Sex differences and predictors of objective cough frequency in chronic cough

Chronic Cough: Characterizing and Quantifying Burden in Adults Using a Nationwide Electronic Health Records Database

Chronic cough is a common condition; until recently, no International Classification of Diseases (ICD) code for chronic cough existed; therefore, the true scope and burden of chronic cough is unclear. Using established algorithms, we examined chronic cough patients and their risk profiles, recurrent cough episodes, and subsequent 1-year health care utilization in the nationwide Cerner EHR data resource, compared with those with acute cough. An ICD-based algorithm was applied to the Cerner Health Facts EHR database to derive a phenotype of chronic cough defined as three ICD-based "cough" encounters 14-days apart over a 56-to-120-day period from 2015 to 2017. Demographics, comorbidities, and outcomes (1-year outpatient, emergency, and inpatient encounters) were collected for the chronic cough cohort and acute cough cohort. The chronic cough cohort was 61.5% female, 70.4% white, and 15.2% African American, with 13.7% being of Asian, Native American, or unknown race. Compared with the acute cough cohort, chronic cough patients were more likely to be older, female, and have chronic pulmonary disease, obesity, and depression. Predictors of recurrent chronic cough were older age and race. Those with chronic cough had more outpatient (2.48 ± 2.10 vs. 1.48 ± 0.99; SMD = 0.94), emergency (1.90 ± 2.26 vs. 1.23 ± 0.68; SMD = 0.82), and inpatient (1.11 ± 0.36 vs. 1.05 ± 0.24, SMD = 0.24) encounters compared with acute cough. While EHR-based data may provide a useful resource to identify chronic cough phenotypes, supplementary data approaches and screening methods for chronic cough can further identify the scope of the problem.

Sex-related disparities in cough-associated symptoms across different age groups

BACKGROUND

Sex-related disparities in the prevalence of chronic cough have been consistently reported globally, with varying male-to-female ratios.

OBJECTIVES

This study aimed to evaluate sex-related differences by comparing correlations between cough-related symptoms in males and females of different age groups.

DESIGN

Adult patients with chronic cough who completed the Leicester Cough Questionnaire (LCQ) were recruited from 16 respiratory centers.

METHODS

Correlation networks were constructed based on Spearman's correlation coefficients in males and females of various age groups. The distinct relationships of cough-related symptoms between subgroups were validated by an independent cohort.

RESULTS

A total of 255 patients were enrolled in this study (male-to-female ratio, 1:1.71). The following LCQ items were highly correlated: embarrassment and interference with daily work, anxiety, and interference with overall life enjoyment/feeling of being fed up, interference with daily work and overall life enjoyment, interference with overall life enjoyment and feeling of being fed up, and feeling of being fed up and annoyance to partner/family/friends. The patterns of these correlations between LCQ items varied in males and females of different ages. The strongest interrelationship was observed in male patients aged >50 years old, which was similar to those in the validation cohort.

CONCLUSION

The correlation patterns between cough-related symptoms vary significantly according to age and sex. Understanding the mechanisms underlying the development of cough-related symptoms may facilitate sex- and age-specific strategies for chronic cough.

Chronic cough: more than just a persistent cough: a systematic literature review to understand the impact of chronic cough on quality of life

PURPOSE

Chronic cough (CC), defined as a cough persisting ≥ 8 weeks, can have a substantial negative impact on health-related quality of life (HRQoL). This is exacerbated by challenges with timely diagnosis and a lack of approved therapies. A systematic literature review (SLR) was conducted to identify evidence on HRQoL and health state utility values associated with refractory CC or unexplained CC.

METHODS

Electronic database searches were supplemented with searches of conference proceedings and health technology assessment body websites. Two independent reviewers assessed all citations for inclusion based on predefined inclusion/exclusion criteria. Key inclusion criteria were patient populations with CC and reporting of patient-reported outcomes or utilities using generic or disease-specific measures.

RESULTS

Following screening, 65 studies were identified for inclusion in the SLR. Of these, 23 studies assessed HRQoL among patients with CC who were not treated or treated with unspecified interventions, and 42 studies in patients who were treated with specified interventions. The studies indicated a substantial decrement to HRQoL as a result of CC, characterized by generic and disease-specific patient-reported outcome measures. HRQoL was impacted across multiple domains, including physical, psychological, and social functioning. The studies also demonstrated the potential for treatments to have a significant positive impact on HRQoL.

CONCLUSIONS

CC can substantially affect HRQoL in patients, across physical, psychological, and social domains. Although treatments can improve HRQoL in these patients, the available evidence is limited. There remains an unmet need for approved pharmacological treatments to alleviate CC and improve HRQoL for these patients.

How often do healthy people cough?

Objective cough frequency has been reported in several respiratory conditions but the amount that healthy individuals cough daily is unclear. Seventy-nine healthy volunteers (38 males, median [IQR] age 41y [IQR 30-53]) completed 24-hour ambulatory cough monitoring (VitaloJAK™). The audio recording was filtered using a custom written algorithm to remove non-cough sounds and then all individual explosive cough sounds in the filtered file were tagged electronically by trained cough counters. Most coughing occurred during the day and cough numbers over 24 h were generally low (geometric mean of 4.6 coughs) but there was large variability; ranging from 0 to 136 coughs overall. Cough frequency was independent of participant characteristics apart from sex with males coughing significantly, 4-5 fold, more than females during the day and over 24 h (median [IQR] 16.1 [3.8-33.4] vs. 4.1 [1.0-15.0] total coughs; p = 0.015). This is the first report to describe cough frequency in a balanced group of healthy adults using an accurate cough monitoring system. The data reveal a further example of sexual dimorphism in cough, which warrants additional investigation.

Risk factors for cough after pulmonary resection

BACKGROUND

To investigate the risk factors for cough after pulmonary resection.

METHODS

The PubMed, Embase, Web of Science, ClinicalTrials.gov, and China National Knowledge Network databases were searched from inception to November 2022. The Q tests and I2 statistic were used to evaluate the heterogeneity. Odds ratios (OR) were combined using the inverse variance method. All statistical analyses were performed by RevMan 5.4.1.

RESULTS

Nineteen studies with 4755 patients were included, the incidence of postoperative cough was 21.1%-55.8%. The results showed that young age [OR = 0.66, 95% CI (0.46, 0.96), p = 0.03], female sex [OR = 1.69, 95% CI (1.07, 2.66), p = 0.02], preoperative cough [OR = 5.96, 95% CI (2.58, 13.73), p < 0.01], right lobe operation [OR = 2.14, 95% CI (1.44, 3.19), p < 0.01], lobectomy [OR = 3.70, 95% CI (1.73, 7.90), p < 0.01], subcarinal lymph node dissection [OR = 3.45, 95% CI (1.86, 6.39), p < 0.01], mediastinal lymph node removal [OR = 3.49, 95% CI (2.07, 5.89), p < 0.01], closure of bronchial stump with stapler [OR = 5.19, 95% CI (1.79, 15.07), p < 0.01], peritracheal lymph node resection [OR = 3.05, 95%CI (1.40,6.64), p < 0.01], postoperative acid reflux [OR = 11.07, 95%CI (4.38,28.02), p < 0.01] were independent risk factors for cough after pulmonary resection.

CONCLUSIONS

Young age, female sex, preoperative cough, right lobe operation, lobectomy, subcarinal lymph node dissection, mediastinal lymph node removal, closure of bronchial stump with stapler, peritracheal lymph node resection, and postoperative acid reflux are independent risk factors for cough after pulmonary resection.

Burden of chronic cough on social participation, healthcare resource utilisation and activities of daily living in the Canadian Longitudinal Study on Aging (CLSA)

BACKGROUND

Chronic cough is a common troublesome condition, but it is unclear whether dry or productive chronic cough and sex, impacts the burden of cough differently.

METHODS

The Canadian Longitudinal Study on Aging is a nationally generalizable, stratified random sample of adults aged 45-85 years. Chronic cough was identified based on a self-reported daily cough in the last 12 months assessed at baseline (2011-2015) and follow-up (2015-2018). Odds ratios (95 % CI) for cough status and change in social participation activities (SPA), healthcare resource utilisation (HCRU), basic activities of daily living (ADLs) and instrumental activities of daily living (IADLs) were estimated using a weighted generalised estimating equation (WGEE). Results were stratified by sex, and adjusted for age, sex, smoking, body mass index, education, respiratory diseases and retirement status.

RESULTS

Overall, chronic cough was associated with less SPA, greater HCRU and impaired ADL/IADLs. Productive chronic cough in males was associated with SPA limited by health, ED visits and hospitalisation. Females with productive chronic cough was associated with reduced frequency of SPA and ED visit. Dry chronic cough in females was associated with SPA limited by health and ED visits. Both types of cough was associated with at least 1 impaired basic ADL, but only in females with productive chronic cough was there an association with any impairment in IADLs.

CONCLUSION

Chronic cough is associated with a greater burden on social participation, healthcare use and personal care.

Performance evaluation of human cough annotators: optimal metrics and sex differences

INTRODUCTION

Despite its high prevalence and significance, there is still no widely available method to quantify cough. In order to demonstrate agreement with the current gold standard of human annotation, emerging automated techniques require a robust, reproducible approach to annotation. We describe the extent to which a human annotator of cough sounds (a) agrees with herself (intralabeller or intrarater agreement) and (b) agrees with other independent labellers (interlabeller or inter-rater agreement); we go on to describe significant sex differences in cough sound length and epochs size.

MATERIALS AND METHODS

24 participants wore an audiorecording smartwatch to capture 6-24 hours of continuous audio. A randomly selected sample of the whole audio was labelled twice by an expert annotator and a third time by six trained annotators. We collected 400 hours of audio and analysed 40 hours. The cough counts as well as cough seconds (any 1 s of time containing at least one cough) from different annotators were compared and summary statistics from linear and Bland-Altman analyses were used to quantify intraobserver and interobserver agreement.

RESULTS

There was excellent intralabeller (less than two disagreements per hour monitored, Pearson's correlation 0.98) and interlabeller agreement (Pearson's correlation 0.96), using cough seconds as the unit of analysis decreased annotator discrepancies by 50% in comparison to coughs. Within this data set, it was observed that the length of cough sounds and epoch size (number of coughs per bout or attach) differed between women and men.

CONCLUSION

Given the decreased interobserver variability in annotation when using cough seconds (vs just coughs) we propose their use for manually annotating cough when assessing of the performance of automatic cough monitoring systems. The differences in cough sound length and epochs size may have important implications for equality in the development of cough monitoring tools.

TRIAL REGISTRATION NUMBER

NCT05042063.

Evaluation and management of chronic cough in adults

Background: Chronic cough (CC), a cough that lasts > 8 weeks, has an overall prevalence of 5-11% in adults, peaking between 60 and 80 years of age. Of the 15% of patients who remain undiagnosed or refractory to treatment, two thirds are women. Objective: The objective was to present an updated evidence-based algorithmic approach for evaluating and managing CC, with emphasis on treatment modalities for refractory CC. Methods: A literature search was conducted of medical literature data bases for guidelines, position papers, systematic reviews, and clinical trials from January 2022 to June 2023, on the evaluation and management of CC. Results: The initial assessment should be limited to a detailed history, physical examination, chest radiograph, spirometry, exhaled nitric oxide, blood eosinophil count, and measurement of cough severity and quality of life by using validated instruments. The top diagnoses to consider are asthma, chronic obstructive pulmonary disease, nonasthmatic eosinophilic bronchitis, gastroesophageal reflux disease, and upper airway cough syndrome. Additional studies are only obtained when red flags are present or the patient fails to respond after avoidance of high-risk factors, e.g., smoking and angiotensin-converting enzyme inhibitors, and 4-6 weeks of empiric treatment for the most likely respiratory and gastrointestinal diseases. When diagnostic tests and/or specific directed treatments fail to control CC, low-dose morphine (preferred), gabapentin, pregabalin, and/or cough control therapy are recommended. Non-narcotic purinergic 2×3 (P2×3) receptor antagonists, gafapixant and campilixant, are currently being studied for CC. Conclusion: For the evaluation and management of patients with CC, clinicians should use an algorithmic approach and identify "red flags," reduce high-risk factors, and use empiric treatment for the five top diagnoses before extensive diagnostic testing. Current treatment for refractory cough is limited to symptomatic management.

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 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.

Chronic cough in postmenopausal women and its associations to climacteric symptoms

BACKGROUND

Postmenopausal women often have chronic cough. Hormonal changes might be affecting lung function and the mucous membrane of the airways, causing hypersensitivity of the cough reflex. Therefore, postmenopausal hormonal changes could play a key role in the association between increased cough and menopause. The aim of this study is to evaluate the relation of chronic cough and postmenopausal symptoms.

METHODS

We performed a questionnaire-based cohort study in generally healthy postmenopausal women (age 45-65 years). Women with cough explained by a pre-existing diagnosis were excluded. Comorbidities, medication and baseline data were collected. The Menopause Rating Scale II (MRS II) was combined with the Leicester Cough Questionnaire. Groups were divided in chronic cough versus non-coughing participants, chronic cough was defined as symptoms over 8 weeks. We performed correlations and logistic regression for predicting cough based on postmenopausal symptoms.

RESULTS

Sixty-six of 200 women (33%) reported symptoms of chronic cough over 8 weeks. No significant differences in baseline data (age, BMI, onset of menopause, years since menopause, concomitant diseases, and medication) were found between coughing and non-coughing women. The MRS II showed higher menopausal symptoms in patients with cough, with significant differences in 2 of the 3 MRS-domains (urogenital (p < 0.001) and somato-vegetative (p < 0.001)). Climacteric symptoms correlated strongly with parameters of cough (p < 0.001). On the basis of the MRS total score (p < 0.001) and the somato-vegetative and urogenital domains (p < 0.05), the prediction for respiratory complaints could be shown.

DISCUSSION

Chronic cough was significantly associated with menopausal symptoms. Therefore chronic cough as a possible climacteric symptom and its underlying mechanisms should be further explored.

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.

Treatment with the P2X3-Receptor Antagonist Gefapixant for Acute Cough in Induced Viral Upper Respiratory Tract Infection: A Phase 2a, Randomized, Placebo-Controlled Trial

INTRODUCTION

Available therapies for acute cough, a condition frequently caused by a viral upper respiratory tract infection (URTI), have shown limited evidence of efficacy. Gefapixant, a P2X3-receptor antagonist, has demonstrated efficacy and safety in studies of the treatment of refractory or unexplained chronic cough, but its efficacy for treating acute cough has not been previously studied.

METHODS

This was a phase 2a, randomized, double-blind, placebo-controlled, parallel-group, pilot study. Healthy volunteers were randomized 1:1 to receive twice-daily gefapixant 45 mg or placebo and inoculated with human rhinovirus 16 to induce URTI and cough. Participants were observed while quarantined for 7 days after the start of treatment. The primary endpoint was awake cough frequency on day 3, which was objectively measured with a cough-recording device. Secondary endpoints included change from baseline to day 3 in subjective cough severity measures (cough severity visual analog scale, Cough Severity Diary) and cough-specific quality of life (Leicester Cough Questionnaire-acute).

RESULTS

Of the 46 participants who met inclusion criteria [mean (standard deviation, SD) age, 24.6 (6.5) years; females, n = 8], 40 completed the study (gefapixant, n = 21; placebo, n = 19). There was no significant difference in awake cough frequency on day 3 between the gefapixant and placebo groups [least squares means, 2.4 versus 2.7 coughs per hour, respectively; mean difference (95% confidence interval, CI), -0.3 (-2.3, 1.7); P = 0.75]. There were no significant between-group differences for any of the secondary endpoints. Peak cough frequency was low and occurred later in the study than expected (days 4-5). The safety profile was consistent with that of previous studies of gefapixant.

CONCLUSION

Compared with placebo, gefapixant did not reduce the frequency or severity of acute cough secondary to induced URTI. Induced viral URTI produced mild symptoms, including lower cough frequency than observed in previous studies of patients selected for acute cough associated with naturally occurring URTI.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT03569033; EudraCT, 2017-000472-28; protocol number, MK-7264-013.

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.

Cough detection using a non-contact microphone: A nocturnal cough study

An automatic non-contact cough detector designed especially for night audio recordings that can distinguish coughs from snores and other sounds is presented. Two different classifiers were implemented and tested: a Gaussian Mixture Model (GMM) and a Deep Neural Network (DNN). The detected coughs were analyzed and compared in different sleep stages and in terms of severity of Obstructive Sleep Apnea (OSA), along with age, Body Mass Index (BMI), and gender. The database was composed of nocturnal audio signals from 89 subjects recorded during a polysomnography study. The DNN-based system outperformed the GMM-based system, at 99.8% accuracy, with a sensitivity and specificity of 86.1% and 99.9%, respectively (Positive Predictive Value (PPV) of 78.4%). Cough events were significantly more frequent during wakefulness than in the sleep stages (p < 0.0001) and were significantly less frequent during deep sleep than in other sleep stages (p < 0.0001). A positive correlation was found between BMI and the number of nocturnal coughs (R = 0.232, p < 0.05), and between the number of nocturnal coughs and OSA severity in men (R = 0.278, p < 0.05). This non-contact cough detection system may thus be implemented to track the progression of respiratory illnesses and test reactions to different medications even at night when a contact sensor is uncomfortable or infeasible.

Burden and impact of chronic cough in UK primary care: a dataset analysis

OBJECTIVE

Chronic cough (CC) is a debilitating respiratory symptom, now increasingly recognised as a discrete disease entity. This study evaluated the burden of CC in a primary care setting.

DESIGN

Cross-sectional, retrospective cohort study.

SETTING

Discover dataset from North West London, which links coded data from primary and secondary care. The index date depicted CC persisting for ≥8 weeks and was taken as a surrogate for date of CC diagnosis.

PARTICIPANTS

Data were extracted for individuals aged ≥18 years with a cough persisting ≥8 weeks or cough remedy prescription, between Jan 2015 and Sep 2019.

MAIN OUTCOME MEASURES

Demographic characteristics, comorbidities and service utilisation cost, including investigations performed and treatments prescribed were determined.

RESULTS

CC was identified in 43 453 patients from a total cohort of 2 109 430 (2%). Median (IQR) age was 64 years (41-87). Among the cohort, 31% had no recorded comorbidities, 26% had been given a diagnosis of asthma, 17% chronic obstructive pulmonary disease, 12% rhinitis and 15% reflux. Prevalence of CC was greater in women (57%) and highest in the 65-74 year age range. There was an increase in the number of all investigations performed in the 12 months before and after the index date of CC diagnosis, and in particular for primary care chest X-ray and spirometry which increased from 6535 to 12 880 and from 5791 to 8720, respectively. This was accompanied by an increase in CC-associated healthcare utilisation costs.

CONCLUSION

One-third of individuals had CC in the absence of associated comorbidities, highlighting the importance of recognising CC as a condition in its own right. Overall outpatient costs increased in the year after the CC index date for all comorbidities, but varied significantly with age. Linked primary-care datasets may enable earlier detection of individuals with CC for specialist clinic referral and targeted treatment.

Assessing gender differences among presumed and diagnosed patients with pulmonary TB: observations from Guinea-Bissau

BACKGROUND

Globally, more males than females are diagnosed with pulmonary TB (PTB); however, the cause of this gender disparity remains unknown. We aimed to assess gender differences in an observational cohort of patients with presumed PTB (prePTB) at the Bandim Health Project, Guinea-Bissau.

METHODS

Adult patients with signs and symptoms suggestive of PTB seeking medical care were invited to participate and were referred to comprehensive diagnostic work-up.

RESULTS

We included 2020 patients with prePTB; 54.6% were female. Females were younger than males and more often infected with HIV. More male patients with prePTB were diagnosed with PTB and the proportion of smear-positive cases was greater among males. There was no gender difference in loss to follow-up during the diagnostic process. Of 219 patients with PTB, 205 started treatment, with no difference between genders regarding pretreatment loss to follow-up or treatment outcome.

CONCLUSIONS

More women sought help for symptoms indicative of PTB, yet more men were diagnosed. Women did not have more clinically severe disease at presentation, did not drop out of diagnostic procedures more frequently and did not experience a worse outcome than men. This suggests that the gender gap in PTB is unlikely to be due solely to differences in care-seeking behaviour or diagnostic procedures in our setting.

Evaluation of sex-based differences in airway size and the physiological implications

Recent evidence suggests healthy females have significantly smaller central conducting airways than males when matched for either height or lung volume during analysis. This anatomical sex-based difference could impact the integrative response to exercise. Our review critically evaluates the literature on direct and indirect techniques to measure central conducting airway size and their limitations. We present multiple sources highlighting the difference between male and female central conducting airway size in both pediatric and adult populations. Following the discussion of measurement techniques and results, we discuss the functional implications of these differences in central conducting airway size, including work of breathing, oxygen cost of breathing, and how these impacts will continue into elderly populations. We then discuss a range of topics for the future direction of airway differences and the benefits they could provide to both healthy and diseased populations. Specially, these sex-differences in central conducting airway size could result in different aerosol deposition or how lung disease manifests. Finally, we detail emerging techniques that uniquely allow for high-resolution imaging to be paired with detailed physiological measures.

How We Do It: Managing Cough in Idiopathic Pulmonary Fibrosis

In many studies, more than one-half of patients with idiopathic pulmonary fibrosis (IPF) endorse cough. In IPF (as in other conditions), when chronic, cough may be frustrating and lead to significant impairments in quality of life. In patients with IPF, comorbid conditions such as gastroesophageal reflux can cause or contribute to cough; when stemming from IPF itself, chronic cough likely arises from multiple mechanisms including mechanical and neurosensory changes. In this article, we review our approach at attempting to identify causes of chronic cough in patients with IPF; these include gastroesophageal reflux disease or upper airway cough syndrome and IPF itself. We cursorily summarize the current evidence for the treatment of chronic cough in IPF, briefly review data on the treatment of unexplained chronic cough and extrapolate it to the treatment of refractory cough in IPF, but we focus our attention on our approaches to evaluation and management, recognizing that some may not be supported by a robust cache of data.

Gender Difference in Chronic Cough: Are Women More Likely to Cough?

Chronic cough is a common complaint for patients to seek medical cares all over the world. Worldwide, about two thirds of chronic cough patients are females. However, in some regions of China the prevalence of chronic cough between sexes is roughly the same. Estrogen and progesterone can not only have an effect on transient receptor potential vanilloid 1 channel, eosinophils and mast cells, but also influence laryngeal dysfunction, gastroesophageal reflux disease and obstructive sleep apnea hypopnea syndrome, which may lead to increased cough sensitivity in women. On the other hand, the quality of life was adversely affected more in female patients with chronic cough. Both hormones possibly cause gender difference in chronic cough.

Gender difference in the association between cough severity and quality of life among patients with postinfectious cough

Background

Despite close link exists between cough severity and quality of life (QoL), whether gender difference is implied in the effect of cough on QoL has not been studied yet. This study primarily aims to investigate whether the association between cough severity and QoL is modified by gender in patients with postinfectious cough.

Methods

Secondary analyses were performed in 180 participants with postinfectious cough in a multisite randomized controlled trial. Baseline demographics, clinical characteristics and score of cough specific quality of life questionnaire (CQLQ) were collected. Linear regression analyses were conducted to examine gender difference in CQLQ score and the association between cough severity and CQLQ score.

Results

Difference between women and men was not significant in CQLQ total score in the unadjusted analysis (P = 0.077). Women had a 2.20-point higher CQLQ total score than men (95% confidence interval (CI) 0.11–4.30; P = 0.039), after adjusting for age, cough duration, cough severity, and clinical center. Gender significantly modified the association between cough severity and CQLQ total score (coefficient 1.80, 95% CI 0.29–3.30; P = 0.020), after adjusting for age, cough duration, and study center. An increase of 1-point in cough severity was associated with a 2.55-point (95% CI 1.16–3.95) increase in CQLQ total score in women versus a 1.26-point (95% CI 0.20–2.31) increase in men (P = 0.020).

Conclusions

Female sex may be associated with worse QoL than men, and women’s QoL may be more significantly impaired as cough symptom deteriorates. Gender difference should be taken into account in the clinical settings and research of cough and cough related QoL.

Trial registration: Chinese Clinical Trial Registry, ChiCTRTRC12002297. Registered 19 June 2012, http://www.chictr.org.cn/abouten.aspx.

Patient-Reported Burden of Chronic Cough in a Managed Care Organization

BACKGROUND

The burden of chronic cough (CC) requires better understanding.

OBJECTIVE

To determine the severity, health status, and health care resource utilization among patients with CC identified by electronic health records on 2 visits separated by ≥1 year.

METHODS

Information on cough-related burden was collected through survey from patients with CC, including validated questionnaires (the cough health status Leicester Cough Questionnaire [LCQ], the cough hypersensitivity Hull Airway Reflux Questionnaire [HARQ], and the Cough Quality of Life Questionnaire [CQLQ]), CC-associated respiratory and gastrointestinal comorbidities, and treatment responses. Spearman correlation coefficients were reported to examine the associations among the LCQ, HARQ, and CQLQ. Patient demographics and patient-reported CC features were compared between males and females, and among ethnic groups using Robust Poisson regression models.

RESULTS

The survey was completed by 565 patients who were 64.8 ± 12.6 years, 75.8% female, and 60.4% white. CC duration was 8.6 ± 10.5 years with an average weekly severity of 5.3 ± 2.3 (maximum 10). The LCQ score was 11.3 ± 3.9 (maximum 21). The HARQ score was 33.3 ± 13.6 (normal ≤13). The CQLQ score was 56.9 ± 17.5 (maximum 112, worse with higher scores). The Spearman rank correlations were high between the LCQ and HARQ (-0.65), the LCQ and CQLQ (-0.80), and the HARQ and CQLQ (0.69). Patients with CC-associated respiratory and gastrointestinal comorbidities generally showed similar results regarding the above questionnaires. Treatment responses were suboptimal. Women compared with men and non-whites compared with whites reported significantly worse cough severity and poorer LCQ, HARQ, and CQLQ scores.

CONCLUSIONS

CC is self-reported as a burdensome condition, particularly in women and non-white minorities, which markedly affects daily living with inadequate response to treatments.

Gender effects on quality of life and symptom burden in patients with lung cancer: results from a prospective, cross-cultural, multi-center study

Background

Lung cancer causes impairment of health-related quality of life (QoL), but little is known about gender aspects in QoL and symptom burden of lung cancer patients. The aim of this study was to investigate gender differences in QoL as assessed by the European Organization for Research and Treatment of Cancer (EORTC) QLQ-C30 and the updated lung cancer module.

Methods

In a prospective, international, cross-cultural, multicenter study that was undertaken to update the lung cancer-specific module EORTC QLQ-LC13, patients filled in the core questionnaire EORTC QLQ-C30 and the updated lung cancer module. Gender differences were calculated for all QoL scores using ANCOVAs that controlled for known and suspected confounders. Comparisons with historic data were drawn.

Results

A total of 200 patients (82 female and 118 male, median age 65 years) were recruited. With the exception of coughing (estimated marginal means: women 33.86 and men 43.52, P=0.022) and diarrhea (estimated marginal means: women 26.01 and men 17.93, P=0.038) there were no significant QoL gender differences. Fatigue was the most pronounced symptom in both, men and women, outpacing typical respiratory symptoms. Quite generally, our sample of lung cancer patients showed considerably worse QoL in all scores when compared to EORTC reference data (lung cancer and combined cancer diagnoses, mean differences up to 13.70 and 21.54 score points, respectively) and to a German norm reference sample (up to 35.37 score points).

Conclusions

This study adds to the literature in showing that the typical QoL gender difference effect (women doing worse than men) may not be generalizable across all patient samples.

Perspectives on chronic cough in Korea

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

The present and future of cough counting tools

The widespread use of cough counting tools has, to date, been limited by a reliance on human input to determine cough frequency. However, over the last two decades advances in digital technology and audio capture have reduced this dependence. As a result, cough frequency is increasingly recognised as a measurable parameter of respiratory disease. Cough frequency is now the gold standard primary endpoint for trials of new treatments for chronic cough, has been investigated as a marker of infectiousness in tuberculosis (TB), and used to demonstrate recovery in exacerbations of chronic obstructive pulmonary disease (COPD). This review discusses the principles of automatic cough detection and summarises key currently and recently used cough counting technology in clinical research. It additionally makes some predictions on future directions in the field based on recent developments. It seems likely that newer approaches to signal processing, the adoption of techniques from automatic speech recognition, and the widespread ownership of mobile devices will help drive forward the development of real-time fully automated ambulatory cough frequency monitoring over the coming years. These changes should allow cough counting systems to transition from their current status as a niche research tool in chronic cough to a much more widely applicable method for assessing, investigating and understanding respiratory disease.

The demographic and clinical characteristics of an Italian population of adult outpatients with chronic cough

BACKGROUND

Chronic cough is a major health problem worldwide and patients are best managed in specialised tertiary centres. Little information is available on the characteristics of chronic cough patients in several European countries, including Italy.

AIMS

We report on the demographic, anthropometric and clinical features of a large Italian population of adult chronic cough outpatients (about 1200), who were referred to a specialised clinic in Florence, Italy, from 2008 to 2018.

METHODS

Demographic, environmental, lifestyle and clinical information was collected at enrolment by means of a custom-designed electronic questionnaire that only allowed for uniform responses. A subjective measure of cough-related discomfort (cough score) was also obtained using a modified Borg Scale. A multivariable logistic regression model was defined to identify the patients' characteristics associated with the cough score.

RESULTS

The characteristics of the examined population (n = 1204 outpatients) were strikingly similar to those described elsewhere. Female patients outnumbered the males [n = 847 females, (70.0%)]; both females and males displayed the same average cough score. The median age of outpatients was 61 (quartile 1 = 48; quartile 3 = 70) years; age and cough duration were unrelated to the cough score. Nasal obstruction, coughing during consultation, coughing during meals, throat clearing and the presence of respiratory abnormalities were correlated with the degree of discomfort caused by coughing.

DISCUSSION

The features of chronic cough patients are similar worldwide. The process of cough reflex hypersensitisation may soothe sex-related perceptual differences, leading to similar levels of discomfort.

CONCLUSIONS

There seem to be clinical indicators that help in assessing the level of cough-related discomfort.

Burden of Specialist-Diagnosed Chronic Cough in Adults

BACKGROUND

The burden of chronic cough (CC) in patients seeking specialist care is infrequently researched.

OBJECTIVE

To describe patient characteristics and disease burden associated with specialist-diagnosed CC.

METHODS

Using administrative pharmacy and medical data, we identified patients aged 18 to 85 years with CC diagnosed by pulmonologists, allergists, otolaryngologists, or gastroenterologists. Patients were stratified into 4 subgroups on the basis of the presence or absence of common respiratory diseases or gastroesophageal reflux disease (GERD). Clinical features and health care resource utilization (HCRU) in the baseline and outcome years were compared between the CC subgroups. The baseline factors associated with persistence of CC and a comparison of the CC cohort to a matched noncough cohort were also determined.

RESULTS

The 11,290 patients with specialist-diagnosed CC were aged about 61 years and 66.7% were females. The CC cohort experienced frequent GERD (44.1%), asthma (31.2%), obesity (24.3%), upper airway cough syndrome (20.4%), common cough complications (19.4%), and hospitalizations (9.8%). The patients with CC with both respiratory disease and GERD exhibited at baseline and follow-up the most common cough comorbidities, higher HCRU, specialist care, and dispensed respiratory and nonrespiratory medications including proton pump inhibitors, antitussives, psychotherapeutics, oral corticosteroids, and antibiotics compared with the other subgroups. A 40.6% persistence of CC occurred similarly between CC subgroups. In addition, patients with CC in the matched analysis experienced significantly more comorbidities, laboratory evaluations, HCRU, and antitussives than patients without cough.

CONCLUSIONS

Specialist-diagnosed CC was associated with considerable disease burden, particularly among those with both respiratory disease and GERD. In addition, CC burden was more pronounced than in matched patients without cough.

Gefapixant in two randomised dose-escalation studies in chronic cough

Background and objectives

Gefapixant has previously demonstrated efficacy in the treatment of refractory chronic cough at a high daily dose. The current investigations explore efficacy and tolerability of gefapixant, a P2X3 receptor antagonist, for the treatment of chronic cough using a dose-escalation approach.

Materials and methods

Two randomised, double-blind, placebo-controlled, crossover, dose-escalation studies recruited participants with refractory chronic cough. Patients were assigned to receive ascending doses of gefapixant (study 1: 50–200 mg, study 2: 7.5–50 mg) or placebo for 16 days, then crossed-over after washout. The primary end-point was awake cough frequency assessed using a 24-h ambulatory cough monitor at baseline and on day 4 of each dose. Patient-reported outcomes included a cough severity visual analogue scale and the cough severity diary.

Results

In clinical studies, gefapixant doses ≥30 mg produced maximal improvements in cough frequency compared with placebo (p<0.05); reported cough severity measures improved at similar doses. Taste disturbance exhibited a different relationship with dose, apparently maximal at doses ≥150 mg.

Conclusions

P2X3 antagonism with gefapixant demonstrates anti-tussive efficacy and improved tolerability at lower doses than previously investigated. Studies of longer duration are warranted.

Current Status and Future Directions of Chronic Cough in China

Chronic cough is one of the most common complaints for which patients in China seek medical attention. However, there are no nationwide data on the prevalence and socioeconomic burden of chronic cough. Although approximately 50% of Chinese men smoke, the vast majority of patients presenting for evaluation of chronic cough are never smokers. An equal sex distribution and a middle-aged predominance have been observed in the Chinese chronic cough population, despite demonstration of a higher cough reflex sensitivity in females and older patients. The role of air pollution in the distinct age and sex distribution requires further study. In terms of the etiologies of chronic cough in China, cough-variant asthma, upper airway cough syndrome, nonasthmatic eosinophilic bronchitis, and atopic cough are the most common causes, comprising 75.2% to 87.6% of cases across different regions. Chinese Guidelines for Diagnosis and Treatment of Cough were initially published in 2005, and updated in 2009 and 2016. In addition, the China Cough Coalition was established in 2016. Great progress has been made in both cough-related clinical practice and research in recent years, however, there are still challenges ahead. To facilitate optimal management of chronic cough in China, efforts promoting the dissemination and application of published guidelines will be essential, especially in community-based healthcare and in rural regions. As chronic refractory cough has been identified as a huge challenge to clinicians worldwide, continued international cooperation will be essential in optimizing evaluation and management of chronic cough.

A cross sectional study to determine the prevalence of cough and its impact in patients with lung cancer: a patient unmet need

BACKGROUND

There is absence of literature related to cough prevalence and its characteristics in lung cancer patients, with information deriving only from broader symptoms occurrence studies. The aims of this study were to provide a snapshot of the prevalence of all-cause-cough in lung cancer patients and to characterise cough in terms of its impact and severity.

METHODS

A cross-sectional study recruiting consecutive lung cancer patients over a pre-defined period of time and using cough-specific validated tools in a tertiary referral centre in the UK, including a cough severity VAS and the Manchester Cough in Lung Cancer scale (MCLCS).

RESULTS

Data was collected from 202 patients. All-cause cough prevalence was 57% (through VAS) both in the screened (N = 223) and research (N = 202) population or 67% (through the MCLCS), and cough severity was moderate at a mean of 32 mm (in a 100 mm VAS). Age, sex, smoking status, lung cancer histology, stage and comorbidities were not associated with cough prevalence. The only variable associated with lower cough reports was being 'on anticancer treatment'; fewer patients on treatment reported a cough (40%) compared to those off treatment (54%) (p = 0.04). The impact of cough (as measured by MCLCS) was also significant (mean score = 22). About 18% of patients felt moderate/severe distress from their cough and about 15% often or always reported disturbed sleep due to coughing. Half the patients felt their cough warranted treatment.

CONCLUSIONS

Cough is a common symptom in lung cancer with considerable impact on patients' lives. Cough presence and severity should regularly be assessed in clinical practice. There is an urgent need to focus on developing more potent antitussive treatments and improve the management of this complex and distressing symptom.

Clinical impact of gastroesophageal reflux disease in patients with subacute/chronic cough

BACKGROUND

While gastroesophageal reflux disease (GERD) is one of the commonest causes of subacute/chronic cough along with cough-variant asthma (CVA) and rhinosinusitis, its clinical impact remains unknown. Therefore, we sought to investigate the impact of GERD in patients with subacute/chronic cough.

METHODS

Between April 2012 and March 2018, a total of 312 patients presenting subacute or chronic cough lasting for ≥3 weeks [median cough duration, 4.9 (0.7-434) months] underwent diagnostic tests. GERD symptoms and cough-specific QoL were evaluated through the Frequency Scale for Symptoms of Gastroesophageal reflux (FSSG) and the Japanese version of the Leicester Cough Questionnaire (J-LCQ). According to the FSSG domains, patients with GERD were arbitrarily categorized into 3 groups; acid-reflux predominant, dysmotility predominant, and pauci-symptoms groups, respectively.

RESULTS

The average scores of J-LCQ was 12.5 (SD3.7). One hundred-forty three were diagnosed as having GERD-related cough based on classical reflux symptoms including heartburn and characteristic triggers of cough such as phonation, rinsing, lying, and eating. Most of them (89.8%) had other causative diseases including CVA. Cough lasted longer (p = 0.019) and required a longer time until alleviation (p = 0.003) in patients with GERD than in those without GERD. They also scored lower J-LCQ than counterpart group (p < 0.0001). In terms of symptom stratification, dysmotility predominant group showed significant more response to specific GERD treatments than the remnants (p = 0.002).

CONCLUSIONS

These results indicate that GERD is associated with the aggravation of other causes including CVA. Particularly, dysmotility symptoms may be potential therapeutic target for GERD-related cough.

A systematic review of methods of citric acid cough reflex testing

INTRODUCTION

This systematic review summarises and appraises methods of citric acid cough reflex testing (CRT) documented in published literature.

METHODS

Electronic databases, MEDLINE, EMBASE, CINAHL, PsychINFO, Scopus were searched up to and including 11th February 2018. Studies reporting a method of citric acid CRT, published in peer-reviewed journals in English or Spanish, were assessed for the inclusion criteria. Of the selected studies, information on the instrumentation and CRT protocol was extracted.

RESULTS

A total of 129 studies were included. Instrumentation and protocols differed widely across studies. Reporting of methods of citric acid CRT was sub-standard, with many crucial methodological components omitted from published manuscripts, preventing their full replication.

CONCLUSIONS

Considerable methodological variability exists for citric acid CRT in published literature. The findings suggest that caution is warranted in comparing citric acid cough thresholds across studies. Full replication of previously published methods of citric acid CRT is limited due to crucial elements of the citric acid CRT protocol being omitted from published manuscripts. These findings have implications on the use of citric acid CRT in clinical and pharmaceutical studies to evaluate the effects of antitussive medications and cough therapies.

Prevalence and correlates of chronic obstructive pulmonary disease and chronic respiratory symptoms in rural southwestern Uganda: a cross-sectional, population-based study

Background

The global burden of chronic obstructive pulmonary disease (COPD) disproportionately affects resource-limited settings such as sub-Saharan Africa (SSA), but population-based prevalence estimates in SSA are rare. We aimed to estimate the population prevalence of COPD and chronic respiratory symptoms in rural southwestern Uganda.

Methods

Adults at least 18 years of age who participated in a population-wide census in rural southwestern Uganda completed respiratory questionnaires and lung function testing with bronchodilator challenge at health screening events in June 2015. We defined COPD as post-bronchodilator forced expiratory volume in one second to forced vital capacity ratio less than the lower limit of normal. We fit multivariable linear and log binomial regression models to estimate correlates of abnormal lung function and respiratory symptoms, respectively. We included inverse probability of sampling weights in models to facilitate population-level estimates.

Results

Forty-six percent of census participants (843/1814) completed respiratory questionnaires and spirometry, of which 565 (67%) met acceptability standards. COPD and respiratory symptom population prevalence were 2% (95% confidence interval (CI)  = 1%-3%) and 30% (95% CI = 25%-36%), respectively. Respiratory symptoms were more prevalent and lung function was lower among women and ever-smokers (P < 0.05). HIV serostatus was associated with neither respiratory symptoms nor lung function.

Conclusions

COPD population prevalence was low despite prevalent respiratory symptoms. This work adds to the growing body of literature depicting lower-than-expected COPD prevalence estimates in SSA and raises questions about whether the high respiratory symptom burden in rural southwestern Uganda represents underlying structural lung disease not identified by screening spirometry.

Roles of citric acid in conjunction with saline nebulization in experimental tracheostomy in guinea pigs

PURPOSE

Tracheostomy usually accompanied by the impairment of cough reflex, which may affect the clearance of secretions and result in the occurrence and development of pulmonary inflammation. Previous research has demonstrated that citric acid could effectively evoke cough. However, there are limited data available on this topic specific to the cough stimulation method, and the roles of citric acid in tracheostomy still remain obscure. The aims of present study were to identify the potential roles of citric acid in conjunction with saline nebulization in tracheostomy in guinea pigs.

MATERIALS AND METHODS

Experimental tracheostomy model was induced in guinea pigs, and different nebulization interventions were implemented. The expression of P-selectin and platelet count were analyzed by flow cytometer and automatic globulimeter, the histological changes in trachea and lung tissue were assessed by hematoxylin and eosin staining, and the inflammatory cytokines and substance P (SP) levels in bronchoalveolar lavage fluid were evaluated by enzyme-linked immunosorbent assay.

RESULTS

Tracheostomy resulted in the disorder of trachea mucosa and cilia, the inflammatory cell infiltration in lung tissue, the increase of IL-6, TNF-α levels and the decrease of SP level. Citric acid alone increase the SP level, and the joint action of citric acid and saline nebulization further showed significantly beneficial effects on pathological, inflammatory changes and SP level.

CONCLUSIONS

Citric acid combined with saline nebulization contributes to the alleviation of tracheotomy-induced tracheal damage and pulmonary inflammation in an experimental tracheostomy model in guinea pigs. This may provide novel insights into the inflammation management and cough recovery after tracheostomy.

[From acute cough to chronic cough in adults: Overview on a common reason for consultation]

Cough is divided into two categories: acute cough lasting less than 3 weeks, and chronic cough lasting more than 8 weeks. Acute cough is usually triggered by a viral infection of the upper airways. Evidence of treatment effectiveness is low and management of acute cough is complex in clinical practice. Chronic cough is a common reason for consultation in medicine. The most frequent causes are upper airway diseases, gastroesophageal reflux disease, asthma, eosinophilic bronchitis, and drugs. Before investigation, smoking cessation and drug withdrawal must be achieved for 4 to 6 weeks. Once this step is completed, simple investigations have to be performed in order to find common causes of chronic cough (questioning, physical examination, spirometry, chest X-ray). If no causes have been identified or cough remains despite optimal treatment, exhaustive exploration has to be performed to rule out rare causes. A chronic cough hypersensitivity syndrome is suggested if any causes have been found despite exhaustive assessment or if cough remains with optimal treatments. This syndrome is characterized by an increase in the sensitivity of cough peripheral receptors and is not sensitive to usual therapies. The therapeutic options are limited but innovative treatments such as P2X3 receptor antagonists are in development.

Age and Sex Distribution of Chinese Chronic Cough Patients and Their Relationship With Capsaicin Cough Sensitivity

PURPOSE

An older female predominance has been reported among chronic cough patients in Western countries, which is considered to be associated with a higher cough sensitivity in females. However, the characteristics of Chinese chronic cough patients remain unclear. This study aimed to explore the age and sex distribution as well as their relationship with cough reflex sensitivity to capsaicin in Chinese chronic cough patients.

METHODS

We analyzed the demographic features of 1,882 consecutive chronic cough patients who attended our cough clinic in Guangzhou, China. Cough sensitivity to capsaicin, which was defined as the lowest concentration of capsaicin causing 5 coughs or more (C5), was measured in 539 of the 1,882 patients and 68 healthy volunteers.

RESULTS

The mean age of the patients was 43.0 ± 13.7 years and patients aged <50 years accounted for more than two-thirds of the study population. Around 87% of the patients were never-smokers. The proportion of females (51.5%) was almost equal to that of males (48.5%). The pattern of the age and sex distribution was consistently reflected within most common causes of chronic cough, while a female predominance was shown in patients with cough-variant asthma and patients aged ≥50 years. Female patients had higher cough sensitivity to capsaicin than male patients (log C5: 1.58 ± 0.84 vs. 2.04 ± 0.84 μmol/L, P = 0.001), and patients aged ≥50 years had higher cough sensitivity to capsaicin than patients aged <50 years.

CONCLUSIONS

In China, patients with chronic cough have a roughly equal sex distribution and a middle-aged predominance, irrespective of a higher cough sensitivity to capsaicin in females and older patients.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02591550.

Cough in Patients With Lung Cancer: A Longitudinal Observational Study of Characterization and Clinical Associations

BACKGROUND

Cough is common in patients with lung cancer, and current antitussive treatments are suboptimal. There are little published data describing cough in patients with lung cancer or work assessing clinical associations. The aim of this study is to fill that gap.

METHODS

This was a longitudinal prospective observational single-cohort study over 60 days. Patients were assessed through self-reported validated scales and, in a subsample, ambulatory cough monitoring at study entry (day 0), day 30, and day 60.

RESULTS

At study entry, 177 patients were included and 153 provided data at day 60. The median duration of cough was 52 weeks (interquartile range, 8.5-260). Cough was described as severe enough to warrant treatment in 62% of the patients. Depending on the scale used, performance status was associated with both cough severity and cough impact (P < .001) at study entry, whereas higher cough severity at study entry was associated with female sex (P = .02), asthma (P = .035), and reflux disease (P < .001). Cough impact at study entry was additionally associated with experiencing nausea (P = .018). Cancer characteristics (ie, cancer stage, histology) were not associated with cough severity nor cough impact; neither was smoking or COPD.

CONCLUSIONS

This is the first study to describe characteristics of cough in patients with lung cancer and to identify clinical associations that may be relevant for its treatment. Our data suggest that cough is a frequent and distressing symptom and an unmet clinical need. Its association with gastrointestinal symptoms in this study may improve our understanding of pathophysiology and therapeutic options for cough occurring in patients with lung cancer.

Communication of health in experimentally sick men and women: A pilot study

The way people communicate their ill-health and the factors involved in ill-health communication remain poorly known. In the present study, we tested how men and women communicate their sickness and assessed whether sickness-related variables (i.e., body temperature, immune response, subjective sickness symptoms) predicted communicative behaviors. Twenty-two participants were filmed during experimentally induced sickness, triggered by lipopolysaccharide administration (2ng/kg body weight), and after placebo administration, in presence of female care providers. Two trained raters scored participants' communicative behaviors (verbal complaints, moaning and sighs/deep breaths). The physiological and subjective sickness responses were similar in both sexes. Participants were more likely to moan and complain when sick, although the frequency of these behaviors remained low and no clear sex differences was observed. Nevertheless, frequency of sighs/deep breaths was increased amongst sick men but not in women. Sickness-related variables did not predict sigh/deep breath frequency. In this setting, sick men appear to display a lower threshold of expressing their malaise as compared to similarly sick women.

The research of the possible mechanism and the treatment for capsaicin-induced cough

Unexplained chronic cough (UCC) affects millions of patients worldwide. New therapeutic approaches to this condition are urgently needed, since current treatment options provide only symptomatic relief. Cough reflex hypersensitivity has been shown to play an important role in the pathogenesis of UCC. The transient receptor potential vanilloid type 1 (TRPV1) is present on peripheral terminals of airway sensory nerves and modulation of its activity represents a potential target for the pharmacological treatment of UCC. The aim of this study was to explore the efficacy and the possible mechanism of SB705498, a TRPV1 antagonist, for cough in a capsaicin-induced cough animal model (i.e. guinea pigs). Induction of cough by capsaicin was successfully implemented in the guinea pigs, and the animals that met the inclusion criteria were randomly divided into four treatment groups: (1) Saline inhalation group (NSInh group, N = 10, negative control group), (2) Codeine phosphate intraperitoneal injection group (CPInp group, N = 10, positive control group), (3) SB705498 inhalation group (SBInh group, N = 10), (4) SB705498 intragastric administration group (SBIng group, N = 10). After treatment with above compounds, the capsaicin-induced cough experiment was performed again. The cough numbers and the cough incubation periods were recorded to evaluate the antitussive effect of SB705498. Enzyme-linked immunosorbent assay (ELISA) testing and Immunohistochemistry (IHC) staining for substance P (SP), calcitonin gene related peptide (CGRP) and neurokinin A (NKA) expression in lung and brain tissues were performed as an indication of neurogenic inflammation. Hematoxylin-Eosin (H&E) staining was used to observe the pathology morphology of lung and brain tissues. When the CPInp, SBInh and SBIng groups were compared to the NSInh group, the cough numbers were significantly reduced (p < .001), while the cough incubation periods were significantly prolonged (P < .001). In addition, the expression of SP, CGRP and NKA in lung and brain tissue was reduced (P < .05). None of the animals in the four groups exhibited lung and brain parenchymal inflammation. The results from this study showed that SB705498 had a significant antitussive effect, could reduce the neurogenic inflammation by reducing the expression of SP, CGRP and NKA in a capsaicin-induced cough model of guinea pigs. The results further indicated that TRPV1 played an important role in UCC and SB705498 might be a promising therapeutic agent for UCC.

Asthma phenotypes: do cough and wheeze predict exacerbations in persistent asthma?

Little is known of the long-term symptom profile in uncontrolled asthma and whether symptoms can predict distinct phenotypes. The primary objective of these analyses was to assess diurnal profile of cough and wheeze in an uncontrolled asthma population. Secondary outcomes were to examine how these symptom profiles influence response to treatment.Twice-daily electronically recorded data from 1701 patients were examined in relation to the population demographics. Reliever treatment with salbutamol was then compared with extra-fine beclometasone/formoterol maintenance and reliever therapy (MART). Exacerbation frequency was then correlated with the symptom profile.Symptoms were commoner in older patients with an increased body mass index. In most patients, reported cough and wheeze were closely correlated (r=0.73). Two phenotypes of cough- and wheeze-predominant patients were identified; the former were overweight, older females and the latter older males. Diurnal symptoms of cough and wheeze were similarly attenuated by both therapies. MART reduced exacerbation frequency by a third compared with salbutamol, and this effect was greatest in patients with fewest reported symptoms.While cough and wheeze are highly correlated in uncontrolled asthma, some patients predominantly have cough whereas others wheeze. Symptoms and exacerbation frequency appear poorly associated, suggesting an alternative pathophysiology. MART may be the preferred option in those with fewest symptoms.

Does FeNO Predict Clinical Characteristics in Chronic Cough?

Purpose

To evaluate whether exhaled nitric oxide measurement can facilitate in the assessment of chronic cough patients based on their airway inflammatory phenotype.

Methods

We have studied consecutive patients attending a specialist cough clinic. 30 patients with high FeNO (> 30 ppb) and 20 patients with low FeNO (< 20 ppb) were recruited.

Results

There was a significant correlation between FeNO, B-Eos and sputum eosinophil count (p < 0.001). The number of recorded coughs in 24 h and HARQ scores were significantly (p < 0.05) higher in patients with a low FeNO. In contrast to the high FeNO group (48%), the greater proportion of these patients were women (90%). LCQ scores were worse in the low FeNO group but it was not significant.

Conclusion

A strong relationship between FeNO, blood eosinophils and sputum eosinophils confirming phenotypic identity was observed. Whether the observed gender disparity accounts for the different cough frequency characteristics is unknown.

Risk Factors for Chronic Cough Among 14,669 Individuals From the General Population

BACKGROUND

Risk factors for chronic cough in the general population have not been described systematically. We identified and ranked chronic cough risk factors at the individual and community level using data from 14,669 individuals from the Copenhagen General Population Study.

METHODS

Severity of chronic cough was assessed using the Leicester Cough Questionnaire (LCQ). We ranked chronic cough risk factors based on magnitude of age-adjusted ORs at the individual level and of the population attributable risks (PARs) at the community level.

RESULTS

Prevalence of chronic cough in the general population was 4% overall and 3% in never smokers, 4% in former smokers, and 8% in current smokers. Median score of the LCQ was 5.8 (25th-75th percentile, 5.0-6.3) for physical domain, 5.6 (25th-75th percentile, 4.6-6.3) for psychologic domain, 6.3 (25th-75th percentile, 5.5-6.8) for social domain, and 17.3 (25th- 75th percentile, 15.4-18.9) in total. At the level of the individual, age-adjusted ORs for the three top-ranked risk factors were 5.0 (95% CI, 1.4-18) for bronchiectasis, 2.6 (95% CI, 1.7-3.9) for asthma and 2.3 (95% CI, 1.5-3.4) for gastroesophageal reflux disease in never smokers, 7.1 (95% CI, 2.6-20) for bronchiectasis, 3.1 (95% CI, 2.2-4.4) for asthma and 2.2 (95% CI, 1.5-3.2) for occupational exposure to dust/fumes in former smokers, and 1.9 (95% CI, 1.3-2.9) for airflow limitation in current smokers. At the level of the community, the three top-ranked risk factors were female sex (PAR, 19%), asthma (PAR, 10%), and gastroesophageal reflux disease (PAR, 8%) in never smokers; abdominal obesity (PAR, 20%), low income (PAR, 20%), and asthma (PAR, 13%) in former smokers; and airflow limitation (PAR, 23%) in current smokers.

CONCLUSIONS

Risk factors for chronic cough differ at the level of the individual and community, and by smoking status. Strategies to prevent and treat modifiable chronic cough risk factors should be tailored accordingly.

Cough associated with gastro-oesophageal reflux disease (GORD): Japanese experience

Differences in the aetiology as well as patient background of chronic cough have been recognised among US, UK, and Japan. One of the marked differences has been the prevalence of gastro-oesophageal reflux disease (GORD), which has been one of the top three causes in Western countries. It was indeed uncommon or rare in Japan, but, with the increasing prevalence of GOR itself, chronic cough associated with GORD seems to have become more common. In this article, cough associated with GORD will be reviewed based on literature and our Japanese experience. Further, potentially broader relevance of GORD in chronic cough will also be mentioned, highlighting the potential importance of dysmotiliy/non-acid reflux.