What Is Chronic Cough? Terminology

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.

Antitussive, Expectorant and Antipyretic Effect of the Ethanolic Extract of the Leaves of Momordica charantia L

The traditional use of the M. charantia L. plant to treat coughs, fever and expectoration is widely practiced in different cultures, but its effectiveness and safety still require scientific investigation. This study sought to perform a chemical analysis and evaluate the antitussive, expectorant and antipyretic effects of the ethanolic extract of M. charantia leaves (EEMc) in rats and mice. The EEMc was subjected to chemical analysis by HPLC-DAD, revealing the presence of the flavonoids astragalin and isoquercetin. Acute oral toxicity in mice did not result in deaths, although changes in liver weight and stool consistency were observed. EEMc demonstrated an antitussive effect at doses of 100 and 300 mg/kg in mice subjected to cough induction by citric acid nebulization. Furthermore, it showed expectorant activity at a dose of 300 mg/kg, assessed based on the elimination of the phenol red marker in bronchoalveolar lavage. In the evaluation of antipyretic activity in rats, fever induced by Saccharomyces cerevisiae was reduced at all doses tested during the first hour after treatment. This innovative study identified the presence of astragalin and isoquercetin in EEMc and indicated that the extract has antitussive, expectorant and antipyretic properties. Therefore, EEMc presents itself as a promising option in herbal medicine for the treatment of respiratory symptoms and fever.

Chronic Cough and Cerebellar Ataxia With Neuropathy and Bilateral Vestibular Areflexia Syndrome (CANVAS): Screening for Mutations in Replication Factor C Subunit 1 (RFC1)

INTRODUCTION

A common complaint in patients is chronic cough (CC), which may be refractory (RCC) or unexplained (UCC). Recent studies point, as a possible cause of CC, to the hereditary cerebellar ataxia with neuropathy and bilateral vestibular areflexia syndrome (CANVAS), with an estimated carrier prevalence of 1 in 20000.

AIM

In patients with CC, determine the prevalence of the biallelic (AAGGG)exp mutation in replication factor C subunit 1 (RFC1) responsible for CANVAS, test the usefulness of the Rydel-Seiffer fork test, and evaluate patient quality of life (QoL).

METHODS

Clinical and functional data were collected for the 33 included patients undergoing CC studies in our specialized unit. Performed were an etiological study of CC following European Respiratory Society recommendations, a genetic study of RFC1 mutations, and Rydel-Seiffer fork testing to detect possible peripheral vibratory sensitivity impairment. Administered to evaluate QoL were 4 questionnaires.

RESULTS

Prevalence of biallelic (AAGGG)exp in RFC1 was 6.1% (n=2) overall, increasing to 7.1% in the RCC subgroup, and to 33.3% in the Rydel-Seiffer fork altered results subgroup. Prevalence of monoallelic (AAGGG)exp in RFC1 was 18.2% (n=6) overall, rising to 50.0% (n=2) in the UCC subgroup.

CONCLUSION

Genetic screening for (AAGGG)exp in RFC1, and also use of the Rydel-Seiffer fork test, should be considered in specialized CC consultations for patients with RCC and UCC. Detecting possible CANVAS symptoms in CC studies would identify candidates for early genetic screening, of interest in reducing the disease burden for patients and health systems alike.

An observational study to understand burden and cost of care in adults diagnosed with refractory chronic cough (RCC) or unexplained chronic cough (UCC)

BACKGROUND

Refractory and unexplained chronic cough (RCC and UCC) necessitate frequent referral for specialist evaluations, but data on healthcare resource utilisation and costs are lacking.

METHODS

This observational study enrolled adults with RCC or UCC attending a specialist cough clinic and included a control cohort, both from North West England, matched 1:5 for age, gender and smoking history. Primary and secondary care data were obtained for the 5 years prior to and 2 years post initial clinic visit (index). The primary endpoint was the total 5-year healthcare cost to the UK NHS pre-RCC or UCC diagnosis compared to the control cohort.

RESULTS

Mean age at index for the 200 RCC or UCC consented patients was 62.2 ± 11.4 years; 71% were female, and 68% had never smoked. Mean duration of symptoms pre-diagnosis was 8.0 ± 9.4 years. Mean cough severity score was 63.7 ± 23.2 mm at index on a Visual Analog Scale, and Leicester Cough Questionnaire total score was 10.9 ± 4.1. GP data were available for 80 patients and mean total cost over the 5 years pre-diagnosis (index date) was 3.0-fold higher (95% CI 2.3, 3.9) than in the control cohort (p < 0.001). Most excess costs were related to visits and procedures carried out in secondary care. RCC- or UCC-associated costs decreased post-diagnosis, but remained higher than those of controls.

CONCLUSION

Diagnosis of RCC or UCC requires significant health resource utilisation in the 5 years prior to a specialist clinic diagnosis. Resource utilisation was less after diagnosis, but remained higher than in a matched control cohort.

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.

Chronic cough diagnosis, treatment, and referral practices among family physicians in the United States: a survey study

BACKGROUND

Cough is one of the most common presenting problems for patients in primary care and is largely managed in primary care clinical settings. Family physicians' familiarity with chronic cough guidelines and the extent to which these guidelines translate into everyday practice have not been well described. The objective of this study was to characterize current diagnosis, treatment, and referral practices among family physicians and to identify potentially impactful strategies to optimize chronic cough management in primary care.

METHODS

We conducted a cross-sectional survey of 5,000 family physicians to explore diagnosis, treatment, and referral practices related to chronic cough management in adults in primary care. Respondents completed the survey via paper or online. The outcome measures were self-reported numeric ratings and responses related to the survey elements.

RESULTS

588 surveys were completed (11.8% response rate). About half (49.6%) of respondents defined chronic cough in a manner consistent with the American College of Chest Physicians (ACCP) chronic cough guidelines, with the rest differing in opinion primarily regarding duration of symptom presentation. Respondents reported trying to rule out most common causes of chronic cough themselves before referring (mean 3.41 on a 4-point scale where 4 is "describes me completely") and indicated a desire for more resources to help them manage and treat chronic cough. Years in practice and rural/urban setting influenced diagnosis and referral practices.

CONCLUSIONS

Family physicians see chronic cough as a complicated condition that can be and is often diagnosed and treated entirely in a primary care setting. They also value the ability to refer in complex cases. Our results support that family physicians provide evidence-based management of chronic cough.

Clinical Parameters of the Speech-Language Pathology Assessment of the Chronic Cough: A Scoping Review

OBJECTIVE

to map the clinical parameters used in the speech-language pathology assessment of the chronic cough.

METHODS

a scoping review was performed to answer the clinical question: "What are the clinical parameters included in the speech-language pathology assessment of patients with chronic cough?" Evidence was searched by electronic and manual search. The electronic search included: MEDLINE, Cochrane Library, EMBASE, Web of Science, SCOPUS, and LILACS. Each database had a specific search strategy. The manual search included Journal of Voice, Chest, and Thorax, Brazilian Library of Theses and Dissertations, Open Grey, and Clinical Trials, in addition to scanning the references of the included studies. The extracted data considered information regarding the publication, sample, assessment, and measures used when assessing chronic cough.

RESULTS

the electronic search found 289 studies; the manual search found 1036 studies; 12 were selected for the present study. The most used assessments were: self-assessment (75%), aerodynamic analysis (66.67%), the perceptual auditory judgment of the voice quality (58.33%), acoustic analysis of the voice (41.67%), cough frequency, and cough threshold (41.67%) and electroglottography (25%).

CONCLUSIONS

the subjective instruments were used more frequently, while specific objective instruments, which are recent, were used less frequently. Complementary assessments such as vocal assessment, have been frequently used, also, with no other parameter. A lack of homogeneity was identified in the speech-language pathology assessment and measures of patients with chronic cough, thus, the comparison among studies and clinical analysis is difficult.

ERS International Congress 2023: highlights from the Airway Diseases Assembly

In this review, early career and senior members of Assembly 5 (Airway Diseases, Asthma, COPD and Chronic Cough) present key recent findings pertinent to airway diseases that were presented during the European Respiratory Society International Congress 2023 in Milan, Italy, with a particular focus on asthma, COPD, chronic cough and bronchiectasis. During the congress, an increased number of symposia, workshops and abstract presentations were organised. In total, 739 abstracts were submitted for Assembly 5 and the majority of these were presented by early career members. These data highlight the increased interest in this group of respiratory diseases.

Patient preferences for the treatment of chronic cough: a discrete choice experiment

BACKGROUND

Chronic cough is common, negatively affects quality of life and has limited treatment options. Inhibition of purinergic signalling is a promising therapeutic approach but is associated with taste-related adverse effects. Little is known about treatment preferences from the perspective of patients with chronic cough, such as trade-offs between efficacy and side effect.

METHODS

Patients with chronic cough completed an online discrete choice experiment survey in which they answered a series of questions requiring a choice between two constructed treatment options characterised by varying attribute levels. Selection of cough and taste-related attributes was informed by qualitative interviews and clinical trial data. Logit-based models were used to analyse resulting choice data.

RESULTS

The discrete choice experiment survey was completed by 472 participants with chronic cough. Among study attributes, frequency of intense cough attacks was the most important to participants, followed by taste change, frequency of night-time coughing and frequency of daytime coughing. To accept the least preferred taste disturbance of a bitter, metallic, chalky or oily taste change, participants required either: (1) elimination of night-time cough along with a slight reduction in daytime cough; (2) elimination of daytime cough along with a pronounced reduction in night-time or (3) reduction in intense cough attacks from 7 to 2 times per week. Two distinct preference patterns were identified, each placing different importance on efficacy versus side effect trade-offs.

CONCLUSIONS

Participants with chronic cough were willing to accept some taste disturbances in exchange for improved efficacy of chronic cough treatments. Knowledge of patient preferences can facilitate shared decision-making.

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

INTRODUCTION

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

MAIN RECOMMENDATIONS

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

CHANGES IN MANAGEMENT AS A RESULT OF THIS STATEMENT

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

Systematic literature review of treatments used for refractory or unexplained chronic cough in adults

BACKGROUND

Refractory or unexplained chronic cough (RCC or UCC) is difficult to manage and is usually treated by the off-label use of drugs approved for other indications.

OBJECTIVE

The objectives of this systematic literature review (SLR) were to identify and characterize the current published body of evidence for the efficacy and safety of treatments for RCC or UCC.

METHODS

The SLR was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The SLRs pre-defined population included patients ≥18 years of age who were diagnosed with chronic cough. The review was not restricted to any intervention type or study comparator, nor by timeframe.

RESULTS

A total of 20 eligible publications from 19 unique trials were included. Seventeen of these trials were randomized controlled trials and most (14/17) were placebo-controlled. There was considerable variability between trials in the definition of RCC or UCC, participant exclusion and inclusion criteria, outcome measurement timepoints, and the safety and efficacy outcomes assessed. Several trials identified significant improvements in cough frequency, severity, or health-related quality of life measures while participants were on treatment, although these improvements did not persist in any of the studies that included a post-treatment follow-up timepoint.

CONCLUSIONS

In the absence of an approved therapy, placebo remains the most common comparator in trials of potential RCC or UCC treatments. The between-study comparability of the published evidence is limited by heterogeneity of study design, study populations, and outcomes measures, as well as by concerns regarding study size and risk of bias.

Feasibility and Utility of a Smartphone Application-Based Longitudinal Cough Monitoring in Chronic Cough Patients in a Real-World Setting

PURPOSE

This study evaluated the feasibility and utility of longitudinal cough frequency monitoring with the Hyfe Cough Tracker, a mobile application equipped with cough-counting artificial intelligence algorithms, in real-world patients with chronic cough.

METHODS

Patients with chronic cough (> 8-week duration) were monitored continuously for cough frequency with the Hyfe app for at least one week. Cough was also evaluated using the Leicester Cough Questionnaire (LCQ) and daily cough severity scoring (0-10). The study analyzed adherence rate, the correlation between objective cough frequency and subjective scores, day-to-day variability, and patient experience.

RESULTS

Of 65 subjects consecutively recruited, 43 completed the study. The median cough monitoring duration was 13.9 days, with a median adherence of 91%. Study completion was associated with baseline cough severity, and the adherence rate was higher in younger subjects. Cross-sectional correlation analyses showed modest correlations between objective and subjective cough measures at the group level. However, in time series correlation analyses, correlations between objective and subjective measures widely varied across individuals. Cough frequency had greater day-to-day variability than daily cough severity scores in most subjects. A patient experience survey found that 70% of participants found the cough monitoring helpful, 86% considered it acceptable, and 84% felt it was easy to use.

CONCLUSION

Monitoring cough frequency longitudinally for at least one week may be feasible. The substantial day-to-day variability in objective cough frequency highlights the need for continuous monitoring. Grasping the implications of daily cough variability is crucial in both clinical practice and clinical trials.

Interdisciplinary collaboration in the diagnosis and management of chronic cough: the role and importance of primary care providers

Chronic cough (CC) is associated with many conditions, so identifying contributing causes poses a diagnostic challenge. However, guidelines written for US physicians do not explicitly outline suggested roles for primary care providers (PCPs) in the approach to patients with CC, including refractory or unexplained CC. The objective of this review is to describe the role of PCPs in the diagnosis and treatment of CC in adults. This narrative review draws upon literature (identified via a PubMed search performed January 9, 2023, using primary care/disease state-related terms) and expertise from specialist physicians to provide recommendations for CC management in primary care. Cough is one of the top reasons patients seek care from PCPs; accordingly, PCPs are often the first physicians to conduct workup and initiate treatment. Patients with CC often experience a burdensome cough that lasts for years, have high healthcare resource utilization (HCRU), undergo multiple or failed treatment trials, and have limited success finding an etiology. Although specialist referral may be needed for many diagnostic tests, initial aspects of CC workup and management should be completed in primary care. Often more accessible than specialists, real-world evidence on HCRU suggests PCPs are important stakeholders in diagnosing and managing CC, including during initial workup and treatment for the most common causes of CC (i.e. upper-airway cough syndrome, asthma, noneosinophilic asthmatic bronchitis, and gastroesophageal reflux disease). Thorough workup at the primary care level may facilitate earlier identification of CC cause(s), improving patient journey to diagnosis and management.

Burden of refractory and unexplained chronic cough on patients' lives: a cohort study

Background

Chronic cough (cough lasting for ≥8 weeks) can lead to significant impairment in quality of life (QoL). Using patient-reported outcomes, this cohort study assessed the perceived impact of chronic cough on QoL and everyday life in patients from outpatient hospital clinics with refractory chronic cough (RCC) or unexplained chronic cough (UCC).

Methods

This was a multicentre, non-interventional survey study. Cough severity was assessed on a 0-100 mm Visual Analogue Scale (VAS). Frequency, intensity and disruptiveness of cough were assessed using an adaptation of the Cough Severity Diary. The impact of cough on QoL was assessed using the Leicester Cough Questionnaire (LCQ). The physical impact of cough and associated impact on everyday life activities were explored using purpose-designed questions.

Results

191 patients responded to the survey; 121 (63.4%) had RCC and 149 were women (78.0%). Mean score on the cough severity VAS was 62.9 mm. Mean LCQ total score of 11.9 indicated reduced QoL. Cough impaired patients' everyday life, including the inability to speak fluently (58.0% of patients) and feeling tired/drained (46.6%). Women perceived poorer chronic cough-related QoL than men, as reflected by lower LCQ scores, and greater impairment of physical health, including cough-related stress urinary incontinence, and psychological health.

Conclusions

Patients with RCC/UCC experience a significant burden in their everyday life, including impaired QoL, and perceive a negative impact on physical and psychological health and everyday activities, affecting work, relationships and leisure activities. The impact appears to be greater in women than men for several of the aspects studied.

Efficacy and safety of gefapixant for chronic cough: a meta-analysis of randomised controlled trials

BACKGROUND

The efficacy and safety of gefapixant in adults with chronic cough remain unclear. Our objective was to assess the efficacy and safety of gefapixant using updated evidence.

METHODS

MEDLINE, Cochrane Central Register of Controlled Trials (CENTRAL) and Embase databases were searched from inception through September 2022. Subgroup analysis based on dose of gefapixant (i.e. ≤20, 45-50 and ≥100 mg twice daily for low, moderate and high doses, respectively) was performed to explore a potential dose-dependent effect.

RESULTS

Five studies involving seven trials showed the efficacy of moderate- or high-dose gefapixant for reducing objective 24-h cough frequency (estimated relative reduction 30.9% and 58.5%, respectively) (i.e. primary outcome) and awake cough frequency (estimated relative reduction 47.3% and 62.8%, respectively). Night-time cough frequency was only reduced with high-dose gefapixant. Consistently, the use of moderate- or high-dose gefapixant significantly alleviated cough severity and improved cough-related quality of life, but increased the risk of all-cause adverse events (AEs), treatment-related AEs and ageusia/dysgeusia/hypogeusia. Subgroup analysis showed dose dependency in both efficacy and AEs with a cut-off dose being ≥45 mg twice daily.

CONCLUSIONS

This meta-analysis revealed dose-dependent efficacy and adverse effects of gefapixant against chronic cough. Further studies are required to investigate the feasibility of moderate-dose (i.e. 45-50 mg twice daily) gefapixant in clinical practice.

Characteristics and Management of Patients with Refractory or Unexplained Chronic Cough in Outpatient Hospital Clinics in Spain: A Retrospective Multicenter Study

PURPOSE

Chronic cough (cough that persists for ≥ 8 weeks) can cause a range of physical symptoms and psychosocial effects that significantly impair patients' quality of life. Refractory chronic cough (RCC) and unexplained chronic cough (UCC) are challenging to diagnose and manage, with substantial economic implications for healthcare systems.

METHODS

This retrospective multicenter non-interventional study aimed to characterize the profile and health resource consumption of patients with RCC or UCC who attended outpatient clinics at Spanish hospitals. Data were collected from medical records of patients with RCC or UCC for up to 3 years before study inclusion.

RESULTS

The patient cohort (n = 196) was representative of the chronic cough population (77.6% female, mean age 58.5 years). Two-thirds of patients (n = 126) had RCC. The most frequently visited doctors were pulmonologists (93.4% of patients) and primary care physicians (78.6%), with a mean of 5 visits per patient over three years' observation. The most common diagnostic tests were chest x-ray (83.7%) and spirometry with bronchodilation (77.0%). The most commonly prescribed treatments were proton pump inhibitors (79.6%) and respiratory medications (87.8%). Antibiotics were prescribed empirically to 56 (28.6%) patients. Differences between RCC or UCC groups related mainly to approaches used to manage cough-associated conditions (gastroesophageal reflux disease, asthma) in patients with RCC.

CONCLUSION

RCC and UCC are responsible for high health resource utilization in Spanish hospitals. Specific treatments targeting the pathological processes driving chronic cough may provide opportunities to reduce the associated burden for patients and healthcare systems.

The "vicious circle" of chronic cough: the patient experience - qualitative synthesis

Aim

The aim of this study was to systematically search and synthesise findings from peer-reviewed qualitative studies describing the experiences of those living with chronic cough.

Methods

A systematic search was conducted to identify all studies that used qualitative methodology to report on the experiences of adults living with chronic cough. A thematic synthesis of the first-hand narratives was undertaken. Key themes in relation to personal perspectives and experiences of living with chronic cough were identified and grouped into analytical themes.

Results

Six studies met the inclusion criteria. The thematic synthesis generated three analytical themes: 1) "It's just a cough"; 2) "Constant cough and constant worry"; and 3) "No light at the end of the tunnel", highlighting the biopsychosocial nature of chronic cough. The synthesis highlights chronic cough as a heterogeneous experience that may appear idiosyncratic, completely consuming the lives of those living with it.

Conclusion

This is to our knowledge the first qualitative synthesis reporting on the perceptions and experiences of adults living with chronic cough. Our review draws attention to the paucity of literature that utilises qualitative methodology to explore the experience of living with chronic cough. We highlight the missing voice of people living with chronic cough in the contemporary literature. There is now a requirement for research exploring the narratives of those living with chronic cough, to gain an understanding of the condition beyond simple quantification.

Determining What Represents Value in the Treatment of Refractory or Unexplained Chronic Cough from the Perspective of Key Stakeholders in Spain Using Multi-Criteria Decision Analysis

BACKGROUND AND OBJECTIVE

Chronic cough is defined as cough lasting for more than 8 weeks. It can be described as refractory when persisting despite thorough clinical assessment and treatment of any cough-related underlying condition, or unexplained when no underlying cough-related condition can be identified. Refractory or unexplained chronic cough (RCC|UCC) greatly affects patient health-related quality of life (HRQoL). Although around 10% of the population suffer from chronic cough (with 40-60% of these patients suffering from RCC|UCC), there is limited information available in the literature about the condition and the assessment of treatment success. This study aimed to determine what represents value in the treatment of RCC|UCC from the perspective of key stakeholders in Spain using Multi-Criteria Decision Analysis (MCDA) methodology.

METHODS

A literature review was conducted to adapt the MCDA framework to the specific context of RCC|UCC. A total of 24 participants were involved, representing three key stakeholder groups (7 patients, 9 physicians and 8 hospital pharmacists). The study was structured in two phases. In Phase 1, participants validated the adapted MCDA framework and assigned relative weights (100-point allocation) to the framework's value criteria/sub-criteria during three individual stakeholder meetings, one per each stakeholder group. In Phase 2, participants were brought together in a multi-stakeholder meeting to review findings of each stakeholder group, after which stakeholders repeated the weighting exercise as a collective group. All meetings included reflective discussion by participants of each value criteria/sub-criteria included within the adapted MCDA framework, where stakeholders shared their perspectives and opinions on what represents value in RCC|UCC.

RESULTS

Refractory or unexplained chronic cough is regarded as a chronic medical condition, with variable severity across patients and the potential to heavily impact their HRQoL (including physical, psychological and social/work productivity domains). Current treatments used by healthcare professionals, which have not been specifically developed and are not approved for RCC|UCC, show limited clinical effectiveness and associated safety and tolerability issues, which result in frequent treatment discontinuations. The reduction of the average cough frequency over a 24-h period is regarded as the primary goal of treatment by stakeholders, with the aim of improving HRQoL. Improvement of other cough symptoms, such as intensity, is also considered important. Minor adverse events and a slower onset of treatment effect would be acceptable to stakeholders if accompanied by strong efficacy and improvement in HRQoL. Given the inability to measure cough frequency in clinical practice, Patient-Reported Outcomes (PROs) could be considered a proxy of treatment effectiveness. A multidisciplinary approach to the condition is regarded as key for treatment success.

CONCLUSIONS

Refractory or unexplained chronic cough is a medical condition that seriously impacts patients' HRQoL. The primary goal of treatment is to improve patients' HRQoL by reducing the frequency and intensity of cough.

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).

Validation and Meaningful Change Thresholds for an Objective Cough Frequency Measurement in Chronic Cough

PURPOSE

Objective cough frequency is used to assess efficacy of chronic cough (CC) treatments. The objective of this study was to explore the relationship between objective cough frequency and cough-specific patient-reported outcomes (PROs) and estimate a clinically meaningful change threshold (MCT) for objective cough frequency.

METHODS

Data collected in a phase 2b study in participants with refractory or unexplained CC were used to investigate the relationship between 24-h cough frequency (measured using an ambulatory cough monitor) and cough-specific PROs (i.e., cough severity visual analog scale, cough severity diary, Leicester Cough Questionnaire). Convergent validity was assessed using Spearman ρ. An MCT for 24-h cough frequency was estimated using the patient global impression of change (PGIC) scale as an anchor.

RESULTS

Correlations between 24-h cough frequency and cough-specific PROs at baseline, Week 4, and Week 12 were significant (P < 0.0001) but low to moderate in strength (ρ = 0.30-0.58). Participants categorized as very much improved/much improved (i.e., PGIC of 1 or 2) or minimally improved (i.e., PGIC of 3) had mean 24-h cough frequency reductions of 55% and 30%, respectively. Receiver operating characteristic curve analysis suggested that a 24-h cough frequency reduction of 38% optimizes sensitivity and specificity for predicting a PGIC score of 1-3.

CONCLUSION

Objective 24-h cough frequency is significantly associated with cough-specific PROs, but cough frequency and PROs most likely capture distinct aspects of CC. A ≥ 30% reduction in 24-h cough frequency is a reasonable MCT to define treatment response in CC clinical trials.

The Diagnosis and Time of Onset of Voice Disorders in Patients with Chronic Cough

OBJECTIVES

Chronic cough is a complaint of up to 46% of patients referred to specialist clinics. Patients with cough often report hoarseness at the time of the cough diagnosis. When the cough fails to resolve with standard medications, referrals to other specialists including otolaryngologists are made. This is the first study to report the specific diagnosis and length of time it took to obtain a specific voice disorder diagnosis in patients with chronic cough.

STUDY DESIGN

Case Series METHODS: The charts of 105 patients referred to the Loma Linda Voice and Swallowing Center were reviewed. The first complaint of cough and/or hoarseness and the specific voice disorder diagnosis following otolaryngologic evaluation were identified. Voice disorders were divided into neurogenic or other/functional disorders and common comorbidities were identified. Statistical analysis between diagnostic groups, gender, and age were obtained.

RESULTS

The specific voice disorders in the cohort were identified. There was a high prevalence of neurogenic voice disorders (n = 85, 81%). There were significant relationships between chronic cough and the two most common neurogenic voice disorders, vocal fold paresis and vocal fold atrophy. The average length of time between complaint of hoarseness and the specific voice disorder diagnosis was 32.3 months. Most patients (86%) complained of voice problems after diagnosis of chronic cough. A significant association was found in prevalence of asthma (OR = 4.52, P = 0.02) and dyspnea (OR = 4.24, P = 0.02) in the cohort who presented first with voice complaints and later developed chronic cough.

CONCLUSIONS

There is a high incidence of neurogenic voice disorders accompanying patients with chronic cough. Understanding the relationship between chronic cough and hoarseness provides the clinician with specific diagnostic information in the treatment of both disorders.

The disease burden and quality of life of chronic cough patients in South Korea and Taiwan

Background

Chronic cough (CC) is a common condition, but the burden of CC in general populations remains largely unknown. This study aims to investigate the disease prevalence and burden among community-based CC patients in South Korea and Taiwan, using structured tools.

Methods

A population-based cross-sectional study uses data from the 2020 South Korea and Taiwan National Health and Wellness Survey (NHWS) as well as a CC survey conducted between January–February 2020 and March–April 2020, respectively. Health outcome measures included health-related quality of life (HRQoL), health state utilities, work productivity and activity impairment (WPAI), and measurement of depression, anxiety, and insomnia among CC patients.

Results

The weighted lifetime and 12-month prevalence of CC was 6.20% and 4.34% in South Korea, and 8.27% and 5.55% in Taiwan. Compared to matched non-CC controls, CC patients reported poorer HRQoL (SF-12v2) in terms of physical component summary (PCS) score (South Korea: 47.69 ± 7.68 vs. 50.08 ± 7.29; Taiwan: 48.58 ± 7.15 vs. 50.50 ± 7.30) and mental component summary (MCS) score (44.15 ± 8.85 vs. 46.28 ± 8.50; 42.44 ± 7.78 vs. 44.60 ± 8.08), health state utilities EQ-5D index (0.73 ± 0.23 vs. 0.82 ± 0.16; 0.82 ± 0.13 vs. 0.86 ± 0.14), and more visits to healthcare professionals (7.80 vs. 4.61; 6.09 vs. 4.20) (p < 0.05). In terms of WPAI, CC patients reported higher impairments in presenteeism (32.8% vs. 21.0%; 25.9% vs. 19.4%), total work productivity (36.2% vs. 22.3%; 27.7% vs. 20.6%), and total activity (34.2% vs. 23.2%; 27.7% vs. 20.3%) than non-CC controls (p < 0.001). CC patients in South Korea and Taiwan experienced anxiety, depression, and insomnia more than non-CC controls. Poorer health outcomes were associated with the severity of CC. Patients with severe CC (visual analogue scale [VAS]>4) in both nations reported lower PCS score (45.80 vs. 49.48; 47.41 vs. 49.22) and higher absenteeism (8.5% vs. 3.6%; 5.5% vs. 1.8%) than patients with mild CC (VAS≤4) (p < 0.05).

Conclusions

The findings revealed that the disease burden of CC in general populations of South Korea and Taiwan is considerable with a negative impact on the overall quality of life, social and work life, and psychological comorbidities and is significantly associated with increased severity of the CC. There is an unmet need for further treatment interventions for CC patients to relieve the burden of CC in both nations.

Understanding physician's knowledge and perception of chronic cough in Switzerland

BACKGROUND

Cough is one of the most common health issues for which medical attention is sought. A chronic cough (CC) is understood as a cough that lasts longer than 8 weeks. CC encompasses two subsets referred to as refractory chronic cough (RCC) and unexplained chronic cough (UCC). This study aims to assess the current understanding and perceptions of a RCC and UCC, from a physician's perspective in Switzerland and how this understanding and practical work leads to the relevant diagnosis and treatment.

METHODS

In October 2020, 549 GPs and 338 pulmonologists in Switzerland, received an invite to participate in the online-based quantitative survey. Data collection was carried out through a 25-minute online survey. The questionnaire was based on structured questions, and conducted on a randomized sample of doctors (general practitioners -GPs and pulmonologists) in the German- and French-speaking part of Switzerland.

RESULTS

Overall, 33 pulmonologists and 52 GPs participated in the online survey. Only 39% of GPs, but 73% of pulmonologists, defined chronic cough as a cough lasting 8 weeks or longer. The majority of physicians (72%), especially pulmonologists (88%), perceived a clinical gap regarding the treatment of persistent cough. 74% of the sampled physicians agreed that persistent cough is a high burden of disease for patients. Based on the answers, the annual number of new patients with RCC and UCC in Switzerland is estimated at 9322 patients.

CONCLUSIONS

Results of this study have highlighted differences in the terminology used to describe CC (RCC and UCC), in the diagnostic tests used and, in the treatments used between GPs and pulmonologists. These findings suggest the need to align the current language regarding the disease to facilitate a standardized approach for diagnosis and treatment and towards improving patient care and reduce burden of disease for CC (RCC and UCC) patients.

Cough Presentation and Cough-Related Healthcare Utilization in Tertiary Care: Analysis of Routinely Collected Academic Institutional Database

PURPOSE

Routinely collected data (RCD) from electronic health records (EHR) are useful for studying disease epidemiology in the real world. We examined cough presentation and cough-related healthcare utilization using an academic institutional EHR database in Korea.

METHODS

In this retrospective cohort study, patients with subacute (3-8 weeks) or chronic cough (> 8 weeks in duration) referred to allergy and asthma clinics were studied. Cases were identified using the search term "cough" or "coughing," which is the chief complaint, in the data fields. Structured data, including demographics, medical history, symptoms, and diagnostic tests, were analyzed. Healthcare utilization was assessed for drug prescriptions, additional tests, or outpatient visits for 1 year.

RESULTS

Cough was the chief complaint in 13,223 cases (46.7%) among 28,312 new referrals for 8 years. A total of 3810 subacute and 7150 chronic cough patients were analyzed. The common demographic profile was middle-aged woman (mean age 52.1 years), reported in 63% of the cases. Cough was frequently accompanied by anterior nasal (about 50%), lower airway (30%), or acid reflux disease symptoms (20%), and by test abnormalities in chest X-rays (14%), spirometry (23%), or T2 inflammation markers (40%). Chronic cough patients frequently required additional tests (chest CT scan: 24%), drug prescriptions (codeine: 21.5% and oral steroids: 9.9%), and long-term healthcare utilization (16.0%) for 1 year.

CONCLUSIONS

Cough is a common chief complaint at allergy and asthma clinics, but the clinical presentation may be heterogeneous. Further studies are needed to understand long-term outcomes and reduce the disease burden.

Cough hypersensitivity and chronic cough

Chronic cough is globally prevalent across all age groups. This disorder is challenging to treat because many pulmonary and extrapulmonary conditions can present with chronic cough, and cough can also be present without any identifiable underlying cause or be refractory to therapies that improve associated conditions. Most patients with chronic cough have cough hypersensitivity, which is characterized by increased neural responsivity to a range of stimuli that affect the airways and lungs, and other tissues innervated by common nerve supplies. Cough hypersensitivity presents as excessive coughing often in response to relatively innocuous stimuli, causing significant psychophysical morbidity and affecting patients' quality of life. Understanding of the mechanisms that contribute to cough hypersensitivity and excessive coughing in different patient populations and across the lifespan is advancing and has contributed to the development of new therapies for chronic cough in adults. Owing to differences in the pathology, the organs involved and individual patient factors, treatment of chronic cough is progressing towards a personalized approach, and, in the future, novel ways to endotype patients with cough may prove valuable in management.

Evaluation of Cough Medication Use Patterns in Ambulatory Care Settings in the United States: 2003-2018

Using 2003−2018 National Ambulatory Medical Care Survey data for office-based visits and 2003−2018 National Hospital Ambulatory Medical Care Survey data for emergency department (ED) visits, we conducted cross-sectional analyses to examine cough medication (CM) use trends in the United States (US) ambulatory care settings. We included adult (≥18 years) patient visits with respiratory-infection-related or non-infection-related cough as reason-for-visit or diagnosis without malignant cancer or benign respiratory tumor diagnoses. Using multivariable logistic regressions, we examined opioid antitussive, benzonatate, dextromethorphan-containing antitussive, and gabapentinoid use trends. From 2003−2005 to 2015−2018, opioid antitussive use decreased in office-based visits (8.8% to 6.4%, Ptrend = 0.03) but remained stable in ED visits (6.3% to 5.9%, Ptrend = 0.99). In both settings, hydrocodone-containing antitussive use declined over 50%. Benzonatate use more than tripled (office-based:1.6% to 4.8%; ED:1.5% to 8.0%; both Ptrend < 0.001). Dextromethorphan-containing antitussive use increased in ED visits (1.8% to 2.6%, Ptrend = 0.003) but stayed unchanged in office-based visits (3.8% to 2.7%; Ptrend = 0.60). Gabapentinoid use doubled in office-based visits (1.1% in 2006−2008 to 2.4% in 2015−2018, Ptrend < 0.001) but was negligible in ED visits. In US office-based and ED ambulatory care settings, hydrocodone-containing antitussive use substantially declined from 2003 to 2018, while benzonatate use more than tripled, and dextromethorphan-containing antitussive and gabapentinoid use remained low (<3%).

A phase 3, randomized, double-blind, clinical study to evaluate the long-term safety and efficacy of gefapixant in Japanese adult participants with refractory or unexplained chronic cough

BACKGROUND

In two phase 3, global clinical trials (COUGH-1 and COUGH-2), the P2X3-receptor antagonist gefapixant significantly reduced objective 24-h cough frequency in participants with refractory or unexplained chronic cough (RCC or UCC) at a dosage of 45 mg twice daily (BID), with an acceptable safety profile. The primary objective of this phase 3, randomized, double-blind, parallel-group study was to assess the safety and tolerability of gefapixant in Japanese participants with RCC or UCC (ClinicalTrials.gov, NCT03696108; JAPIC-CTI, 184154).

METHODS

Participants aged ≥20 years with chronic cough lasting ≥4 months and a diagnosis of RCC or UCC despite treatment in accordance with Japanese Respiratory Society guidelines were randomized 1:1 to receive gefapixant 15 or 45 mg BID for 52 weeks. The primary objective was to evaluate the safety and tolerability of gefapixant, including adverse events (AEs) and discontinuations due to AEs. Cough-specific quality of life was assessed using the Leicester Cough Questionnaire as a secondary objective.

RESULTS

Of 169 randomized and treated participants, 63% were female and mean age was 58 years. Adverse events were reported by 79 (94%) and 82 (96%) participants in the 15- and 45-mg BID groups, respectively. Most treatment-related AEs were taste related. Discontinuations due to AEs occurred in 6 (7%) and 17 (20%) participants receiving gefapixant 15 or 45 mg BID, respectively. There were no serious treatment-related AEs or deaths. Leicester Cough Questionnaire total scores improved from baseline through Week 52.

CONCLUSIONS

Gefapixant had an acceptable safety profile, with no serious treatment-related AEs in Japanese participants.

A Randomized, Placebo-Controlled Study to Investigate the Safety, Tolerability, and Pharmacokinetics of 3 Weeks of Orally Administered Gefapixant in Healthy Younger and Older Adults

PURPOSE

Patients with chronic cough are typically female and have a mean age of ~ 60 years. However, initial pharmacokinetic (PK) characterization of the P2X3-receptor antagonist gefapixant, developed to treat refractory or unexplained chronic cough, was performed in healthy participants who were predominantly younger adult males. The objective of this Phase 1 study was to assess the safety, tolerability, and PK of gefapixant in younger (18-55 years) and older (65-80 years) males and females.

METHODS

A randomized, double-blind, placebo-controlled study was conducted. Healthy adult participants were stratified into 4 cohorts by age and sex (younger males/females and older males/females) and randomized 4:1 (younger adults) or 3:1 (older adults) to receive gefapixant 300 mg twice daily (BID) for 1 week, followed by gefapixant 600 mg BID for 2 weeks or placebo. Safety, tolerability, and PK were assessed.

RESULTS

Of 36 randomized and treated participants, 28 (100%) receiving gefapixant and 6 (75%) receiving placebo reported ≥ 1 adverse event (AE). The most common treatment-related AEs in the gefapixant group were taste related. Predefined renal/urologic AEs were reported by 7 (25%) participants receiving gefapixant (all mild to moderate in severity). Gefapixant exposure was generally lower in younger males compared with younger females and older adults; however, differences may have been due to estimated glomerular filtration rate.

CONCLUSION

The safety profile of gefapixant 300-600 mg BID was generally consistent with previous studies. Additional characterization of gefapixant PK as a function of age and sex using population PK modeling is warranted.

Chronic cough in adults: recommendations from an Italian intersociety consensus

BACKGROUND

Chronic cough (CC) is a burdensome health problem in adult and older people, with a major impact on quality of life. Its management is often troublesome, and many guidelines have been released. Notwithstanding, a proportion of cases still do not reach a definite diagnosis and resolutive treatment. A coordinated approach between different specialists would be highly recommended, but its implementation in clinical practice suffers from the lack of shared protocols and poor awareness of the problem. The present consensus document has been implemented to address these issues.

AIMS

To develop evidence-based recommendations for the management of adults with CC.

METHODS

A 12-member expert task force of general practitioners, geriatricians, pneumologists, allergologists, otorhynolaringologists and gastroenterologists was established to develop evidence-based recommendations for the diagnostic and therapeutic approach to subjects with CC. A modified Delphi approach was used to achieve consensus, and the US Preventive Services Task Force system was used to rate the strength of recommendations and the quality of evidence.

RESULTS

A total of 56 recommendations were proposed, covering 28 topics and concerning definitions and epidemiology, pathogenesis and etiology, diagnostic and therapeutic approach along with the consideration of specific care settings.

CONCLUSION

These recommendations should ease the management of subjects with CC by coordinating the expertise of different specialists. By providing a convenient list of topics of interest, they might assist in identifying unmet needs and research priorities.

Risk Factors for Persistent Chronic Cough During Consecutive Years: A Retrospective Database Analysis

BACKGROUND

The identification of patients at high risk for diseases provides clinicians essential information to better manage such patients. Persistent chronic cough (PCC) is a condition with high clinical burden and limited knowledge of the risk factors that drive the persistent symptoms.

OBJECTIVE

To understand the risk factors of PCC in patients with CC diagnosed by specialists.

METHODS

In this retrospective study, adults aged 18 to 85 years diagnosed with CC by a pulmonologist, allergist, otolaryngologist, or gastroenterologist in the period 2011 to 2016 were identified. PCC was defined by another CC code or at least 2 cough events at least 8 weeks but no more than 4 months apart in each of the 2 consecutive years beginning 1 year after the original CC diagnosis. Unadjusted and adjusted risk ratios with 95% CI for patient characteristics at baseline in relationship to PCC were estimated by Poisson regression models with robust error variance.

RESULTS

Of the adults with CC, 3270 (27.4%) had PCC and 5302 (44.5%) did not have CC during follow-up; 3341 (28.1%) had CC in only 1 follow-up year and were excluded from the analysis. Compared with patients without PCC, patients with PCC were noted to have significantly increased adjusted risk ratios for the following baseline features: (1) demographic characteristics (elderly, females, and less educated); (2) comorbidities (chronic obstructive pulmonary disease, chronic sinusitis, bronchiectasis, pulmonary fibrosis, hypertension, depression, and cough complications); (3) medication dispensed (inhaled corticosteroids/long-acting beta-agonists, leukotriene modifiers, nasal corticosteroids, nasal short-acting muscarinic antagonists, proton pump inhibitors, antitussives with narcotics, and neuromodulators); and (4) specialist care, particularly with pulmonologists.

CONCLUSIONS

Knowledge of the independent risk factors associated with PCC should aid clinicians in identifying such patients and improve their management.

Symptoms of the Eruption of Permanent Teeth

This prospective study examined a population of 520 urban and rural children aged 5 to 9 years. Every 2−4 weeks, the clinical symptoms accompanying primary tooth replacement such as a cough, a runny nose, pain, and body temperature were assessed in each child’s medical records. The authors were able to show in a statistically significant manner that the frequency, time, and type of cough were strongly related to the type of erupting teeth (p < 0.001 for each relationship). A cough dependent on the type of erupting teeth was observed in 86% to 92% of the examined children, with a morning bronchial cough being connected with an eruption of the lower teeth, and an eruption of the upper teeth producing an all-day pharyngeal cough caused by mucus secretions dripping down the back of the throat. A statistically significant relationship was also confirmed between the type of erupting teeth and the incidence of a runny nose (p < 0.001), the frequency of a runny nose (p < 0.001), and the time when runny nose symptoms occurred (p < 0.001). This study shows that the period when primary dentition is replaced with permanent teeth in children is characterized by a physiological cough and a runny nose.

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.

Prevalence of chronic cough in China: a systematic review and meta-analysis

Background

Individual studies have indicated variable prevalence for chronic cough, but thus far, there has been no systematic report on the prevalence of this condition.

Methods

In this study, we performed a systematic review and meta-analysis by searching databases including PubMed, Cochrane Library, Web of Science, China National Knowledge Infrastructure, Chinese biomedical literature service system, Wanfang Database, and VIP database, for studies on chronic cough in China published before December 28, 2020. A random effects model was used to calculate pooled prevalence estimates with 95% confidence interval [95%CI], weighted by study size.

Results

Fifteen studies with 141,114 community-based adults were included in the study, showing a prevalence of 6.22% (95% CI 5.03–7.41%). And 21 studies with 164,280 community-based children were included, presenting a prevalence of 7.67% (95% CI 6.24–9.11%). In subgroup meta-analyses, the prevalence in adults was 4.38% (95% CI 2.74–6.02%) in southern China and 8.70% (95% CI 6.52–10.88%) in northern China. In the children population, the prevalence in northern China was also higher than in southern China (northern vs. southern: 7.45% with a 95% CI of 5.50–9.41%, vs. 7.86% with a 95% CI of 5.56–10.16%).

Conclusions

Our population-based study provides relatively reliable data on the prevalence of chronic cough in China and may help the development of global strategies for chronic cough management.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12890-022-01847-w.

Chronic cough in Germany: results from a general-population survey

Background

Chronic cough (CC) which is defined ≥8 weeks is a common condition in clinical practice. However, estimates of prevalence and associated comorbidities in German adults and key subgroups of age and gender are lacking.

Methods

Cross-sectional study based on a representative panel of 15 020 adult subjects of the general population who completed the German National Health and Wellness Survey, reporting CC and questions about comorbidities. Lifetime and 12-month prevalence are presented as unweighted estimates.

Results

The lifetime CC prevalence was 6.5% (range across age groups 5.1%-8.3%) and the 12-month prevalence was 4.9% (range 3.7-5.7%). The prevalence of diagnosed CC was 2.8% (range 0.9-4.1%) and the prevalence of persons currently on any prescription to treat CC was 0.6% (range 0.2-1.4%). Respondents who experienced CC were 52.0±17.0 years old, with a higher prevalence in those aged 50 years and older. Persons with CC had higher morbidity scores and were diagnosed with an increased number of comorbidities, most frequently diagnoses of the respiratory system (71.0%), followed by digestive tract disorders (34.0%) and sleep disorders (37.6%).

Conclusions

In a broadly representative sample of German adults, lifetime and 12-month prevalence of CC was greatest in current and former smokers and those older ≥50 years of age. Comorbidities are frequent and may complicate management of these patients.

Supraglottic Botulinum Toxin Improves Symptoms in Patients with Laryngeal Sensory Dysfunction Manifesting as Abnormal Throat Sensation and/or Chronic Refractory Cough

Laryngeal sensory dysfunction (LSD) encompasses disorders of the vagal sensory pathways. Common manifestations include chronic refractory cough (CRC) and abnormal throat sensation (ATS). This study examined clinical characteristics and treatment outcomes of LSD using a novel approach of laryngeal supraglottic Onabotulinum toxin Type A injection (BTX). This was a retrospective review of clinical data and treatment outcomes of supraglottic BTX in patients with LSD. Between November 2019 and May 2021, 14 patients underwent 25 injection cycles of supraglottic BTX for treatment of symptoms related to LSD, including ATS and CRC. Primary outcome measures included the Newcastle Laryngeal Hypersensitivity Questionnaire (LHQ), Cough Severity Index (CSI), Reflux Symptom Index (RSI), and Voice Handicap Index-10 (VHI-10) at baseline and within three months of treatment. Pre- and post-treatment data were compared using a linear mixed model. After supraglottic BTX, LHQ scores improved by 2.6. RSI and CSI improved by 8.0 and 5.0, respectively. VHI-10 did not change as a result of treatment. Short-term response to SLN block was significantly associated with longer term response to BTX treatment. These findings suggest that LSD presents clinically as ATS and CRC along with other upper airway symptoms. Supraglottic BTX injection is a safe and effective technique in the treatment of symptoms of LSD.

Utility of Cough Provocation Tests in Chronic Cough and Respiratory Diseases: A Comprehensive Review and Introduction of New Reference Ranges for the Capsaicin Test

Cough provocation tests (CPTs) are an objective measurement of the sensitivity of the cough reflex arc. However, they are not established in clinical practice because a large variability of response in healthy subjects limits their diagnostic value. There is a paucity of studies that have investigated CPT reference ranges in healthy subjects. This systematic review describes the variability of the responses to CPTs in healthy subjects and factors that influence it. A new analysis of 134 healthy subjects was conducted to create reference ranges for single-breath capsaicin CPT by calculating the interquartile ranges for the provocative concentration of capsaicin to induce 2 and 5 coughs. Female subjects had a more sensitive cough reflex than male counterparts. The ability of CPTs to distinguish various respiratory diseases from healthy subjects was also reviewed. Cough sensitivity was consistently heightened in the following groups: unselected patients with chronic, refractory, or recurrent cough, unexplained chronic cough, gastro-esophageal reflux-associated cough, cough-variant asthma, lower airway symptoms induced by chemical irritants, and fibrotic interstitial lung diseases. In the following groups, hypersensitivity of the cough reflex was present in those individuals whose symptom profile was predominated by cough: asthma, chronic obstructive pulmonary disease (COPD), bronchiectasis, and sarcoidosis. In the following conditions, patients usually cough in order to expectorate mucus from their airways, not because of a hypersensitive cough reflex arc: productive cough, asthma, upper airway cough syndrome, COPD, bronchiectasis, cystic fibrosis, and chronic respiratory infections. CPTs have the potential to identify patients with chronic respiratory symptoms due to cough reflex hypersensitivity, thereby providing a targeted approach for therapy.

ACR Appropriateness Criteria® Chronic Cough

Chronic cough is defined by a duration lasting at least 8 weeks. The most common causes of chronic cough include smoking-related lung disease, upper airway cough syndrome, asthma, gastroesophageal reflux disease, and nonasthmatic eosinophilic bronchitis. The etiology of chronic cough in some patients may be difficult to localize to an isolated source and is often multifactorial. The complex pathophysiology, clinical presentation, and variable manifestations of chronic cough underscore the challenges faced by clinicians in the evaluation and management of these patients. Imaging plays a role in the initial evaluation, although there is a lack of high-quality evidence guiding which modalities are useful and at what point in time the clinical evaluation should be performed. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Validation of a visual analog scale for assessing cough severity in patients with chronic cough

Introduction:

Patients with chronic cough experience considerable burden. The cough severity visual analog scale (VAS) records patients’ assessment of cough severity on a 100-mm linear scale ranging from “no cough” (0 mm) to “worst cough” (100 mm). Although cough severity scales are widely used in clinical practice and research, their use in patients with refractory or unexplained chronic cough has not been formally validated.

Methods:

This analysis includes data from a phase 2b randomized controlled trial of the P2X3-receptor antagonist gefapixant for treatment of refractory or unexplained chronic cough (NCT02612610). Cough severity VAS scores were assessed at baseline and Weeks 4, 8, and 12. The cough severity VAS was validated using several outcomes, including the Cough Severity Diary (CSD), Leicester Cough Questionnaire (LCQ), patient global impression of change (PGIC) scale, and objective cough frequency. Validation metrics included test–retest reliability, convergent and known-groups validity, responsiveness, and score interpretation (i.e., clinically meaningful change threshold).

Results:

The analysis included 253 patients (median age, 61.0 years; females, 76%). Test–retest reliability of the cough severity VAS was moderate (intraclass correlation coefficient, 0.51). The cough severity VAS had acceptable convergent validity with other related measures (Pearson r of 0.53 and -0.41 for CSD and LCQ total scores, respectively; p < 0.0001 for each). Known-groups validity was supported by significant differences in mean cough severity VAS scores across severity groups defined using CSD, LCQ, and cough frequency tertiles. A large effect size was observed in patients with the greatest improvements in PGIC (Cohen d = -1.8). A ⩾ 30-mm reduction in the cough severity VAS was estimated as a clinically meaningful change threshold for clinical trials in chronic cough.

Conclusions:

The cough severity VAS is a valid and responsive measure. A cough severity VAS reduction of ⩾ 30 mm can discriminate clinically meaningful changes in chronic cough severity in clinical studies.

Epidemiology of adult chronic cough: disease burden, regional issues, and recent findings

Chronic cough is a common medical condition that has a significant impact on patients' quality of life. Although it was previously considered a symptom of other disorders, it is now regarded as a pathologic state that is characterized by a deviation from the intrinsic protective functions of the cough reflex, especially in adults. There are several factors that may underlie the cough reflex hypersensitivity and its persistence, such as age, sex, comorbidities, viral infection, exposure to irritants or environmental pollutants, and their interactions may determine the epidemiology of chronic cough in different countries. With a deeper understanding of disease pathophysiology and advanced research methodology, there are more attempts to investigate cough epidemiology using a large cohort of healthcare population data. This is a narrative overview of recent findings on the disease burden, risk factors, Asia-Pacific issues, and longitudinal outcomes in adults with chronic cough. This paper also discusses the approaches utilizing routinely collected data in cough research.

Prevalence and Burden of Chronic Cough in the United States

BACKGROUND

Chronic cough is a common complaint but there are little population-based data on its burden in the United States.

OBJECTIVE

To determine the prevalence of chronic cough and its burden on individuals and the health care system.

METHODS

This was a survey of respondents who completed the 2018 National Health and Wellness Survey and questions about sleep and health care resource use. Chronic cough was defined as having a daily cough for 8 or more weeks. Respondents without chronic cough were selected through propensity score matching. Chronic cough prevalence was estimated using poststratification sampling weights calculated using U.S. Census data and post-data Horvitz-Thompson sampling weights to adjust for sampling bias.

RESULTS

Of 74,977 National Health and Wellness Survey respondents, 3,654 had experienced chronic cough in the previous 12 months, for a weighted prevalence of 5.0%. Respondents with chronic cough were older and more predominantly female than respondents without chronic cough (both P < .001). Compared with matched respondents without chronic cough, those with chronic cough had lower mean scores on the Medical Outcomes Study 36-item Short Form Survey v2 physical (P < .001) and mental (P < .001) component summary scores. More respondents with chronic cough than matched controls experienced severe anxiety and severe depression in the past 2 weeks, work productivity impairment, impaired sleep quality and daytime sleepiness, as well as more emergency department visits and hospitalizations in the past 6 months (P < .001 for all comparisons).

CONCLUSIONS

The burden of chronic cough manifests itself as reduced health-related quality of life, increased anxiety and depression, impaired sleep and work productivity, and greater health care utilization.

[Perceptions of family doctors, pulmonologists and allergists on the approach to patients with chronic cough. Results of an anonymous survey]

OBJECTIVE

To understand the perception of family doctors, pulmonologists and allergists about the current approach to chronic cough and its impact on patients' quality of life.

MATERIAL AND METHODS

Cross-sectional and anonymous survey disseminated through the scientific societies SEAIC, SEMERGEN, semFYC, SEMG and SEPAR. The participants were 620 family doctors, 92 pulmonologists and 62 allergists. A descriptive analysis of the answers was conducted. Response percentages, medians and interquartile intervals were presented. The differences in the percentages between specialties were evaluated with the chi-square.

RESULTS

Only half of the respondents chose a duration greater than 8 weeks as a criterion for diagnosing chronic cough, and less than half considered refractory/unexplained chronic cough a disease in itself. Family doctors perceived that chronic cough had less impact on patients than did pulmonologists or allergists. After a diagnosis of refractory/unexplained chronic cough, all 3specialties considered the most common approach to be to initiate treatment and to do the follow-up of the patient themselves. Most stated that they had no protocols for managing chronic cough, and more than 90% considered these to be necessary.

CONCLUSIONS

The management of patients with chronic cough by family doctors, pulmonologists or allergists seems to be heterogeneous. There is a need for protocols that standardise diagnosis, referral and treatment criteria to optimise patients' management and reduce the impact of chronic cough.

Addressing unmet needs for diagnosis and management of chronic cough in the primary care setting

Chronic cough (i.e. cough lasting >8 weeks) has a global prevalence of approximately 10% and is associated with substantial patient burden, including social, psychological, and physical impairments. This burden can be long-lasting, with some patients experiencing cough for many years. Although chronic cough is often a symptom of respiratory diseases (e.g. interstitial lung disease, chronic obstructive pulmonary disease) or is associated with comorbid conditions (e.g. asthma, gastroesophageal reflux disease) and may resolve after targeted treatment of these conditions, some patients continue to cough despite optimal treatment of associated conditions (refractory chronic cough (RCC)) or have no identifiable conditions presumed to be contributing to the cough (unexplained chronic cough (UCC)). As both RCC and UCC are diagnoses of exclusion, it is critical to perform a thorough initial patient assessment with adherence to diagnostic guidelines to accurately identify RCC and UCC and provide appropriate treatment. Primary care physicians may be in an important position to provide the initial diagnostic workup of patients with chronic cough as well as identify when referral to specialists (e.g. pulmonologists, allergists, otolaryngologists) is appropriate. In this narrative review, current diagnosis and management guidelines for chronic cough are summarized and recommendations for diagnostic workup in a primary care setting are provided. Increased appreciation of chronic cough as a distinct condition, rather than as only a symptom of other diseases, may help overcome current challenges in diagnosing and managing chronic cough and reduce patient burden.

Characterization of Patients With Refractory or Unexplained Chronic Cough Participating in a Phase 2 Clinical Trial of the P2X3-Receptor Antagonist Gefapixant

Purpose

This analysis assesses clinical characteristics of patients with refractory chronic cough (RCC) or unexplained chronic cough (UCC) enrolled in a phase 2 study to better understand this patient population.

Methods

Patients with RCC/UCC lasting for ≥ 1 year and cough severity visual analog scale (VAS) score of > 40 mm at screening were eligible. Demographics, clinical characteristics, and medical history were collected at baseline. Cough-related measures included cough severity VAS, Cough Severity Diary (CSD), Leicester Cough Questionnaire (LCQ), and a structured cough-trigger questionnaire. Medication history included all medications 30 days before screening and chronic cough treatments within 1 year before screening. Data were summarized using descriptive statistics.

Results

Patients (N = 253; female, 76%; mean age, 60 years) had severe (mean cough severity VAS, 57.5 mm) and long-lasting (median duration, 11 years) cough. The most burdensome self-reported aspects included psychological and social factors (LCQ) and cough frequency and intensity (CSD). Patient-reported triggers were consistent with cough hypersensitivity (e.g., 95% to 96% reported irritation or tickle in throat). Common reported comorbidities included gastroesophageal reflux disease (GERD; 56%), allergic rhinitis (47%), and asthma (30%); 12% of patients had been diagnosed with all 3 conditions. The most common prior medications included inhaled or oral steroids (21%), antihistamines (15%), and antacids (15%).

Conclusion

Patients with RCC/UCC had severe, long-lasting, and burdensome cough with clinical features of cough hypersensitivity. Many patients had been diagnosed with GERD, allergic rhinitis, and asthma but had a persistent cough despite treatment of these conditions.

Trial registration: ClinicalTrials.gov, NCT02612610; registered November 20, 2015

Global Physiology and Pathophysiology of Cough: Part 1: Cough Phenomenology - CHEST Guideline and Expert Panel Report

The purpose of this state-of-the-art review is to update the American College of Chest Physicians 2006 guideline on global physiology and pathophysiology of cough. A review of the literature was conducted using PubMed and MEDLINE databases from 1951 to 2019 and using prespecified search terms. We describe the basic phenomenology of cough patterns, behaviors, and morphological features. We update the understanding of mechanical and physiological characteristics of cough, adding a contemporary view of the types of cough and their associated behaviors and sensations. New information about acoustic characteristics is presented, and recent insights into cough triggers and the patient cough hypersensitivity phenotype are explored. Lastly, because the clinical assessment of patients largely focuses on the duration rather than morphological features of cough, we review the morphological features of cough that can be measured in the clinic. This is the first of a two-part update to the American College of Chest Physicians 2006 cough guideline; it provides a more global consideration of cough phenomenology, beyond simply the mechanical aspects of a cough. A greater understanding of the typical features of cough, and their variations, may allow a more informed interpretation of cough measurements and the clinical relevance for patients.