Controversies in the evaluation and management of chronic cough

Clinical Characteristics and Impact of Inducible Laryngeal Obstruction in the UK National Registry

BACKGROUND

Inducible laryngeal obstruction (ILO) describes inappropriate laryngeal closure during respiration, with airflow obstruction occurring at the glottic and/or supraglottic level, leading to breathlessness.

OBJECTIVE

There is a paucity of data describing the demographics and impact of ILO. We aimed to report the clinical and demographic features of ILO in individuals entered prospectively in the UK national ILO registry.

METHODS

Data were entered into a Web-based registry from participants with endoscopically confirmed ILO who were attending four established UK-wide specialist ILO centers between March 2017 and November 2019. All patients provided written informed consent.

RESULTS

Data from 137 individuals were included. Most (87%) had inspiratory ILO and required provocation during endoscopy to induce symptoms. There was a female predominance (80%), mean age 47 years (SD, 15 years). The most common comorbidities included asthma (68%) and reflux (57%). Health care use was high: 88% had attended emergency health care with symptoms at least once in the previous 12 months and nearly half had been admitted to the hospital. A fifth had required admission to critical care owing to ILO symptoms. Patient morbidity was substantial; 64% reported impaired functional capacity (≥3 on the Medical Research Council Dyspnoea Scale) and a third stated that symptoms affected working capability.

CONCLUSION

We describe the first multicenter prospective characterization of individuals with endoscopically diagnosed ILO. Analysis of our multicenter data set identified ILO as associated with a high burden of morbidity and health care use, comparable to severe asthma. These data will support the development of health care resources in the future and guide research priorities.

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.

Chronic cough: is the end nigh?

Chronic cough (lasting more than 8 weeks) is a common condition with substantial psychosocial impact. Despite huge efforts following robust guidelines, chronic cough in many patients remains refractory or unexplained (RU-CC). Recent insights support a significant role for cough hypersensitivity in RU-CC, including neuropathophysiological evidence from inhalational cough challenge testing, functional magnetic resonance imaging, and airway nerve biopsy. Along with improved approaches to measuring cough, this knowledge has developed in tandem with repurposing neuromodulator medications, including gabapentin, and evidence for non-pharmacological treatments. Most significantly, there is now a pipeline for novel classes of drugs specifically for chronic cough. The P2X3 receptor antagonist gefapixant is the first such drug to be approved in Europe. However, challenges persist. The field of chronic cough needs more robust epidemiological data, enhanced diagnostic tools, further well-designed clinical trials accounting for the effects of placebo, and treatments with minimal side-effects. Addressing these challenges are novel chronic cough registries, improved International Classification of Diseases (10th revision) coding, genetic testing options and further mechanistic studies. This Viewpoint article discusses these facets and considers how, whilst the end of chronic cough may not be imminent for all patients, the evolving landscape looks increasingly optimistic.

Clinical Practice Guideline: Chronic Cough

BACKGROUND

Chronic cough, i.e., cough lasting longer than eight weeks, affects approximately 10% of the population and is a common reason for outpatient medical consultation. Its differential diagnosis is extensive, and it is generally evaluated in poorly structured fashion with a variety of diagnostic techniques. The German Clinical Practice Guideline on Acute and Chronic Cough was updated in 2021 and contains a description of the recommended stepwise, patient-centered, and evidence-based procedure for the management of chronic cough.

METHODS

The guideline has been updated in accordance with the findings of a systematic search of the literature for international guidelines and systematic reviews. All recommendations were developed in an interdisciplinary manner and agreed upon by formal consensus. The target group consists of adult patients with cough.

RESULTS

History-taking, after the exclusion of red flags, should include questioning about smoking status, medications, and relevant present and past illnesses (COPD, asthma). Subsequent diagnostic testing should include a chest x-ray and pulmonary function tests. If the patient is taking an ACE inhibitor, a test of drug discontinuation can be carried out first. Radiologically detected pulmonary masses or evidence of rare diseases (interstitial lung diseases, bronchiectasis) are an indication for chest CT or for direct referral to an appropriate specialist. If the imaging studies and pulmonary function tests are normal, the patient is most likely suffering from a disease entity that can be treated empirically, such as upper airway cough syndrome or cough variant asthma. Any patient with an unexplained or refractory cough must receive proper patient education; individual therapeutic trials of physiotherapeutic or speechtherapeutic methods are possible, as is the off-label use of gabapentin or morphine.

CONCLUSION

Chronic cough should be evaluated according to an established diagnostic algorithm in collaboration with specialists. Treatments such as inhaled corticosteroids should be tested exhaustively in accordance with the guidelines, and the possibility of multiple causes as well as the role of patient compliance should be kept in mind before a diagnosis of unexplained or intractable cough is assigned.

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.

Animal models of cough

Cough is a vital airway reflex that keeps the respiratory tract wisely protected. It is also a sign of many diseases of the respiratory system and it may become a disease in its own right. Even though the efficacy of antitussive compounds is extensively studied in animal models with promising results, the treatment of pathological cough in humans is insufficient at the moment. The limited translational potential of animal models used to study cough causes, mechanisms and possible therapeutic targets stems from multiple sources. First of all, cough induced in the laboratory by mechanical or chemical stimuli is far from natural cough present in human disease. The main objective of this review is to provide a comprehensive summary of animal models currently used in cough research and to address their advantages and disadvantages. We also want to encourage cough researchers to call for precision is research by addressing the sex bias which has existed in basic cough research for decades and discuss the role of specific pathogen-free (SPF) animals.

A new simple score of chronic cough: cough evaluation test

Background

Chronic cough has an important impact on physical, social and psychological aspects. A simple and effective method to assess different aspects of chronic cough severity is required. We aimed to develop a simple, self-completed test, Cough Evaluation Test (CET), to evaluate cough severity and its impact on health.

Method

The items of preliminary CET were generated based on literature review and clinical practice. Items reduction was conducted by modified Delphi method. Patients with chronic cough were recruited to complete CET, Cough Visual Analog Scales (VAS), Mandarin Chinese version of the Leicester Cough Questionnaire (LCQ-MC), and Cough Symptom Score (CSS). Reassessments were performed at 1 week apart before treatment, and after more than 2 weeks treatments. Concurrent validation, internal consistency, repeatability, responsiveness and the minimal important difference (MID) were determined.

Results

CET consists of five items with a 5-point Likert scale (1–5 scaling of items, 5–25 score range). The Cronbach’s alpha values for CET was 0.80. CET showed a stronger correlation with LCQ-MC (r = − 0.74) compared to that between LCQ-MC with VAS (r = − 0.61). CET also showed a stronger correlation with VAS (r = 0.70) compared to that between VAS with other measures. Intraclass correlation coefficients for CET was 0.84. In patients undergoing treatment, CET scores significantly changed (p < 0.0001). The MID of CET was 2.

Conclusion

Cough Evaluate Test is a reliable, valid and responsive tool to simply evaluate impact of cough on physical, social and psychological aspects.

Cough: A Practical and Multifaceted Approach to Diagnosis and Management

Cough is a common symptom often confronted in the clinical setting. Time and resources attributed to cough place an undue burden on patients and the health care system. One characteristic of cough that likely contributes to this is the multifactorial nature of cough. Physicians are trained to find a single diagnosis to explain symptoms. With cough, if all factors contributing are not identified and treated together, the cough often remains unresolved. This article provides a practical approach to treatment and management of cough, emphasizing causes and potentiators.

Controversies in Cough Management: An Indian Perspective

Chronic cough is one of the most common symptoms for patients-seeking consultation in an outpatient clinic. It is associated with substantial psychological, physical, and social burdens and impaired quality of life. This review highlights some of the major diagnostic and management challenges confronted in the field of cough with a special focus on the Indian perspective. Heterogeneity in definitions and classifications and challenges associated with over-the-counter drug use and irrational drug use are some of the major controversies. Streamlined diagnostic approach involving a combination of subjective and objective tools, evidence-based amendments in clinical practice, and stringent implementation of regulatory guidelines are mandatory to address controversies in cough management in developing countries.

IFN-γ Enhances the Cough Reflex Sensitivity via Calcium Influx in Vagal Sensory Neurons

RATIONALE

Cough hypersensitivity syndrome is often triggered by a viral infection. The viral infection might trigger cough hypersensitivity via increasing the release of IFN-γ from T lymphocytes in the lung.

OBJECTIVES

To investigate effects of IFN-γ on the vagal sensory neurons and the cough reflex.

METHODS

Effects of IFN-γ on the cough reflex were investigated in guinea pigs. Cellular immunofluorescence imaging, calcium imaging, and patch clamp techniques were used to study effects of IFN-γ in primary cultured rat vagal sensory neurons.

MEASUREMENTS AND MAIN RESULTS

Intratracheal instillation of IFN-γ enhanced the cough response to citric acid in vivo. IFN-γ significantly increased levels of phosphorylated signal transducer and activator of transcription-1 but not phosphorylated transient receptor potential vanilloid 1 in vitro. Not only did IFN-γ enhance the response of neurons to capsaicin and electric stimulation, but also it directly induced Ca²⁺ influx, membrane depolarization, and action potentials in neurons via the Janus kinase, protein kinase A, and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid pathways. However, IFN-γ did not elicit Ca²⁺ release from the endoplasmic reticulum via the phospholipase C pathway. Although IFN-γ-induced action potentials were suppressed by Ca²⁺ influx inhibitors, IFN-γ-induced Ca²⁺ influx was not altered by an inhibitor of rapid sodium channels.

CONCLUSIONS

The membrane potential in vagal sensory neurons may be depolarized by IFN-γ-induced Ca²⁺ influx. The depolarization of membrane potentials may enhance the cough reflex sensitivity and cause action potentials. IFN-γ may be a new target for treating cough hypersensitivity syndrome and postviral cough.

Efficacy and predictors of response to inhaled corticosteroid treatment for chronic cough

BACKGROUND/AIMS

Inhaled corticosteroids (ICS) are a treatment of choice for eosinophilic airway diseases, but their efficacy for other causes of chronic cough is controversial.

METHODS

We conducted a prospective observational study to determine the ICS efficacy and clinical predictors of response to ICS in patients with upper airway cough syndrome (UACS) or unexplained chronic cough (UCC). Sixty-eight patients with UACS and 33 patients with UCC (duration of cough ≥ 8 weeks) were treated with ICS: 250 µg of fluticasone propionate or 400 µg of budesonide twice a day at physician's discretion. They were followed after 2 weeks to assess persistent cough which was measured as 0% to 100% compared with baseline cough frequency.

RESULTS

The median grade of persistent cough after 2-week ICS treatment was 40% (interquartile range [IQR], 10 to 70) in UACS and was 50% (IQR, 20 to 70) in UCC. The only adverse event was infrequent, mild hoarse voice (five UACS and one UCC). Long duration of cough (≥ 52 weeks) and cough not aggravated by cold air exposure were predictors of a poorer response to short course ICS treatment (logistic regression analysis, p = 0.018 and p = 0.031, respectively). However, prolonged treatment with ICS more than 2 weeks was more effective in patients with long cough duration (≥ 52 weeks).

CONCLUSION

Short course ICS treatment has modest efficacy on UACS and UCC without significant adverse events. Duration of cough and cough triggered by cold air exposure were the clinical factors associated with ICS response. Extended treatment with ICS may be beneficial in patients with long duration of cough.

Exposure to bioaerosols at open dumpsites: A case study of bioaerosols exposure from activities at Olusosun open dumpsite, Lagos Nigeria

Activities associated with the open dumping of municipal solid waste has the potential for greater impact on the environment and public health compared to other forms of waste-to-land treatment of such wastes. However, there is a lack of quantitative data on the exposure to bioaerosols from open dumpsites, hence impeding the development of effective interventions that would reduce the risk of respiratory symptoms among scavengers and waste workers at such dumpsites. This study investigated exposure to bioaerosols at Olusosun open dumpsite, Lagos Nigeria using three methodologies; (1) Conducting a cross-sectional survey on the respiratory health of the population on the dumpsite, (2) Measuring bioaerosol concentrations in the ambient air by measuring four bioaerosols indicator groups (total bacteria, gram-negative bacteria, Aspergillus fumigatus and total fungi) using a Anderson six stage impactor sampler, (3) Measuring activity related exposures to bioaerosols using an SKC button personal sampler. After a cross sectional health survey of 149 participants (waste workers, scavengers, middlemen, food vendors and business owners), smokers reported higher symptoms of chronic cough (21%) and chronic phlegm (15%) compared to non-smokers (chronic cough 15%, chronic phlegm 13%). Years of work > 5 years showed no statistically significant association with chronic phlegm (OR 1.2, 95% CI 0.4-3.4; p > 0.05) or asthma (OR 1.8, 95% CI 0.6-5.2; p > 0.05). At the 95th percentile, the concentration of total bacteria was the highest (2189 CFU/m³), then gram negative bacteria (2188 CFU/m³), total fungi (843 CFU/m³) and Aspergillus fumigatus (441 CFU/m³) after ambient air sampling. A comparison of the data showed that the activity-based sampling (undertaken using body worn personal sampler) had higher bioaerosols concentrations (10⁴ -10⁶ CFU/m³), i.e. 2-3 logs higher than those recorded from static ambient air sampling. Bioaerosol exposure was highest during scavenging activities compared to waste sorting and site supervision. Particle size distributions showed that 41%, 46%, 76% and 63% of total bacteria, gram-negative bacteria, Aspergillus fumigatus and total fungi respectively were of respirable sizes and would therefore be capable of penetrating deep into the respiratory system, posing a greater human health risk. This study has shown that exposure to bioaerosols can be associated with activities undertaken at open dumpsites and may contribute to the high prevalence of the chronic respiratory symptoms among the workers in such environments.

Impaired cough suppression in chronic refractory cough

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.

Efficacy and Safety of Gabapentin in the Treatment of Chronic Cough: A Systematic Review

Despite recent clinical guidelines, the optimal therapeutic strategy for the management of refractory chronic cough is still a challenge. The present systematic review was designed to assess the evidence for efficacy and safety of gabapentin in the treatment of chronic cough. A systematic search of PubMed, Embase, Cochrane Library databases, and publications cited in bibliographies was performed. Articles were searched by two reviewers with a priori criteria for study selection. Seven relevant articles were identified, including two randomized controlled trials, one prospective case-series designed with consecutive patients, one retrospective case series of consecutive patients, one retrospective case series with unknown consecutive status, and two case reports comprising six and two patients, respectively. Improvements were detected in cough-specific quality of life (Leicester Cough Questionnaire score) and cough severity (visual analogue scale score) following gabapentin treatment in randomized controlled trials. The results of prospective case-series showed that the rate of overall improvement of cough and sensory neuropathy with gabapentin was 68%. Gabapentin treatment of patients with chronic cough showed superior efficacy and a good safety record compared with placebo or standard medications. Additional randomized and controlled trials are needed.

Managing patients with chronic cough: challenges and solutions

Chronic cough is a common complaint and a frequent cause of medical consultation. Its management can be difficult. We present here an overview of the current guidelines for the management of chronic cough. Different steps are detailed, including the initial research of an obvious etiology and alert signs that should lead to further investigation of underlying condition. The diagnosis of the most frequent causes: asthma, non-asthmatic eosinophilic bronchitis, gastroesophageal reflux disease and upper airway cough syndrome should be considered, assessed and treated accordingly. Recent advances have been made in the comprehension of refractory chronic cough pathophysiology as well as its pharmacologic and non-pharmacologic treatment, especially speech pathology therapy.

Physiotherapy and Speech and Language therapy intervention for chronic cough

There are few effective pharmacological therapies available to treat refractory chronic cough. Functional MRI studies of the brain have recently shown that patients with chronic cough have dysfunctional inhibitory control of cough. Self-management therapies delivered by physiotherapists or speech therapists are effective at suppressing cough. They enable patients to consciously suppress the urge to cough. The intervention consists of education, laryngeal hygiene, cough suppression and distraction measures and behaviour modification. The efficacy of Physiotherapy and Speech And Language Intervention (PSALTI) has been confirmed in two randomised control trials. In one trial, there was a 41% reduction in cough frequency with PSALTI, assessed objectively with the Leicester Cough Monitor, and a clinically significant improvement in quality of life. Importantly, the improvement in cough was sustained when therapy was discontinued. The addition of the Speech Pathology Treatment to neuromodulator drug therapy, Pregabalin has also been evaluated in a clinical trial. There was a clinically significant improvement in quality of life, and this was sustained when therapy was discontinued. The mechanism of action of PSALTI is not known and this should be investigated in future. Further studies are needed to identify the components of PSALTI that deliver the most benefit, and determine whether PSALTI is effective in cough associated with other chronic lung disorders.

Physiotherapy, and speech and language therapy intervention for patients with refractory chronic cough: a multicentre randomised control trial

BACKGROUND

Physiotherapy, and speech and language therapy are emerging non-pharmacological treatments for refractory chronic cough. We aimed to investigate the efficacy of a physiotherapy, and speech and language therapy intervention (PSALTI) to improve health-related quality of life (HRQoL) and to reduce cough frequency in patients with refractory chronic cough.

METHODS

In this multicentre randomised controlled trial, patients with refractory chronic cough were randomised to four weekly 1:1 sessions of either PSALTI consisting of education, laryngeal hygiene and hydration, cough suppression techniques, breathing exercises and psychoeducational counselling or control intervention consisting of healthy lifestyle advice. We assessed the change in HRQoL at week 4 with the Leicester Cough Questionnaire (LCQ). Secondary efficacy outcomes included 24-hour objective cough frequency (Leicester Cough Monitor) and cough reflex sensitivity. The primary analysis used an analysis of covariance adjusted for baseline measurements with the intention-to-treat population. This study was registered at UK Clinical Research Network (UKCRN ID 10678).

FINDINGS

Between December 2011 and April 2014, we randomly assigned 75 participants who underwent baseline assessment (34 PSALTI and 41 controls). In the observed case analysis, HRQoL (LCQ) improved on average by 1.53 (95% CI 0.21 to 2.85) points more in PSALTI group than with control (p=0.024). Cough frequency decreased by 41% (95% CI 36% to 95%) in PSALTI group relative to control (p=0.030). The improvements within the PSALTI group were sustained up to 3 months. There was no significant difference between groups in the concentration of capsaicin causing five or more coughs.

INTERPRETATION

Greater improvements in HRQoL and cough frequency were observed with PSALTI intervention. Our findings support the use of PSALTI for patients with refractory chronic cough.

TRIAL REGISTRATION NUMBER

UKCRN ID 10678 and ISRCTN 73039760; Results.

'Chronic cough, cause unknown': A qualitative study of patient perspectives of chronic refractory cough

Chronic refractory cough patients have persistent, unexplained, treatment-resistant symptoms. Very little is known about non-physiological processes underlying chronic refractory cough or patients' experience of the condition. In all, 14 patients participated in semi-structured interviews. Interviews were based on the comprehensive cognitive behavioural model and analysed thematically. Eight key themes emerged illustrating that the experience of the onset and persistence of chronic refractory cough is complex, often involving multiple interlinking factors. Themes highlighted the involvement of biological and psychological factors, and the prominent role of the social dimension in how the cough is experienced, perceived and managed. Implications for intervention development are discussed.

Cough frequency monitors: can they discriminate patient from environmental coughs?

BACKGROUND

Objective cough frequency measurements are increasingly applied in clinical research. Technological advances enable automated detection and counting of cough events from sound recordings of many hours' duration. A possible limitation of sound-based cough frequency measurement is the contamination of recordings by environmental coughs (coughs from persons other than the patient). This study aimed to investigate the accuracy of a sound-based cough monitor for detecting and discriminating patient cough from environmental cough.

METHODS

As part of a stroke trial (ISRCTN40298220), patients on a hospital ward underwent 15-minute recordings using the Leicester Cough Monitor (LCM), a sound-based cough monitor ('semi-automated counts'). Participants and other persons in the environment were prompted to cough. An observer present in the room recorded the number of patient and environmental coughs ('live counts'). LCM counts were also compared against a manual cough count, the most commonly used gold standard to determine accuracy ('manual sound counts' from listening to recordings), by a blinded assessor who cross-referenced timed cough events from the respective methods. Data for automated, manual and live cough counts were analyzed using agreement statistics.

RESULTS

On sound recordings from five patients, there were 65 patient coughs and 78 environmental coughs (manual counts). Absolute agreement for patient cough count between all three measurement methods (LCM automated, live, and manual sound counts) was high, with intra-class correlation coefficient of 0.94 [95% confidence intervals (CI): 0.74, 0.99]. The proportion of exact agreements for patient cough between LCM and manual count was 0.92, and kappa was 0.84 (95% CI: 0.75, 0.93). The LCM showed sensitivity of 0.94 (95% CI: 0.84, 0.98), specificity of 0.91 (95% CI: 0.82, 0.96), positive predictive value of 0.90 (95% CI: 0.79, 0.95) and negative predictive value of 0.95 (95% CI: 0.86, 0.98) for detecting patient coughs.

CONCLUSIONS

This preliminary study supports the validity of the cough monitor for detecting and discriminating patient from environmental cough. Further validation is recommended, to describe the level of accuracy with greater precision.

Evidence-based Evaluation and Management of Chronic Cough

Chronic cough is common and has a significant impact on the wellbeing of patients and the use and cost of health care services. Traditionally the approach to chronic cough in patients who are nonsmokers and are not taking an angiotensin-converting enzyme inhibitor has focused on the diagnosis and management of the upper airway cough syndrome, asthma, and reflux disease. The evaluation of patients with chronic cough frequently involves trials of empiric therapy for these 3 conditions. Chronic cough may be perpetuated by abnormalities of the cough reflex and sensitization of its afferent and central components.

Causes of Chronic Cough in Non-smoking Patients

Chronic cough is a common medical problem. The aim of the study was to analyze chronic cough causes in non-smoking patients and to search for demographic factors associated with different cough reasons. The etiology of cough was determined by medical history, diagnostic tests and response to specific treatment. Patients with significant abnormalities in the chest radiograph or spirometry were not included. The study included 131 non-smoking patients; median age 54 years, 77 % female. The most frequent causes of cough were gastroesophageal reflux disease (GERD) (62 %) and upper airway cough syndrome (UACS) (46 %). Cough variant asthma and non-asthmatic eosinophilic bronchitis (NAEB) were diagnosed in 32 (25 %) and 19 (15 %) patients, respectively. Other cough causes were found in 27 patients (21 %). Asthma was a significantly more common cause of chronic cough in women than in men (31 % vs. 3 %, p = 0.005). A reverse relationship was demonstrated for UACS (39 % vs. 67 %, p = 0.01). Patients with chronic cough aged >50 yrs were more likely to be diagnosed with less common cough causes. In conclusion, the most common chronic cough reasons are GERD and UACS. Asthma-related cough is diagnosed more frequently in females, while UACS-related cough is more frequent in males.

Chronic cough and a normal chest X-ray - a simple systematic approach to exclude common causes before referral to secondary care: a retrospective cohort study

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.

The Intensity of Voluntary, Induced, and Spontaneous Cough

BACKGROUND

The intensity of cough is an important determinant of cough severity. Few studies have quantified cough intensity in patients with chronic cough with objective measures. We investigated the intensity of voluntary, induced, and spontaneous cough in patients with chronic cough and healthy control subjects.

METHODS

Patients with chronic cough and control subjects underwent physiologic assessment of the intensity of maximum voluntary, capsaicin-induced, and spontaneous cough. Assessments included measurement of gastric pressure (Pga) and esophageal pressure (Pes) during cough, peak cough flow (PCF), expiratory muscle strength (twitch gastric pressure [TwPga]), and cough compression phase duration (CPD). Subjective perception of cough intensity was assessed using a visual analog scale (VAS).

RESULTS

Pes, Pga, and PCF during maximum voluntary cough were significantly greater in patients with chronic cough compared with control subjects (P = .003-.042). There was no difference in TwPga between patients and control subjects. CPD was increased in female patients compared with control subjects (mean ± SD, 0.50 ± 0.22 s vs 0.28 ± 0.17 s; P = .007). Mean ± SD Pes during spontaneous cough was comparable to induced cough (128 ± 28 cm H2O vs 122 ± 37 cm H2O, P = .686) but less than maximum voluntary cough (170 ± 46 cm H2O, P = .020). Median within-subject correlation coefficients between cough intensity VAS and Pes, Pga, and PCF were r = 0.82 to 0.86.

CONCLUSIONS

Maximum voluntary cough intensity was increased in patients with chronic cough compared with control subjects. There was no significant difference in expiratory muscle contractility. Further studies should evaluate the compressive phase of cough in more detail. Physiologic measures of cough intensity correlated strongly with subjective perception of intensity in patients with chronic cough and may be relevant objective outcome measures for clinical studies.

Efficacy and safety of Maekmoondong-tang for chronic dry cough: a study protocol for a randomized controlled trial

Background

Chronic cough, defined it lasts more than 8 weeks. The symptom is common, but highly troublesome, and it reduces quality of life. Despite much effort to develop a protocol for diagnosis and treatment of chronic cough, it remains problematic to determine its cause. As a result, treatment is often unsuccessful. Thus, there is much interest regarding the use of symptomatic drugs to control chronic cough.

Maekmoondong-tang is widely used in East Asian countries to treat chronic dry cough. Several experimental studies have reported that the herbal medicine has immunomodulatory and antitussive effects. Clinical studies involving Maekmoondong-tang have also been carried out; however, these studies have involved treating various diseases as a whole rather than chronic cough itself. Thus, we aim to evaluate the efficacy and safety of Maekmoondong-tang in chronic dry cough patients with a randomized controlled trial.

Methods/Design

This study is designed as an exploratory, single-center, placebo-controlled, double-blind, randomized, parallel group clinical trial. Patients with dry cough that has lasted more than 8 weeks will be recruited, after a 1-week run-in period, and randomly allocated to either the Maekmoondong-tang treatment group or the placebo group. The patients will receive Maekmoondong-tang or placebo granules 3 times daily for 4 weeks, with a 2-week follow-up. The primary outcome is a 10-point cough diary that will be recorded on a daily basis. The secondary outcomes comprise a cough visual analog scale, the Leicester Cough Questionnaire (Korean version), the Pattern Identification for Chronic Cough Questionnaire, biomarkers, safety testing, etc. Adverse events will also be reported.

Discussion

This trial will assess the efficacy and safety of Maekmoondong-tang in chronic dry cough.

Trial registration

Korean Clinical Trial Registry (http://cris.nih.go.kr; registration number: KCT0001646). Date of registration: October 5 2015

Cough in Sarcoidosis

Sarcoidosis is a granulomatous disorder that frequently affects the lungs. Cough is commonly reported by patients and can significantly reduce health-related quality of life. The mechanism of cough is unknown but airway inflammation, mechanical distortion from pulmonary fibrosis and disruption of the vagus nerve are possible. Recent evidence suggests cough reflex hypersensitivity may also be an important mechanism and predictor of the frequency of cough. The investigation of cough should evaluate common causes such as asthma, gastro-oesophageal reflux and rhinitis. In patients with suspected cough due to sarcoidosis, a trial of corticosteroids should be considered. The severity of cough should be evaluated with validated outcome measures such as visual analogue scales, cough severity diary, health-related quality of life questionnaires such as the Leicester Cough Questionnaire and objective cough monitors. Future studies are needed to identify targets for therapeutic development.

Cough in obstructive sleep apnoea

Obstructive Sleep Apnoea (OSA) has recently been reported to be a cause of chronic cough. It should be considered when cough remains unexplained following investigations and treatments for common causes. The presence of nocturnal cough, snoring and gastro-oesophageal reflux may be helpful in identifying patients who require further investigation. Daytime somnolence is often absent. Continuous positive airway pressure (CPAP) therapy has been reported to be effective in alleviating cough. Therapy for gastro-oesophageal reflux disease, if present, should be optimised. The mechanism of the association between OSA and cough is not clear, but airway inflammation, gastro-oesophageal reflux disease, increased cough reflex sensitivity and tracheobronchomalacia are possible explanations. Further studies should identify clinical predictors of OSA-cough, establish mechanisms and the optimal therapy.

Advances in upper airway cough syndrome

Upper airway cough syndrome (UACS), previously referred to as postnasal drip syndrome, is one of the most common causes of chronic cough. However, the pathogenesis of UACS/postnasal drip syndrome remains unclear, and physicians in countries throughout the world have different definitions and ways of treating this disease. The various proposed pathogeneses of UACS include the early postnasal drip theory, subsequent chronic airway inflammation theory, and a recent sensory neural hypersensitivity theory. Additionally, some researchers suggest that UACS is a clinical phenotype of cough hypersensitivity syndrome. While the general principles involved in treating UACS are similar throughout the world, the specific details of treatment differ. This review summarizes the various definitions, pathogenic mechanisms, treatments, and other aspects of UACS, to aid clinicians in expanding their knowledge of how to diagnose and treat this syndrome.

Adult and paediatric cough guidelines: Ready for an overhaul?

Cough is one of the most common reasons that patients seek medical attention. Cough guidelines from numerous countries and societies are available to assist the clinician to investigate and manage patients with cough. We review some of the recent progress in the field of cough that may lead to revision of these guidelines. In adults with chronic cough, new causes such as obstructive sleep apnoea have been identified. A new terminology, cough hypersensitivity syndrome (CHS), has been proposed for patients with chronic cough, which emphasises cough reflex hypersensitivity as a key feature. New therapeutic options are now available, particularly for patients with refractory or idiopathic chronic cough, which include gabapentin, speech pathology management and morphine. There has been great progress in the assessment of cough with the development of validated quality of life questionnaires and cough frequency monitoring tools. In children, common aetiologies differ from adults and those managed according to guidelines have better outcomes compared to usual care. New diagnostic entities such as protracted bacterial bronchitis have been described. Paediatric-specific cough assessment tools such as the Parent/Child Quality of Life Questionnaire will help improve the assessment of patients. Further research is necessary to improve the evidence base for future clinical guideline recommendations. Guidelines in future should also aim to reach a wider audience that includes primary care physicians, non-specialists and patients.

Chronic dry cough: Diagnostic and management approaches

Cough is the most common symptom for which medical treatment is sought in the outpatient setting. Chronic dry cough poses a great diagnostic and management challenge due to myriad etiologies. Chronic cough has been commonly considered to be caused by gastroesophageal reflux, post-nasal drip or asthma. However, recent evidences suggest that many patients with these conditions do not have cough, and in those with cough, the response to specific treatments is unpredictable at best. This raises questions about the concept of a triad of treatable causes for chronic cough. This article discusses the mechanism and etiology of cough, along with recent advances in the field of cough, highlighting some of the diagnostic and management challenges.

Supraesophageal Reflux: Correlation of Position and Occurrence of Acid Reflux-Effect of Head-of-Bed Elevation on Supine Reflux

BACKGROUND

Supraesophageal reflux of gastric contents can contribute to perennial nasopharyngitis, cough, and asthma. However, effective treatment strategies for supraesophageal reflux disease (SERD) remain inadequately defined.

OBJECTIVE

The purpose of this study is to assess the prevalence and timing of SERD and to investigate the efficacy of head-of-bed elevation in its treatment.

METHODS

A retrospective chart review of patients seen at Scripps Clinic Division of Allergy, Asthma and Immunology was performed who had undergone overnight nasopharyngeal pH monitoring with a commercially available nasopharyngeal pH-monitoring device, Dx-pH Measurement System from Restech, San Diego, Calif. Subjects with reflux were classified based on the position of reflux as either supine only, upright only, or both supine and upright. In a subset of subjects with supine-only reflux, pH monitoring was compared before and after elevating the head of bed 6 inches.

RESULTS

Adequate nasopharyngeal pH-monitoring data were obtained for 235 patients. Reflux was detected in 113 (48%) patients. The pattern of reflux observed was 62 (55%) supine only, 4 (4%) upright only, and 47 (42%) upright and supine. Sequential overnight nasopharyngeal pH monitoring before and after head-of-bed elevation was obtained in 13 individuals with supine-only reflux. Ten subjects demonstrated significant improvement, 8 of whom demonstrated complete resolution of supine reflux with 6 inches of head-of-bed elevation.

CONCLUSION

This study provides new evidence that SERD frequently occurs in the supine position and that 6 inches of head-of-bed elevation is effective in reducing supine SERD.

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.

A review on the efficacy and safety of gabapentin in the treatment of chronic cough

INTRODUCTION

Effective antitussives available to control cough are limited. Consolidation among different afferent branches of the vagus nerve is needed to bring about cough. A general, widely accepted view is that the chronic increase in the sensitivity of the cough reflex is associated with inflammatory hypersensitivity such as from gastro-esophageal reflux disease. There is increasing evidence that an important mechanism is a sensory disorder of the laryngeal branches of the vagus nerve. Neuromodulating drugs are effectively used in the treatment of chronic pain and neuropathic disorders and may have a role in the treatment of refractory chronic cough (CC).

AREAS COVERED

Current evidence on the efficacy and safety of gabapentin in the treatment of CC is reviewed. Relevant randomized controlled trials, case reports and reviews were identified through a PubMed search of English-language literature referring to cough, sensory neuropathy and gabapentin over the last 10 years.

EXPERT OPINION

Gabapentin appears to be effective and well tolerated in the treatment of CC and in other sensory neuropathic disorders. Relevant clinical trials investigating its efficacy and safety profile in the treatment of cough are limited and further studies are needed. Gabapentin has been shown to cause minimal to no toxicity in overdose.

Chronic cough - assessment of treatment efficacy based on two questionnaires

INTRODUCTION

Efficacy of chronic cough treatment is ambiguous. The aim of the study was to analyze chronic cough alleviation after specific treatment and the relationship between cough etiology and treatment efficacy.

MATERIAL AND METHODS

A stepwise diagnostic approach was used to diagnose cough etiology in non-smoking adults with chronic cough. In all patients specific treatment was applied. Two different questionnaires - a visual analog scale and a 5-degree scale - were used to assess cough severity before and after 4-6 months of treatment.

RESULTS

A significant correlation between pre-treatment and post-treatment results of both questionnaires was found (Spearman coefficient 0.43, p = 0.0003 and 0.73, p < 0.0001, respectively). Baseline questionnaire analysis revealed no differences in cough severity between patients with different cough causes or multiple cough causes. Although specific treatment resulted in a significant decrease of cough severity in the entire group, only partial improvement was noted. According to the visual analogue scale, a decrease of cough severity by at least 50% was achieved only in 54.4% of patients (37/68). Similarly, satisfactory improvement was noted in only 54.4% (37/68) of patients when using the 5-point scale. There were three sub-groups of patients, in whom no relevant decrease of cough severity was observed despite treatment: patients with 1. three coexisting cough causes, 2. non-asthmatic eosinophilic bronchitis, and 3. chronic idiopathic cough.

CONCLUSIONS

Cough severity does not depend on its etiology. Efficacy of chronic cough treatment in non-smoking patients is only moderate.

Atopic cough and fungal allergy

We have shown that some patients presenting with chronic bronchodilator-resistant non-productive cough have a global atopic tendency and cough hypersensitivity without nonspecific bronchial hyperresponsiveness, abbreviated as atopic cough (AC). The cough can be treated successfully with histamine H1 antagonists and/or glucocorticoids. Eosinophilic tracheobronchitis and cough hypersensitivity are pathological and physiological characteristics of AC. Fungus-associated chronic cough (FACC) is defined as chronic cough associated with basidiomycetous (BM) fungi found in induced sputum, and recognition of FACC has provided the possibility of using antifungal drugs as new treatment strategies. Bjerkandera adusta is a wood decay BM fungus, which has attracted attention because of its potential role in enhancing the severity of cough symptoms in FACC patients by sensitization to this fungus. Before making a diagnosis of "idiopathic cough" in cases of chronic refractory cough, remaining intractable cough-related laryngeal sensations, such as "a sensation of mucus in the throat (SMIT)," which is correlated with fungal colonization, should be evaluated and treated appropriately in each patient. The new findings, i.e., the detection of environmental mushroom spores that should not be present in the human airways in addition to the good clinical response of patients to antifungal drugs, may lead to the development of novel strategies for treatment of chronic cough.

Nonpharmacological interventions for refractory chronic cough patients: systematic review

BACKGROUND

For people with refractory chronic cough, nonpharmacological interventions are emerging as alternatives to antitussive medications. These treatments generally are delivered by physiotherapists and speech and language therapists and consist of education, breathing exercises, cough suppression techniques, and counselling. Although the number of studies investigating these treatment options has increased in recent years there has not been a systematic review of the efficacy of these treatment options.

METHODS

Studies were searched for in EMBASE, AMED, Medline, CINAHL, and PsycINFO databases. Bibliographies of studies and reviews were searched by hand. Critical appraisal was carried out by one reviewer using the SIGN appraisal tools and Cochrane handbook for systematic reviews.

RESULTS

From a total of 184 studies, 5 full-text English language articles were included in the review. Nonpharmacological interventions were found to significantly reduce cough reflex sensitivity, improve quality of life, and lead to reductions in cough severity and frequency. However, few studies used validated and reliable tools to measure cough severity and frequency thereby limiting the robustness of these findings.

CONCLUSION

Present data support the use of two to four sessions of education, cough suppression techniques, breathing exercises, and counselling in order to achieve improvements in cough sensitivity and cough-related quality of life for people with chronic refractory cough. Due to the lack of validated outcome measures, results for other aspects of cough should be interpreted with caution. There is a need for additional larger-powered comparative studies investigating nonpharmacological interventions for refractory chronic cough.

Chronic cough: an otorhinolaryngology perspective

PURPOSE OF REVIEW

Cough lasting more than 8 weeks is a common presenting complaint to the otolaryngologist. Historically, chronic cough has been attributed to post-nasal drip, laryngopharyngeal reflux and cough-variant asthma. This study reviews chronic cough from the viewpoint of an otolaryngologist.

RECENT FINDINGS

More recent studies suggest the influence of laryngeal neuropathy and its interplay with laryngopharyngeal reflux. There is limited evidence for post-nasal drip or cough-variant asthma causing chronic cough.

SUMMARY

In this study, we review the evidence for cause of chronic cough, as well as up to date techniques for the otolaryngologist, including transnasal esophagoscopy, to assess the patient in clinic allowing accurate diagnosis. Treatment options for the otolaryngologist are discussed and the role of multidisciplinary input emphasized.

Gastroesophageal reflux in chronic cough and cough syncope and the effect of antireflux treatment: case report and literature review

OBJECTIVE

This study aimed to evaluate the efficacy of antireflux treatment on gastroesophageal reflux (GER)-related cough syncope.

METHODS

The method used was a retrospective review of the outcomes of antireflux treatment with proton pump inhibitor (PPI), Stretta radiofrequency (SRF), or laparoscopic fundoplication (LF) of 8 patients with chronic cough and cough syncope that was clinically evaluated to be GER related over a period of 2 to 5 years.

RESULTS

In the 8 selected cases, the typical GER symptoms disappeared in 7 cases and were significantly eased in 1 case. The chronic cough diminished to mild and occasional occurrence in 6 cases and was completely relieved in 2 cases. Meanwhile, the cough syncope disappeared in all cases. Seven of the patients resumed physical and social functions after the antireflux treatments, except for 1 person, who had a stroke due to other causes.

CONCLUSION

For chronic cough and cough syncope of unknown cause, the GER assessment could be valuable. In treating well-selected GER-related chronic cough and cough syncope, PPI, SRF, and LF can be considered. Moreover, satisfactory restoration of physical and social functions could be achieved after effective antireflux therapy.

Evaluation and treatment of chronic cough

Chronic cough is a frustrating and common problem, resulting in significant psychological and physical sequelae as well as enormous financial costs in terms of health care expense and time lost from work. Decreased QoL and depression are common. However, using a systematic approach, including assessing whether the patient uses ACE-I and cigarettes, excluding the presence of red flags and risk factors for life-threatening diseases, and obtaining and normal chest radiograph, more than 90% of cases of chronic cough are diagnosed as being caused by UACS, asthma, or GERD. It is recommended to address these conditions sequentially, starting with UACS. Nonasthmatic eosinophilic bronchitis and pertussis infections are unrecognized by primary care providers and should be considered after UACS, asthma, and GERD have been addressed. Finally, cough hypersensitivity syndrome is a new area of research and has been hypothesized to be the underlying factor in many cases of chronic cough, regardless of the inciting factor. More clinical research is needed to further elucidate the cough reflex pathway and the factors involved in modulating its sensitivity, which may eventually lead to new antitussive therapeutics.

Capsaicin cough sensitivity is related to the older female predominant feature in chronic cough patients

Purpose

The present study aimed to examine the age and gender distributions among chronic cough patients referred to a tertiary cough clinic in Korea, and to investigate clinical factors related to the demographic findings.

Methods

Study participants were unselectively recruited from adult chronic cough patients who attended the cough clinic for the first time during one year. To validate their representativeness, their age and gender distributions were compared to the entire chronic cough population, or with those presenting with other chronic disease. Data from the baseline investigations were analyzed to identify clinical factors related to the demographic findings.

Results

A total of 272 chronic cough patients were included. They had a middle-aged female predominant feature (mean age: 52.8±15.7 years and female 69.1%). Their age and gender distributions were almost identical to the entire chronic cough population, but were distinct from patients with hypertension. Among clinical factors, the older female predominance was associated with enhanced capsaicin cough sensitivity, and also with the presence of 'cough by cold air' symptom. Allotussia and laryngeal paresthesia were highly common in chronic cough patients, affecting 94.8% and 86.8% of them, respectively.

Conclusions

The present study demonstrated older female predominance among adult chronic cough patients attending a referral cough clinic in Korea. The demographic features were significantly associated with the capsaicin cough responses and also potentially with allotussia (particularly cold air as the trigger). These findings suggest a role of cough reflex sensitization in the pathophysiology of chronic cough in adults.

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 real - life observational pilot study to evaluate the effects of two-week treatment with montelukast in patients with chronic cough

Background

Different conditions make the proximal airways susceptible to tussigenic stimuli in the chronic cough (CC) syndrome. Leukotrienes can be implicated in the inflammatory mechanism at play in it. Montelukast is a selective cysteinyl-leukotriene receptor antagonist with proven effectiveness in patients with asthma. The aim of our real-life pilot study was to use montelukast to relieve cough symptoms in patients with CC allegedly due to the two frequent causes other than asthma – upper airway cough syndrome and gastroesophageal reflux (GER).

Methods

14 consecutive patients with CC were evaluated before and after 2 weeks of treatment with montelukast 10 mg daily. Cough was assessed by validated cough questionnaire. Questionnaires regarding the presence of gastroesophageal reflux were also completed. Cough reflex sensitivity to incremental doubling concentrations of citric acid and capsaicin was measured. Lung function, airway hyperresponsiveness and exhaled breath temperature (EBT), a non-invasive marker of lower airway inflammation, were evaluated to exclude asthma as an underlying cause. Thorough upper-airway examination was also conducted. Cell counts, eosinophil cationic protein (ECP), lactoferrin, myeloperoxidase (MPO) were determined in blood to assess systemic inflammation.

Results

Discomfort due to cough was significantly reduced after treatment (P < 0.001). Cough threshold for capsaicin increased significantly (P = 0.001) but not for citric acid. The values of lactoferrin and ECP were significantly reduced, but those of MPO rose. EBT and pulmonary function were not significantly affected by the treatment.

Conclusion

Patients with CC due to upper airway cough syndrome or gastroesophageal reflux (GER) but not asthma reported significant relief of their symptoms after two weeks of treatment with montelukast. ECP, lactoferrin, MPO altered significantly, highlighting their role in the pathological mechanisms in CC. Clinical trial ID at Clinicaltrials.gov is NCT01754220.

Allergic bronchopulmonary aspergillosis presenting as chronic cough in an elderly woman without previously documented asthma

A nonsmoking woman in her mid-70s presents to the allergist for consultation of a chronic cough of almost 3-years' duration without a specific diagnosis as to etiology in spite of numerous diagnostic tests and therapeutic trials. This is a case report from a specialist point of view that includes a comprehensive review of her clinical course pre- and postconsultation along with a brief but pertinent review of the literature as it relates to this particular unusual and protracted case, which was ultimately successfully diagnosed and treated.

Airway oxidative stress in chronic cough

BACKGROUND

The mechanisms of chronic cough are unclear. Many reactive oxygen species affect airway sensory C-fibres which are capable to induce cough. Several chronic lung diseases are characterised by cough and oxidative stress. In asthma, an association between the cough severity and airway oxidative stress has been demonstrated. The present study was conducted to investigate whether airway oxidative stress is associated with chronic cough in subjects without chronic lung diseases.

METHODS

Exhaled breath condensate samples were obtained in 43 non-smoking patients with chronic cough and 15 healthy subjects. Exclusion criteria included a doctor's diagnosis of any lung disorders and any abnormality in lung x-ray. The concentration of 8-isoprostane was measured. In addition, the patients filled in Leicester Cough Questionnaire and underwent hypertonic saline cough provocation test, spirometry, ambulatory peak flow monitoring, nitric oxide measurement, and histamine airway challenge. In a subgroup of patients the measurements were repeated during 12 weeks' treatment with inhaled budesonide, 800 ug/day.

RESULTS

The 8-isoprostane concentrations were higher in the cough patients than in the healthy subjects (24.6 ± 1.2 pg/ml vs. 10.1 ± 1.7 pg/ml, p = 0.045). The 8-isoprostane concentration was associated with the Leicester Cough Questionnaire total score (p = 0.044) but not with the cough sensitivity to saline or other tests. Budesonide treatment did not affect the 8-isoprostane concentrations.

CONCLUSIONS

Chronic cough seems to be associated with airway oxidative stress in subjects with chronic cough but without chronic lung diseases. This finding may help to develop novel antitussive drugs.

TRIAL REGISTRATION

The study was registered in ClinicalTrials.gov database (KUH5801112), identifier NCT00859274.

Chronic cough and obstructive sleep apnoea in a sleep laboratory-based pulmonary practice

BACKGROUND

Obstructive sleep apnoea (OSA) has recently been identified as a possible aetiology for chronic cough. The aim of this study was to compare the incidence of chronic cough between patients with and without OSA and the impact of continuous positive airway pressure (CPAP) treatment in resolving chronic cough.

METHODS

Patients referred to the sleep laboratory from January 2012 to June 2012 were retrospectively enrolled. Clinical data, treatment course and resolution of chronic cough were analysed. Specifically, gastro-oesophageal reflux (GERD), upper airway cough syndrome, asthma, apnoea-hypopnoea index and the impact of CPAP treatment on chronic cough were assessed.

RESULTS

A total of 131 patients were reviewed. The incidence of chronic cough in the OSA group was significantly higher than the non-OSA group (39/99 (39.4%) vs. 4/32 (12.5%), p = 0.005). Both GERD and apnoea-hypopnoea index were significantly associated with chronic cough in univariate analysis. After multivariate logistic regression, GERD was the only independent factor for chronic cough. Moreover, the resolution of chronic cough was more significant in the OSA patients with CPAP treatment compared with those not receiving CPAP treatment (12/18 (66.7%) vs. 2/21 (9.5%), p = 0.010).

CONCLUSION

The incidence of chronic cough was significantly higher in the OSA patients. In addition, CPAP treatment significantly improved chronic cough. Therefore, OSA may be a contributory factor to chronic cough.