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Background: Cough is predictive of exacerbations of chronic obstructive pulmonary disease (COPD). Little is known about cough reflex sensitivity during exacerbation of COPD and whether it is associated with exacerbation frequency. This pilot study aimed to investigate cough reflex sensitivity during and following recovery from exacerbation of COPD, and its association with the frequency of future exacerbations. In addition, the repeatability of cough reflex sensitivity in stable COPD was investigated., Methods: Twenty participants hospitalised with exacerbation of COPD underwent inhaled capsaicin challenge during exacerbation and after 6 weeks of recovery. The frequency of future exacerbations was monitored for 12 months. The repeatability of cough reflex sensitivity was assessed in separate participants with stable COPD, who underwent 2 capsaicin challenge tests, 6 weeks apart., Results: Cough reflex sensitivity was heightened during exacerbation of COPD. Geometric mean (SD) capsaicin concentration thresholds to elicit 5 coughs (C5) during exacerbation and after 6 weeks of recovery were 1.76 (3.73) vs. 8.09 (6.25) μmol L -1 , respectively (p < 0.001). The change in C5 from exacerbation to 6-week recovery was associated with the frequency of future exacerbations (ρ = - 0.687, p = 0.003). C5 was highly repeatable over 6 weeks in stable COPD, and intraclass correlation coefficient was 0.85., Conclusion: Cough reflex sensitivity is heightened during exacerbation of COPD and reduces after recovery. The persistence of cough reflex hypersensitivity at recovery was associated with the frequency of future exacerbations.

The accurate and consistent assessment of cough is essential not only for optimum standards of clinical care but also to drive forward advances in our understanding of cough. A range of tools for the subjective and objective measurement of cough exists, and their ongoing development has coincided with growth in clinical and preclinical research in cough, resulting in novel findings and promising new treatments. The most widely used and most fruitful approaches to assessing cough are discussed, along with some newer and preliminary techniques and directions for the future. These include methods for measuring cough-specific quality of life, subjective severity, cough frequency, intensity, and sensitivity of the underlying cough reflex. Ongoing development and more widespread adoption of cough assessment tools should help describe the heterogeneity of cough phenotypes, and may better guide treatment by enabling prediction of responses to pharmacological and nonpharmacological antitussive therapies. More detailed assessments of cough may also bring benefits in measuring the transmission of respiratory infections, or in managing reduced airway protection in neuromuscular disease. Population-wide assessments should also help understand the epidemiology of cough and assist in screening for disease., (Copyright © 2019 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.)

Functional brain imaging in individuals with chronic cough demonstrates reduced activation in cortical regions associated with voluntary cough suppression. Little is known about the ability of patients with chronic cough to suppress cough. This study aimed to compare the ability to voluntarily suppress cough during inhaled capsaicin challenge in participants with chronic refractory cough with that in healthy controls. In addition, this study aimed to assess the repeatability of capsaicin challenge test with voluntary cough suppression.Participants with chronic refractory cough and healthy controls underwent inhaled capsaicin challenge tests while attempting to suppress their cough responses. After 5 days, either a conventional capsaicin challenge test with no cough suppression attempt, or a repeat test with an attempt at cough suppression was performed. Threshold capsaicin concentrations required to elicit one, two and five coughs were calculated by interpolation. Objective 24-h cough frequency was measured in individuals with chronic refractory cough.Healthy controls were able to suppress capsaicin-evoked cough while participants with chronic refractory cough were not. Geometric mean±sd capsaicin dose thresholds for five coughs with (CS5) and without (C5) suppression attempts were 254.40±3.78 versus 45.89±3.95 µmol·L -1 , respectively, in healthy controls (p=0.033) and 3.34±5.04 versus 3.86±5.13 µmol·L -1 , respectively, in participants with chronic refractory cough (p=0.922). Capsaicin dose thresholds for triggering five coughs with self-attempted cough suppression were significantly lower in participants with chronic refractory cough than in healthy controls; geometric mean±sd 4.94±4.43 versus 261.10±4.34 µmol·L -1 , respectively; mean difference (95% CI) 5.72 (4.54-6.91) doubling doses (p<0.001). Repeatability of cough suppression test in both patients and healthy controls was high; intraclass correlation coefficients of log(CS5) values 0.81 and 0.87, respectively. CS5 was associated with objective cough frequency (ρ=-0.514, p=0.029).Participants with chronic refractory cough were less able to voluntarily suppress capsaicin-evoked cough compared to healthy controls. This may have important implications for the pathophysiology and treatment of chronic cough., Competing Interests: Conflict of interest: P.S.P. Cho reports a grant from Merck outside the submitted work. Conflict of interest: H.V. Fletcher has nothing to disclose. Conflict of interest: R.D. Turner has nothing to disclose. Conflict of interest: C.J. Jolley has nothing to disclose. Conflict of interest: S.S. Birring reports grants and personal fees for advisory board work from Merck, personal fees for advisory board work from Bayer, GSK, Menlo and Sanofi, and conference travel expenses from Boehringer Ingelheim, outside the submitted work., (Copyright ©ERS 2019.)

Cough is a prominent symptom of pulmonary tuberculosis (TB), one of the oldest and most prevalent infectious diseases. Coughing probably has a pivotal role in transmission of the causative organism Mycobacterium tuberculosis. Despite this, little research to date has addressed this subject. Current knowledge of the mechanisms of cough in TB and how exactly coughing patterns predict infectiousness is scant, but this is changing. This overview summarises the existing evidence for the infectiousness of cough in TB, clinical correlates, and possible causes of cough in TB. Potential unique characteristics of cough in the disease are discussed, as is treatment and the subjective awareness of coughing in the disease., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Setting: Although cough in tuberculosis (TB) is presumed to be important for transmission, there is little objective supporting evidence., Objective: To describe 24-h cough frequency in a group with TB, and investigate associations with household rates of infection., Design: Patients with a new diagnosis of pulmonary TB underwent 24-h cough frequency measurement at or just before initiation of anti-tuberculosis treatment. A group with latent Mycobacterium tuberculosis infection (LTBI) acted as controls. Rates of infection among household contacts of sputum smear-positive TB were measured using the interferon-gamma release assay and the tuberculin skin test, and compared with variables relating to the contacts themselves, and to the index case, including cough frequency., Results: Daily cough frequency in TB patients (n = 44) was variable (geometric mean [GM] 174, interquartile range [IQR] 68-475 coughs/24 h), higher than in LTBI (n = 17; GM 19 coughs/24 h, IQR 8-53; P < 0.001), and higher during the day than overnight (GM 8.9 coughs/h, IQR 4.1-19.0 vs. GM 2.9 coughs/h, IQR 0.7-13.4; P < 0.0001). Also, 24-h cough frequency in TB was associated with sputum smear status (P = 0.040), but not smoking (P = 0.475). Multivariable logistic regression confirmed that infection in contacts was independently associated with index case sputum smear grade (P = 0.014) and cough frequency (P = 0.022)., Conclusion: Measurement of 24-h cough frequency in pulmonary TB helps predict infectiousness and transmission patterns.

Chronic cough is common in the community and can cause significant morbidity. It is not clear how closely treatment guidelines are used in general practice, or how often specialist referral is indicated. We aimed to assess the management of chronic cough in primary care before referral to a cough clinic, and to assess the outcome of managing chronic cough with an approach of simple investigation and empirical treatment trials. Data were extracted from the records of all patients attending a district general hospital respiratory clinic over a two-year period with isolated chronic cough lasting ⩾8 weeks. The clinic assessed symptoms with a cough-severity visual analogue scale and the Leicester Cough Questionnaire. Among 266 patients, the most frequent diagnoses were asthma (29%), gastro-oesophageal reflux (22%) and angiotensin-converting enzyme inhibitor use (14%). In all, 12% had unexplained chronic cough. Common diagnoses had often not been excluded in primary care: only 21% had undergone spirometry, 86% had undergone chest radiography and attempts to exclude asthma with corticosteroids had been made only in 39%. In the clinic few investigations were conducted that were not available in primary care. Substantial improvements in symptoms occurred with a median (interquartile range) total of 2 (2-3) clinic visits. We estimated that 87% of patients could have been managed solely in primary care; we did not identify distinguishing characteristics among this group. Most cases of chronic cough referred to secondary care could be managed with a simple and systematic approach, which is potentially transferrable to a community setting.

Cough is a predominant feature of respiratory infection and, in tuberculosis, is of prime importance for transmitting infection. Tuberculosis is transmitted by the air, yet the process by which bacilli are aerosolized has received little attention. Features of cough may account for differences in transmission rates from source cases of pulmonary disease. We review the literature on the mechanisms and characteristics of cough in tuberculosis in the context of the dissemination of infection. Coughing is probably more important than other respiratory maneuvers, and characteristics of mucus may have an important role but data are scarce. Direct mechanisms of cough in tuberculosis are unknown, as are temporal and other patterns that correlate with the release of viable airborne bacilli. Other than antituberculous chemotherapy and masks, there are few methods of modulating cough in tuberculosis. This is an increasingly important area for research., (© The Author 2014. Published by Oxford University Press on behalf of the Infectious Diseases Society of America. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.)

Background: Cough causes morbidity and transmits disease yet has been under-researched. The best method for recognising and counting coughs remains unclear. We tested the accuracy of the human ear and measured the influence of visual data on cough counting. We also evaluated PulmoTrack®, a potentially fully-automated cough monitor., Methods: Consistency amongst listeners and the effect of visual data: Three 14–22-min sequences containing 45–79 coughs were played to 15 respiratory physicians on at least two occasions. Only sound was played on the first occasions but on the final occasion a simultaneous display of audio activity was included. Counts of cough sounds across methods and listeners were compared. Evaluation of PulmoTrack®: 20-h recordings were made from 10 patients with cough. Automated counts were compared with assessment by one investigator., Results: Agreement among listeners was high. The intraclass correlation coefficient (ICC) for cough counts by ear alone was 0.89 (95% CI, 0.65–1.00). With a concurrent visual display of sound amplitude it was 0.94 (0.80–1.00). 4.8% (0.6–9.5) fewer coughs were counted using visual data than by listening alone (mean [SD] total coughs: 190.2 [3.4] vs 200.7 [14.6]; p = 0.04). Cough frequencies reported by PulmoTrack® and the researcher differed substantially (ICC 0.23, −0.51 to 0.34, p = 0.87); PulmoTrack® had a sensitivity of 26% for detecting coughs identified by ear., Conclusion: Coughs are well recognised by different listeners. The method used to count coughs should be clearly described as visual information has a significant influence. Non-automated cough counting remains the gold standard method of quantifying cough.