Methods of Cough Assessment

A systematic review of the psychometric properties of the Leicester Cough Questionnaires based on the COSMIN Guidelines

BACKGROUND

Chronic cough affects around 10% of the general adult population, impairing all aspects of quality of life.

RESEARCH QUESTION

What are the Leicester Cough Questionnaire's psychometric properties?

STUDY DESIGN AND METHODS

Electronic searches of PubMed, CINAHL, and ScienceDirect databases were conducted from inception until October 1rst 2022. All full-text articles, published in French or English, aimed at evaluating the LCQ's content validity or psychometric properties were included. The COSMIN Risk of Bias checklist was applied to assess their methodological quality and results. Results were qualitatively summarised and rated by a modified GRADE approach.

RESULTS

40 studies were included accounting for 8,731 adults, subject to cough or a respiratory condition. Chronic cough (> 8 weeks) was the most represented. The LCQ's total score is relevant and comprehensible for the assessment of the impact of cough on QoL. The original 3-factor model showed a satisfactory model fit. Good convergent validity was found for the total and physical domain scores. These scores demonstrate good internal consistency and test retest reliability, with some variability noted and they are responsive to change. Recent estimates of MID thresholds were 1.7 and 0.4 for total and domain scores respectively. The quality of the studies is globally poor.

INTERPRETATION

The LCQ is a valid outcome to assess the intra-individual impact of cough on QoL and to detect large changes in quality of life mainly in a short-term clinical trial setting.

CLINICAL TRIAL REGISTRATION

The protocol was registered with PROSPERO (CRD42XXXXX).

Development of an Italian version of the Leicester cough questionnaire and its relationship with other symptom-specific measures for patients with chronic cough

OBJECTIVE

To implement subjective methods for measuring the impact of chronic cough on patients' daily life, including an Italian version of the symptom-specific, health status measure for patients with chronic cough, i.e. the Leicester Cough Questionnaire (LCQ).

METHODS

Sixty-five chronic cough patients attended a tertiary cough clinic on two separate occasions 8 weeks apart. The visual analogue scale for cough severity (VAS), the LCQ and the cough disturbance score (CDS) were administered on both occasions. The LCQ was adapted for Italian conditions following a forward-backward translation procedure. Concurrent validation, internal consistency, repeatability and responsiveness were determined.

RESULTS

The CDS, VAS and LCQ were correlated (r coefficients ranging from 0.69 to 0.94, p < 0.01). The internal consistency for each LCQ domain was high (alpha coefficient range 0.87-0.93), as was the 8-week repeatability of the LCQ in the patients (n = 36, 60 %) who displayed no change in CDS and VAS (intra-class correlation coefficient = 0.86, p < 001) over the same period. Patients who reported an improvement in CDS and VAS after 8 weeks (n = 29) also demonstrated significant improvements in each LCQ domain. The mean difference in LCQ total score before and after improvements was 2.26 (95 % CI: 1.58-4.47).

CONCLUSIONS

The Italian version of the LCQ appears to be just as valid as the other language versions of the questionnaire. In addition, the CDS appears to be a clinically useful, symptom-specific measure of the overall disturbance provoked by 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.

Potassium-Competitive Acid Blocker Versus Proton Pump Inhibitor: A Pilot Study on Comparable Efficacy in the Treatment of Gastroesophageal Reflux-Related Cough

Acid inhibitors have been considered in treating gastroesophageal reflux-related cough (GERC). Compared to proton pump inhibitors (PPIs), potassium-competitive acid blockers (P-CABs) have more potent and durable effects on anti-acid secretion. However, whether vonoprazan and esomeprazole have different therapeutic effects on GERC remains unknown. Patients diagnosed with GERC were enrolled in our study and randomly treated with vonoprazan (20 mg, once daily, P-CAB) or esomeprazole (20 mg, twice daily, PPI) for two months. A prokinetic agent was also administered. Patients were followed up once a month. Cough severity visual analogue scale (VAS) was measured as the primary outcome, while cough symptom score (CSS) and scores for cough-related quality-of-life or reflux-related symptoms were the secondary endpoints. A total of 50 patients completed the study, with 25 patients in each group. P-CAB and PPI groups showed similar decreases in cough severity VAS and CSS scores after the 2-month treatment (all P < 0.001). For quality-of-life, the Leicester Cough Questionnaire (LCQ) score increased significantly from baseline in both groups, but the P-CAB group had greater improvement and a higher LCQ score in month 2 (all P ≤ 0.05). For reflux-related symptoms, the Hull Airway Reflux Questionnaire (HARQ) score declined substantially over time in the P-CAB group, while the reflux symptom index (RSI) score decreased in both groups. The P-CAB group tended to have a lower HARQ (P = 0.051) and RSI (P = 0.069) scores in month 2. In conclusion, vonoprazan may be comparable to esomeprazole in cough symptom relief in GERC during the 2-month treatment period, but possibly provides better gains on classic reflux symptoms and quality-of-life. The long-term efficacy of P-CABs on GERC may be worth further exploration. Trial Registration: Chinese Clinical Trial Registry Identifier: ChiCTR2200067089.

Patient Global Impression of Severity Scale in Chronic Cough: Validation and Formulation of Symptom Severity Categories

BACKGROUND

The Patient Global Impression of Severity (PGI-S) scale is a self-reported, single-item categorical scale that is increasingly used when assessing chronic cough (CC).

OBJECTIVE

This study aimed to establish validity, repeatability, and responsiveness of the PGI-S scale in CC and use the scale to define discrete categories of severity when measured with other commonly used patient-reported outcome (PRO) tools.

METHODS

Consecutive patients with CC completed the PGI-S scale, cough severity and urge to cough visual analog scales (VAS), and cough-specific health status Leicester Cough Questionnaire (LCQ) at a clinic visit. Validity, repeatability, and responsiveness were assessed, and threshold scores for PRO severity categories determined.

RESULTS

A total of 482 participants completed the assessments; the median (interquartile range [IQR]) age was 57 (46-67) years, 71% were female, and the median (IQR) duration of cough was 48 (24-120) months. They reported a median (IQR) PGI-S score of 3 (3-4; moderate severity), cough severity VAS of 57 (31-75) mm, urge to cough VAS of 62 (40-81) mm, and LCQ of 11.5 (8.7-14.4). There were strong associations between PGI-S scores and cough severity VAS (ρ = 0.81), urge to cough VAS (ρ = 0.73), and LCQ (ρ = -0.73) (all P < .001). Repeatability of the PGI-S scale was high (n = 77); the intraclass correlation coefficient (95% confidence interval) was 0.85 (0.77-0.91) (P < .001). The PGI-S scale was responsive in participants with a treatment response (P < .001). The suggested PRO thresholds to define severe cough are ≥61 mm (cough severity VAS), ≥71 mm (urge to cough VAS), and ≤10 (LCQ).

CONCLUSION

The PGI-S scale is a simple and valid tool that characterizes cough severity and is repeatable and responsive in CC. The proposed categorical severity thresholds for VAS and LCQ can provide intuitive meaning for patients and clinicians.

Changes in Cough Airflow and Acoustics After Injection Laryngoplasty

OBJECTIVE/HYPOTHESIS

We explored the following hypotheses in a cohort of patients undergoing injection laryngoplasty: (1) glottic insufficiency affects voluntary cough airflow dynamics and restoring glottic competence may improve parameters of cough strength, (2) cough strength can be inferred from cough acoustic signal, and (3) glottic competence changes cough sounds and correlates with spectrogram morphology.

STUDY TYPE/DESIGN

Prospective interventional study.

METHODS

Subjects with glottic insufficiency secondary to unilateral vocal fold paresis, paralysis, or atrophy, and scheduled for injection laryngoplasty completed an instrumental assessment of voluntary cough airflow using a pneumotachometer and a protocolized voluntary cough sound recording. A Wilcoxon signed-rank test was used to compare the differences between pre- and post-injection laryngoplasty in airflow and acoustic measures. A Spearman rank-order correlation was used to evaluate the association between airflow and acoustic cough measures.

RESULTS

Twenty-five patients (13F:12M, mean age 68.8) completed voluntary cough airflow measurements and 22 completed cough sound recordings. Following injection laryngoplasty, patients had a statistically significant decreased peak expiratory flow rise time (PEFRT) (mean change: -0.03 s, SD: 0.06, p = 0.04) and increased cough volume acceleration (mean change: 13.1 L/s2 , SD: 33.9, p = 0.03), suggesting improved cough effectiveness. Correlation of cough acoustic measures with airflow measures showed a weak relationship between PEFRT and acoustic energy (coefficient: -0.31, p = 0.04) and peak power density (coefficient: -0.35, p = 0.02).

CONCLUSIONS

Our study thus indicates that injection laryngoplasty may help avert aspiration in patients with glottic insufficiency by improving cough effectiveness and that improved cough airflow measures may be tracked with cough sounds.

LEVEL OF EVIDENCE

3 Laryngoscope, 133:S1-S14, 2023.

Health-related experiences of adults with chronic cough: Empirical research mixed methods

AIM

To describe adults' health-related experiences with chronic cough.

DESIGN

Survey and interviews.

METHODS

Participants completed questionnaires and interviews, to explore chronic cough's impact and management.

DATA SOURCES

Patients aged 18-85 years with at least three cough-related encounters within 56-120 days.

RESULTS

Forty-one patients were surveyed. Mean cough severity was 4.5 (scale 0-9). Chronic cough-related problems included embarrassment (66%), fatigue (56%), and anxiety or depression (49%). Testing was judged insufficient by 44%. Only 28% were satisfied with treatment; 20% reported abandoning treatment due to ineffectiveness. Interview themes (N = 30) included frustration with diagnostic uncertainty, and feelings of therapeutic futility. Some reported psychological distress. Work and socializing were commonly disrupted.

CONCLUSION

Diagnostic uncertainty, perceived limitations of testing, and treatment failures suggest needs for better approaches to evaluating and treating chronic cough. Special attention to identifying and addressing mental health issues appears warranted.

Effect of Capsaicin Atomization on Cough and Swallowing Function in Patients With Hemorrhagic Stroke: A Randomized Controlled Trial

BACKGROUND

Patients with hemorrhagic stroke have high mortality and disability rates. Nevertheless, early rehabilitation interventions can improve their outcomes. We aimed to apply capsaicin atomization as early intervention to patients with hemorrhagic stroke and explore improvements in cough and swallowing functions.

METHOD

Patients with hemorrhagic stroke were randomly divided into the control group, which received routine care, and the intervention group, which underwent the capsaicin solution nebulization scheme in addition to routine care. Differences in the presence/absence of cough reflex and number of coughs in response to capsaicin, the presence/absence of swallowing reflex in response to water, the presence/absence of postswallow residue, substance P (SP) concentration, and pulmonary inflammation between the two groups were determined before and after the intervention.

RESULTS

A total of 53 patients with hemorrhagic stroke were included. Results showed no statistically significant difference in cough reflex in both groups after the intervention (p > .05). The degree of cough in the intervention group was stronger than that in the control group (p = .046). No statistically significant difference was observed in the number of patients with swallowing reflex in response to water between the groups (p > .05). The presence/absence of postswallow residue of the intervention group was stronger than that of the control group (p = .032). No statistically significant difference was observed between the Glasgow Coma Scale scores of the groups after the intervention (p > .05). SP in the intervention group was significantly increased (p = .031). The Clinical Pulmonary Infection Score was significantly lower in the control group, and the difference was statistically significant (p = .028).

CONCLUSIONS

Capsaicin nebulization can help enhance the number of coughs in response to capsaicin, reduce postswallow residue, and increase the level of SP in patients with hemorrhagic stroke and has a positive effect on pulmonary inflammation. This study provides intervention points for cough and swallowing rehabilitation after a hemorrhagic stroke.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.21956903.

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.

Making cough count in tuberculosis care

Cough assessment is central to the clinical management of respiratory diseases, including tuberculosis (TB), but strategies to objectively and unobtrusively measure cough are lacking. Acoustic epidemiology is an emerging field that uses technology to detect cough sounds and analyze cough patterns to improve health outcomes among people with respiratory conditions linked to cough. This field is increasingly exploring the potential of artificial intelligence (AI) for more advanced applications, such as analyzing cough sounds as a biomarker for disease screening. While much of the data are preliminary, objective cough assessment could potentially transform disease control programs, including TB, and support individual patient management. Here, we present an overview of recent advances in this field and describe how cough assessment, if validated, could support public health programs at various stages of the TB care cascade.

Zimmer et al. discuss the importance of cough assessment in clinical management of tuberculosis (TB). They describe how acoustic epidemiology, which uses recording devices and artificial intelligence to detect, record and analyze cough, can be used in TB control and individual patient management.

Acoustic surveillance of cough for detecting respiratory disease using artificial intelligence

Research question

Can smartphones be used to detect individual and population-level changes in cough frequency that correlate with the incidence of coronavirus disease 2019 (COVID-19) and other respiratory infections?

Methods

This was a prospective cohort study carried out in Pamplona (Spain) between 2020 and 2021 using artificial intelligence cough detection software. Changes in cough frequency around the time of medical consultation were evaluated using a randomisation routine; significance was tested by comparing the distribution of cough frequencies to that obtained from a model of no difference. The correlation between changes of cough frequency and COVID-19 incidence was studied using an autoregressive moving average analysis, and its strength determined by calculating its autocorrelation function (ACF). Predictors for the regular use of the system were studied using a linear regression. Overall user experience was evaluated using a satisfaction questionnaire and through focused group discussions.

Results

We followed-up 616 participants and collected >62 000 coughs. Coughs per hour surged around the time cohort subjects sought medical care (difference +0.77 coughs·h−1; p=0.00001). There was a weak temporal correlation between aggregated coughs and the incidence of COVID-19 in the local population (ACF 0.43). Technical issues affected uptake and regular use of the system.

Interpretation

Artificial intelligence systems can detect changes in cough frequency that temporarily correlate with the onset of clinical disease at the individual level. A clearer correlation with population-level COVID-19 incidence, or other respiratory conditions, could be achieved with better penetration and compliance with cough monitoring.

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.

Development and technical validation of a smartphone-based pediatric cough detection algorithm

INTRODUCTION

Coughing is a common symptom in pediatric lung disease and cough frequency has been shown to be correlated to disease activity in several conditions. Automated cough detection could provide a noninvasive digital biomarker for pediatric clinical trials or care. The aim of this study was to develop a smartphone-based algorithm that objectively and automatically counts cough sounds of children.

METHODS

The training set was composed of 3228 pediatric cough sounds and 480,780 noncough sounds from various publicly available sources and continuous sound recordings of 7 patients admitted due to respiratory disease. A Gradient Boost Classifier was fitted on the training data, which was subsequently validated on recordings from 14 additional patients aged 0-14 admitted to the pediatric ward due to respiratory disease. The robustness of the algorithm was investigated by repeatedly classifying a recording with the smartphone-based algorithm during various conditions.

RESULTS

The final algorithm obtained an accuracy of 99.7%, sensitivity of 47.6%, specificity of 99.96%, positive predictive value of 82.2% and negative predictive value 99.8% in the validation dataset. The correlation coefficient between manual- and automated cough counts in the validation dataset was 0.97 (p < .001). The intra- and interdevice reliability of the algorithm was adequate, and the algorithm performed best at an unobstructed distance of 0.5-1 m from the audio source.

CONCLUSION

This novel smartphone-based pediatric cough detection application can be used for longitudinal follow-up in clinical care or as digital endpoint in clinical trials.

High-throughput digital cough recording on a university campus: A SARS-CoV-2-negative curated open database and operational template for acoustic screening of respiratory diseases

Objective

Respiratory illnesses have information-rich acoustic biomarkers, such as cough, that can potentially play an important role in screening populations for disease risk. To realize that potential, datasets of paired acoustic-clinical samples are needed for the development and validation of acoustic screening models, and protocols for collecting acoustic samples must be efficient and safe. We collected cough acoustic signatures at a high-throughput SARS-CoV-2 testing site on a college campus. Here, we share logistical details and the dataset of acoustic cough signatures paired with the gold standard in SARS-CoV-2 testing of SARS-CoV-2 genomic sequences using qRT-PCR.

Methods

Cough recordings were collected in winter-spring 2021 at a rural residential college (Sewanee, TN, USA), where approximately 2000 students were tested for SARS-CoV-2 on a weekly basis. Cough collection was managed by student volunteers using custom software.

Results

4302 coughs were recorded from 960 participants over 11 weeks. All coughs were COVID-19 negative. Approximately 30 s were required to check-in a participant and collect their cough.

Conclusion

The value of acoustic screening tools depends upon our ability to develop and implement them reliably and quickly. For that to happen, high-quality datasets and logistical insights must be collected and shared on an ongoing basis.

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

BACKGROUND

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

OBJECTIVES

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

OUTCOMES

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

Effect of Capsaicin Atomization-Induced Cough on Sputum Excretion in Tracheotomized Patients After Hemorrhagic Stroke: A Randomized Controlled Trial

Background Timely and effective removal of respiratory secretions is of great significance for tracheotomized patients. The purpose of this study is to investigate the effectiveness of capsaicin nebulization to stimulate cough to promote early clearance of respiratory secretions in tracheotomized patients after hemorrhagic stroke. Method This study implemented a randomized controlled design. Sixty-three patients who were tracheotomized following a hemorrhagic stroke completed this randomized controlled trial. In the control group, 33 cases were given a routine care after tracheotomy. In the intervention group, 30 cases were given a capsaicin solution nebulization in addition to the routine care. The daily sputum output and the number of sputum suctioning were observed. The differences in sputum viscosity, cough function, and Clinical Pulmonary Infection Score (CPIS) were compared between the two groups before and after the intervention. Vital sign changes during capsaicin nebulization and suctioning were compared between the two groups in a pilot study. Results The daily sputum output of the capsaicin intervention group was significantly higher than that of the control group (p < .05). The number of sputum suctioning of capsaicin group was less than that of the control group after intervention (p < .05). The CPIS score of the capsaicin group was lower than that of the control group (p < .05) after a 1-week intervention. Patients' heart rate, respiratory rate, and oxygen saturation during capsaicin nebulization were not statistically different from those during routine sputum suctioning (p > .05). Conclusions Capsaicin atomization-induced cough can effectively promote sputum excretion of hemorrhagic stroke patients undergoing tracheotomy and has a good safety profile. The Clinical Trial registration number of this study is ChiCTR2000037772 (http://www.chictr.org.cns). Supplemental Material https://doi.org/10.23641/asha.16821352.

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.

Cough in Idiopathic Pulmonary Fibrosis

Chronic cough is experienced by most patients with idiopathic pulmonary fibrosis (IPF). It is often the first symptom and is associated with reduced quality of life, increased rates of depression and anxiety, more severe physiological impairment, and disease progression. Although not fully understood, recent gains in understanding the pathophysiology of chronic cough in IPF have been made. The pathophysiology is likely multifactorial and includes alterations in mucous production and clearance, architectural distortion, and increased cough reflex sensitivity, suggesting a role for targeted therapies and multidisciplinary treatment. Modifiable comorbidities can also induce cough in patients with IPF. There is a renewed emphasis on measuring cough in IPF, with clinical trials of novel and repurposed therapies for chronic cough emerging in this population. This review provides an update on the clinical characteristics, pathophysiology, and measurement of chronic cough in patients with IPF and summarizes recent developments in non-pharmacological and pharmacological therapies.

Predictive Value of Cough Frequency in Addition to Aspiration Risk for Increased Risk of Pneumonia in Dysphagic Stroke Survivors: A Clinical Pilot Study

BACKGROUND

Post-stroke dysphagia leads to increased risk of aspiration and subsequent higher risk of pneumonia. It is important to not only diagnose post-stroke dysphagia early but also to evaluate the protective mechanism that counteracts aspiration, i.e., primarily cough. The aim of this study was to investigate the predictive value of cough frequency in addition to aspiration risk for pneumonia outcome.

METHODS

This was a single-center prospective observational study. Patients with first-ever strokes underwent clinical swallowing evaluation, fibreoptic endoscopic evaluation of swallowing (FEES), and overnight cough recording using LEOSound^® (Löwenstein Medical GmbH & Co. KG, Bad Ems, Germany ). Penetration-Aspiration Scale (PAS) ratings and cough frequency measurements were correlated with incidence of pneumonia at discharge.

RESULTS

11 women (37%) and 19 men (63%), mean age 70.3 years (SD ± 10.6), with ischemic stroke and dysphagia were enrolled. Correlation analysis showed statistically significant relationships between pneumonia and PAS (r = 0.521; p < 0.05), hourly cough frequency (r = 0,441; p < 0.05), and categories of cough severity (r = 0.428 p < 0.05), respectively. Logistic regression showed significant predictive effects of PAS (b = 0.687; p = 0.014) and cough frequency (b = 0.239; p = 0.041) for pneumonia outcome.

CONCLUSION

Cough frequency in addition to aspiration risk was an independent predictor of pneumonia in dysphagic stroke survivors.

A novel automatic cough frequency monitoring system combining a triaxial accelerometer and a stretchable strain sensor

Objective evaluations of cough frequency are considered important for assessing the clinical state of patients with respiratory diseases. However, cough monitors with audio recordings are rarely used in clinical settings. Issues regarding privacy and background noise with audio recordings are barriers to the wide use of these monitors; to solve these problems, we developed a novel automatic cough frequency monitoring system combining a triaxial accelerator and a stretchable strain sensor. Eleven healthy adult volunteers and 10 adult patients with cough were enrolled. The participants wore two devices for 30 min for the cough measurements. An accelerator was attached to the epigastric region, and a stretchable strain sensor was worn around their neck. When the subjects coughed, these devices displayed specific waveforms. The data from all the participants were categorized into a training dataset and a test dataset. Using a variational autoencoder, a machine learning algorithm with deep learning, the components of the test dataset were automatically judged as being a “cough unit” or “non-cough unit”. The sensitivity and specificity in detecting coughs were 92% and 96%, respectively. Our cough monitoring system has the potential to be widely used in clinical settings without any concerns regarding privacy or background noise.

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.

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.

Mechanisms and Rationale for Targeted Therapies in Refractory and Unexplained Chronic Cough

Chronic cough, defined as a cough lasting > 8 weeks, is a common medical condition that exerts a substantial physical, mental, and social burden on patients. A subset of patients with chronic cough are troubled with a cough that persists despite optimal treatment of presumed associated common and uncommon conditions (refractory chronic cough; RCC) or in which no diagnosable cause for cough can be identified despite extensive assessment (unexplained chronic cough; UCC). Many of these patients exhibit clinical features of cough hypersensitivity, including laryngeal paresthesia, hypertussia, and allotussia. Over-the-counter cough remedies are ineffective and can lead to intolerable side effects when used for RCC/UCC, and the lack of approved treatments indicated for these conditions reflects a major unmet need. An increased understanding of the anatomy and neurophysiology of protective and pathologic cough has fostered a robust clinical development pipeline of several targeted therapies for RCC/UCC. This manuscript reviews the mechanisms presumed to underly RCC/UCC together with the rationale and clinical evidence for several targeted therapies currently under clinical investigation, including transient receptor potential channel antagonists, P2X3-receptor antagonists, voltage-gated sodium channel blockers, neuromodulators, and neurokinin-1-receptor antagonists. Finally, we provide an overview of targets that have been investigated in preclinical models of cough and other airway diseases that may hold future promise for clinical studies in RCC/UCC. Development of targeted therapies with different sites of action may foster a precision medicine approach to treat this heterogeneous, underserved patient population.

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.

Prevalence and Characteristics of Chronic Cough in Adults Identified by Administrative Data

CONTEXT

International Classification of Diseases-9/10 codes for chronic cough (CC) do not exist, limiting investigation.

OBJECTIVE

To develop a computerized algorithm to determine CC prevalence and its characteristics.

DESIGN

This observational study using administrative data identified hierarchically patients aged 18 to 85 years with CC from 2013 to 2016. First, a specialist-diagnosed CC group was identified using an internal CC encounter code during an outpatient visit to a pulmonologist, allergist, otolaryngologist, or gastroenterologist. Subsequently, an event-diagnosed CC group was identified based on clinical notes through natural language processing, ICD-9/ICD-10 cough codes, and dispensed antitussives.

MAIN OUTCOME MEASURES

Prevalence of CC and comparison of clinical characteristics between specialist-diagnosed and event-diagnosed CC subgroups.

RESULTS

A total of 50,163 patients with CC of more than 8 weeks were identified. Of these, 11,290 (22.5%) were specialist diagnosed, and 38,873 (77.5%) were event diagnosed. The CC cohort was 57.4 ± 16.5 years of age; 67.6% were female. The overall prevalence was 1.04% (95% confidence interval = 1.03-1.06) in 2016. Prevalence in 2016 was higher in female patients (1.21%) than in male patients (0.81%), higher in patients aged 65 to 85 years (2.2%) than in patients aged 18 to 44 years (0.43%), and higher in Blacks (1.38%) than in Whites (1.21%). Compared with patients with event-diagnosed CC, patients with specialist-diagnosed CC exhibited significantly higher frequencies of laboratory tests and respiratory and nonrespiratory comorbidities and dispensed medication and lower frequency of pneumonia, all-cause and respiratory-cause emergency department visits and hospitalizations, and dispensed antitussives.

CONCLUSIONS

We identified a CC cohort using electronic data in a managed care organization. Prevalences varied by sex, age, and ethnicity. Clinical characteristics varied between specialist-diagnosed and event-diagnosed CC.

Clinical Characteristics of Cough Frequency Patterns in Patients with and without Asthma

BACKGROUND

Cough is a frequent symptom of asthma. Cough frequency (CoFr) monitoring devices are now available to objectively measure cough counts and offer a novel endpoint to assess asthma. However, little is known about CoFr in asthma.

OBJECTIVE

The aims were, first, to determine whether unique features of CoFr exist in asthmatic and nonasthmatic patients and, secondly, to evaluate relationships between CoFr and pathophysiological parameters of asthma.

METHODS

In the current study, 73 asthmatic and 63 nonasthmatic patients suffering from persistent cough were enrolled. At study entry, the Leicester Cough Questionnaire (LCQ health status), cough visual analog scale (VAS), Leicester Cough Monitor (LCM), fractional exhaled nitric oxide (FeNO) measurements, and spirometry were performed. In asthmatic patients, the bronchial hyperresponsiveness (BHR) test was conducted if applicable. In 28 asthmatic and 17 nonasthmatic patients, LCQ, VAS, and LCM were examined before and after treatment.

RESULTS

CoFr during nighttime (asleep) was significantly higher in asthmatic patients than in nonasthmatic patients. Twenty-four-hour CoFr significantly decreased after appropriate treatment and was correlated with changes in VAS and LCQ in all patients. The improvement in cough in asthmatic patients was greater during nighttime than during daytime (awake). CoFr in asthmatic patients was significantly correlated with BHR, but not with FeNO.

CONCLUSIONS

In asthmatic patients, nocturnal CoFr can be associated with BHR, was significantly higher before treatment, but improved more after treatment compared with nonasthmatic patients. Monitoring nocturnal CoFr may provide unique and valuable information on making an early prediction of therapeutic effects in asthma.