New Insights Into Refractory Chronic Cough and Unexplained Chronic Cough: A 6-Year Ambispective Cohort Study

PURPOSE

Only limited studies have depicted the unique features and management of refractory chronic cough (RCC) and unexplained chronic cough (UCC). These led to the initiation of this study, which reported the demographic characteristics, manifestations, and long-term outcomes on a large series of consecutive RCC/UCC patients, providing a guideline-led real-world clinical experience.

METHODS

Retrospective baseline information was obtained from Clinical Research Database (January 2016 to May 2021). At least 6 months after the last clinic visit, included subjects were prospectively followed up.

RESULTS

Three hundred and sixty-nine RCC and UCC patients (199 females, 53.9%) were analyzed. The median cough duration was 24.0 (12.0-72.0) months. Laryngeal symptoms were reported in 95.9% of the patients. The common triggers for coughing were talking (74.9%), pungent odors (47.3%), eating (45.5%), and cold air (42.8%). RCC was considered in 38.2%, and the remainder of 228 patients had UCC, with an equal sex distribution (P = 0.66). Among the 141 RCCs, 90.8% (128) had refractory reflux cough, which was more responsive to current treatments (P < 0.01). Although most features and test results between RCC and UCC were similar, UCC was more commonly inappropriately treated (P < 0.01). Nineteen (7.7-41.1) months after the final clinic visit, 31.2% still coughed persistently, while 68.8% reported cough improvement or remission. RCC reported more favorable treatment outcomes (including cough improvement, control, and spontaneous remission) than UCC (P < 0.01). Coughs with long duration before the initial cough clinic visit (P < 0.01), frequent urinary incontinence (P < 0.01), and being sensitive to "talking" (P < 0.01) or "cold air" (P < 0.01) were less likely to be solved.

CONCLUSIONS

The current treatments only improve cough symptoms in two-thirds of patients. Clinical indicators for treatment failure were those coughing for long duration and being sensitive to "talking" or "cold air."

Consensus goals and standards for specialist cough clinics: the NEUROCOUGH international Delphi study

Background

Current guidelines on the management of chronic cough do not provide recommendations for the operation of specialist cough clinics. The objective of the present study was to develop expert consensus on goals and standard procedures for specialist cough clinics.

Methods

We undertook a modified Delphi process, whereby initial statements proposed by experts were categorised and presented back to panellists over two ranking rounds using an 11-point Likert scale to identify consensus.

Results

An international panel of 57 experts from 19 countries participated, with consensus reached on 15 out of 16 statements, covering the aims, roles and standard procedures of specialist cough clinics. Panellists agreed that specialist cough clinics offer optimal care for patients with chronic cough. They also agreed that history taking should enquire as to cough triggers, cough severity rating scales should be routinely used, and a minimum of chest radiography, spirometry and measurements of type 2 inflammatory markers should be undertaken in newly referred patients. The importance of specialist cough clinics in promoting clinical research and cough specialty training was acknowledged. Variability in healthcare resources and clinical needs between geographical regions was noted.

Conclusions

The Delphi exercise provides a platform and guidance for both established cough clinics and those in planning stages.

Ingredients of Vicks VapoRub inhibit rhinovirus-induced ATP release

Background

Over-the-counter therapies, such as Vicks VapoRub, are frequently used in the management of upper respiratory tract infection symptoms. Of these, acute cough is the most bothersome; however, the mechanisms involved have not been fully elucidated. The temperature-sensitive transient receptor potential (TRP) channels, including TRPA1, TRPV1, TRPM8 and TRPV4, are potential candidates. TRPV4 is also thought to be involved in cough through the TRPV4-ATP-P2X3 pathway. Here, we hypothesise that Vicks VapoRub ingredients (VVRIs) modulate the TRP cough channels.

Methods

Stably transfected HEK cells expressing TRP channels were challenged with VVRIs, individually or in combination, and the agonist and antagonist effects were measured using calcium signalling responses. In addition, rhinovirus serotype-16 (RV16)-infected A549 airway epithelial cells were pre-incubated with individual or combinations of VVRIs prior to hypotonic challenge and extracellular ATP release analysis.

Results

Calcium signalling reconfirmed some previously defined activation of TRP channels by specific VVRIs. The combined VVRIs containing menthol, camphor and eucalyptus oil activated TRPV1, TRPV4, TRPM8 and untransfected wild-type HEK293 cells. However, pre-incubation with VVRIs did not significantly inhibit any of the channels compared with the standard agonist responses. Pre-incubation of RV16-infected A549 cells with individual or combined VVRIs, except menthol, resulted in a 0.45-0.55-fold reduction in total ATP release following hypotonic stimulation, compared with infected cells not treated with VVRIs.

Conclusion

These findings suggest that some VVRIs may reduce symptoms associated with upper respiratory tract infection by modulating specific TRP receptors and by reducing RV16-induced ATP release.

Unravelling vagal hypersensitivity in chronic cough: A distinct disease

Chronic cough (CC) is a common but poorly understood disease that has a negative impact on quality of life. For years, clinicians have been trying to find the underlying diagnosis and using existing disease models to describe the patients' illness. This presents a confusing picture of CC. Most patients with CC present with hypersensitivity of the cough reflex, which is characterised by laryngeal paraesthesia and an increased response to the tussive stimuli or an innocuous stimulus that would not trigger coughing in healthy people. Recently, it has been proposed that CC is a unique disease characterised by vagal hypersensitivity that projects to the central nervous system altering responsiveness. The evidence supports the hypothesis that CC is primarily a neurological disorder, consisting of different phenotypes.

From bench to bedside: The role of cough hypersensitivity in chronic cough

BACKGROUND

Chronic cough is a burdensome condition characterized by persistent cough lasting longer than 8 weeks. Chronic cough can significantly affect quality of life, physical function and productivity, with many people troubled with a cough that lasts for months or even years. People with chronic cough commonly report a persistent urge to cough with frequent bouts of coughing triggered by innocuous stimuli, which has led to the concept of cough hypersensitivity.

MAIN BODY

Both central and peripheral neural pathways regulate cough, and although mechanisms driving development of cough hypersensitivity are not fully known, sensitization of these neural pathways contributes to excessive cough triggering in cough hypersensitivity. Effective therapies that control chronic cough are currently lacking. Recent therapeutic development has focused on several ion channels and receptors involved in peripheral activation of cough (e.g., transient receptor potential channels, P2 × 3 receptors and voltage-gated sodium channels) or central cough processing (e.g., neurokinin-1 [NK-1] receptors and nicotinic acetylcholine receptors).

CONCLUSION

These targeted therapies provide novel insights into mechanisms underlying cough hypersensitivity and may offer new treatment options for people with chronic cough. In this review, we explore preclinical and clinical studies that have improved our understanding of the mechanisms responsible for chronic cough and discuss the most promising targeted approaches to date, including trials of P2 × 3-receptor antagonists and NK-1-receptor antagonists.

Burden of chronic cough in the UK: results from the 2018 National Health and Wellness Survey

Background

Chronic cough, defined as daily cough for at least 8 weeks, negatively affects quality of life and work productivity and increases healthcare resource utilisation. We aimed to determine the prevalence and burden of chronic cough in the UK.

Methods

Study participants were general population respondents to the 2018 UK National Health and Wellness Survey (NHWS). Respondents completed survey questions relating to health, quality of life, work productivity and activity impairment, and use of healthcare resources. Prevalence estimates were projected to the UK population using post-stratification sampling weights to adjust for sampling bias. The population with chronic cough was matched 1:3 with a group without chronic cough, using propensity score matchingon age, sex and the modified Charlson Comorbidity Index.

Results

Of 15 000 NHWS respondents, 715 reported chronic cough in the previous 12 months and 918 during their lifetime. Weighted to the UK adult population, the 12-month prevalence of chronic cough was 4.9% and lifetime prevalence was 6.2%. Prevalence of chronic cough was higher among older respondents and those with smoking histories. Chronic cough respondents experienced higher rates of severe anxiety and depression in the past 2 weeks than matched controls. Poor sleep quality and loss of work productivity were also observed. More chronic cough respondents visited a healthcare provider in the past 6 months than respondents without chronic cough with a mean of 5.8 and 3.7 visits per respondent, respectively.

Conclusion

Adults with chronic cough report lower quality of life, reduced work productivity and greater healthcare resource utilisation than matched controls without chronic cough.

Efficacy and Safety of Eliapixant in Refractory Chronic Cough: The Randomized, Placebo-Controlled Phase 2b PAGANINI Study

INTRODUCTION

The PAGANINI study evaluated the efficacy and safety of the selective P2X3 antagonist eliapixant in patients with refractory chronic cough (RCC).

METHODS

PAGANINI was a randomized, double-blind, parallel-group, placebo-controlled, multicenter, dose-finding, phase 2b study. Adults with RCC lasting ≥ 12 months and cough severity ≥ 40 mm on a visual analog scale at screening were enrolled. Participants were randomized 1:1:1:1 to twice-daily 25 mg, 75 mg, or 150 mg oral eliapixant or placebo for 12 weeks. The primary endpoint was change from baseline in 24-h cough count after 12 weeks of intervention.

RESULTS

Overall, 310 participants were randomized to twice-daily eliapixant 25 mg (n = 75), 75 mg (n = 78), 150 mg (n = 80), or placebo (n = 77). A statistically significant dose-response signal with eliapixant was detected for the primary endpoint (all dose-response models, adjusted p < 0.1; one-sided). Adverse events (AEs) were reported in 39 (51%) participants with placebo and 43-51 (57-65%) participants receiving eliapixant. The most common AE was dysgeusia, occurring in 1% (n = 1) of the placebo group and 1-16% (n = 1-13) of the eliapixant groups in a dose-related manner. One case of a moderate drug-induced liver injury occurred in a participant receiving 150 mg twice-daily eliapixant.

CONCLUSION

Eliapixant demonstrated efficacy and a favorable taste tolerability profile in RCC. However, a drug-induced liver injury contributed to intensified liver monitoring in clinical trials with eliapixant and discontinuation of the entire development program in all indications by Bayer AG.

TRIAL REGISTRATION

ClinicalTrials.gov identifier NCT04562155; registered September 18, 2020.

Subcutaneous octreotide as a therapeutic option for refractory chronic cough: subjective response pattern and adverse effects from a retrospective single-centre case series

Therapeutic antitussive effect of octreotide on intractable cough https://bit.ly/3mVMEc6.

The P2X3 receptor antagonist filapixant in patients with refractory chronic cough: a randomized controlled trial

BACKGROUND

P2X3 receptor antagonists seem to have a promising potential for treating patients with refractory chronic cough. In this double-blind, randomized, placebo-controlled study, we investigated the efficacy, safety, and tolerability of the novel selective P2X3 receptor antagonist filapixant (BAY1902607) in patients with refractory chronic cough.

METHODS

Following a crossover design, 23 patients with refractory chronic cough (age: 60.4 ± 9.1 years) received ascending doses of filapixant in one period (20, 80, 150, and 250 mg, twice daily, 4-days-on/3-days-off) and placebo in the other. The primary efficacy endpoint was the 24-h cough frequency on Day 4 of each dosing step. Further, subjective cough severity and health-related quality of life were assessed.

RESULTS

Filapixant at doses ≥ 80 mg significantly reduced cough frequency and severity and improved cough health-related quality of life. Reductions in 24-h cough frequency over placebo ranged from 17% (80 mg dose) to 37% (250 mg dose), reductions over baseline from 23% (80 mg) to 41% (250 mg) (placebo: 6%). Reductions in cough severity ratings on a 100-mm visual analog scale ranged from 8 mm (80 mg) to 21 mm (250 mg). No serious or severe adverse events or adverse events leading to discontinuation of treatment were reported. Taste-related adverse events occurred in 4%, 13%, 43%, and 57% of patients treated with filapixant 20, 80, 150, and 250 mg, respectively, and in 12% treated with placebo.

CONCLUSIONS

Filapixant proved to be efficacious, safe, and-apart from the occurrence of taste disturbances, especially at higher dosages-well tolerated during the short therapeutic intervention. Clinical trial registration EudraCT, eudract.ema.europa.eu, 2018-000129-29; ClinicalTrials.gov, NCT03535168.

Antitussive efficacy of the current treatment protocol for refractory chronic cough: our real-world experience in a retrospective cohort study

BACKGROUND

The management of refractory chronic cough (RCC) is a great challenge. Neuromodulators have long been used for RCC with imperfect efficacy.

OBJECTIVES

We summarized the outcomes of the current treatments used at our specialist cough clinic, which provides a guideline-led service and real-world experience for the future management of RCC.

DESIGN

This is a single-centre retrospective observational cohort study.

METHODS

Consecutive RCC patients (the first clinic visit between January 2016 and May 2021) were included into this observational cohort study. Medical records in the Chronic Cough Clinical Research Database were fully reviewed using uniform criteria. The included subjects were followed-up for at least 6 months after the final clinic visit via instant messages with the link to self-scaled cough-associated questionnaires.

RESULTS

Overall, 369 RCC patients were analysed with a median age of 46.6 years and a cough duration of 24.0 months. A total of 10 different treatments were offered. However, 96.2% of patients had been prescribed at least one neuromodulator. One-third of patients had alternative treatments prescribed given the poor response to the initial therapy and 71.3% favourably responded to at least one of the treatments. Gabapentin, deanxit, and baclofen had comparable therapeutic efficacy (56.0%, 56.0%, and 62.5% respectively; p = 0.88) and overall incidences of adverse effects (28.3%, 22.0%, and 32.3% respectively; p = 0.76). However, 19.1 (7.7-41.8) months after the last clinic visit, 65.0% reported improvement (24.9%) or control of their cough (40.1%); 3.8% reported a spontaneous remission and 31.2% still had a severe cough. Both HARQ (n = 97; p < 0.001) and LCQ (n = 58; p < 0.001) demonstrated marked improvement.

CONCLUSION

Trying different neuromodulators is a pragmatic strategy for RCC, which helped around two-thirds of patients. Relapse is common on withdrawal or reduction of dosage. Novel medication for RCC is an urgent clinical need.

PLAIN LANGUAGE SUMMARY

This is the first report that fully represented a guideline-led treatment protocol for refractory chronic cough (RCC) based on a large series of patients, which evaluated the short- and long-term effects of the currently available treatments for RCC. We found that the therapeutic trial of different neuromodulators is a pragmatic strategy, which helped around two-thirds of patients. Gabapentin, deanxit (flupentixol/melitracen), and baclofen had similar therapeutic outcomes. This study may offer real-world experience for the future management of RCC.

Demographic, clinical, and patient-reported outcome data from 2 global, phase 3 trials of chronic cough

BACKGROUND

The current characterization of patients with refractory or unexplained chronic cough (RCC and UCC, respectively) primarily stems from relatively small clinical studies.

OBJECTIVE

To report the baseline medical history and clinical characteristics of individuals with RCC or UCC who were enrolled in COUGH-1 and COUGH-2, 2 large, global, phase 3 trials of gefapixant, a P2 × 3-receptor antagonist.

METHODS

Adults with a chronic cough lasting for more than 1 year, diagnosis of RCC or UCC, and score greater than 40 mm on a 100-mm cough severity visual analog scale at both screening and baseline were eligible for enrollment. Demographics, medical history, and cough characteristics were collected at baseline. Cough-related measures included objective cough frequency, cough severity visual analog scale, Leicester Cough Questionnaire, and Hull Airway Reflux Questionnaire. The data were summarized using descriptive statistics.

RESULTS

Of 2044 participants, 75% were women; mean age was 58 years, and mean cough duration was approximately 11 years. Among all participants, 73% were previously diagnosed with asthma, gastroesophageal reflux disease, or upper airway cough syndrome. The mean Leicester Cough Questionnaire total score was 10.4, with domain scores reflecting impaired cough-specific quality of life across physical, psychological, and social domains. The mean Hull Airway Reflux Questionnaire score was 39.6, with some of the most burdensome reported items being consistent with features of cough-reflex hypersensitivity. Participant characteristics and cough burden were comparable across geographic regions.

CONCLUSION

Participants with RCC or UCC had characteristics consistent with published demographics associated with chronic cough. These data reflect a global population with burdensome cough of long duration and substantial impairment to quality of life.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov Identifiers: COUGH-1, NCT03449134 (https://www.

CLINICALTRIALS

gov/ct2/show/NCT03449134); COUGH-2, NCT03449147 (https://clinicaltrials.gov/ct2/show/NCT03449147).

Modulation of transient receptor potential (TRP) channels by plant derived substances used in over-the-counter cough and cold remedies

BACKGROUND

Upper respiratory tract infections (URTIs) impact all age groups and have a significant economic and social burden on society, worldwide. Most URTIs are mild and self-limiting, but due to the wide range of possible causative agents, including Rhinovirus (hRV), Adenovirus, Respiratory Syncytial Virus (RSV), Coronavirus and Influenza, there is no single and effective treatment. Over-the-counter (OTC) remedies, including traditional medicines and those containing plant derived substances, help to alleviate symptoms including inflammation, pain, fever and cough.

PURPOSE

This systematic review focuses on the role of the major plant derived substances in several OTC remedies used to treat cold symptoms, with a particular focus on the transient receptor potential (TRP) channels involved in pain and cough.

METHODS

Literature searches were done using Pubmed and Web of Science, with no date limitations, using the principles of the PRISMA statement. The search terms used were 'TRP channel AND plant compound', 'cough AND plant compound', 'cough AND TRP channels AND plant compound', 'cough AND P2X3 AND plant compound' and 'P2X3 AND plant compound' where plant compound represents menthol or camphor or eucalyptus or turpentine or thymol.

RESULTS

The literature reviewed showed that menthol activates TRPM8 and may inhibit respiratory reflexes reducing irritation and cough. Menthol has a bimodal action on TRPA1, but inhibition may have an analgesic effect. Eucalyptus also activates TRPM8 and inhibits TRPA1 whilst down regulating P2X3, aiding in the reduction of cough, pain and airway irritation. Camphor inhibits TRPA1 and the activation of TRPM8 may add to the effects of menthol. Activation of TRPV1 by camphor, may also have an analgesic effect.

CONCLUSIONS

The literature suggests that these plant derived substances have multifaceted actions and can interact with the TRP 'cough' receptors. The plant derived substances used in cough and cold medicines have the potential to target multiple symptoms experienced during a cold.

Airway disease: a confusion inside an enigma

Current diagnostic categories of airway disease are conflicting and contradictory. Historically, we were reliant on airway physiology. However, pathology is the study of disease. A reappraisal is necessary. https://bit.ly/3CZSqiQ.

Chronic cough-the limitation and advances in assessment techniques

Accurate and consistent assessments of cough are essential to advance the understanding of the mechanisms of cough and individualised the management of patients. Considerable progress has been made in this work. Here we reviewed the currently available tools for subjectively and objectively measuring both cough sensitivity and severity. We also provided some opinions on the new techniques and future directions. The simple and practical Visual Analogue Scale (VAS), the Leicester Cough Questionnaire (LCQ), and the Cough Specific Quality of Life Questionnaire (CQLQ) are the most widely used self-reported questionnaires for evaluating and quantifying cough severity. The Hull Airway Reflux Questionnaire (HARQ) is a tool to elucidate the constellation of symptoms underlying the diagnosis of chronic cough. Chemical excitation tests are widely used to explore the pathophysiological mechanisms of the cough reflex, such as capsaicin, citric acid and adenosine triphosphate (ATP) challenge test. Cough frequency is an ideal primary endpoint for clinical research, but the application of cough counters has been limited in clinical practice by the high cost and reliance on aural validation. The ongoing development of cough detection technology for smartphone apps and wearable devices will hopefully simplify cough counting, thus transitioning it from niche research to a widely available clinical application.

Investigating the diagnostic utility of high-resolution oesophageal manometry in patients with refractory respiratory symptoms

BACKGROUND

The interaction between the respiratory and gastrointestinal systems, and the role of the latter in the development of respiratory pathology, has been examined with a focus on gastro-oesophageal reflux disease (GORD). However, little data exists examining the link between oesophageal motility and respiratory disease.

AIMS AND OBJECTIVES

In this study, we examined patterns in oesophageal motility using high-resolution oesophageal manometry (HROM) in patients with refractory respiratory symptoms.

METHODS

Data were collected retrospectively for all patients that were investigated using HROM at a single centre for refractory respiratory symptoms between January 1st, 2011-December 1st, 2021. Patients were selected for investigation based on airway reflux symptoms, measured by the Hull Airways Reflux Questionnaire (HARQ).

RESULTS

441 patients were investigated with HROM (64% female, mean age = 56.5 [SD = 13.9]). The commonest diagnoses of these patients were Chronic Cough (77%, n = 339), Asthma (10%, n = 44), and Interstitial Lung Disease (7%, n = 29). The prevalence of oesophageal dysmotility was 66% in our cohort. Those with oesophageal dysmotility had significantly higher HARQ scores than those with normal motility (40.6 vs 35.3, p < 0.001) and there was a significant inverse correlation between HARQ scores and distal contractile integral (DCI), a measure of oesophageal contractility.

CONCLUSIONS

Two-thirds of patients with refractory respiratory symptoms were found to have oesophageal dysmotility on HROM. These findings suggest motility disorders of the oesophagus may contribute to the development and progression of respiratory disease. This study highlights the need for further prospective study of the relationship between oesophageal dysmotility and respiratory disease.

ATP, an attractive target for the treatment of refractory chronic cough

Chronic cough is the most common complaint in respiratory clinics. Most of them have identifiable causes and some may respond to common disease-modifying therapies. However, there are many patients whose cough lacks effective aetiologically targeted treatments or remains unexplained after thorough assessments, which have been described as refractory chronic cough. Current treatments for refractory chronic cough are limited and often accompanied by intolerable side effects such as sedation. In recent years, various in-depth researches into the pathogenesis of chronic cough have led to an explosion in the development of drugs for the treatment of refractory chronic cough. There has been considerable progress in the underlying mechanisms of chronic cough targeting ATP, and ongoing or completed clinical studies have confirmed the promising antitussive efficacy of P2X3 antagonists for refractory cough. Herein, we review the foundation on which ATP target was developed as potential antitussive medications and provide an update on current clinical progresses.

Efficacy and safety of gefapixant, a P2X3 receptor antagonist, in refractory chronic cough and unexplained chronic cough (COUGH-1 and COUGH-2): results from two double-blind, randomised, parallel-group, placebo-controlled, phase 3 trials

BACKGROUND

Gefapixant is an oral P2X₃ receptor antagonist that has previously shown efficacy and safety in refractory chronic cough and unexplained chronic cough. We therefore aim to confirm the efficacy and safety of gefapixant in participants with refractory chronic cough and unexplained chronic cough.

METHODS

COUGH-1 and COUGH-2 were both double-blind, randomised, parallel-group, placebo-controlled, phase 3 trials. COUGH-1 was done in 156 sites in 17 countries and COUGH-2 in 175 sites in 20 countries. We enrolled participants who were 18 years or older with a diagnosis of refractory chronic cough or unexplained chronic cough of 1 year duration or more. Participants were also required to have a cough severity visual analogue scale score of 40 mm or more at screening and baseline. Eligible participants were randomly allocated (1:1:1), using a computer-generated allocation schedule, to one of three treatment groups: placebo, gefapixant 15 mg twice per day, or gefapixant 45 mg twice per day. All study treatments were given orally. Participants were treated over a 12-week main study period in COUGH-1 and a 24-week main study period in COUGH-2; followed by extension periods for a total of up to 52 weeks of treatment in both trials. The primary outcome was placebo-adjusted mean change in 24-h cough frequency at 12 weeks in COUGH-1 and 24 weeks in COUGH-2. Both studies were registered with ClinicalTrials.gov, NCT03449134 (COUGH-1) and NCT03449147 (COUGH-2).

FINDINGS

From March 14, 2018, (first participant screened) to July 26, 2019, (last participant screened) 732 patients were recruited in COUGH-1 and 1317 in COUGH-2. COUGH-1 randomly assigned and treated 730 participants (243 [33×3%] with placebo, 244 [33×4%] with gefapixant 15 mg twice per day, and 243 [33×3%] with gefapixant 45 mg twice per day); COUGH-2 randomly assigned and treated 1314 participants (435 [33×1%] with placebo, 440 [33×5%] with gefapixant 15 mg twice per day, and 439 [33×4%] with gefapixant 45 mg twice per day). Participants were mostly female (542 [74×2%] of 730 in COUGH-1 and 984 [74×9%] of 1314 in COUGH-2). The mean age was 59×0 years (SD 12×6) in COUGH-1 and 58×1 years (12×1) in COUGH-2, and the mean cough duration was 11·6 years (SD 9·5) in COUGH-1 and 11·2 years (9·8) in COUGH-2. Gefapixant 45 mg twice per day showed significant reductions in 24-h cough frequency compared with placebo at week 12 in COUGH-1 (18·5% [95% CI 32·9-0·9]; p=0·041) and at week 24 in COUGH-2 (14·6% [26·1-1·4]; p=0·031). Gefapixant 15 mg twice per day did not show a significant reduction in cough frequency versus placebo in both studies. The most common adverse events were related to taste disturbance: ageusia (36 [4·9%] of 730 in COUGH-1 and 86 [6·5%] of 1314 in COUGH-2), dysgeusia (118 [16·2%] in COUGH-1 and 277 [21·1%] in COUGH-2), hypergeusia (3 [0·4%] in COUGH-1 and 6 [0×5%] in COUGH-2), hypogeusia (19 [2·6%] in COUGH-1 and 80 [6·1%] in COUGH-2), and taste disorder (28 [3·8%] in COUGH-1 and 46 [3·5%] in COUGH-2).

INTERPRETATION

Gefapixant 45 mg twice per day is the first treatment to show efficacy with an acceptable safety profile in phase 3 clinical trials for refractory chronic cough or unexplained chronic cough.

FUNDING

Merck Sharp & Dohme.

Objective cough frequency monitoring in real-world practice

There are possibilities and obstacles to the use of objective cough monitoring in real-world practice. Advances in technology will overcome the difficulties and continuous real-time cough monitoring will then provide a valuable tool in cough management. https://bit.ly/3lu5cfk.

The Cough Reflex: The Janus of Respiratory Medicine

In clinical practice, we commonly face adversity when encountering dysfunction of the cough reflex. Similar to ancient Roman deity Janus, it often presents with one of two opposing "faces". Continual aberrant activation of the cough reflex, also known as chronic cough, can cause great detriment to quality of life and many of these patients are left misdiagnosed and undertreated. In contrast, loss of normal functioning of the cough reflex is the cause of a significant proportion of mortality in the elderly, primarily through the development of aspiration pneumonia. In this review we discuss both hyper- and hypo-activation of the cough reflex and how airway reflux and chronic aspiration may be involved in the aetiology and sequalae of both disease states. We detail the physiological and pharmacological mechanisms involved in cough, and how the recent development of P2X3 receptor antagonists may lead to the first pharmaceutical agent licensed for chronic cough. The treatment and prevention of loss of the cough reflex, which has been largely neglected, is also discussed as novel low-cost interventions could help prevent a number of hospital and domiciliary deaths from both acute and chronic aspiration.

Domiciliary Cough Monitoring for the Prediction of COPD Exacerbations

Introduction

Acute exacerbations of COPD (AE-COPD) are a leading cause of health service utilisation and are associated with morbidity and mortality. Identifying the prodrome of AE-COPD by monitoring symptoms and physiological parameters (telemonitoring) has proven disappointing and false alerts limit clinical utility. We report objective monitoring of cough counts around AE-COPD and the performance of a novel alert system identifying meaningful change in cough frequency.

Methods

This prospective longitudinal study of cough monitoring included chronic obstructive pulmonary disease (COPD) patients experienced in telemonitoring that had two or more AE-COPD in the past year. Participants underwent cough monitoring and completed a daily questionnaire for 90 days. The automated system identified deteriorating trends in cough and this was compared with alerts generated by an established telemonitoring questionnaire.

Results

28 patients [median age 66 (range 46–86), mean FEV-1% predicted 36% (SD 18%)] completed the study and had a total of 58 exacerbations (43 moderate and 15 severe). Alerts based on cough monitoring were generated mean 3.4 days before 45% of AE-COPD with one false alert every 100 days. In contrast, questionnaire-based alerts occurred in the prodrome of 88% of AE-COPD with one false alert every 10 days.

Conclusion

An alert system based on cough frequency alone predicted 45% AE-COPD; the low false alert rate with cough monitoring suggests it is a practical and clinically relevant tool. In contrast, the utility of questionnaire-based symptom monitoring is limited by frequent false alerts.

COVID-19 controversy: when to intubate?

Opinions differ as to when to escalate ventilatory support to intubation and mechanical ventilation https://bit.ly/3wgmS2B.

Drug-Induced Cough

Since the recognition of angiotensin-converting enzyme inhibitors (ACEIs)-induced cough, drug has been considered as a potential cause of chronic cough. This review presents recent knowledge on drug-induced coughs in patients with chronic cough. The focus is placed on ACEIs, for which there are a multitude of studies documenting their associations with cough. Additional drugs are discussed for which there are reports of cough as a side effect of treatment, and the potential mechanisms of these effects are discussed.

Azithromycin for sarcoidosis cough: an open-label exploratory clinical trial

Background

Chronic cough is a distressing symptom for many people with pulmonary sarcoidosis. Continuous treatment with a macrolide antibiotic may improve cough. We aimed to assess the potential efficacy of azithromycin in patients with sarcoidosis and self-reported cough.

Methods

We conducted a noncontrolled, open-label clinical trial of azithromycin 250 mg once daily for 3 months in patients with pulmonary sarcoidosis who reported a chronic cough. The primary outcome was number of coughs in 24 h. Secondary outcomes were cough visual analogue scales and quality of life measured using the Leicester Cough Questionnaire and King's Sarcoidosis Questionnaire. Safety outcomes included QTc interval on ECG. Measurements were made at baseline and after 1 and 3 months of treatment.

Results

All 21 patients were white, median age 57 years, 9 males, 12 females, median 3 years since diagnosis. Five were taking oral corticosteroids and none were taking other immunosuppressants. Twenty patients completed the trial. The median (range) number of coughs in 24 h was 228 (43–1950) at baseline, 122 (20–704) at 1 month, and 81 (16–414) at 3 months (p=0.002, Friedman's test). The median reduction in cough count at 3 months was 49.6%. There were improvements in all patient-reported outcomes. Azithromycin was well tolerated.

Conclusion

In a noncontrolled open-label trial in people with sarcoidosis who reported a chronic cough, 3 months of treatment with azithromycin led to improvements in a range of cough metrics. Azithromycin should be tested as a treatment for sarcoidosis cough in a randomised placebo-controlled trial.

In a noncontrolled open-label trial in people with sarcoidosis who reported a chronic cough, 3 months of treatment with azithromycin led to improvements in a range of cough metricshttps://bit.ly/2FB5tfq

Design and rationale of two phase 3 randomised controlled trials (COUGH-1 and COUGH-2) of gefapixant, a P2X3 receptor antagonist, in refractory or unexplained chronic cough

Background

We present study designs, dose selection and preliminary patient characteristics from two phase 3 clinical trials of gefapixant, a P2X3 receptor antagonist, in refractory chronic cough (RCC) or unexplained chronic cough (UCC).

Methods

COUGH-1 (NCT03449134) and COUGH-2 (NCT03449147) are randomised, placebo-controlled, double-blind, parallel-group trials in subjects with RCC or UCC (age ≥18 years; cough duration ≥1 year; Cough Severity Visual Analogue Scale score ≥40 mm). The primary efficacy study periods are 12 weeks (40-week extension; COUGH-1) and 24 weeks (28-week extension; COUGH-2). Interventions include placebo, gefapixant 15 mg and gefapixant 45 mg (1:1:1 ratio). The primary efficacy endpoints are average 24-h cough frequency at Week 12 (COUGH-1) and Week 24 (COUGH-2). Awake cough frequency, patient-reported outcomes and responder analyses are secondary endpoints.

Results

The doses of 45 mg (to provide maximal efficacy and acceptable tolerability) and 15 mg (to provide acceptable efficacy and improved tolerability) were selected based on phase 1 and 2 studies. In COUGH-1, 730 participants have been randomised and treated; 74% are female with mean age of 59 years (39% over 65 years), and mean baseline duration of cough of 11.5 years. In COUGH-2, 1314 participants have been randomised and treated; 75% are female with mean age of 58 years (33% over 65 years), and mean baseline duration of cough of 11.1 years.

Conclusions

These global studies include participants with baseline characteristics consistent with previous RCC and UCC studies and will inform the efficacy and safety profile of gefapixant in the treatment of patients with RCC and UCC.

This protocol describes the design of two global, phase 3 studies with >2000 participants with refractory or unexplained chronic cough, designed to confirm efficacy and safety of gefapixant, a P2X3 receptor antagonist, at doses of 45 mg and 15 mghttps://bit.ly/2Xzgu74

Rhinovirus-16 increases ATP release in A549 cells without concomitant increase in production

Human rhinovirus (RV) is the most common cause of upper respiratory tract infection (URTI) and chronic airway disease exacerbation. Cough is present in 50–80% of URTI cases, accompanied by heightened airway hypersensitivity, yet no effective treatment currently exists for this infectious cough. The mechanism by which RV causes cough and airway hypersensitivity in URTI is still unknown despite recent advances in potential therapies for chronic cough.

The effect of RV-16 infection (MOI 1) on intracellular ATP stores and ATP release in A549 alveolar epithelial cells was measured.

RV-16 infection was found to significantly increase (by 50% from basal at 24 h) followed by decrease (by 50% from basal at 48 and 72 h) intracellular ATP concentrations, while increasing ATP release (from 72 h) independently of secondary stimulation. This effect was mimicked by intercellular adhesion molecule 1 receptor binding alone through ultraviolet-inactivated sham control. In addition, RV-16-infected cells became more sensitive to secondary stimulation with both hypotonic and isotonic solutions, suggestive of a hypersensitive response. These responses were not mediated via increased TRPV4 or pannexin-1 whole-cell expression as determined by Western blotting. Interestingly, the increased ATP release seen was not a result of increased mitochondrial ATP production.

Thus, this is the first report demonstrating that RV-16 infection of airway epithelial cells causes hypersensitivity by increasing ATP release. These finding provide a novel insight into the process by which viruses may cause cough and identify a potential target for treatment of viral and post-viral cough.

Rhinovirus-infected airway epithelial cells (A549) show increased ATP release with and without a secondary stimulation (mechanical or hypotonic), which may account for increased cough sensitivity seen during respiratory viral infectionshttps://bit.ly/3eABEY9

An audit of COPD: diagnosis and management in general practice

Introduction

COPD is a spectrum of disorders primarily caused by smoking and characterised by progressive, not fully reversible airflow obstruction with a forced expiratory volume in 1 s (FEV₁)/forced vital capacity (FVC) ratio <0.7.

Methods

From November 2016 to March 2017 we audited patients with COPD in five general practices in Hull and East Riding, UK. We looked at deviation from the locally agreed guidelines. We extracted data on severity, exacerbations, medication and eosinophil count.

Results

We assessed 1088 records. Median age was 70.9 years; 577 (53%) were male. About two-thirds of patients on the COPD register have an FEV₁/FVC ratio in the diagnostic range for COPD, however, 388 (36%) out of 1088 had a ratio of ≥0.7. In the patients with a ratio of ≥0.7, 259 (67%) out of 388 had an FEV₁ <80% of predicted. Patients with frequent exacerbations were more likely to be prescribed inhaled corticosteroid (ICS)-containing inhalers (incidence rate ratio of 2). FEV₁ % predicted was a poor indicator of exacerbation frequency; however, the presence of elevated blood eosinophil counts (EOS) on at least two occasions was highly predictive of exacerbations. When ICSs, FEV₁, EOS were examined in combination, they were highly significant predictors for exacerbations.

Conclusion

FEV₁ maybe a more accurate diagnostic parameter in primary care. Historical evidence of blood eosinophilia is a better predictor than FEV₁. The combination of biomarkers may prove more accurate indicator of future exacerbation frequency, leading to targeted intervention.

FEV₁ <80% predicted provides a greater concordance with the primary care clinical diagnosis of COPD. When blood eosinophilia is coupled with ICS prescription and FEV₁, a much-enhanced predictability of exacerbation is achieved.https://bit.ly/2PtYS83

Correlation and causality: a COVID-19 conundrum

I read with interest the two contributions by J.D. Chalmers and co-workers to the July issue of the European Respiratory Journal. In a reply to correspondence concerning the inhaled corticosteroid withdrawal controversy in COPD [1], they suggest that A. Agusti succumbs to the fallacy of post hoc, ergo, propter hoc [2], i.e. A occurred, then B occurred: therefore, A caused B. However, as we know, correlation is not causality.

Predictive models depend heavily on the assumptions made in their constructionhttps://bit.ly/2Eex05F

Cough persistence in adults with chronic cough: A 4-year retrospective cohort study

BACKGROUND

There is very limited evidence regarding long-term prognosis of chronic cough. We examined longitudinal outcomes among patients with chronic cough, and explored predictors of cough persistence.

METHODS

A retrospective cohort was constructed of adults who had newly visited a specialist cough clinic in 2012-2013. All had undergone systematic investigation for chronic cough. The Hull Airway Reflux Questionnaire (HARQ) was administered to assess reflux cough symptoms. A follow-up survey was conducted in 2016-2017 to assess cough persistence.

RESULTS

From 418 candidates, 323 participated in the follow-up study; main analyses focused on patients with chronic persistent cough (n = 64; 19.8%) and remitted cough (n = 193; 59.8%). Compared with remitted cough group, chronic persistent cough group had more family history of chronic cough (17.2% vs. 4.7%, p = 0.001) and cold air-sensitive cough (62.5% vs. 44.6%, p = 0.013). The total HARQ score did not differ; however, two items (cough with eating and cough with certain foods) scored significantly higher in chronic persistent cough. In multivariate analyses, a family history of chronic cough (adjusted odds ratio 4.27 [95% confidence interval 1.35-9.89]), cold air-sensitive cough (2.01 [1.09-3.73]), and cough with eating (1.22 [1.02-1.45]) were associated with chronic persistent cough at 4 years.

CONCLUSIONS

Cough persists in about 20% of patients after 4 years following systematic assessment and treatments. Several cough characteristics, such as family history, cold air-sensitivity, or reflux cough, may be associated with cough persistence. Larger cohort studies are warranted to further understand long-term prognosis and confirm predictors of persistence in patients with chronic cough.

Objective Assessment of Cough: An Early Marker of Response to Biological Therapies in Asthma?

Cough is an important symptom of asthma. The objective assessment of chronic cough has been enhanced by the development of ambulatory cough monitoring systems. Mepolizumab has been demonstrated to reduce exacerbations in eosinophilic asthmatics long-term. We evaluate the utility of objective cough count as an outcome measure in severe eosinophilic asthma treated with mepolizumab. Consecutive, consenting patients initiated on treatment with mepolizumab had a 24-h cough count recorded at baseline; this was repeated at 1, 3 and 6 months. Asthma control questionnaire (ACQ) scores and exacerbation frequency were also recorded. The mean 24-h cough count in 11 subjects (8 females, mean age 53.6 years) was 172.4 at baseline; at 1, 3 and 6 months following initiation of treatment this decreased to 101.4, 92 and 70.8, respectively (p < 0.02). Significant improvements were also observed in mean ACQ score (3-1.6, p < 0.01) and exacerbation frequency (5.5 per year - 1.3, p < 0.01). Objective cough measurement could be used as an early, precise and clinically relevant endpoint in assessing response to asthma therapy.

Editorial comment on: Global burden of COVID-19 pandemic on healthcare workers

This is an important paper but from my personal observations of how we are handling the pandemic in hospitals, it is perhaps not the risk of dealing with the patients that is the problem. In my institution, we have been fortunate to have sufficient personal protective equipment (PPE) and we are well protected when entering the ward environment. However, wearing PPE is uncomfortable and it is disposed of on leaving the patient's room. Staff then congregate at the nurses' station and in the offices, where it is impossible to observe social isolation. I believe that the main threat to healthcare workers its other healthcare workers! We have had ward-based outbreaks with staff all contracting the virus simultaneously, presumably from an asymptomatic carrier in the workplace. This issue needs to be urgently addressed.

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

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

Impact of Chronic Cough on Health-Related Quality of Life in the Korean Adult General Population: The Korean National Health and Nutrition Examination Survey 2010-2016

Purpose

Chronic cough is a prevalent condition in the community and may pose considerable impairment to quality of life (QoL). However, its disease burden remains largely undefined in the general population. The present study investigated the relationship between chronic cough and health-related QoL in a Korean nationwide population database, with an emphasis on clinical conditions which may confound the impact of cough.

Methods

This study analyzed cross-sectional datasets of adults (aged ≥ 40 years) in the Korean National Health and Nutrition Examination Survey 2010–2016. Health-related QoL was assessed using the 3-level EuroQoL 5-dimension component (EQ-5D-3L) index score. The presence of chronic cough and other conditions were defined using structured questionnaires.

Results

The prevalence of chronic cough was 3.48% ± 0.17% among adults aged ≥ 40 years. The overall EQ-5D-3L index score was significantly lower in subjects with than without chronic cough (0.79 ± 0.01 vs. 0.86 ± 0.00, P < 0.001). In subgroup analyses by age and sex, chronic cough had a notably large impact on QoL in women aged ≥ 65 years (vs. those without chronic cough: 0.55 ± 0.04 vs. 0.70 ± 0.01, P < 0.001), although the mean difference in the scores exceeded the minimally important difference score of 0.05 in all subgroups. In multivariate analyses, chronic cough was significantly associated with QoL, independent of confounders including depression, arthritis, asthma, and chronic obstructive pulmonary disease. In dimension analyses, chronic cough was more associated with anxiety/depression, pain/discomfort, and usual activities than with self-care or mobility in the EQ-5D.

Conclusions

The present study demonstrated significant associations between chronic cough and health-related QoL in a nationwide large general adult population aged ≥ 40 years, which were independent of clinical confounders. The impact of chronic cough was greater in women aged ≥ 65 years. These findings indicate a considerable burden of chronic cough in the general population and warrant further investigations to assess the disease burden of chronic cough in a global scale.

XII AIST 2018 Conference: “The thousand faces of cough: clinical and therapeutic updates”

This paper summarizes the presentations submitted for publication of the 12th AIST National Congress (Associazione Italiana Studio Tosse/Italian Association for Cough Study) entitled “The thousand facets of cough. A clinical and therapeutic update”, which occurred last February 2nd-3rd, 2018 in Bologna (Italy). It summarizes the contributions from leading experts of the sector, who, as in the previous editions, also this year have analyzed a problem too often underestimated which still has many dark sides as regards both the diagnosis and the therapy of cough. The Scientific Committee has chosen topics that had less space in previous editions and these are topical subjects representing a concrete opportunity for learning and comparison of opinions, as well as indispensable elements for the correct management of the symptoms. Hereby we report the abstracts of the works submitted for publication in this Meeting report. The main topics have covered Cough relationship with nerve vagus, ATP, air pollution, GERD, imaging, COPD, pediatric and therapy. Of particular interest it is the preliminary data on cough hydration ratio that shows a highly significant correlation between dehydration and cough.

Characterisation of a New Human Alveolar Macrophage-Like Cell Line (Daisy)

Purpose

There is currently no true macrophage cell line and in vitro experiments requiring these cells currently require mitogenic stimulation of a macrophage precursor cell line (THP-1) or ex vivo maturation of circulating primary monocytes. In this study, we characterise a human macrophage cell line, derived from THP-1 cells, and compare its phenotype to the THP-1 cells.

Methods

THP-1 cells with and without mitogenic stimulation were compared to the newly derived macrophage-like cell line (Daisy) using microscopy, flow cytometry, phagocytosis assays, antigen binding assays and gene microarrays.

Results

We show that the cell line grows predominantly in an adherent monolayer. A panel of antibodies were chosen to investigate the cell surface phenotype of these cells using flow cytometry. Daisy cells expressed more CD11c, CD80, CD163, CD169 and CD206, but less CD14 and CD11b compared with mitogen-stimulated THP-1 cells. Unlike stimulated THP-1 cells which were barely able to bind immune complexes, Daisy cells showed large amounts of immune complex binding. Finally, although not statistically significant, the phagocytic ability of Daisy cells was greater than mitogen-stimulated THP-1 cells, suggesting that the cell line is more similar to mature macrophages.

Conclusions

The observed phenotype suggests that Daisy cells are a good model of human macrophages with a phenotype similar to human alveolar macrophages.

Differential effects of atrial and brain natriuretic peptides on human pulmonary artery: An in vitro study

BACKGROUND

The prevalence of cardiovascular diseases, especially heart failure, continues to rise worldwide. In heart failure, increasing levels of circulating atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) are associated with a worsening of heart failure and a poor prognosis.

AIM

To test whether a high concentration of BNP would inhibit relaxation to ANP.

METHODS

Pulmonary arteries were dissected from disease-free areas of lung resection, as well as pulmonary artery rings of internal diameter 2.5–3.5 mm and 2 mm long, were prepared. Pulmonary artery rings were mounted in a multiwire myograph, and a basal tension of 1.61gf was applied. After equilibration for 60 min, rings were pre-constricted with 11.21 µmol/L PGF_2α (EC₈₀), and concentration response curves were constructed to vasodilators by cumulative addition to the myograph chambers.

RESULTS

Although both ANP and BNP were found to vasodilate the pulmonary vessels, ANP is more potent than BNP. pEC50 of ANP and BNP were 8.96 ± 0.21 and 7.54 ± 0.18, respectively, and the maximum efficacy (E_max) for ANP and BNP was -2.03 gf and -0.24 gf, respectively. After addition of BNP, the E_max of ANP reduced from -0.96gf to -0.675gf (P = 0.28).

CONCLUSION

BNP could be acting as a partial agonist in small human pulmonary arteries, and inhibits relaxation to ANP. Elevated levels of circulating BNP could be responsible for the worsening of decompensated heart failure. This finding could also explain the disappointing results seen in clinical trials of ANP and BNP analogues for the treatment of heart failure.

Symptoms and exacerbations in asthma: an apparent paradox?

Background:

There is a dearth of data on prospectively recorded symptoms in patients with uncontrolled asthma. Asthma symptoms and exacerbation rate are commonly thought to be associated. The aim of this study was to analyse asthma symptoms of cough, wheeze, chest tightness and breathlessness in an uncontrolled asthma cohort. We also examined the effect of maintenance and reliever therapy (MART) on these symptoms and its effect on exacerbation rate.

Methods:

Adults with uncontrolled asthma electronically recorded their asthma symptom severity scores twice-daily over a period of 48 weeks following randomisation to beclometasone/formoterol twice daily plus pro re nata (prn) salbutamol or MART. Subjects with symptom scores of ⩾2 (ranging from 0 to 3 for each symptom) were considered more symptomatic, whereas those below a score of 2 were considered less severe. The influence treatment on exacerbation frequency and symptom profiles were then correlated.

Results:

Of the 1701 subjects in the analyses, 1403 were symptomatic with ⩾100 symptom episodes for one symptom. The remaining 298 subjects were classified as pauci-symptomatic. There was poor association between the frequency and symptom severity score for each symptom. Surprisingly, wheeze was the least reported symptom. Females were more likely to be polysymptomatic. MART compared with prn salbutamol markedly attenuated severe asthma exacerbations. This effect was most notable in subjects with fewer symptoms.

Conclusions:

In uncontrolled asthma, there is a poor correlation between reported symptoms and exacerbation frequency. This post hoc analysis suggests that MART should not be reserved for symptomatic subjects but achieves the greatest benefit in pauci-symptomatic patients with asthma.

Trial registration:

ClinicalTrials.gov identifier: NCT00861926

The effect of gefapixant, a P2X3 antagonist, on cough reflex sensitivity: a randomised placebo-controlled study

We evaluated the effect of gefapixant on cough reflex sensitivity to evoked tussive challenge.

In this phase 2, double-blind, two-period study, patients with chronic cough (CC) and healthy volunteers (HV) were randomised to single-dose gefapixant 100 mg or placebo in a crossover fashion. Sequential inhalational challenges with ATP, citric acid, capsaicin and distilled water were performed 1, 3 and 5 h after dosing. Mean concentrations evoking ≥2 coughs (C2) and ≥5 coughs (C5) post dose versus baseline were co-primary endpoints. Objective cough frequency (coughs·h−1) over 24 h and a cough severity visual analogue scale (VAS) were assessed in CC patients. Adverse events were monitored.

24 CC patients and 12 HV were randomised (mean age 61 and 38 years, respectively). The cough challenge threshold increased for ATP by 4.7-fold (C2, p≤0.001) and 3.7-fold (C5, p=0.007) for gefapixant versus placebo in CC patients; in HV, C2 and C5 increased 2.4-fold (C2, p=0.113; C5, p=0.003). The distilled water C2 and C5 thresholds increased significantly (p<0.001) by a factor of 1.4 and 1.3, respectively, in CC patients. Gefapixant had no effect on capsaicin or citric acid challenge. Median cough frequency was reduced by 42% and the least squares mean cough severity VAS was 18.0 mm lower for gefapixant versus placebo in CC patients. Dysgeusia was the most frequent adverse event (75% of HV and 67% of CC patients).

ATP-evoked cough was significantly inhibited by gefapixant 100 mg, demonstrating peripheral target engagement. Cough count and severity were reduced in CC patients. Distilled water may also evoke cough through a purinergic pathway.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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