Prevalence of Depressive Symptoms Among Patients With Chronic Cough

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

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

Update on the clinical development of gefapixant, a P2X3 receptor antagonist for the treatment of refractory chronic cough

Chronic cough, or cough lasting >8 weeks, is often associated with underlying medical conditions (ie, asthma, gastroesophageal reflux disease, nonasthmatic eosinophilic bronchitis, and upper-airway cough syndrome). In some patients with chronic cough, treatment of these underlying conditions does not resolve the cough (refractory chronic cough [RCC]), or none of these conditions are present (unexplained chronic cough [UCC]). Despite appropriate medical evaluation, patients with RCC or UCC frequently experience cough persisting for many years, as there are currently no targeted pharmacological approaches approved for the treatment of these conditions. However, the adenosine triphosphate (ATP)-gated P2X3 receptor, a key modulator of the activation of sensory neurons central to the cough reflex, has recently garnered attention as a potential therapeutic target for the treatment of chronic cough. Gefapixant, a first-in-class, non-narcotic, selective antagonist of the P2X3 receptor, recently demonstrated efficacy and was generally well tolerated in phase 2 clinical trials in patients with RCC, validating the utility of targeting this receptor in patients with chronic cough. On the basis of these data, 2 global phase 3 trials, with combined anticipated enrolment exceeding 2000 patients and with treatment durations of up to 1 year, have been initiated. Together, these trials will further evaluate efficacy and safety of gefapixant in the control of cough in patients with RCC or UCC.

Role and Impact of Chronic Cough in Individuals with Asthma From the General Population

BACKGROUND

Cough is a well-recognized symptom in asthma, but the role and impact of chronic cough in individuals with asthma has not been described in the general population.

OBJECTIVE

We hypothesized that among individuals with asthma, those with chronic cough versus those without have a more severe disease phenotype.

METHODS

We identified individuals with asthma and chronic cough among 14,740 adults from the Copenhagen General Population Study, and investigated respiratory symptoms, health care utilizations, lung function, and biomarkers in blood.

RESULTS

A total of 855 (6%) individuals suffered from asthma, and 70 (8%) had chronic cough. Individuals with asthma and chronic cough had a Leicester Cough Questionnaire median total score of 16.8 (25th and 75th percentiles, 14.8-18.9), corresponding to 5.4 (4.6-6.0) for the physical domain, 5.7 (4.6-6.4) for the psychological domain, and 6.0 (5.3-6.8) for the social domain. Among individuals with asthma, those with chronic cough versus those without reported more often wheezing (70% vs 54%), dyspnea (74% vs 49%), night-time dyspnea (27% vs 11%), sputum production (59% vs 14%), chest pain/tightness (14% vs 4%), acute bronchitis/pneumonia episodes, and general practitioner visits. Furthermore, these individuals had more often FEV₁ predicted value of less than 60% (14% vs 7%) and higher levels of neutrophils, leukocytes, and fibrinogen in blood, but there were no differences with regard to levels of high-sensitive C-reactive protein, eosinophils, and IgE in blood.

CONCLUSIONS

Chronic cough in individuals with asthma is associated with a more severe disease phenotype in terms of worse respiratory symptoms, greater health care utilizations, lower lung function, and higher levels of systemic inflammatory biomarkers in blood.

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.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02591550.

The impacts of cough: a cross-sectional study in a Finnish adult employee population

Given the very high prevalence of cough, little is known about its impacts. A questionnaire was sent via e-mail to all public service employees in two towns in Finland. There were 373 subjects with acute cough, 174 with subacute cough and 421 with chronic cough. Cough-related quality of life was assessed with the Leicester Cough Questionnaire (LCQ) and depressive symptoms with Patient Health Questionnaire-2. In addition, data on doctor's visits and sick leave days were collected. Mean LCQ (95% CI) total scores were 16.2 (15.9-16.5), 14.5 (14.1-15.0) and 14.6 (14.3-14.9) among subjects with acute, subacute and chronic cough, respectively (p<0.001). The prevalence of depressive symptoms was 5.4%, 7.5% and 4.8%, respectively, and 5.0% among subjects without current cough (p=0.50). The respective proportions of subjects with at least one doctor's visit due to cough during the previous year were 27.6%, 44.8%, 49.6% and 16.1% (p<0.001). The respective proportions of subjects with at least one sick leave day due to cough during the previous year were 28.9%, 39.1%, 36.3% and 15.3% (p<0.001). Any current cough was associated with an increased the risk of several (three or more) yearly doctor's visit due to any reason (adjusted odds ratio (aOR) 1.49, 95% CI 1.27-1.76) and several (seven or more) yearly sick leave days due to any reason (aOR 1.43, 95% CI 1.22-1.68). Cough decreases quality of life, and has a large socioeconomic impact by increasing doctor's visits and sick leave days. However, it is not associated with depressive symptoms. The impacts of subacute and chronic cough are comparable, and larger than those of acute cough.

The Use of Online Health Forums by Patients With Chronic Cough: Qualitative Study

Background

Online health discussion forums are used by different patient groups for sharing advice and information. Chronic cough is a common problem, and people with chronic cough use online health forums alongside formal medical therapies.

Objective

The objective of this study was to assess how chronic cough sufferers use online health forums, including the treatment advice they share with one another and the possible clinical uses of online forums in chronic cough.

Methods

Three open-access health forums were searched for threads related to chronic cough. Identified threads were screened against inclusion and exclusion criteria adapted from the British Thoracic Society (BTS) Guidelines related to chronic cough diagnosis. Included data were subjected to qualitative thematic analysis. All study data were cross-validated by a second author and discrepancies were resolved.

Results

In total, 96 threads were included in the analysis, consisting of posts by 223 forum users. Three main themes were identified: the effect of chronic cough on the lives of patients, the treatment advice shared between users, and the provision of support within forums.

Conclusions

Chronic cough symptoms had impacts on multiple aspects of patients’ health and well-being. To try and combat these issues, forum users suggested a variety of treatments to one another, ranging from mainstream traditional therapies to odd alternative remedies. The provision of support and empathy were also prominent themes in discussion threads. Online forums themselves may provide increasing benefit to users through the addition of a moderator.

Change in Psychological, Physiological, and Situational Factors in Adults After Treatment of Chronic Cough

BACKGROUND

We hypothesized that addressing anxiety and depressive mood disorders will improve chronic cough severity and cough quality of life (CQOL).

METHODS

Major tenets of the theory of unpleasant symptoms were examined in a longitudinal observational study of consecutive adults with cough of > 8 weeks' duration treated in our cough clinic. At baseline and 3 and 6 months, subjects completed 3 Punum Ladders rating cough severity, the CQOL Questionnaire, the Depression, Anxiety, and Stress Scales-21, and the Duke Functional Social Support Questionnaire. Cross-sectional baseline and longitudinal regression analyses were conducted.

RESULTS

Eighty subjects (55 women) with a mean age of 58.5 ± 11.1 years and a cough duration of 86.0 ± 123.7 months were enrolled. At baseline, worse cough severity was significantly associated with less education and worse ability to speak bothered by cough and the urge to cough. Worse CQOL was significantly associated with worse depression symptoms, urinary incontinence, and ability to speak; use of self-prescribed remedies; and younger age. Significant improvements in depression and stress symptoms occurred at 3 and 6 months. Anxiety symptoms improved, particularly in the first 3 months. Improvement in cough severity was significantly associated with less education, male sex, and improvement in ability to speak and urge to cough. Improvement in CQOL was significantly associated with improvement in urinary incontinence, urge to cough, anxiety symptoms, and use of self-prescribed remedies.

CONCLUSIONS

Using the theory of unpleasant symptoms, we have come to appreciate that managing psychological, physiological, and situational factors in addition to focusing on identifying the cause of cough is important to maximize improvement in CQOL.

The Emerging Role of The Eosinophil and Its Measurement in Chronic Cough

Although the aetiology of chronic cough in guidelines is clearly stated as asthma and related syndromes, gastro-oesophageal reflux disease (GORD), and upper airways disease, the inflammatory mechanisms underlying these conditions differ. Recent studies on asthma have increasingly focused on its molecular phenotypes instead of clinical characteristics. Here, we proposed the hypothesis that divides cough into two groups; the eosinophilic and neutrophilic. This division will enhance our ability to recognise the type of airway inflammation which, as a consequence will lead us to more targeted and personalized treatment approaches.

Chronic Non-Productive Cough in Patients With Primary Sjögren's Syndrome

Objectives

This study aims to evaluate the frequency of chronic cough due to dryness in the trachea and the relationship between depression and chronic cough in patients with primary Sjögren's syndrome (pSS).

Patients and methods

Eighty non-smoking patients (7 males, 73 females; mean age 47.6±9.2 years; range 18 to 70 years) with newly diagnosed pSS were included. All patients were evaluated clinically, radiologically, and physiologically. Patients with cough were assessed using the Leicester Cough Questionnaire and visual analog scale. Beck Depression Inventory was used to determine the risk of depression in patients with cough. Patients with asthma, rhinosinusitis, gastrooesophageal reflux, and drug use which cause cough and pulmonary involvement in pSS were excluded.

Results

Non-productive cough was detected in 30 patients (37.5%). Fourteen patients (17.5%) were admitted to the hospital with cough at least once before the diagnosis of pSS. The median time between onset of symptoms and firm diagnosis was 24 months (25-75 interquartile ranges: 3-60 months). A significant difference was observed in the Beck Depression Inventory scores between patients with and without cough. There was a significant negative relationship between Leicester Cough Questionnaire and Beck Depression Inventory scores.

Conclusion

Patients with pSS often have symptoms for a long duration that mimic those of more commonly encountered non-specific pulmonary conditions. Xerotrachea should be considered in the differential diagnosis of chronic cough, especially in patients with normal pulmonary function tests and pulmonary imaging.

Psychological profile of individuals presenting with chronic cough

Chronic refractory cough (CRC) is a common problem in respiratory clinics. Adverse effects on quality of life are documented in the literature, but relatively little is known about the underlying psychological factors in this patient population. We aimed to investigate the association of psychological factors with chronic cough, comparing CRC to explained cough and non-cough groups. 67 patients attending a specialist cough clinic (CRC, n=25; explained cough, n=42) and 22 non-cough individuals participated. All participants completed the Hospital Anxiety & Depression Scale, Big Five Inventory (Personality), Chalder Fatigue Scale and Patient Health Questionnaire-15. Cough patients also completed the Illness Perception Questionnaire-Revised. Appropriate statistical analyses were used to compare participant groups. Chronic refractory coughers displayed significantly higher levels of anxiety, depression, fatigue and somatic physical symptoms than non-cough participants. Compared to explained coughers, there were higher depression and fatigue scores and significantly more negative illness representations (specifically, strong beliefs regarding negative consequences, lower illness coherence and higher emotional representations). "Explained" coughers reported significantly increased fatigue and somatic symptoms in comparison to non-coughers. The prevalence of fatigue, low mood, negative illness beliefs and increased physical symptom reporting should be considered in consultations and in developing novel interventions for CRC patients.

Somatic cough syndrome or psychogenic cough-what is the difference?

The term psychogenic cough has been used to describe cough without obvious medical etiology, which is refractory to medical management and considered to have a psychiatric or psychological basis. However there are limitations in the research into psychogenic cough with limited empirical data on how to define the condition or differentially diagnose it from other forms of chronic cough. The term somatic cough syndrome was introduced by the American College of Chest physicians in 2015 during their revision of the 2006 guideline on psychogenic cough. Psychomorbidity can be present in chronic cough arising from a variety of etiologies and can impact on symptom perception and clinical management of the condition. Psychological symptoms can also improve after effective treatment of the chronic cough. The recently published American College of Chest Physicians cough guidelines recommended replacing the term psychogenic cough with the term somatic cough syndrome in order to be consistent with the Diagnostic Statistical Manual of Mental Disorders, 5^th edition (DSM-5) where the term psychogenic is no longer used. This paper outlines the current evidence regarding psychogenic cough, proposes a model for conceptualising psychological issues in chronic cough and discusses strategies for clinical management of psychological issues in patients with chronic cough.

Point prevalence and epidemiological characteristics of chronic cough in the general adult population: The Korean National Health and Nutrition Examination Survey 2010-2012

Cough is frequently self-limiting, but may persist longer in certain individuals. Most of previous studies on the epidemiology of chronic cough have only measured period prevalence, and thus have afforded limited information on the burden and natural course. We aimed to investigate the epidemiology of chronic cough by using a point prevalence measure in a large-scale general population.We analyzed cross-sectional data collected from 18,071 adults who participated in the Korean National Health and Nutrition Examination Survey 2010-2012. Presence and duration of current cough was ascertained by structured questionnaires, and cough was classified into acute (<3 weeks), subacute (3-8 weeks), or chronic cough (≥8 weeks). Demographic and clinical parameters were examined in relation to chronic cough.The point prevalences of acute, subacute, and chronic cough were 2.5 ± 0.2%, 0.8 ± 0.1% and 2.6 ± 0.2%, respectively. The proportion of current cough showed a steep decrease after 1 week of duration. However, 2 peaks in the prevalence of current cough were revealed; cough durations of less than 1 week and longer than 1 year were most common (31.1% and 27.7% of current cough, respectively). Subacute and chronic cough were more prevalent in the elderly (≥65 years); the positive associations with older age were independent of other confounders, including current smoking and comorbidities.This is the first report on the epidemiology of cough using a point prevalence measure in a nationally representative population sample. Our findings indicate a high burden of chronic cough among adults with current cough in the community. The dual-peak of cough duration suggested that the pathophysiology of acute and chronic cough may differ. The preponderance of elderly people in the prevalence of chronic cough warrants further investigation. In addition, more sophistication and validation of tools to define chronic cough will help our understanding of the epidemiology.

'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.

Somatic Cough Syndrome (Previously Referred to as Psychogenic Cough) and Tic Cough (Previously Referred to as Habit Cough) in Adults and Children: CHEST Guideline and Expert Panel Report

BACKGROUND

We conducted a systematic review on the management of psychogenic cough, habit cough, and tic cough to update the recommendations and suggestions of the 2006 guideline on this topic.

METHODS

We followed the American College of Chest Physicians (CHEST) methodologic guidelines and the Grading of Recommendations, Assessment, Development, and Evaluation framework. The Expert Cough Panel based their recommendations on data from the systematic review, patients' values and preferences, and the clinical context. Final grading was reached by consensus according to Delphi methodology.

RESULTS

The results of the systematic review revealed only low-quality evidence to support how to define or diagnose psychogenic or habit cough with no validated diagnostic criteria. With respect to treatment, low-quality evidence allowed the committee to only suggest therapy for children believed to have psychogenic cough. Such therapy might consist of nonpharmacologic trials of hypnosis or suggestion therapy, or combinations of reassurance, counseling, and referral to a psychologist, psychotherapy, and appropriate psychotropic medications. Based on multiple resources and contemporary psychologic, psychiatric, and neurologic criteria (Diagnostic and Statistical Manual of Mental Disorders, 5th edition and tic disorder guidelines), the committee suggests that the terms psychogenic and habit cough are out of date and inaccurate.

CONCLUSIONS

Compared with the 2006 CHEST Cough Guidelines, the major change in suggestions is that the terms psychogenic and habit cough be abandoned in favor of somatic cough syndrome and tic cough, respectively, even though the evidence to do so at this time is of low quality.

The relationship between cough-specific quality of life and abdominal muscle endurance, fatigue, and depression in patients with COPD

BACKGROUND

Cough is a prevalent symptom that impacts quality of life in COPD. The aim of this study was to assess the relationship between cough-specific quality of life, abdominal muscle endurance, fatigue, and depression in stable patients with COPD.

METHODS

Twenty-eight patients with COPD (mean age 60.6±8.7 years) referred for pulmonary rehabilitation participated in this cross-sectional study. Sit-ups test was used for assessing abdominal muscle endurance. Leicester Cough Questionnaire (LCQ) was used to evaluate symptom-specific quality of life. Fatigue perception was evaluated with Fatigue Impact Scale (FIS). Beck Depression Inventory (BDI) was used for assessing depression level.

RESULTS

The LCQ total score was significantly associated with number of sit-ups; BDI score; FIS total; physical, cognitive, and psychosocial scores (P<0.05). Scores of the LCQ physical, social, and psychological domains were also significantly related with number of sit-ups, FIS total score, and BDI score (P<0.05). FIS total score and number of sit-ups explained 58% of the variance in LCQ total score (r=0.76, r (2)=0.577, F(2-20)=12.296, P<0.001).

CONCLUSION

Chronic cough may adversely affect performance in daily life due to its negative effect on fatigue and decrease abdominal muscle endurance in patients with COPD. Decreased cough-related quality of life is related with increased level of depression in COPD patients. Effects of increased abdominal muscle endurance and decreased fatigue in COPD patients with chronic cough need further investigation.

The impact of chronic cough: a cross-sectional European survey

PURPOSE

Studies that investigate the impact of chronic cough have largely focused on patients attending secondary care. Our aim was to investigate the opinions of the wider general population across Europe.

METHODS

An internet survey was made available in 12 languages on the European Lung Foundation website, between January 2012 and April 2013.

RESULTS

Of 1120 respondents from 29 different European countries, 67 % were female, mean age 51 years (SD 15), median cough duration 2-5 years. The majority of respondents reported cough impacted their quality of life, mood and ability to undertake activities. Despite 72 % of respondents having visited their doctor ≥3 times, only 53 % had received a diagnosis. Asthma was the most common diagnosis (23 %). Most respondents reported limited or no effectiveness of medications. 88 % of respondents reported that they would like more information to be available on chronic cough.

CONCLUSIONS

Chronic cough has a negative impact on quality of life. Further work is needed to raise awareness, promote management strategies, develop effective treatments and consider the educational and support needs of patients with chronic cough.

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.

Anatomy and neurophysiology of cough: CHEST Guideline and Expert Panel report

Bronchopulmonary C-fibers and a subset of mechanically sensitive, acid-sensitive myelinated sensory nerves play essential roles in regulating cough. These vagal sensory nerves terminate primarily in the larynx, trachea, carina, and large intrapulmonary bronchi. Other bronchopulmonary sensory nerves, sensory nerves innervating other viscera, as well as somatosensory nerves innervating the chest wall, diaphragm, and abdominal musculature regulate cough patterning and cough sensitivity. The responsiveness and morphology of the airway vagal sensory nerve subtypes and the extrapulmonary sensory nerves that regulate coughing are described. The brainstem and higher brain control systems that process this sensory information are complex, but our current understanding of them is considerable and increasing. The relevance of these neural systems to clinical phenomena, such as urge to cough and psychologic methods for treatment of dystussia, is high, and modern imaging methods have revealed potential neural substrates for some features of cough in the human.

A worldwide survey of chronic cough: a manifestation of enhanced somatosensory response

Reports from individual centres suggest a preponderance of females with chronic cough. Females also have heightened cough reflex sensitivity. Here we have reviewed the age and sex of unselected referrals to 11 cough clinics. To investigate the cause of any observed sex dimorphism, functional magnetic resonance imaging of putative cough centres was analysed in normal volunteers. The demographic profile of consecutive patients presenting with chronic cough was evaluated. Cough challenge with capsaicin was undertaken in normal volunteers to construct a concentration-response curve. Subsequent functional magnetic resonance imaging during repeated inhalation of sub-tussive concentrations of capsaicin observed areas of activation within the brain and differences in the sexes identified. Of the 10,032 patients presenting with chronic cough, two-thirds (6591) were female (mean age 55 years). The patient profile was largely uniform across centres. The most common age for presentation was 60-69 years. The maximum tolerable dose of inhaled capsaicin was lower in females; however, a significantly greater activation of the somatosensory cortex was observed. Patients presenting with chronic cough from diverse racial and geographic backgrounds have a strikingly homogeneous demographic profile, suggesting a distinct clinical entity. The preponderance of females may be explained by sex-related differences in the central processing of cough sensation.

Evaluating cough assessment tools: a systematic review

BACKGROUND

Little is known about the comparative validity, reliability, or responsiveness of instruments for assessing cough frequency or impact, where the term impact encompasses both cough severity and the impact of cough on health-related quality of life.

METHODS

We conducted a systematic review to evaluate instruments that assess cough frequency or impact in adults, adolescents, and children with acute or chronic cough.

RESULTS

Seventy-eight studies were included, of which eight were randomized controlled trials and 70 were observational studies. In all age groups, audio and video electronic recording devices had good reliability compared with other methods of assessing cough frequency but had variable correlation with other cough assessments, such as visual analog scale scores, quality-of-life questionnaires, cough diaries, and tussigenic challenges. Among adult and adolescent patients, the Leicester Cough Questionnaire (LCQ) and the Cough-Specific Quality-of-Life Questionnaire (CQLQ) were valid and reliable, showing high intraclass and test-retest correlations. Among children, the Parent Cough-Specific Quality of Life Questionnaire and Pediatric Cough Questionnaire were valid and reliable.

CONCLUSIONS

Electronic recording devices can be valid assessments of cough frequency. The LCQ and CQLQ for adults and the Parent Cough-Specific Quality of Life questionnaire for children are valid instruments for assessing cough impact. There is limited but insufficient evidence to determine the reliability or concurrent validity of the different types of cough diaries or visual analog scale scores. There are also limited data to support the responsiveness of recording devices. There is good responsiveness data for the LCQ and CQLQ, but more evidence is needed.

Antitussive activity of Withania somnifera and opioid receptors

Arabinogalactan is a polysaccharide isolated from the roots of the medicinal plant Withania somnifera L. It contains 65% arabinose and 18% galactose. The aim of the present study was to evaluate the antitussive activity of arabinogalactan in conscious, healthy adult guinea pigs and the role of the opioid pathway in the antitussive action. A polysaccharide extract was given orally in a dose of 50 mg/kg. Cough was induced by an aerosol of citric acid in a concentration 0.3 mol/L, generated by a jet nebulizer into a plethysmographic chamber. The intensity of cough response was defined as the number of cough efforts counted during a 3-min exposure to the aerosol. The major finding was that arabinogalactan clearly suppressed the cough reflex; the suppression was comparable with that of codeine that was taken as a reference drug. The involvement of the opioid system was tested with the use of a blood-brain barrier penetrable, naloxone hydrochloride, and non-penetrable, naloxone methiodide, to distinguish between the central and peripheral mu-opioid receptor pathways. Both opioid antagonists acted to reverse the arabinogalactan-induced cough suppression; the reversion was total over time with the latter antagonist. We failed to confirm the presence of a bronchodilating effect of the polysaccharide, which could be involved in its antitussive action. We conclude that the polysaccharide arabinogalactan from Withania somnifera has a distinct antitussive activity consisting of cough suppression and that this action involves the mu-opioid receptor pathways.

Epidemiology of cough in relation to China

Cough is one of the most common complaints for which patients seek medical attention. Misdiagnosis and mistreatment of cough exist commonly in China. The prevalence of acute cough caused by upper airway infection fluctuates between 9% and 64% in the community, for chronic cough, the prevalence >10% in most surveys, ranging from 7.2%-33%. The common causes of chronic cough are upper airway cough syndrome (previously called as post nasal drip syndrome [PNDS]), cough variant asthma (CVA), gastroesophageal reflux related cough (GERD) and eosinophilic bronchitis (EB). There is a regional discrepancy regarding the prevalence of common causes of cough and distribution of gender among China, UK, USA, the most common cause of chronic cough in China are CVA, followed by UACS, EB and atopic cough (AC), the male is almost equal to female in numbers in China. The risk factors for cough includes cold air, smoking, environmental pollutants, noxious substances and allergens, and unreasonable diet habits.

Sensorimotor circuitry involved in the higher brain control of coughing

There is an overwhelming body of evidence to support the existence of higher brain circuitries involved in the sensory detection of airways irritation and the motor control of coughing. The concept that cough is purely a reflex response to airways irritation is now superseded by the recognition that perception of an urge-to-cough and altered behavioral modification of coughing are key elements of cough disorders associated with airways disease. Understanding the pathways by which airway sensory nerves ascend into the brain and the patterns of neural activation associated with airways irritation will undoubtedly provide new insights into disordered coughing. This brief review aims to explore our current understanding of higher order cough networks by summarizing data from recent neuroanatomical and functional studies in animals and humans. We provide evidence for the existence of distinct higher order network components involved in the discrimination of signals arising from the airways and the motor control of coughing. The identification of these network components provides a blueprint for future research and the development of targeted managements for cough and the urge-to-cough.

Use of specific neuromodulators in the treatment of chronic, idiopathic cough: a systematic review

OBJECTIVE

The goal of this systematic review was to examine the evidence for the use of the neuromodulating agents, amitriptyline, gabapentin, pregabalin, and baclofen, in the management of chronic, idiopathic cough patients.

DATA SOURCES

Online databases, including PubMed, Embase, Cochrane Review, and Web of Science, and publications cited in bibliographies were used.

REVIEW METHODS

Literature was searched by the 2 authors with a priori criteria for study selection.

RESULTS

Eight relevant articles were identified, including 2 randomized controlled trials, 2 prospective cohort or case-series designs with consecutive patients, 1 retrospective case series of consecutive patients, 1 retrospective case series whose consecutive status was not known, and 2 case reports of 6 and 2 patients, respectively. Improvements in cough-specific quality of life were noted in the randomized controlled trials. Cough severity was reduced in studies that measured this outcome measure. In the remaining studies, cough symptoms were less after neuromodulator treatment.

CONCLUSION

Benefit from neuromodulator treatment with amitriptyline, gabapentin, pregabalin, and baclofen in chronic, idiopathic cough patients was demonstrated. Further investigations using objective and subjective outcome measures are needed as well as studies exploring optimal dose, length of treatment, and relapse rates posttreatment.

Therapy for cough: where does it fall short?

Studies on cough have come a long way but many shortfalls still exist. These shortfalls can be attributed to: the lack of randomized controlled studies with a focus on cough; studies not using robust cough outcome measures, poor definition of target groups in studies and guidelines, the lack of safe and efficacious treatments; difficulty in defining etiological factors, and the lack of data on the predictors of response to therapies for cough dominant etiologies. Addressing shortfalls in cough therapy that focuses on improving the lives of people with cough requires a systematic approach that includes better medications, high quality studies, improved multidisciplinary guidelines and education (of both health professionals and patients). To achieve new cough therapeutics requires an improved understanding of cough in humans (i.e., not just in animals). Development of new medications without substantial adverse events is long awaited for cough.

The experience of cough in patients diagnosed with lung cancer

PURPOSE

The aim of this study was to explore the patient experience of cough in a population of patients with lung cancer.

METHODS

A qualitative exploratory study design was developed and elicited the views of 26 patients with lung cancer who had current or past experience with cough.

RESULTS

The data's four themes highlight the complex and distressing nature of cough, including its interaction with other symptoms, such as breathlessness, fatigue and sleep disturbance. A theme around descriptions of cough suggests typically a dry tickly cough and highlights mechanical and environmental triggers for cough. The theme around the effects of cough in daily life shows the impact of cough in socialising, the embarrassment from cough and the psychological effects experienced by patients. The last theme focuses on strategies for coping with and managing cough, showing the perceived ineffectiveness of current antitussives and the patients' use of a variety of approaches on an ad hoc basis to try to manage their cough often unsuccessfully.

CONCLUSION

Cough has not received the same attention as other cancer symptoms, which means that patients' experience of a distressing and difficult symptom is often unnoticed by health care professionals. More clinical and research attention in this debilitating symptom is necessary.

Psychosocial health status of persons seeking treatment for exposure to libby amphibole asbestos

A cross-sectional exploratory study was conducted to describe the psychosocial health status of persons seeking health care for exposure to Libby amphibole asbestos (LAA). Health indicators including depression, stress, acceptance of illness, and satisfaction with access and financial aspects of care were obtained via electronic and paper-pencil survey. The exposure pathway and demographic data were gleaned from the health record. Of the 386 participants, more than one-third (34.5%) demonstrated significant levels of psychological distress. The oldest group of women had the lowest levels of depression and stress and the highest acceptance of illness. Gender, age, and satisfaction with financial resources were significantly related to depression, stress, and acceptance of illness. Satisfaction with access to care was significant only for stress. No differences in depression, stress, and acceptance of illness were found based on residence, exposure pathway, or insurance status.

Chronic 'cough hypersensitivity syndrome': a more precise label for chronic cough

Chronic cough remains a challenge to many clinicians because there is often no diagnostic link to causation, and because indirect antitussives are largely ineffective. Chronic cough can also be a predominant symptom associated with many chronic respiratory diseases such as COPD, asthma and pulmonary fibrosis. Chronic cough itself does impair the quality of life and is associated with psychological impairment. The symptoms associated with chronic cough include persistent tickling or irritating sensation in the chest or throat, hoarse voice, dysphonia or vocal cord dysfunction. Currently, the clinical diagnosis of cough is associated with chronic cough caused by airway eosinophilic conditions such as asthma, gastrooesophageal reflux disease or post-nasal drip (or upper airway syndrome), which implies cause and effect, or with chronic cough associated with other diseases such as COPD, cancer or heart failure, that does not necessarily imply cause and effect. A recently-recognised category is idiopathic cough, with no associated or causative diagnosis. We suggest that there is a better label needed for chronic cough, that includes the common association with a hypersensitive cough response to tussive stimuli such as capsaicin or citric acid. This would invoke a hypersensitive syndrome, and there are good reasons to use a new label that would encompass the problem of chronic cough: the chronic 'cough hypersensitivity syndrome'. This would focus the problem on the cough symptomatology and lead to greater focus on understanding the mechanisms of cough sensitisation, with the ultimate aim of obtaining more effective antitussives.

Chronic cough: Stepwise application in primary care practice of the ACCP guidelines for diagnosis and management of cough

PURPOSE

To illustrate decision points encountered when using evidence-based guidelines for diagnosis and management of chronic cough by means of a composite case study based on primary care practice.

DATA SOURCE

The American College of Chest Physicians (ACCP) Evidence-Based Clinical Practice Guidelines for Diagnosis and Management of Cough, and review of the scientific literature on cough and related topics.

CONCLUSIONS

The ACCP guidelines offer a systematic approach that uses trials of empirical therapies to diagnose and resolve the very common, often perplexing complaint of chronic cough. The major diagnoses reached are upper airway cough syndrome, cough-variant asthma, gastroesophageal reflux disease, and nonasthmatic eosinophilic bronchitis.

IMPLICATIONS FOR PRACTICE

Cough is the most common reason that patients seek an office visit. Many coughs resolve spontaneously, but coughs that persist significantly impair the quality of life. Use of the ACCP guidelines allows a stepwise empirical approach to the problem of unexplained chronic cough. This approach greatly increases the percentage of chronic coughs that are accurately diagnosed and effectively treated, and avoids unnecessary diagnostic testing.

Assessment and management of patients with chronic cough by Certified Respiratory Educators: a randomized controlled trial

BACKGROUND

The value of other health care professionals is increasingly being recognized to compensate for the shortage of physicians in Canada. Chronic cough is one of the most common reasons for consultation with a respirologist. In the present study, a prospective, randomized, controlled study was undertaken to determine whether Certified Respiratory Educators (CREs) could manage screened patients with chronic cough as effectively as respirologists.

METHODS

An eight-week, prospective, parallel-design, randomized, controlled trial of the management of chronic cough patients was conducted. Patients were screened to exclude those with potentially life-threatening conditions. The primary outcome was the number of patients whose cough resolved or subjectively improved.

RESULTS

A total of 198 patients were randomly assigned, and eight-week data were available on 151 patients. Mean age of the patients was 49.8+/-13.4 years, 70.2% were female and median cough duration was 16 months. The screening process was effective and referral wait times decreased from a median of two months to less than four weeks (P<0.0001). The educators averaged 4.9 contacts per patient compared with 2.7 by the physicians over the eight-week study period (P<0.0001). Most patients had had multiple therapeutic trials before referral. Cough resolved or improved in two-thirds of the patients at eight weeks; however, more patients showed improvement in the educator arm than in the physician arm, P<0.02. Cough-specific quality of life improved similarly in the two study arms at eight weeks (physician arm: 61.5+/-14.1 to 52.6+/-14.4, P<0.0001; CRE arm: 58.1+/-14.9 to 50.0+/-15.8, P=0.0003).

CONCLUSIONS

CREs can safely and effectively assess, as well as appropriately treat, screened patients with chronic cough with a resultant reduction in wait times.

Unexplained cough in the adult

Unexplained cough is a diagnosis of exclusion that should not be made until a thorough validated diagnostic evaluation is performed, specific and appropriate validated treatments have been tried and failed, and uncommon causes have been ruled out. When chronic cough remains troublesome after the initial work up, determine that a protocol has been used that has been shown to lead to successful results. If such a protocol has been used, next consider whether or not pitfalls in management have been avoided. If they have been, the frequency of truly unexplained chronic cough usually should not exceed 10%. While patients with truly unexplained coughs have an overly sensitive cough reflex, the mere presence of an overly sensitive cough reflex does not by itself explain why they do not get better, because most patients with chronic cough, even those who respond to treatment and get better, have demonstrable heightened cough sensitivity. Management options include referral to a cough clinic with interdisciplinary expertise, speech therapy, and self-limited trials of drugs, preferentially with those shown to be effective in randomized, double-blind placebo-controlled trials in patients with unexplained chronic cough.

Pharmacological and non-pharmacological interventions for cough in adults with respiratory and non-respiratory diseases: A systematic review of the literature

The management of cough in adults with respiratory and non-respiratory illnesses is suboptimal and based mostly on clinical opinions rather than evidence. A systematic review was carried out assessing all trials in adult patients with respiratory and non-respiratory diseases (excluding cancer) that had chronic cough as primary or secondary outcome. A total of 1177 trials were retrieved and 75 met the criteria for inclusion in the review. The vast majority were in patients with asthma and chronic obstructive pulmonary disease (COPD). Cough was the primary outcome in less than one-quarter of the studies. The measurement of cough was variable, mostly using unvalidated scales or being part of an overall 'symptoms' score. Positive results were overall seen with the use of corticosteroids, leukotriene receptor antagonists, mast cell stabilizers, ipratropium bromide, neltenexine, iodinised glycerol and lidocaine. Speech pathology training and symptom monitoring through SMS messages (accompanied by treatment adjustments) have also shown promise. Evidence for established anti-tussive agents such as codeine was scarce, with positive studies from the 1960s, whilst more recent studies showed no effect in patients with COPD. Many studies had conflicting results. It is imperative that the management of cough and its evidence base be improved, using higher quality research designs and with cough being the primary outcome of trials.

Quality of life in patients with chronic cough

Chronic cough is a relatively common symptom for which effective, acceptable treatments are lacking. Many patients suffer frequent coughing over several years without resolution and this has significant physical, social and psychological consequences. The recent development of cough-specific quality-of-life tools now allows quantification of the burden of coughing both in patients specifically presenting with chronic cough and also in common respiratory conditions.

Associations of physical and mental health problems with chronic cough in a representative population cohort

BACKGROUND

Although chronic cough is a common problem in clinical practice, data on the prevalence and characteristics of cough in the general population are scarce. Our aim was to determine the prevalence of chronic cough that is not associated with diagnosed respiratory conditions and examine the impact on health status and psychological health, in a representative adult population cohort

METHODS

North West Adelaide Health Study (n stage 1 = 4060, stage 2 = 3160) is a representative population adult cohort. Clinical assessment included spirometry, anthropometry and skin tests. Questionnaires assessed demographics, lifestyle risk factors, quality of life, mental health and respiratory symptoms, doctor diagnosed conditions and medication use.

RESULTS

Of the 3355 people without identified lung disease at baseline, 18.2% reported chronic cough. In multiple logistic regression models, at follow-up, dry chronic cough without sputum production was significantly more common in males (OR 1.5, 95% CI 1.1, 1.9), current smokers (OR 4.9, 95% CI 3.4, 7.2), obesity (OR 1.9, 95% CI 1.3, 2.9), use of ACE inhibitors (OR 1.8, 95% CI 1.1, 2.9), severe mental health disturbance (OR 2.1, 95% CI 1.4, 3.1) and older age (40-59 years OR 1.7 95% CI 1.2, 2.4; > or = 60 years OR 2.1 95% CI 1.3, 3.5). Among non-smokers only, all cough was significantly more common in men, those with severe mental health disturbance and obesity.

CONCLUSIONS

Chronic cough is a major cause of morbidity. Attention to cough is indicated in patients with obesity, psychological symptoms or smokers. Inquiring about cough in those with mental health problems may identify reversible morbidity.

Changes in health-related quality of life and clinical implications in Chinese patients with chronic cough

Background

Chronic cough has negative effects on quality of life. However, the changes in health-related quality of life and clinical implications remain unclear in Chinese patients with chronic cough.

Methods

A standard Chinese version of Leicester cough questionnaire (LCQ) was developed by an established translation procedure and its repeatability was assessed in a preliminary study involving 20 untreated patients with stable chronic cough. The quality of life was measured with the Short form-36 health survey and compared between 110 patients with chronic cough and 90 healthy volunteers. The changes in health-related quality of life were evaluated in the patients with chronic cough with the LCQ just before the specific treatment was initiated and a week after the cough had resolved completely. Cough threshold with inhaled capsaicin, expressed as the lowest concentration of capsaicin required for the induction of ≥5 coughs, was also measured.

Results

The repeatability of the Chinese version of the LCQ was validated at a four day interval with the intraclass correlation coefficients of 0.89-0.94 for total and domain score (n = 20). The scores of the Short form-36 health survey were significantly lower in patients with chronic cough than those in healthy volunteers. In general, there was no significant difference in overall quality of life between different causes of chronic cough or genders although embarrassment, frustration and sleep disturbance were more common in female patients, as indicated by the LCQ. However, the successful treatment of cough obviously increased the total scores of the LCQ from 14.2 ± 2.7 to 19.5 ± 1.9 (t = 13.7, P < 0.0001). There was a significant correlation between the total score of the LCQ and physical (r = 0.39, P < 0.0001) or mental (r = 0.30, P < 0.001) component summary of the Short form-36 health survey but not between the LCQ and capsaicin cough threshold.

Conclusion

The quality of life is significantly impaired in Chinese patients with chronic cough. The Chinese version of the LCQ is a valid measure of cough related quality of life and is repeatable and responsive.

Pediatric cough: children are not miniature adults

Pediatric cough-related issues, like most other conditions in particularly young children, share similarities but also have substantial important differences with adults. These can be understood from physiologically based domains simplified to (1) cough-specific, (2) general respiratory, (3) other direct systems such as the immune system, and (4) other general physiology. Among other reasons, these result in observed differences in etiology, management, and measurement of response between children and adults. For example, while empirical therapy for chronic cough is widely advocated for adults, it is not advocated for children. Indeed, there is some evidence that an empirical approach is potentially harmful; this is related to the use of medications and the delay in obtaining a correct diagnosis such as missed foreign body aspiration.

Effect of the management of patients with chronic cough by pulmonologists and certified respiratory educators on quality of life: a randomized trial

BACKGROUND

The role of certified respiratory educators (CREs) is to educate, assess, and help to manage patients with asthma and COPD in Canada. This study was undertaken to see whether CREs could assist pulmonologists (MDs) in managing patients with chronic cough.

METHODS

An 8-week prospective, parallel design, randomized, controlled trial to determine whether CREs using a protocol-driven algorithmic approach could assist in the management of patients referred to a university tertiary care medical center for the assessment and treatment of chronic cough. Patients were randomly assigned to a CRE-led or MD study arm for the management of chronic cough. Patients were screened to exclude those patients whose cough was due to life-threatening conditions. The primary outcome was measured with the cough-specific quality-of-life questionnaire (CQLQ).

RESULTS

A total of 198 patients were randomized, and 8-week results were available on 151 patients (mean [+/- SD] age, 49.8 +/- 13.4 years; female gender, 70%; median cough duration, 16 months). At 8 weeks, total CQLQ scores improved in the CRE-led patients (score [+/- SD] range, 58.1 +/- 14.9 to 50.0 +/- 15.8; p = 0.0003). CQLQ scores improved in four of six domains but not in the physical or emotional domains. Improvements in CRE-led patients were similar to those in MD-managed patients (initial CQLQ score, p = 0.261 [CRE vs MD]; CQLQ score at 8 weeks, p = 0.42 [CRE vs MD]). In a composite analysis of both CRE and MD patient data, CQLQ scores improved in patients whose cough resolved (56.3 +/- 13.6 to 41.5 +/- 13.6; p < 0.0001), in those whose cough improved but did not disappear (60.9 +/- 14.2 to 50.5 +/- 13.9; p < 0.0001), but did not improve in those whose cough did not improve (58.1 +/- 13.3 to 58.6 +/- 12.7; difference not significant).

CONCLUSIONS

CREs can help to safely, economically, and effectively manage properly screened patients with chronic cough. The use of CREs may shorten wait times for specialist consultation for these patients.

Cough

The management of cough in children should be etiologically based. This requires that all children with cough should be carefully evaluated and managed differently than adults because the etiologic factors and treatment in children are significantly different than that in adults. In all children with cough, exacerbation factors should be sought and intervention options for cessation advised or initiated. Parental expectations and specific concerns should also be sought and addressed.

Chronic cough: epidemiology

Chronic cough is perhaps the commonest symptom of medical importance with some 12% of the general population having the symptom on a daily or weekly basis. Chronic cough causes a large degree of morbidity, with both the physical e.g. incontinence, and the psychological e.g. social isolation, domains. The causes of chronic cough are numerous, but fall into two broad categories; that causing an asthma-like syndrome characterized by eosinophilic infiltration of the airways, and oesophageal disease, particularly weakly acid reflux. Failure to make, particularly this latter, diagnosis leads to enormous consequences in terms of loss of employment, healthcare utilisation and a psychosocial morbidity.

The role of sensory dysfunction in the development of voice disorders, chronic cough and paradoxical vocal fold movement

Sensory function may be important in the pathogenesis of Chronic Cough (CC) and Paradoxical Vocal Fold Movement (PVFM). This paper aims to explore sensory issues related to the pathogenesis, classification, assessment and management of these conditions. Sensory disruption of the vagus nerve can occur through neural plasticity whereby a change occurs in the way a central neuron reacts to an incoming stimulus. Such disruption can be demonstrated through assessment of cough reflex sensitivity and extrathoracic airway hyperresponsiveness both of which may be increased in CC and PVFM. In addition, sensory function may be determined by measuring the laryngeal adductor reflex, however this phenomenon is yet to be explored in CC and PVFM. The similarity in sensory dysfunction between CC and PVFM provides support for a link between the two conditions. There are also similarities in underlying medical conditions and symptom profiles between CC/PVFM and voice disorders such as muscle tension dysphonia. Although coughing and throat clearing may be contributing factors in the development and maintenance of voice disorders, they may occur in response to extrathoracic airway hyperresponsiveness. Dysphonia can occur in CC/PVFM and may improve following behavioural treatment of CC.

New developments in the objective assessment of cough

A variety of different methods are available for measuring cough. In clinical practice and most clinical trials subjective reporting of cough is relied upon, using scoring systems or visual analog scores (VAS). Although these measures give an indication of patients' perceptions of the severity of the symptom, they may be unreliable because they are influenced by other factors such as mood, vigilance, and expectations. An objective measure of cough would therefore be a valuable tool. In the last decade advances in computer technology and the availability of portable digital sound recording devices have resulted in a resurgence of interest in developing ambulatory systems for recording cough. The ultimate goal is an automated detection system of use in the wide variety of conditions that cause cough. Multidisciplinary teams of researchers around the world are applying techniques such as neural networks, voice recognition models, and other signal processing techniques to this problem. The main challenge is achieving high sensitivity with good discrimination of noncough signals. For cough sound detection, this is confounded by both the variability of the acoustics of cough sounds within and between individuals and the amount and variety of speech sounds that must be discriminated. Significant progress is being made and it is likely that accurate automated objective monitoring systems will be available in the near future. These systems have the potential to change the way cough is measured in clinical practice and clinical trials, allowing a better understanding of the effect of existing and novel treatments on this troublesome symptom.

Quality of life and psychosocial aspects of cough

Chronic cough is a common condition that causes considerable physical and psychological morbidity. The physical symptoms of cough are readily apparent; however, the psychosocial symptoms are often overlooked. Appreciation of the impact of cough on health-related quality of life has led to the development of three validated, cough-specific, health-related quality-of-life questionnaires that assess cough severity: Leicester Cough Questionnaire (LCQ), Cough-specific Quality of Life Questionnaire (CQLQ), and Chronic Cough Impact Questionnaire (CCIQ). These tools capture additional information not measured with objective tools and can be used to assess therapy. They should be used in conjunction with other cough severity measures such as cough frequency monitors to obtain a more complete assessment of cough severity. Recent cough guidelines endorse the measurement of cough-specific quality of life and these questionnaires are ideal tools to facilitate this.

Chronic cough: how do cough reflex sensitivity and subjective assessments correlate with objective cough counts during ambulatory monitoring?

BACKGROUND

Cough reflex sensitivity, subjective estimates of cough frequency and cough-related quality of life have been used to assess cough and monitor treatment responses. The relationships between these measures and objective cough monitoring remain unclear and the usefulness of subjective assessments remains questionable.

SUBJECTS

62 patients with chronic cough (39 women) were studied. Mean age of patients was 54.9 (SD 12.2) years, with a median duration of cough of 5.5 (range 1-30) years.

METHODS

Cough reflex sensitivity testing (C5; citric acid) was performed in all patients before fully ambulatory day-time and night-time cough recordings. Patients scored the frequency and severity of their cough (Visual Analogue Scales (VAS) and 0-5 score) for each recording period and completed a cough-related quality-of-life questionnaire, Leicester Cough Questionnaire (LCQ). Ambulatory cough recordings were manually counted and reported in terms of cough seconds per hour (cs/h). Cough rates were log(10) transformed for analysis.

RESULTS

The median time spent coughing was 11.36 (range 1.06-46) cs/h with median day rates of 15.59 (range 2-74.8) cs/h and median night rates of 2.94 (range 0-26.67) cs/h. An inverse relationship was seen between day cough rates and log(10) C5 (r = -0.452, p< or =0.001). Subjective cough scores and visual analogue scales were only moderately associated with objective time spent coughing, with night-time being scores more strongly associated than day-time scores. The strongest correlation with objective cough frequency was cough-related quality of life (LCQ), (r = -0.622, p< or =0.001), mediated through the psychological domain.

CONCLUSIONS

Subjective measures of cough and cough reflex sensitivity are only moderately related to objective time spent coughing, and hence cannot be used as surrogate markers for objective cough-frequency measurements. Cough-related quality of life (LCQ) is most strongly related to objectively counted cough, and may be a useful adjunct to objective measures in the assessment of cough.