Objective measurement of cough in otherwise healthy volunteers with acute cough

Development of the Rapid Cough Questionnaire: Key item identification

BACKGROUND

The Leicester Cough Questionnaire (LCQ) is a reliable tool for measuring the multidimensional impact of cough on patients' quality of life; however, its scoring algorithm is lengthy and complex for routine clinical use.

OBJECTIVE

The study aimed to develop a simplified version of the LCQ, the Rapid Cough Questionnaire (RCQ), as a substitue in clinical practice and validate the RCQ using an independent cohort.

METHODS

To select items for the RCQ score, a correlation network was used to determine the items from each domain that were strongly correlated with the total LCQ score. The final items for the RCQ were selected on the basis of the centrality of the node degree, betweenness, and closeness in the correlation network.

RESULTS

The RCQ score was derived from 3 items: tiredness (LCQ3) in the physical domain, the feeling of being fed up (LCQ13) in the psychological domain, and annoyance with partner/family/friends (LCQ19) in the social domain. The correlation between the LCQ and RCQ was high, with a coefficient of 0.93 (P < .001). The mean score of the RCQ was 11.2 ± 3.2, with scores ranging from 5.15 to 19.55. The minimal clinically important difference in the RCQ score was calculated to be 1.6 using a distribution-based method. The concurrent validity of the LCQ and the RCQ with cough numeric rating scale was similar. In the validation cohort, the correlation between the LCQ and RCQ scores was consistent regardless of sex and etiology.

CONCLUSION

The RCQ score, which is concise, reliable, and valid, can be a valuable tool for patient assessment, particularly in clinical practice.

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.

Contribuciones relativas de las vías de transmisión de la COVID-19 entre el personal sanitario que presta atención a pacientes

RESUMENLas vías de transmisión de la COVID-19 desde pacientes infectados al personal de la salud son actualmente objeto de debate, pero su consideración resulta fundamental para la selección del equipo de protección personal. El objetivo de este documento es explorar las contribuciones de tres vías de transmisión-contacto, gota e inhalación-al riesgo de infección de COVID-19 adquirida por el personal sanitario en el ámbito laboral. El método consistió en la evaluación cuantitativa de los riesgos microbianos y de un modelo de exposición cuyos posibles parámetros se basaron en datos específicos del virus SARS-CoV-2 cuando se disponía de ellos. El hallazgo clave fue que las vías de transmisión por gotas e inhalación predominan sobre la vía de contacto, contribuyendo en promedio 35%, 57% y 8.2% a la probabilidad de infección cuando no se usa equipo de protección personal. En promedio, 80% de la exposición a la inhalación ocurre cuando el personal sanitario está cerca de los pacientes. La contribución relativa de las gotas y la inhalación depende de la emisión de SARS-CoV-2 en las partículas respirables (<10 μm) a través de la exhalación, y la inhalación se vuelve predominante, en promedio, cuando la emisión supera las cinco copias genéticas por minuto. La concentración prevista del SARS-CoV-2 en el aire de la habitación del paciente es baja (<1 copia del gen por m³ en promedio) y probablemente se encuentre por debajo del límite de cuantificación de muchos métodos de muestreo del aire. Los resultados demuestran el valor que supone la protección respiratoria del personal sanitario y que el muestreo de campo puede no ser lo suficientemente sensible para verificar la contribución que realiza la inhalación del SARS-CoV-2 al riesgo de infección de COVID-19 adquirida por el personal. La emisión e ineficacia del SARS-CoV-2 en gotas respiratorias de diferente tamaño es aún una brecha en el conocimiento, fundamental para comprender y controlar la transmisión de la COVID-19.

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.

Relative contributions of transmission routes for COVID-19 among healthcare personnel providing patient care

The routes of COVID-19 transmission to healthcare personnel from infected patients is the subject of debate, but is critical to the selection of personal protective equipment. The objective of this paper was to explore the contributions of three transmission routes-contact, droplet, and inhalation-to the risk of occupationally acquired COVID-19 infection among healthcare personnel (HCP). The method was quantitative microbial risk assessment, and an exposure model, where possible model parameters were based on data specific to the SARS-CoV-2 virus when available. The key finding was that droplet and inhalation transmission routes predominate over the contact route, contributing 35%, 57%, and 8.2% of the probability of infection, on average, without use of personal protective equipment. On average, 80% of inhalation exposure occurs when HCP are near patients. The relative contribution of droplet and inhalation depends upon the emission of SARS-CoV-2 in respirable particles (<10 µm) through exhaled breath, and inhalation becomes predominant, on average, when emission exceeds five gene copies per min. The predicted concentration of SARS-CoV-2 in the air of the patient room is low (< 1 gene copy per m³ on average), and likely below the limit of quantification for many air sampling methods. The findings demonstrate the value of respiratory protection for HCP, and that field sampling may not be sensitive enough to verify the contribution of SARS-CoV-2 inhalation to the risk of occupationally acquired COVID-19 infection among healthcare personnel. The emission and infectivity of SARS-CoV-2 in respiratory droplets of different sizes is a critical knowledge gap for understanding and controlling COVID-19 transmission.

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.

Development and validation of the COugh Assessment Test (COAT)

BACKGROUND AND OBJECTIVE

A cough-specific quality-of-life questionnaire is recommended to assess the impact of cough; however, a simple instrument to quantify cough is required for everyday clinical practice. This study was aimed to develop a short patient-completed questionnaire (COugh Assessment Test, COAT).

METHODS

The COAT was developed and validated by comparison with the Korean version of Leicester Cough Questionnaire (K-LCQ) and cough numeric rating scale (NRS, 0-10, 11-point scale) for chronic cough patients.

RESULTS

Item selection identified five items regarding cough frequency, daily activity, sleep disturbance, fatigue and cough hypersensitivity (0-4 scaling of items, 0-20 score range) through reliability test cohort (n = 78). Test-retest reliability was strong (intra-class correlation coefficient = 0.88). The final COAT was compared with K-LCQ and cough NRS in a validation cohort (n = 323). In Rasch analysis, COAT fitted well to a unidimensional model. Pearson correlations of COAT versus K-LCQ (i) before treatment, (ii) after treatment; COAT versus cough NRS (iii) before treatment, (iv) after treatment; (v) delta-COAT versus delta-cough NRS, (vi) delta-COAT versus delta-K-LCQ were (i) -0.71, (ii) -0.81, (iii) 0.69, (iv) 0.82, (v) -0.66 and (vi) 0.72, respectively.

CONCLUSION

The COAT is a useful, simple questionnaire for assessing and monitoring cough.

Pregabalin and Speech Pathology Combination Therapy for Refractory Chronic Cough: A Randomized Controlled Trial

BACKGROUND

Chronic refractory cough (CRC) is a difficult problem to treat. Speech pathology treatment (SPT) improves symptoms but resolution is incomplete. Centrally acting neuromodulators also improve cough symptoms, but not cough reflex sensitivity, and the effect is short-lived. We hypothesized that combined SPT and centrally acting neuromodulators would have a superior outcome than SPT alone. Our goal was to determine whether combined pregabalin and SPT is more effective than SPT alone.

METHODS

Randomized placebo controlled trial. Forty patients with CRC were randomly assigned to receive either combined SPT and pregabalin 300 mg daily or combined SPT and placebo. Outcome measures were collected at baseline, end of treatment, and 4 weeks after the end of treatment. Primary outcome measures were cough frequency using the Leicester Cough Monitor, cough severity using a visual analog scale (coughVAS), and cough-related quality of life (QOL) using the Leicester Cough Questionnaire (LCQ).

RESULTS

Cough severity, cough frequency, and cough QOL improved in both groups. The degree of improvement in LCQ and coughVAS was greater with combined SPT and pregabalin than SPT alone; the mean difference in LCQ was 3.5, 95%CI of difference 1.1 to 5.8; the mean difference in coughVAS was 25.1, 95% CI of difference 10.6 to 39.6. There was no significant difference in improvement in cough frequency between groups. There was no deterioration in symptoms once pregabalin was withdrawn. Median capsaicin cough sensitivity improved from 15.7 to 47.5 μM with combined SPT and pregabalin and from 3.92 to 15.7 μM with SPT alone.

CONCLUSIONS

Combined SPT and pregabalin reduces symptoms and improves QOL compared with SPT alone in patients with CRC.

Tools for assessing outcomes in studies of chronic cough: CHEST guideline and expert panel report

BACKGROUND

Since the publication of the 2006 American College of Chest Physicians (CHEST) cough guidelines, a variety of tools has been developed or further refined for assessing cough. The purpose of the present committee was to evaluate instruments used by investigators performing clinical research on chronic cough. The specific aims were to (1) assess the performance of tools designed to measure cough frequency, severity, and impact in adults, adolescents, and children with chronic cough and (2) make recommendations or suggestions related to these findings.

METHODS

By following the CHEST methodologic guidelines, the CHEST Expert Cough Panel based its recommendations and suggestions on a recently published comparative effectiveness review commissioned by the US Agency for Healthcare Research and Quality, a corresponding summary published in CHEST, and an updated systematic review through November 2013. Recommendations or suggestions based on these data were discussed, graded, and voted on during a meeting of the Expert Cough Panel.

RESULTS

We recommend for adults, adolescents (≥ 14 years of age), and children complaining of chronic cough that validated and reliable health-related quality-of-life (QoL) questionnaires be used as the measurement of choice to assess the impact of cough, such as the Leicester Cough Questionnaire and the Cough-Specific Quality-of-Life Questionnaire in adult and adolescent patients and the Parent Cough-Specific Quality of Life Questionnaire in children. We recommend acoustic cough counting to assess cough frequency but not cough severity. Limited data exist regarding the performance of visual analog scales, numeric rating scales, and tussigenic challenges.

CONCLUSIONS

Validated and reliable cough-specific health-related QoL questionnaires are recommended as the measurement of choice to assess the impact of cough on patients. How they compare is yet to be determined. When used, the reporting of cough severity by visual analog or numeric rating scales should be standardized. Previously validated QoL questionnaires or other cough assessments should not be modified unless the new version has been shown to be reliable and valid. Finally, in research settings, tussigenic challenges play a role in understanding mechanisms of cough.

An update on measurement and monitoring of cough: what are the important study endpoints?

Considerable progress has been achieved in the development of tools that assess cough. The visual analogue scale (VAS) for cough severity is widely used in clinical practice because it's simple and practical. The Leicester cough questionnaire (LCQ) and the cough-specific quality of life questionnaire (CQLQ) are the most widely used health status questionnaires for adults with chronic cough. They are well validated for assessing the impact of cough. Cough can be assessed objectively with challenge tests that measure the sensitivity of the cough reflex. Cough challenge tests are better used to determine the mechanism of action of therapy, rather than efficacy. Cough frequency monitoring, the preferred tool to objectively assess cough, is increasingly being used as primary end-points in clinical trials. The most widely used cough monitors are the Leicester cough monitor (LCM) and VitaloJak. They are ambulatory devices that consist of a microphone and recording device. Cough frequency monitors do not reflect the intensity or the impact of cough; hence their relationship with subjective measures of cough is weak. Cough should therefore be assessed with a combination of subjective and objective tools. There is a paucity of studies that have investigated the minimal important difference of cough frequency monitors, rendering further investigations needed.

Prostaglandin D2 and the role of the DP1, DP2 and TP receptors in the control of airway reflex events

Prostaglandin D2 (PGD2) causes cough and levels are increased in asthma suggesting that it may contribute to symptoms. Although the prostaglandin D2 receptor 2 (DP2) is a target for numerous drug discovery programmes little is known about the actions of PGD2 on sensory nerves and cough. We used human and guinea pig bioassays, in vivo electrophysiology and a guinea pig conscious cough model to assess the effect of prostaglandin D2 receptor (DP1), DP2 and thromboxane receptor antagonism on PGD2 responses. PGD2 caused cough in a conscious guinea pig model and an increase in calcium in airway jugular ganglia. Using pharmacology and receptor-deficient mice we showed that the DP1 receptor mediates sensory nerve activation in mouse, guinea pig and human vagal afferents. In vivo, PGD2 and a DP1 receptor agonist, but not a DP2 receptor agonist, activated single airway C-fibres. Interestingly, activation of DP2 inhibited sensory nerve firing to capsaicin in vitro and in vivo. The DP1 receptor could be a therapeutic target for symptoms associated with asthma. Where endogenous PGD2 levels are elevated, loss of DP2 receptor-mediated inhibition of sensory nerves may lead to an increase in vagally associated symptoms and the potential for such adverse effects should be investigated in clinical studies with DP2 antagonists.

Antitussive drugs--past, present, and future

Cough remains a serious unmet clinical problem, both as a symptom of a range of other conditions such as asthma, chronic obstructive pulmonary disease, gastroesophageal reflux, and as a problem in its own right in patients with chronic cough of unknown origin. This article reviews our current understanding of the pathogenesis of cough and the hypertussive state characterizing a number of diseases as well as reviewing the evidence for the different classes of antitussive drug currently in clinical use. For completeness, the review also discusses a number of major drug classes often clinically used to treat cough but that are not generally classified as antitussive drugs. We also reviewed a number of drug classes in various stages of development as antitussive drugs. Perhaps surprising for drugs used to treat such a common symptom, there is a paucity of well-controlled clinical studies documenting evidence for the use of many of the drug classes in use today, particularly those available over the counter. Nonetheless, there has been a considerable increase in our understanding of the cough reflex over the last decade that has led to a number of promising new targets for antitussive drugs being identified and thus giving some hope of new drugs being available in the not too distant future for the treatment of this often debilitating symptom.

A longitudinal assessment of acute cough

RATIONALE

Cough can be assessed with visual analog scales (VAS), health status measures, and 24-hour cough frequency monitors (CF(24)). Evidence for their measurement properties in acute cough caused by upper respiratory tract infection (URTI) and longitudinal data is limited.

OBJECTIVES

To assess cough longitudinally in URTI with subjective and objective outcome measures and determine sample size for future studies.

METHODS

Thirty-three previously healthy subjects with URTI completed cough VAS, Leicester Cough Questionnaire (LCQ-acute), and CF(24) monitoring (Leicester Cough Monitor) on three occasions, 4 days apart. Changes in subjects' condition were assessed with a global rating of change questionnaire. The potential for baseline first-hour cough frequency (CF(1)), VAS, and LCQ to identify low CF(24) was assessed.

MEASUREMENTS AND MAIN RESULTS

Mean ± SD duration of cough at visit 1 was 4.1 ± 2.5 days. Geometric mean ± log SD baseline CF(24) and median (interquartile range) cough bouts were high (14.9 ± 0.4 coughs/h and 85 [39-195] bouts/24 h). Health status was severely impaired. There was a significant reduction in CF(24) and VAS, and improvement in LCQ, from visits 1-3. At visit 3, CF(24) remained above normal limits in 52% of subjects. The smallest changes in CF(24), LCQ, and VAS that subjects perceived important were 54%, 2- and 17-mm change from baseline, respectively. The sample sizes required for parallel group studies to detect these changes are 27, 51, and 25 subjects per group, respectively. CF(1) (<20.5 coughs/h) was predictive of low CF(24).

CONCLUSIONS

CF(24), VAS, and LCQ are responsive outcome tools for the assessment of acute cough. The smallest change in cough frequency perceived important by subjects is 54%. The sample sizes required for future studies are modest and achievable.