect the airway from aspiration and infection. Mechanistic understanding of these reflexes remains premature, exemplified by chronic cough-a sensitized cough reflex-being a prevalent unmet clinical need. Here, in mice, a whole-body search for channel synapses-featuring CALHM1/3 channel-mediated neurotransmitter release-and single-cell transcriptomics uncovered subclasses of the Pou2f3+ chemosensory cell family in the throat communicating with vagal neurons via this synapse. They express G protein-coupled receptors (GPCRs) for noxious chemicals, T2Rs, which upon stimulation trigger swallow and cough-like expulsive reflexes in the hypopharynx and larynx, respectively. These reflexes were abolished by Calhm3 and Pou2f3 knockout and could be triggered by targeted optogenetic stimulation. Furthermore, aeroallergen exposure augmented CALHM3-dependent expulsive reflex. This study identifies Pou2f3+ epithelial cells with channel synapses as chemosensory end organs of airway protective reflexes and sites of their hyperresponsiveness, advancing mechanistic understanding of airway defense programs with distinct therapeutic potential.

Clinical characteristics of the early responders in the treatment of chronic cough

Background

Chronic cough (CC) is defined by cough more than 8 weeks. Common causes of CC are upper airway cough syndrome (UACS), asthma, eosinophilic bronchitis (EB), and gastroesophageal reflux diseases (GERD). However, we do not know the characteristics of responding to treatment early. We conducted this study to evaluate the characteristics of the early responder group of CC.

Methods

This study was conducted as multi-center, retrospective observational study. Patients were collected in 15 university hospitals. The severity and quality of life (QOL) of CC were measured by cough numeric rating scale (NRS) and Cough Assessment Test (COAT) scores three times (baseline, 2 weeks, and 4 weeks after treatment). The early responder group was defined by improvement of minimal important difference in both cough NRS and COAT.

Results

Early responder group was more diagnosed as UACS compared to non-early responder group (65.7% vs. 49.2%, P=0.006). They also had higher baseline cough NRS (5.5±1.2 vs. 4.9±1.3, P<0.001). After adjusting confounding factors such as sex, age, cough duration, baseline cough severity and QOL, and diagnoses of UACS, asthma/EB, or GERD, higher cough NRS [odds ratio (OR) 1.44; 95% confidence interval (CI): 1.06-1.97; P=0.02] and diagnosis of UACS (OR 1.76; 95% CI: 1.02-3.02; P=0.04) were associated with being early responder group in the multivariate logistic regression analyses.

Conclusions

We demonstrated the characteristics of early responders of CC treatment. UACS group and higher baseline cough severity group showed earlier response to treatment than other groups.

Development and Validation of Cough Hypersensitivity Assessment Test

BACKGROUND

Cough hypersensitivity is an important clinical and pathophysiologic feature of chronic cough, which involves chemical, mechanical, and thermal stimuli and sensory dysfunction. Currently, there is a need for a comprehensive method to evaluate cough hypersensitivity.

OBJECTIVE

To develop and validate a questionnaire to assess the degree of cough hypersensitivity.

METHODS

The initial items of the Cough Hypersensitivity Assessment Test (CHAT) were made based on a literature review, experts' opinions, and clinical practice. Items were reduced after investigation involving patients with chronic cough. Dimensional allocation, internal reliability, test-retest reliability, construct validity, responsiveness, and cutoff value were determined in the final stage.

RESULTS

The final version of CHAT on a 5-point Likert scale (0-4) includes 18 items consisting of three dimensions: environmental triggers, daily life triggers, and tussive symptoms, with total score ranging from 0 to 72. There was significant difference in CHAT-18 scores between patients and healthy controls (P < .001). Cronbach α for CHAT was 0.832 and intraclass correlation coefficient for CHAT was 0.884. Construct validity was demonstrated with a multitrait-multimethod matrix. There was good responsiveness after treatment. The cutoff value of CHAT was 18 for cough hypersensitivity. There was a mild to moderate correlation between capsaicin cough sensitivity and tussive symptoms and the total score of CHAT.

CONCLUSIONS

The CHAT comprehensively covers a range of cough triggers and shows robust internal reliability, test-retest reliability, construct validity, and responsiveness. This may be useful for measuring cough hypersensitivity.

Systemic inflammation partially mediates the association between non-high-density lipoprotein cholesterol to high-density lipoprotein cholesterol ratio (NHHR) and chronic cough

BACKGROUND

Non-high-density lipoprotein cholesterol to high-density lipoprotein cholesterol ratio (NHHR), a new biomarker, reflects blood lipid status. Nevertheless, the association between NHHR and chronic cough remains uncertain.

METHOD

This investigation included 9725 individuals from the NHANES. This research employed multiple statistical models to illustrate the association between NHHR and chronic cough. These models included logistic regression models, the Shapley Additive Explanations (SHAP) model, trend tests, mediation analysis, restricted cubic splines (RCS), and subgroup analyses.

RESULT

The logistic regression model, adjusting all covariables, showed a positive association between NHHR with chronic cough (OR: 1.08; 95% CI: 1.02-1.14). Trend tests and RCS further proved that NHHR and chronic cough had a linear and positive association. The mediation analysis proved that systemic immune inflammation index (SII) and systemic inflammatory response index (SIRI) partially mediated the association between NHHR and chronic cough. The SHAP model suggested that the top five important markers for predicting chronic cough were SII, smoking, NHHR, BMI, and SIRI.

CONCLUSION

This investigation discovered that NHHR was positively associated with chronic cough. Regular NHHR monitoring may serve as a potential tool for identifying individuals at higher risk of chronic cough.

Cough in pulmonary rehabilitation: a retrospective analysis of responders and nonresponders

Background

Pulmonary rehabilitation (PR) is essential for people with chronic respiratory diseases (CRDs), yet its impact on cough-related quality of life (CR-QoL) remains unexplored. We assessed the effects of PR on CR-QoL, described the characteristics of responders and nonresponders to PR, and explored determinants of responsiveness in this health domain in individuals with CRDs.

Methods

A retrospective study was conducted. We assessed CR-QoL using the Leicester Cough Questionnaire (LCQ) and the impact of the disease with the COPD Assessment Test (CAT), before and after PR. Cut-offs of <17.05 in LCQ total score and ≥10 in CAT were used to detect low CR-QoL and medium impact of the disease. Responders were defined as achieving a minimal clinically important difference (MCID) of ≥1.3 on the LCQ total score. Pre- versus post-PR analysis involved the t-test, Wilcoxon test or McNemar test and comparisons between groups included the independent t-test, Mann-Whitney U-test or Fisher's exact test. Logistic regression was employed to investigate factors influencing MCID achievement.

Results

135 participants with CRDs (39% females; age 68±10 years; 61% COPD; forced expiratory volume in 1 s (FEV1) % pred 62.6±23.0%) were included. After PR, significant improvements were observed in all LCQ domains and CAT. 31% of participants were identified as responders in the LCQ (36% females; age 66±10 years; 62% COPD; FEV1 % pred 60.0±22.3%), showcasing significant differences in the LCQ and CAT compared to nonresponders. People with low CR-QoL and medium/high impact of the disease at baseline were 11 and 4 times more likely to respond to PR in CR-QoL, respectively.

Conclusion

PR enhances CR-QoL. Identification of CR-QoL and disease impact traits at baseline offers insights to optimise this outcome responsiveness to PR.

Cough-Variant Asthma: A Review of Clinical Characteristics, Diagnosis, and Pathophysiology

Chronic cough is among the most common symptoms prompting medical care. Cough-variant asthma (CVA) is an asthma subset where cough is the primary symptom, without wheezing, chest tightness, or dyspnea. It is an important cause of chronic cough, estimated to account for 25% to 42% of cases, but likely underdiagnosed due to delayed recognition and pitfalls of diagnostic testing. Early recognition and treatment can reduce morbidity and delay its progression to more typical asthma. This review details the clinical characteristics, diagnosis, pathophysiology, and treatment of CVA and contrasts it with classic asthma and other causes of chronic cough.

Multiple Neural Networks Originating from the Lateral Parabrachial Nucleus Modulate Cough-like Behavior and Coordinate Cough with Pain

It has been reported that experimental pain can diminish cough sensitivity and that the lateral parabrachial nucleus (LPBN) coordinates pain with breathing, but whether the LPBN regulates cough-like behaviors and pain-induced changes in cough sensitivity remains elusive. We investigated the roles of LPBN γ-aminobutyric acidergic (GABAergic) and glutamatergic neurons in the regulation of cough sensitivity and its relationship with pain in mice via chemogenetic approaches. Adenovirus-associated virus tracing combined with chemogenetics was used to map the projections of LPBN GABAergic and glutamatergic neurons to the periaqueductal gray. LPBN neurons were activated by cough challenge, and nonspecific inhibition of LPBN neurons suppressed cough-like behavior. Chemogenetic suppression of LPBN GABAergic neurons reduced cough sensitivity in mice, whereas suppression of LPBN glutamatergic neurons counteracted the pain-driven decrease in cough sensitivity, and so did silencing LPBN glutamatergic neurons projecting to the periaqueductal gray. Our data suggest that GABAergic and glutamatergic neurons in the LPBN critically are involved in cough sensitivity and coordinate pain with cough through inhibitory or activating mechanisms at the midbrain level.

Cough Reflex Hypersensitivity as a Key Treatable Trait

Cough reflex hypersensitivity is emerging as a key treatable trait in chronic cough and other cough-associated respiratory conditions. This review examines the neurological basis of cough, highlighting the complex interplay between peripheral and central mechanisms. The concept of cough hypersensitivity aims to address unmet clinical needs by recognizing chronic cough as a distinct disorder rather than merely a symptom. Evidence from clinical trials supports cough hypersensitivity as a treatable trait in chronic cough, with opiates, gabapentinoids, and novel P2X3 antagonists showing efficacy. Cough hypersensitivity is also relevant in conditions presenting with persistent cough, such as asthma, bronchiectasis, and idiopathic pulmonary fibrosis, though more research is needed. Recognizing cough reflex hypersensitivity as a treatable trait offers new avenues for management, particularly for patients with persistent cough despite etiology-targeted therapies. We propose redefining chronic cough as a distinct disease entity in which cough hypersensitivity is a common feature and key therapeutic target, potentially leading to better patient care and the development of novel therapies.

WAO - ARIA consensus on chronic cough: Executive summary

Acute cough is a highly prevalent symptom in clinical practice. Chronic cough is a complex disease with significant impact on quality of life. The mechanistic pathways of chronic cough in cough-comorbid clinical phenotypes are elusive. Mounting evidence suggests presence of a hypersensitive cough reflex and implication of transient receptor potential channels and P2X receptors in cough neuronal pathways. Previously, the World Allergy Organization (WAO)/Allergic Rhinitis and its Impact on Asthma (ARIA) Joint Committee on Chronic Cough published updated experimental and clinical data on chronic cough, in addition to a multidisciplinary care pathway approach to its management. The goal of this manuscript is to provide clinicians with a succinct summary of chronic cough pathophysiology, clinical phenotypes, and management strategies in both primary and cough specialty care. This executive summary is a primer for clinicians on chronic cough. Increasing awareness on the topic among primary care physicians will improve the outcome of management of patients with chronic cough.

Sputum Metabolomic Signature and Dynamic Change of Cough Variant Asthma

Cough variant asthma (CVA), a common reason for chronic cough, is a globally prevalent and burdensome condition. The heterogeneity of CVA and a lack of knowledge concerning the exact molecular pathogenesis has hampered its clinical management. This study presents the first sputum metabolome of patients with CVA, revealing the dynamic change during treatment and exploring biomarkers related to the occurrence and treatment response of CVA. We found that arginine biosynthesis, purine metabolism, and pyrimidine metabolism pathways were enriched in CVA compared with healthy controls. Part of the metabolic disturbances could be reversed by antiasthmatic medication. The levels of dipeptides/tripeptides (alanyl tyrosine, Gly-Tyr-Ala, Ala-Leu, and Thr-Leu) were significantly associated with sputum neutrophil or eosinophil percentages in patients with CVA. Differential metabolites before treatment between effective and ineffective treatment groups were enriched in purine metabolism, thiamine metabolism, and arginine metabolism. 2-Isopropylmalate was downregulated in CVA and increased after treatment, and the effective treatment group had a lower 2-isopropylmalate level before treatment. Random forest and logistic regression models identified glutathione, thiamine phosphate, alanyl tyrosine, and 2'-deoxyadenosine as markers for distinguishing CVA from healthy controls (all areas under the curve >0.8). Thiamine phosphate might also be promising for predicting therapy responsiveness (area under the curve, 0.684). These findings imply that disturbed mitochondrial energy metabolism and imbalanced oxidation-reduction homeostasis probably underlay the metabolic pathogenesis of CVA.

Prevalence and risk factors of chronic cough in an adult community-dwelling Portuguese population

Background

Chronic cough is associated with high individual and social costs, mainly due to doctor visits and diagnostic investigations. The aim of the present study was to estimate the prevalence of chronic cough and identify risk factors associated with chronic cough in a community-based sample in the scope of the EpiCOUGH study.

Methods

From 1 June to 31 August 2023, we recruited adults from the largest primary healthcare centres in Lisbon, Portugal, and invited them to participate in an online survey. Participants aged ≥20 years with a registered email address were eligible. Data collection included a health questionnaire that recorded the presence, duration, frequency and impact of cough on daily activities. Chronic cough was defined as lasting longer than 8 weeks.

Results

Of the 7285 adult healthcare users who agreed to participate, 2309 (31.7%) completed the questionnaire. Most were female (59.2%) and the mean±sd age was 51.6±13.5 years. The estimated prevalence of chronic cough was 7.23% (95% CI 6.24-8.36%). Chronic cough was associated with older age, being divorced/widowed, current smoking, obesity, asthma, working in a dusty environment and pet ownership. No cause was diagnosed in 23.36% of patients who consulted a doctor.

Conclusion

Chronic cough was relatively common in the population studied. Our data emphasise the need to treat patients with chronic cough with strategies that address risk factors. This study also highlights the complexity of chronic cough management and the need for further research and diagnostic tools to improve patient outcomes.

Nonpharmacological Approaches to Chronic Cough

Although cough is a protective reflex, it can occur in the absence of any physical need to clear the airway. In chronic cough, cough can be triggered by innocuous stimuli and persist despite medical treatment. Nonpharmacological interventions such as cough control therapy, provided by speech pathologists, have gained popularity in recent years. Intervention targets refractory or unexplained chronic cough, and efficacy has been studied in randomized controlled trials. Key elements of cough control therapy include education, anticipation, and control of the urge to cough, reducing laryngeal irritation and psychoeducational counseling. Our understanding of the mechanisms behind the success of nonpharmacological treatment is developing. It is likely the mechanisms of action are multifactorial across peripheral, central, and higher cortical regions. Nonpharmacological cough control therapy interventions are now included in international cough guidelines. However, approach to service delivery is not standardized and varies between regions and countries.

The Clinical Approach to Chronic Cough

Chronic cough remains a significant clinical challenge, affecting approximately 10% of the population and leading to significant impairment in psychological, social, and physical quality of life. In recent years, efforts have intensified to elucidate the mechanisms underlying chronic cough and to focus on investigating and treating refractory chronic cough (RCC). A "treatable trait" approach, which focuses on identifying and addressing the specific associated causes of chronic cough, has gained traction. In some patients, RCC is likely driven by a neuropathic mechanism due to dysregulation of the neuronal pathways involved in the cough reflex, often clinically described as cough hypersensitivity syndrome. Although the initial treatment of underlying conditions remains central to managing treatable traits, the therapeutic options for RCC have expanded to include targeting cough hypersensitivity. First-line treatments now include neuromodulators and speech therapy with one P2X3 receptor antagonist (gefapixant) recently licensed in the European Union, United Kingdom, and Japan. Despite these advances, patient responses remain variable, underscoring the ongoing need for research into the pathophysiology and treatment of RCC. This article reviews current investigations and management options in treating chronic cough and RCC.

Association between clinical and pulmonary function features and diagnosis of cough variant asthma: a case-control study

OBJECTIVES

To compare physical information, such as age, sex, height, weight, body mass index (BMI) and pulmonary function test (PFT) results, between cough variant asthma (CVA) and chronic cough (CC) and establish a diagnostic model of CVA.

DESIGN

A case-control study of patients with suspected CVA enrolled at The First Affiliated Hospital of Zhejiang Chinese Medical University.

SETTING

One leader unit of the National Key Specialised Pulmonary Disease Cooperation Group in China.

PARTICIPANTS

Enrolled 545 patients who underwent PFT and bronchial provocation tests.

OUTCOME MEASURES

We obtained physical information and pulmonary test data and established the model using logistic regression analysis. The Hosmer-Lemeshow goodness-of-fit test, area under the receiver operating characteristic curve (AUC), calibration plot and decision curve analysis were used to evaluate this model. All data were analysed using SPSS V.27 and RStudio software.

RESULTS

The CVA group had more female patients (%) (68.12% vs 51.48%, p value<0.001) and lower height (m) (1.61 (0.40) vs 1.65 (3.26), p value<0.001), weight (kg) (60 (56) vs 63 (85), p value<0.001) and BMI (kg/m2) (22.59 (17.91) vs 23.28 (21.81), p value=0.016) than the CC group. Differences between CVA and CC in forced vital capacity (FVC) in percent predicted values (FVC% pred)(94.4 (57.3) vs 91.60 (94.10), p value=0.006), forced expiratory volume in 1 s/FVC (FEV1/FVC) (%) (84.65±6.82 vs 86.91±6.71, p value<0.001), peak expiratory flow in per cent predicted values (PEF% pred) (93.00 (81.10) vs 98.00 (108.00), p value=0.005), maximal mid-expiratory flow in percent predicted values (MMEF% pred) (74.50 (100.60) vs 90.85 (170.30), p value<0.001), forced expiratory flow (FEF) at 50% of FVC in per cent predicted values (FEF50% pred) (78.9(113.50) vs 93.10(169.80), p value<0.001) and FEF at 75% of FVC in per cent predicted values (FEF75% pred) (69.70 (137.60) vs 85.60 (225.80), p value<0.001) were significant. Patients with CVA were more in number compared with patients with CC at a lower degree (<65%) of MMEF% pred (32.37% vs 14.50%, p value<0.001), FEF50% pred (26.09% vs 13.02%, p value<0.001) and FEF75% pred (39.13% vs 23.67%, p value<0.001). FVC% pred, FEV1/FVC, BMI and MMEF% pred aided in establishing a model with an AUC of 0.733 (95% CI: 0.6829 to 0.7831). The model was tested using internal and external data (p value=0.2865 and p value=0.3197, respectively).

CONCLUSION

BMI, FVC% pred, FEV1/FVC (%) and MMEF% pred were used to establish the diagnostic model. Our model potentially indicates CVA.

TRIAL REGISTRATION NUMBER

NCT06199830.

The extract from Quzhou Aurantii Fructus attenuates cough variant asthma through inhibiting the TRPV1/Ca2+/NFAT/TSLP pathway and ferroptosis via TRPV1 mediation in ovalbumin-induced mice

ETHNOPHARMACOLOGICAL RELEVANCE

Cough variant asthma (CVA), a prevalent chronic inflammatory disease, is the most common cause of chronic cough. Over the years, the aqueous extract of Quzhou Aurantii Fructus (QAFA) has been widely used to treat respiratory diseases, particularly cough.

AIM OF THE STUDY

This study aimed to elucidate the therapeutic effect of QAFA on allergen-induced CVA, providing deep insights into the underlying mechanisms.

MATERIALS AND METHODS

Ultra-high performance liquid chromatography quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS) was employed to characterize the compositions, while UPLC was used to quantify the contents of its major components in QAFA. CVA model was established via sensitization and atomization with ovalbumin (OVA), and received 600 and 1200 mg/kg of QAFA via intragastric gavage. Cough response was assessed by stimulation with capsaicin (CAP). Then, airway hyperresponsiveness (AHR), ELISA, western blotting, RT-qPCR, and histological analyses, were applied to assess pulmonary function, pathological changes, and investigate mechanisms in CVA mice following QAFA treatment through the TRPV1/Ca2+-dependent NFAT-induced expression of TSLP and ferroptosis. Additionally, the effects and mechanisms of QAFA were validated using IL-4, CAP for stimulation, capsazepine (CPZ) for inhibition, and TRPV1 siRNA transfection in cells.

RESULTS

Chemical analysis revealed that QAFA primarily contained sixteen compounds, with four main components including narirutin, naringin, hesperidin, and neohesperidin. In vivo, QAFA treatment alleviated cough and AHR, while concurrently reducing airway inflammation and mucus secretion in CVA mice. These effects were achieved by suppressing the TRPV1/NFAT/TSLP pathway and modulating the expression of ferroptosis-related proteins. In vitro, siTRPV1-transfected BEAS-2B cells demonstrated the involvement of the TRPV1 channel in IL-4-mediated Ca2+ influxes, ferroptosis, and regulation of TSLP production. QAFA and CPZ suppressed IL-4-induced TSLP production via the TRPV1/NFAT pathway and regulated the levels of ferroptosis-related proteins, while CAP counteracted the effect of QAFA on TSLP production in BEAS-2B cells. Furthermore, QAFA reduced IL-4 or CAP induced Ca2+ influx and IL-4 induced ferroptosis through TRPV1 mediation.

CONCLUSIONS

This study demonstrated that QAFA improved pulmonary function and alleviated asthmatic inflammatory response in treating CVA probably through suppressing the TRPV1/Ca2+/NFAT/TSLP pathway and ferroptosis via TRPV1 mediation.

Refractory Chronic Cough: A State-of-the-Art Review for Otolaryngologists

OBJECTIVE

Patients with refractory chronic cough (RCC) are being seen in increasing numbers within otolaryngology clinics. Identifying the next steps in the evaluation and management of cough in patients who have had first-line treatment for gastroesophageal reflux, sinonasal disease, pulmonary disease, and angiotensin-converting enzyme inhibitor-related cough is paramount. This state-of-the-art review focuses on emerging treatments for RCC from an otolaryngology perspective.

DATA SOURCES

Pubmed.

REVIEW METHODS

The available literature on chronic cough, with a focus on RCC, emerging paradigms concerning pathophysiology, and evolving treatment approaches was reviewed and summarized.

CONCLUSIONS

Guided by a more detailed understanding of refractory cough physiology, a myriad of new treatment options have been developed to treat RCC. These are primarily aimed at disrupting what is thought to be a hypersensitive cough reflex, whether by a dampening of its sensory inputs or an alteration in motor activity, and are inclusive of neuromodulator treatments, superior laryngeal nerve blockade, vocal fold augmentation, botulinum toxin injection, topical capsaicin, and potentially the eventual use of P2X3 antagonists. Improved laryngopharyngeal reflux diagnosis and management, as well as the potential benefit of behavioral cough suppression therapy, are also discussed.

IMPLICATIONS FOR PRACTICE

The literature supporting each of these strategies is growing-and as more patients with RCC seek otolaryngology care, knowledge of these various approaches may improve the overall treatment of this condition.

Diagnosis in Children With Prolonged or Recurrent Cough: Findings From the Swiss Paediatric Airway Cohort

INTRODUCTION

Prolonged or recurrent cough is a common reason for referral to pediatric pulmonologists, yet few studies have assessed its causes. We examined records of children visiting respiratory outpatient clinics in Switzerland and assessed how diagnoses vary by age.

METHODS

We analyzed data from the multicenter Swiss Paediatric Airway Cohort study. We included 363 children (median age 6 years, range 0-16) referred for prolonged or recurrent cough. From outpatient records, we extracted information on diagnostic investigations, final diagnoses proposed by pediatric pulmonologists, and treatments prescribed.

RESULTS

Asthma and asthma-like conditions (cough variant asthma, episodic viral wheeze, and recurrent obstructive bronchitis) were diagnosed in 132 (36%) of 363 children, respiratory tract infections (RTI) including protracted bacterial bronchitis (PBB) in 51 (14%), upper airway cough syndrome (UACS) in 48 (13%), and postinfectious cough in 36 (10%); other diagnoses including gastroesophageal reflux disease (GERD) and somatic cough syndrome or tic cough were found in 23 (6%). No etiology was found in 73 children (20%). Asthma was diagnosed 3.5 times more often in schoolchildren while RTI including PBB was diagnosed three times more often in preschoolers. Inhaled corticosteroids were prescribed for 84% of children diagnosed with asthma and asthma-like conditions, antibiotics for 43% of children with RTI, and nasal corticosteroids for 83% of those with UACS.

CONCLUSION

Coughing children received a wide spectrum of diagnoses that differed between preschool and schoolchildren. Asthma accounted for 36% of diagnoses, which emphasizes the importance of comprehensive investigation beyond asthma in children with prolonged or recurrent cough.

Challenges of symptom management in interstitial lung disease: dyspnea, cough, and fatigue

INTRODUCTION

Interstitial lung disease (ILD) is a broad group of conditions characterized by fibrosis of the lung parenchyma. Idiopathic pulmonary fibrosis (IPF) is the most common subvariant. IPF is marked by considerable symptom burden of dyspnea, cough and fatigue that is often refractory to optimal disease-directed treatment.

AREAS COVERED

In this narrative review, we searched MEDLINE for articles related to the current evidence regarding management of chronic dyspnea, cough, and fatigue as three of the most prevalent and distressing symptoms associated with IPF and other ILDs. Each symptom shares common features of multi-factorial etiology and a lack of safe and effective pharmacological therapies. Both corticosteroids and opioids have been utilized in this context, yet there is insufficient evidence of therapeutic benefit and considerable risk of harms. Whilst some may benefit from symptom-directed pharmacological management, usage must be carefully monitored. Use of non-pharmacological strategies, such as breathing techniques and speech therapy represent low risk and low-cost option, yet broader validation of these therapies' effectiveness is needed.

EXPERT OPINION

Symptom management in IPF and other ILDs requires an iterative and individualized approach. Leveraging the expertise of multidisciplinary teams within an integrated care setting is an important opportunity to maximize health outcomes.

Post COVID-19 and Long COVID Symptoms in Otorhinolaryngology-A Narrative Review

Post/Long COVID (syndrome) is defined as a condition with symptoms persisting for more than 12 weeks after the onset of SARS-CoV-2 infection that cannot be explained otherwise. The prevalence of self-reported otorhinolaryngological Post/Long COVID symptoms is high. The aim of this review was to analyze the current literature regarding the actual prevalence, knowledge of the etiopathology, and evidence-based treatment recommendations of otorhinolaryngology-related Post/Long COVID symptoms. A systematic literature search of articles published since 2019 in PubMed and ScienceDirect was performed and resulted in 108 articles. These were the basis for this review and formed a comprehensive series of consented therapy statements on the most important of otorhinolaryngology-related Post/Long COVID symptoms. Otorhinolaryngological symptoms did not appear isolated but as part of a multi-organ syndrome. Self-reported otorhinolaryngology-related Post/Long COVID symptoms were often not confirmed by objective testing. The confirmed prevalence estimated for anosmia, dysgeusia, cough, facial palsy, hoarseness/dysphonia, acute hearing loss, tinnitus, and vertigo/dizziness was about 4%, 2%, 4-19%, 0%, 17-20%, 8%, 20%, and 5-26%, respectively. There are manifold theoretical concepts of the etiopathology of different symptoms, but there is no clear evidence-based proof. This certainly contributes to the fact that there is no effective specific treatment option for any of the symptoms mentioned. Healthcare pathways must be established so that otorhinolaryngological Post/Long COVID symptoms can be recognized and evaluated and otorhinolaryngologists can provide counseling. This would also help to establish and selectively include patients in clinical trials investigating specific therapeutic concepts.

20S-Ginsenoside Rh2, the major bioactive saponin in Panax notoginseng flowers, ameliorates cough by inhibition of NaV1.7 and TRPV1 channel currents and downregulation of TRPV1 expression

ETHNOPHARMACOLOGICAL RELEVANCE

Panax notoginseng flowers, which are the buds of the traditional Chinese medicinal herb Sanqi, are widely used in China for their cough-ameliorating properties, with demonstrated therapeutic effects in the treatment of both acute and chronic coughs. However, both the antitussive mechanism and active compound basis of P. notoginseng flowers remain poorly understood.

AIM OF THE STUDY

We investigated the antitussive effects of P. notoginseng flowers, identified the bioactive constituents responsible for alleviating cough symptoms, and elucidated the underlying pharmacological mechanisms.

MATERIALS AND METHODS

We analyzed the major chemical constituents of aqueous extracts of P. notoginseng flowers using liquid chromatography-mass spectrometry and quantitatively analyzed the key component, 20S-ginsenoside Rh2, using high-performance liquid chromatography. Using a cough reflex model in healthy mice and an ovalbumin-induced, highly sensitive guinea pig cough model, we verified the suppressive effects of P. notoginseng flowers and their saponin constituents on coughing. Furthermore, we explored the mechanisms of action of the key ion channels, NaV1.7 and TRPV1, using whole-cell patch-clamp techniques and molecular docking. Finally, the therapeutic mechanisms of P. notoginseng flowers on pathological cough were revealed using hematoxylin and eosin staining, immunohistochemistry, and western blotting.

RESULTS

The active components of P. notoginseng flowers were primarily protopanaxadiol-type saponins, among which 20S-ginsenoside Rh2 had the highest content (51.46 mg/g). In the mouse model, P. notoginseng flowers exhibited antitussive effects comparable to those of pentoxyverine citrate. Although its main saponin component, 20S-ginsenoside Rh2, showed slightly weaker effects, it still demonstrated concentration-dependent inhibition of channel activity. The whole-cell patch-clamp technique and virtual molecular docking showed that Rh2 might exert its effects by directly binding to the NaV1.7 and TRPV1 channels. In the guinea pig model, P. notoginseng flowers and their saponin components not only reduced cough frequency and prolonged the latency period before cough onset, but also significantly inhibited tracheal and pulmonary inflammation and the overexpression of TRPV1.

CONCLUSIONS

20S-Ginsenoside Rh2, the major bioactive saponin in P. notoginseng flowers, exhibits potent antitussive effects. The potential mechanism of action of 20S-Ginsenoside Rh2 in the treatment of cough may involve inhibiting NaV1.7 and TRPV1 channel currents through direct binding to core protein active sites and downregulating TRPV1 expression.

Peripheral antitussives affect temporal features of tracheobronchial coughing in cats

The influence of peripheral antitussive drugs on spatiotemporal features of coughing has not been reported. We hypothesized that this class of compounds would alter the cough motor pattern, in part, by lengthening cough phases. Peripherally acting antitussives, 3-aminopropylphosphinic acid (3APPi, 5 mg/kg) and levodropropizine (Levo, 3 mg/kg) were injected intravenously in anesthetized spontaneously breathing cats (13 males, 2 females; 4.38 ± 0.19 kg). Spatio-temporal analysis of cough induced by mechanical stimulation of the trachea showed significant reductions in cough number and expiratory cough efforts after the administration of each drug. A significant reduction in inspiratory cough efforts occurred after Levo. Both drugs induced temporal changes in the cough motor pattern, including prolongations of inspiratory phase, inspiratory-expiratory transition, total cough diaphragm activity, and total cough cycle duration. Levo also significantly lengthened the expiratory phase of cough. A shortening of the overlap between diaphragm and abdominal activity and cough abdominal electromyogram (EMG) activity was observed after the administration of 3APPi. No significant changes in cardiorespiratory data were seen, with the exception of prolonged expiratory phase after 3APPi and lower blood pressure after Levo. Peripherally induced cough suppression is accompanied with changes in cough temporal characteristics that are not observed after the administration of centrally acting antitussives. The motor output produced by the cough central pattern generator differs significantly when coughing is perturbed by peripherally and centrally acting antitussives.NEW & NOTEWORTHY In a study on anesthetized cats, peripherally acting antitussives 3-aminopropylphosphinic acid (3APPi) and levodropropizine (Levo) significantly reduced cough number and expiratory efforts, with Levo also reducing inspiratory efforts. Both antitussives altered the cough motor pattern, extending various cough phases. 3APPi shortened diaphragm-abdominal activity overlap, whereas Levo decreased the respiratory rate. These changes contrast with those induced by centrally acting antitussives.

Repeat expansions in RFC1 gene in refractory chronic cough

Introduction

Refractory chronic cough (RCC), persisting despite addressing contributory diagnoses, is likely underpinned by neurally mediated cough hypersensitivity. RFC1 disorders are genetic neurodegenerative conditions caused by biallelic RFC1 repeat expansion sequences, commonly presenting with cough, followed by neurological features including cerebellar ataxia with neuropathy and vestibular areflexia syndrome (CANVAS). The prevalence and identifying clinical characteristics of RFC1 repeat-expansion disorders in patients with RCC are unknown.

Methods

Consecutive patients with RCC underwent RFC1 genotyping, cough severity visual analogue scale (VAS) and cough-specific health status assessment (Leicester Cough Questionnaire (LCQ)). Participants with biallelic RFC1 repeat expansions (RFC1++) also underwent nerve conduction studies, brain imaging (MRI) and cough reflex sensitivity testing.

Results

51 participants with RCC were recruited; 36 (71%) female, median (IQR) age 65 (56-70) years, duration of cough 12.8 (6.9-20.0) years. Four (8%) were RFC1++, five (10%) monoallelic carriers (RFC1+-) and 42 (82%) of wild-type genotype (RFC1--). No difference was observed in age, sex, cough duration, spirometry, VAS or LCQ scores between RFC1++ and RFC1-- subjects (p>0.05). The symptom of pins and needles was more frequent in RFC1++ (n=4, 100%) compared to RFC1-- (n=12, 33%) (p=0.01). RFC1++ participants had impaired sensory action potentials, and one had cerebellar atrophy. RFC1++ participants had heightened cough reflex sensitivity to capsaicin, similar to previous CANVAS and RCC studies.

Conclusion

Biallelic RFC1 repeat expansions (RFC1++) were present in 8% of RCC patients. RFC1++ participants demonstrated features of cough reflex hypersensitivity. RFC1++ chronic cough had few identifying features, although symptoms of pins and needles were more common.

How to distinguish PPI-refractory from PPI-responsive patients in gastro-oesophageal reflux-induced chronic cough: post-reflux swallow induced peristaltic wave index and mean nocturnal baseline impedance provide new predictive factors

Background

The results of empirical trials with proton pump inhibitors (PPIs) for management of gastro-oesophageal reflux-induced chronic cough (GERC) have resulted in considerable controversy, and the mechanism of PPI refractoriness remains unclear. Our study aims to identify the predictors of PPI refractoriness of GERC in a retrospective clinical study.

Methods

In total, 128 GERC patients were enrolled between March 2018 and October 2022. Regression analysis was utilised to create a model for predicting PPI-refractory of GERC using retrospective analysis of the general data and MII-pH indicators.

Results

The post-reflux swallow induced peristaltic wave index (PSPWI) was lower in the PPI-refractory group than the PPI-responsive group (33.89±7.38 versus 39.45±9.47, respectively, p<0.001), as were the mean nocturnal baseline impedance (MNBI) and proximal MNBI (2092.11 (IQR: 652.23)] versus 2426.52 (IQR: 917.39) Ω, respectively, p=0.012; 1599.50 (IQR: 1206.63) versus 2274.50 (IQR: 1775.29) Ω, respectively, p=0.001). Multivariate logistic regression analysis identified the PSPWI (odds ratio 0.919, p=0.001) as an independent predictor of PPI-refractory GERC.

Conclusions

The diagnostic value of both proximal MNBI ≤39.90% and MNBI ≤2233.58 Ω had moderate sensitivity (71.67%) and specificity (75.00%) to identify PPI-refractory GERC.

Guiding therapy by fractional exhaled nitric oxide & impulse oscillometry parameters in non-asthmatic individuals with chronic cough

Background & objectives Chronic airway inflammation and airway hyperresponsiveness are typical pathophysiological features of cough variant asthma. However, the characteristics of airway inflammation and airflow restriction in individuals with non-asthmatic chronic cough and their guiding value of clinical treatment remain to be determined. This study explored the characteristics and correlations between fractional exhaled nitric oxide (FeNO) and impulse oscillometry (IOS) in non-asthmatic individuals with chronic cough. It also investigated the possibility of chronic cough developing into asthma. Methods In total, 65 study participants with negative bronchial provocation test (BPT) were included in this retrospective study. Data were extracted from chronic cough patients' electronic medical records, including the demographics, FeNO, IOS and spirometric parameters before and after BPT. Study participants were divided into high-FeNO group (FeNO≥25 ppb) and low-FeNO group (FeNO< 25 ppb) based on FeNO levels. The correlation between the markers was investigated using the Spearman rank correlation test. Results We observed that individuals with non-asthmatic chronic cough exhibited significant increases in Z5, Fres, R5 and R5-R20 after BPT compared to before BPT. In addition, the IOS values of Z5, Fres, R5, and Rc were higher in the low-FeNO group than in the high-FeNO group, but a decrease in FEV1. Correlation analysis: IOS parameters showed a negative correlation with FeNO. However, there were positive correlations of FeNO with FEV1 and PEF. Interpretation & conclusions Our findings showed that individuals with non-asthmatic chronic cough may have varying levels of small airway resistance and inflammation severity. A combined use of FeNO and IOS measurements is conducive to the early clinical treatment of individuals with non-asthmatic chronic cough.

Cough and itch: Common mechanisms of irritation in the throat and skin

Cough and itch are protective mechanisms in the body. Cough occurs as a reflex motor response to foreign body inhalation, while itch is a sensation that similarly evokes a scratch response to remove irritants from the skin. Both cough and itch can last for sustained periods, leading to debilitating chronic disorders that negatively impact quality of life. Understanding the parallels and differences between chronic cough and chronic itch may be paramount to developing novel therapeutic approaches. In this article, we identify connections in the mechanisms contributing to the complex cough and scratch reflexes and summarize potential shared therapeutic targets. An online search was performed using various search engines, including PubMed, Web of Science, Google Scholar, and ClinicalTrials.gov from 1983 to 2024. Articles were assessed for quality, and those relevant to the objective were analyzed and summarized. The literature demonstrated similarities in the triggers, peripheral and central nervous system processing, feedback mechanisms, immunologic mediators, and receptors involved in the cough and itch responses, with the neuronal sensitization processes exhibiting the greatest parallels between cough and itch. Given the substantial impact on quality of life, novel therapies targeting similar neuroimmune pathways may apply to both itch and cough and provide new avenues for enhancing their management.

Chronic Cough Patient Perspective: questionnaire validation and symptom impact

Background

Chronic cough (CC) is underevaluated and underreported. The introduction of a tool that is easy to complete, score and interpret and with the psychometric properties requested for use in individual patients could improve clinical practice.

Objective

This cross-sectional study aimed to validate the Chronic Cough Patient Perspective (CCPP) for assessing CC in daily practice.

Methods

A provisional CCPP was created by iteratively reducing the Chronic Cough Impact Questionnaire (CCIQ). Its psychometric properties were tested in CC patients at baseline (visit 1) and after 1 month (visit 2).

Results

The reduction process yielded an 8-item provisional version, subsequently validated in 150 patients (36.33% males, mean age 50±16.9 years). Exploratory factor analysis revealed a one-dimensional structure, with one item being deleted as it did not align with the extracted dimension. The 7-item version of the CCPP showed a strong correlation with the CCIQ (r=0.902 at visit 1, r=0.932 at visit 2) and internal consistency (Cronbach's alpha values: 0.85 at visit 1, 0.93 at visit 2); discriminant and convergent validity were satisfactory. The reliability, assessed in 21 patients with no change in CC (Global Rating Scale=0), was high (concordance correlation coefficient=0.815; interclass coefficient=0.823). A score ≤5 indicates optimal health-related quality of life (HRQoL) attainment, with a minimum important difference of 3. The mean CCPP score was 20.5±6.24 at enrolment, and only 37.33% of the participants achieved an optimal HRQoL at visit 2.

Conclusion

The CCPP exhibited good psychometric properties suitable for clinical use, providing a valid, reliable and standardised assessment of CC's impact on HRQoL.

Gastro-oesophageal reflux-related chronic cough: can new tools improve patient assessment?

Novel impedance pH monitoring parameters, such as mean nocturnal baseline impedance and post-reflux swallow induced peristaltic wave index, may be better markers for assessing chronic cough related to oesophageal hypersensitivity https://bit.ly/41woxTD.

Cough frequency has a high daily variation in patients with chronic cough

Continuous cough monitoring using a wearable device analysed by machine learning for automated cough detection has revealed considerable day-to-day variability in cough counts. Single-day recording is thus subject to error. https://bit.ly/3yYCRbX.

Flexible bronchoscopy in the diagnosis of chronic cough causes in non-smoking adults

A chronic cough (CC) is reported in 4-10% of the adult population and negatively affects quality of life [1-5]. Diagnosing and managing CC is challenging [3-5]. Initial evaluation typically includes chest radiography, spirometry, blood cell count (to detect blood eosinophils) and exhaled nitric oxide fraction, if available [4, 5]. Further diagnostic tests are warranted if clinical symptoms and basic tests cannot identify the cause of CC. Secondary diagnostic tests include oesophageal manometry or pH/impedance monitoring, induced sputum for eosinophils, laryngoscopy, bronchial provocation challenge, chest computed tomography (CT) and bronchoscopy [3-5].

Characterization and clinical outcomes of outpatients with subacute or chronic post COVID-19 cough: a real-world study

Background

Limited research exists on the features and management of post-COVID cough. This real-world study investigates outpatients with subacute or chronic post-COVID cough, aiming to delineate characteristics and regimen responses within the population.

Method

We enrolled eligible patients from our outpatient unit between August 2023 and February 2024. Comprehensive clinical data, prescriptions, and patient-reported cough severity were collected during the primary visit and subsequent follow-ups.

Result

A total of 141 patients, aged: 42 ± 14 years old, were included, with 70% being female. The median cough duration was 8 weeks (interquartile range 4-12 weeks). Sixty percent presented with a dry cough, while the rest had coughs with phlegm. Over half reported abnormal laryngeal sensations (54%). Twenty-one percent coughed during the day, while 32% coughed constantly, and 48% experienced nocturnal episodes. Compound methoxyphenamine capsules were the most prescribed, but our study found ICS/LABA to be the most effective, followed by compound methoxyphenamine capsules, montelukast, and Chinese patent drugs.

Conclusion

Females exhibit a higher prevalence of post-COVID cough, and our study recommends ICS/LABA as the preferred treatment. These findings warrant validation through larger, prospectively designed studies.

Nationwide study of chronic codeine use and its impact on cough related diseases in South Korea

Codeine is widely used to control coughs, although concerns about its overuse arise due to its side-effects. This study aimed to evaluate the status of codeine usage according to various medical conditions. The Korean National Health Insurance Service sample cohort was analyzed. Subjects with more than continuous sixty days of antitussive and codeine were defined as chronic users. It was evaluated according to age, smoking status, chronic obstructive pulmonary disease (COPD), asthma, allergic rhinitis (AR), bronchiectasis, chronic cough (CC), gastroesophageal reflux disease (GERD), and lung cancer. A total of 89,289 chronic antitussive users were identified, of whom 589 were chronic codeine users. The chronic codeine users were older, more likely to be smokers, and more likely to have multimorbidity (P < 0.001, all). After adjusting age, chronic codeine use showed a positive correlation with lung cancer (adjusted odds ratio [aOR]: 6.99), COPD (aOR: 2.04), GERD (aOR: 1.93), and CC (aOR: 1.60). Multimorbidity also revealed positive correlations, increasing as the number of comorbidities rose (P < 0.001). Our findings highlight that chronic codeine usage is associated with underlying cough-inducing diseases, emphasizing the need for monitoring and guidelines to ensure safer use, especially among older adults and those with chronic respiratory conditions.

Current opinion in refractory and/or unexplained chronic cough

PURPOSE OF REVIEW

Otolaryngologists are vital to successfully managing chronic cough in adults. This review presents updates regarding rapidly evolving concepts in chronic cough.

RECENT FINDINGS

Significant growth is occurring in chronic cough research, strengthening the evidence of its major psychosocial impacts. Elucidation of the neural underpinnings of normal and abnormal cough within both the peripheral and central nervous systems highlight the previously underappreciated complexity of cough. Recent clinical practice recommendations emphasize personalized treatment approaches through addressing treatable traits of chronic cough. Investigations are ongoing to better distinguish chronic cough subgroups, and multiple types of important clinical outcome measures are being characterized. Newer research about chronic cough treatment encompasses pharmacologic and nonpharmacologic interventions, including oral and inhaled medications, superior laryngeal nerve blocks, and behavioral therapy.

SUMMARY

As knowledge about chronic cough in adults continues to expand in both research and clinical practice, otolaryngologists can continue to raise awareness of the role of the larynx in cough and promote ongoing multidisciplinary collaborations. In the coming years, more pharmacologic options and personalized treatment approaches will likely emerge for chronic cough.

Integrating hot topics and implementation of treatable traits in asthma

People with asthma experience many different problems related to their illness. The number and type of problems differ between patients. This results in asthma being a complex and heterogeneous disorder which mandates a personalised approach to management. These features pose very significant challenges for the effective implementation of evidence-based management. "Treatable traits" is a model of care that has been specifically designed to address these issues. Traits are identified in the pulmonary, extrapulmonary (comorbidity) and behavioural/risk factor domains. Traits are clinically relevant, recognisable with validated trait identification markers and treatable using evidence-based therapies. The clinician and patient agree on a personalised management plan that addresses the relevant traits, and trials show superiority of this approach with significant improvements in asthma control and quality of life. A number of tools have now been developed to assist the clinician in the implementation of this approach. The success of the treatable traits model of care is now being realised in other disease areas.

The Associations of Long-Term Temperature and Precipitation with Chronic Respiratory Symptoms: Projections for the Changing Climate

PURPOSE

To clarify the associations of climatic indices with chronic respiratory symptoms, with a final aim to approximate the effects of climate change on them.

METHODS

An e-mail survey was directed to the members of the Finnish Pensioners` Federation. The mean 20-years' precipitation and temperature in each subjects' home municipality were obtained from the Finnish Meteorological Institute, separately for summer and winter. Adjusted multivariate models were utilized to investigate the associations of the climatic indices with chronic rhinosinusitis, chronic cough, wheezing with dyspnea, and sleep apnea.

RESULTS

There were 6189 responders from 283 municipalities. Chronic rhinosinusitis and chronic cough were most prevalent in the southeastern regions of the country, where the precipitation counts were highest. In the multivariate models, winter precipitation in the home municipality increased the risks of chronic rhinosinusitis and chronic cough [adjusted OR 1.80 (1.30-2.51) per 100 mm, p < 0.001, and 1.57 (1.19-2.07) per 100 mm, p = 0.001, respectively]. Wheezing with dyspnea and sleep apnea were not associated with the climatic indices.

CONCLUSION

Chronic rhinosinusitis and chronic cough were associated with long-term winter precipitation. Given the anticipated increase in winter precipitation in Northern America and Northern Europe, the prevalences of chronic rhinosinusitis and chronic cough may increase there.

Brainstem opioid peptidergic neurons regulate cough reflexes in mice

Cough is a vital defensive reflex for expelling harmful substances from the airway. The sensory afferents for the cough reflex have been intensively studied. However, the brain mechanisms underlying the cough reflex remain poorly understood. Here, we developed a paradigm to quantitatively measure cough-like reflexes in mice. Using this paradigm, we found that prodynorphin-expressing (Pdyn+) neurons in the nucleus of the solitary tract (NTS) are critical for capsaicin-induced cough-like reflexes. These neurons receive cough-related neural signals from Trpv1+ vagal sensory neurons. The activation of Pdyn+ NTS neurons triggered respiratory responses resembling cough-like reflexes. Among the divergent projections of Pdyn+ NTS neurons, a glutamatergic pathway projecting to the caudal ventral respiratory group (cVRG), the canonical cough center, was necessary and sufficient for capsaicin-induced cough-like reflexes. These results reveal that Pdyn+ NTS neurons, as a key neuronal population at the entry point of the vagus nerve to the brainstem, initiate cough-like reflexes in mice.

Benefit-Risk Profile of P2X3 Receptor Antagonists for Treatment of Chronic Cough: Dose-Response Model-Based Network Meta-Analysis

BACKGROUND

Refractory or unexplained chronic cough disrupts quality of life and burdens health care systems around the world. The P2X3 receptor antagonist gefapixant is approved in many countries for its antitussive effects, but taste disturbances are a common adverse effect. Four newer, more selective P2X3 receptor antagonists have been developed to address this problem.

RESEARCH QUESTION

How does the benefit-risk profile vary across the five available P2X3 receptor antagonists?

STUDY DESIGN AND METHODS

A systematic review and network meta-analysis was conducted to evaluate the efficacy of P2X3 receptor antagonists, including gefapixant, sivopixant, eliapixant, camlipixant, and filapixant. Primary outcomes were a reduction rate in 24-hour cough frequency and incidence of taste disturbance. Dose-response curves and median effective dose (ED50) were calculated. Effect size at ED50 was ranked according to the surface under the cumulative ranking curve. The confidence was evaluated by Confidence In Network Meta-Analysis.

RESULTS

Sixteen randomized controlled trials involving 4,904 participants were analyzed. The gefapixant regimen demonstrated an ED50 of 90.7 mg/d for cough frequency reduction. Gefapixant showed the highest antitussive effectiveness at ED50 (reduction rate in 24-hour cough frequency: median, 28.1%; 95% credible interval [CrI], 21.0%-35.6%; ranked 1 of 5; moderate certainty) but the highest prevalence of taste disturbance (absolute risk difference per 100 patients: median, 38; 95% CrI, 27-51; ranked 5 of 5; high certainty) and the highest prevalence of discontinuation. Camlipixant had a well-balanced profile (reduction rate in 24-hour cough frequency: median, 14.7%; 95% CrI, 5.4%-26.0%; ranked 3 of 5; low certainty; and taste disturbance; absolute risk difference per 100 patients; median, 2; 95% CrI, 1-6; ranked 2 of 5; low certainty). Placebo had a mean of 33.1% reduction in 24-hour cough frequency.

INTERPRETATION

When used at safe doses, gefapixant had a favorable risk-benefit profile compared with the other four agents. Camlipixant showed initial promise, which may be further investigated by phase III trials currently underway.

CLINICAL TRIAL REGISTRATION

University Hospital Medical Information Network Center (UMIN-CTR); No. UMIN000050622; URL: https://center6.umin.ac.jp.

Current and emerging opioids for the treatment of chronic cough: a mini review

INTRODUCTION

Chronic cough has increasingly been recognized as a distinct clinical entity that affects a significant portion of the global population. Despite advancements in understanding its pathophysiology, treatment options remain limited. Opioid analgesics have long been used for cough, and some have proven clear antitussive potential. However, these have yet to be approved by regulatory authorities for the treatment of chronic cough. Several novel synthetic opioid modulators that demonstrated antitussive effects in early-stage studies also failed to translate into clinical practice.

AREAS COVERED

This mini review aims to summarize the implications of opioid receptors in the development of cough medicines and highlight recent advances in opioid analgesics in cough trials. PUB MED/CINAHL/Web of Science/Scopus was searched (September 2024).

EXPERT OPINION

Our understanding of the precise sites of action and the involvement of peripheral opioid receptors in cough remains limited. Despite these gaps in knowledge, opioids remain a viable option for some patients until more novel effective treatments are available. Due to the frequent opioid side effects, new opioid derivatives with improved properties are needed. The development of tailored or biased delta-opioid receptor ligands and mixed agonists of opioid receptor-like 1/mu receptors may offer hope for new opioid-based drug discovery for chronic cough.

Could cough hypersensitivity symptom profile differentiate phenotypes of chronic cough?

Background

Recently, cough reflex hypersensitivity has been proposed as a common underlying feature of chronic cough in adults. However, symptoms and clinical characteristics of cough hypersensitivity have not been studied amongst phenotypes of chronic cough. This study aimed to compare symptom features, such as cough triggers and associated throat sensations, of cough hypersensitivity in patients with asthmatic chronic cough and those with refractory chronic cough (RCC).

Methods

Patients with chronic cough from the Korean Chronic Cough Registry were prospectively evaluated over 6 months. Physicians determined the aetiological diagnosis based on clinical evaluations and responses to treatment at the 6-month follow-up visit. Symptoms of cough hypersensitivity and cough-specific quality of life were assessed using the Cough Hypersensitivity Questionnaire (CHQ) and the Leicester Cough Questionnaire (LCQ), respectively.

Results

The analysis included 280 patients who completed the follow-up: 79 with asthmatic cough (cough variant asthma or eosinophilic bronchitis) and 201 with RCC. Baseline CHQ scores were similar between the groups (8.3±3.7 in asthmatic cough versus 8.9±3.9 in RCC; p=0.215, adjusted for age, sex and LCQ score). There were no significant between-group differences in the LCQ and cough severity Visual Analog Scale scores. Both groups showed a similar negative correlation with LCQ scores (asthmatic cough: r=-0.427, p<0.001; RCC: r=-0.306, p<0.001).

Conclusions

The symptoms of cough hypersensitivity may not distinguish between asthmatic cough and RCC. This suggests that chronic cough is the primary diagnosis in both phenotypes. It indicates a shared mechanism in their cough pathogenesis, despite having potentially different treatable traits.

Manometric Abnormalities in Patients With and Without Chronic Cough

PURPOSE

This study examines the relationship between chronic cough and vagal hypersensitivity by measuring baseline esophageal motility, with interest in the upper esophageal sphincter (UES).

MATERIALS AND METHODS

Patients undergoing workup for dysphagia were assigned to a chronic cough or control group based on self-reported symptoms. Differences in demographics, medical comorbidities, and high resolution esophageal manometry findings were obtained retrospectively.

RESULTS

62.5% of our cohort had chronic cough (30/48). There were no significant differences between the two groups with respect to sex, age, and race/ethnicity. Laryngopharyngeal reflux (LPR) was the only statistically significant predictor of CC (OR 74.04, p = 0.010). Cough patients had upper esophageal sphincter relaxation duration (734 ms) significantly longer than the non-cough patients (582 ms; p = 0.03), though both groups had similar upper esophageal mean basal pressure, mean residual pressure, relaxation time-to-nadir, and recovery time. No significant difference was found in the median intrabolus pressure and UES motility mean peak pressure between groups.

CONCLUSION

Subtle differences in high-resolution manometry between patients with and without cough suggest, in line with previous studies, baseline alterations of upper esophageal function may manifest in patients with chronic cough through an undetermined mechanism that may include underlying vagal hypersensitivity. These findings encourage further manometric study examining the relationship between UES dysfunction and chronic cough.

Cough severity visual analog scale scores and quality of life in patients with refractory or unexplained chronic cough

BACKGROUND

Refractory chronic cough (RCC) and unexplained chronic cough (UCC) adversely affect patients' quality of life (QoL). This multicenter, non-interventional study evaluates the relationship between cough severity and QoL and other patient-reported outcomes (PROs) in Spanish outpatients.

METHODS

RCC/UCC patients self-administered a printed survey comprising the cough-severity visual analog scale (VAS), adapted Cough Severity Diary (CSD), and Leicester Cough Questionnaire (LCQ), plus purpose-designed items regarding the physical and everyday-life impact of cough. Patients were stratified into VAS score tertiles. The impact of cough on QoL and other PROs in each tertile, and relationships between LCQ scores and the tertiles, were assessed.

RESULTS

The VAS was completed by 189 patients, and VAS score tertiles were identified as 0-50, 60-70, and 80-100 mm. The only between-tertile difference in demographic or cough characteristics was cough duration. VAS score tertiles were linearly associated with mean LCQ domain and total scores, as well as the proportion of patients with the highest scores on all adapted CSD items, and almost all physical and everyday-life impact items. In multiple linear-regression models, an increase of one tertile in the VAS score was associated with a decrease of 2.23 points in the LCQ total score, indicating poorer cough-related QoL.

CONCLUSION

As self-assessed in patients with RCC/UCC, cough-severity VAS scores were strongly associated with the impact of cough on QoL and everyday life. Patients with VAS scores of 60-100 mm reported the greatest impact and thus may benefit the most from targeted cough therapies.

Efficacy and safety of gefapixant in women with chronic cough and cough-induced stress urinary incontinence: a phase 3b, randomised, multicentre, double-blind, placebo-controlled trial

BACKGROUND

Approximately two-thirds of women with chronic cough have cough-induced stress urinary incontinence (CSUI). We aimed to evaluate the efficacy and safety of gefapixant in reducing CSUI episodes in women with refractory or unexplained chronic cough.

METHODS

This phase 3b, double-blind, randomised, placebo-controlled trial done at 90 sites in 12 countries enrolled women aged 18 years or older who had chronic cough for at least 1 year, a diagnosis of refractory or unexplained chronic cough, a cough severity visual analogue scale score of 40 mm or more (100 mm maximum), and CSUI for 3 months or more. Participants were randomised 1:1 to oral gefapixant or placebo for 12 weeks. The primary outcome was percentage change from baseline in daily CSUI episodes (7-day average) at week 12. This study is registered with ClinicalTrials.gov (NCT04193176).

FINDINGS

From May 10, 2020, to Sept 2, 2022, 375 participants were randomised to and treated with gefapixant 45 mg twice daily (n=185) or placebo (n=190). Mean age was 56·4 years (SD 11·4), with mean chronic cough duration of 5·2 years (SD 6·6) and SUI duration of 4·0 years (SD 5·9). Least-squares mean percentage change from baseline in daily CSUI episodes was -52·8% (95% CI -58·4 to -47·1%) for gefapixant and -41·1% (-46·7 to -35·4%) for placebo (estimated treatment difference: -11·7% [95% CI -19·7 to -3·7]; p=0·004). 129 (70%) of 185 participants who received gefapixant and 71 (37%) of 190 participants who received placebo had at least one adverse event. Safety and tolerability were consistent with previous trials of gefapixant; the most frequent adverse events were taste related.

INTERPRETATION

Gefapixant 45 mg twice daily is the first treatment to show efficacy versus placebo in reducing CSUI episodes in participants with refractory or unexplained chronic cough.

FUNDING

Merck Sharp & Dohme, a subsidiary of Merck & Co.

Chronic cough as a disease

Chronic cough is a frequent reason for medical consultation and has significant impact on quality of life. Due to the limited effectiveness of currently available treatments, and delays in accessing care, patients are often inadequately managed. There remains an overreliance by clinicians on outdated management algorithms, addressing chronic cough only as symptom of other medical conditions, and advocating investigation and trials of treatment of diseases which are often not present. This may lead to unnecessary cost, frustration and potential harm. Newer clinical guidelines in essence consider chronic cough as a disease in itself, resulting from afferent neuronal hypersensitivity and central nervous system dysfunction. Secondary factors which aggravate chronic cough (smoking, asthma, gastro-oesophageal reflux, etc.) are better considered as treatable traits associated with the primary disease process rather than direct "causes" of cough. Explicitly approaching chronic cough as a discrete entity is consistent with the way in which "diseases" are generally characterised, and has advantages. The patient should be better able to understand their condition, and may have better confidence in attempts at management. The clinician should have better focus and avoid unfruitful treatments and investigation. In general, considering chronic cough as a disease should help to raise the profile of the condition, improve organisation of health service pathways, increase attention for research, and further the development of new treatments.