The Korean Cough Guideline: Recommendation and Summary Statement

Development of the Rapid Cough Questionnaire: Key item identification

BACKGROUND

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Sex-related disparities in cough-associated symptoms across different age groups

BACKGROUND

Sex-related disparities in the prevalence of chronic cough have been consistently reported globally, with varying male-to-female ratios.

OBJECTIVES

This study aimed to evaluate sex-related differences by comparing correlations between cough-related symptoms in males and females of different age groups.

DESIGN

Adult patients with chronic cough who completed the Leicester Cough Questionnaire (LCQ) were recruited from 16 respiratory centers.

METHODS

Correlation networks were constructed based on Spearman's correlation coefficients in males and females of various age groups. The distinct relationships of cough-related symptoms between subgroups were validated by an independent cohort.

RESULTS

A total of 255 patients were enrolled in this study (male-to-female ratio, 1:1.71). The following LCQ items were highly correlated: embarrassment and interference with daily work, anxiety, and interference with overall life enjoyment/feeling of being fed up, interference with daily work and overall life enjoyment, interference with overall life enjoyment and feeling of being fed up, and feeling of being fed up and annoyance to partner/family/friends. The patterns of these correlations between LCQ items varied in males and females of different ages. The strongest interrelationship was observed in male patients aged >50 years old, which was similar to those in the validation cohort.

CONCLUSION

The correlation patterns between cough-related symptoms vary significantly according to age and sex. Understanding the mechanisms underlying the development of cough-related symptoms may facilitate sex- and age-specific strategies for chronic cough.

Cough Characteristics and Their Association Patterns According to Cough Etiology: A Network Analysis

Although cough is a common respiratory symptom, determining its cause is challenging. We aimed to explore how cough severity and characteristics vary with different etiologies, while investigating their interrelations with demographic features. Adult patients (n = 220) with chronic cough and completed diagnostic work-up and the COugh Assessment Test were enrolled. A correlation network analysis was used to examine the associations between the demographic features and cough severity/characteristics across various etiologies such as upper airway cough syndrome, asthma, eosinophilic bronchitis, gastroesophageal reflux disease (GERD), and idiopathic cough. Demographic features like age and sex showed complex associations with cough characteristics and severity. Cough severity decreased with age, especially in cases of eosinophilic bronchitis and GERD. Women with eosinophilic bronchitis reported more severe cough, while men with idiopathic cough reported more severe cough. Asthma was significantly linked to more sleep disturbance and fatigue, independent of age and sex, whereas GERD showed less sleep disturbance and fatigue. Network analysis revealed overall close associations between cough characteristics, though hypersensitivity in asthma and sleep disturbance in GERD were not linked with other cough traits. In conclusion, the demographic features and cough characteristics were interrelated, exhibiting distinct patterns based on the etiology.

Herbal Medicine Maekmundong-Tang on Patients with Nonspecific Chronic Cough: Study Protocol for a Double-Blind, Randomized Controlled Clinical Trial

As the treatment of nonspecific chronic cough with conventional medications that treat cough according to the cause is limited, Maekmundong-tang (comprising Liriopis seu Ophiopogonis Tuber, Pinelliae Tuber, Oryzae Semen, Zizyphi Fructus, Ginseng Radix, and Glycyrrhizae Radix et Rhizoma) has been used empirically in the clinical setting of East Asian traditional medicine. This study is the first to explore the feasibility, preliminary effect, safety, and cost-effectiveness of Maekmundong-tang for nonspecific chronic cough. This study protocol is that of a double-blind, randomized, active-controlled, parallel-group clinical trial for comparing Maekmundong-tang with Saengmaek-san (comprising Liriopis seu Ophiopogonis Tuber, Ginseng Radix, and Schisandrae Fructus), a Korean national health insurance-covered herbal medicine for cough. A total of 30 nonspecific chronic cough patients will participate and receive the assigned herbal medicine for 6 weeks, and clinical parameters will be assessed at weeks 0 (baseline), 3 (midterm assessment), 6 (primary endpoint), 9, and 24 (follow-up). Study feasibility outcomes, including recruitment, adherence, and completion rates, will be assessed. Preliminary effects on cough severity, frequency, and quality of life will be evaluated using outcome measures, such as the Cough Symptom Score, Cough Visual Analog Scale, and the Leicester Cough Questionnaire. Adverse events and laboratory tests will be monitored for safety evaluation, and exploratory economic evaluations will be conducted. The results will provide evidence of Maekmundong-tang in the treatment of nonspecific chronic cough.

Clinical phenotypes of chronic cough categorised by cluster analysis

BACKGROUND

Chronic cough is a heterogeneous disease with various aetiologies that are difficult to determine. Our study aimed to categorise the phenotypes of chronic cough.

METHODS

Adult patients with chronic cough were assessed based on the characteristics and severity of their cough using the COugh Assessment Test (COAT) and the Korean version of the Leicester Cough Questionnaire. A cluster analysis was performed using the K-prototype, and the variables to be included were determined using a correlation network.

RESULTS

In total, 255 participants were included in the analysis. Based on the correlation network, age, score for each item, and total COAT score were selected for the cluster analysis. Four clusters were identified and characterised as follows: 1) elderly with mild cough, 2) middle-aged with less severe cough, 3) relatively male-predominant youth with severe cough, and 4) female-predominant elderly with severe cough. All clusters had distinct demographic and symptomatic characteristics and underlying causes.

CONCLUSIONS

Cluster analysis of age, score for each item, and total COAT score identified 4 distinct phenotypes of chronic cough with significant differences in the aetiologies. Subgrouping patients with chronic cough into homogenous phenotypes could provide a stratified medical approach for individualising diagnostic and therapeutic strategies.

Efficacy of non-sedating H1-receptor antihistamines in adults and adolescents with chronic cough: A systematic review

Background

Nasal symptoms frequently coexist in patients with chronic cough, and non-sedating H1-receptor antihistamines (nsH1RAs) are often prescribed for cough management in several countries. However, recommendations on the use of nsH1RAs vary among chronic cough guidelines. This study aimed to examine the efficacy of nsH1RAs over placebos in adolescents or adults with chronic cough or allergic respiratory conditions that may present as chronic cough.

Methods

Electronic databases were searched for studies published until November 2020. Randomized placebo-controlled trials of nsH1RAs reporting cough endpoints in adolescents or adults with chronic cough or cough-associated allergic respiratory conditions (allergic rhinitis, allergic asthma, or atopic cough) were included.

Results

A total of 10 placebo-controlled trials were identified. Three studies (one study each involving allergic rhinitis, allergic rhinitis with comorbid asthma, and atopic cough) described baseline and post-treatment cough scores, and all reported significant improvements in subjective cough scores; however, the magnitude of improvement was greater in the 2 studies of patients with atopic cough (relative improvement in cough frequency score: −36.6 ± 8.4%) or seasonal allergic rhinitis-associated cough (cough frequency score: −44.0 ± 7.3% and cough intensity score: −65.7 ± 8.3%) than in the 1 study of allergic rhinitis patients with comorbid asthma (−4.0 ± 1.3%). Meanwhile, the other 7 trials found conflicting results but lacked information on the baseline cough score and did not use validated cough measurement tools; thus, their clinical relevance could not be determined.

Conclusion

Despite the widespread use of nsH1RAs in patients with chronic cough, only a few clinical trials examining their benefits on cough outcomes have been conducted. There may be a subgroup of patients, particularly those with seasonal allergic rhinitis-associated cough or atopic cough, whose cough may improve with nsH1RA treatment. However, adequately powered trials with validated cough measurement tools are warranted to confirm the role of nsH1RAs in the management of patients with allergic phenotypes of chronic cough.

Chronic cough is associated with depressive mood in women regardless of smoking status and lung function

BACKGROUND

Chronic cough is a common respiratory symptom, and, if persistent, the patient's quality of life can worsen and result in a depressive mood, or vice versa. Although previous reports suggest a relationship between chronic cough and depression, we further investigated this relationship according to smoking status and lung function.

METHODS

This observational study used cross-sectional data from the 6^th Korean National Health and Nutrition Examination Survey (2014 and 2016). Propensity score matching using age, sex, smoking status, and lung function was performed for participants with and without chronic cough to reduce the confounding effects associated with depressive mood. Questionnaires recorded coughs persisting for >3 months and the Patient Health Questionnaire-9 (PHQ-9) assessed the severity of depressive mood.

RESULTS

Among 12 494 participants who were >18 years old, 226 with chronic cough were matched with 226 with non-chronic cough. Overall, chronic cough participants showed higher PHQ-9 scores than the non-chronic cough participants (4.29 ± 5.23 vs. 2.63 ± 3.38, P < .001). When stratified by sex, the difference remained significant in women (5.69 ± 5.96 vs. 3.05 ± 3.97, P < .001) but not in men (3.18 ± 4.27 vs. 2.31 ± 3.65, P = .092). When stratified by lung function status, the difference remained significant for those with normal lung function (4.32 ± 5.32 vs. 2.78 ± 3.86, P = .003) and reduced lung function (4.19 ± 4.93 vs. 2.11 ± 3.55, P ≤ 0.001). Multivariate logistic regression analysis revealed that chronic cough was associated with PHQ-9 score (odds ratio [OR], 1.06; 95% confidence interval [CI], 1.014-1.27, P = .014), chronic obstructive pulmonary disease (OR, 4.87; 95% CI, 1.041-22.86, P = .044) and physician-diagnosed bronchial asthma (OR, 2.93; 95% CI, 1.162-7.435, P = .023).

CONCLUSIONS

Depressive mood is significantly correlated with chronic cough in females.

Differential features of chronic cough according to etiology and the simple decision tree for predicting causes

Finding etiology of chronic cough is an essential part of treatment. Although guidelines include many laboratory tests for diagnosis, these are not possible in many primary care centers. We aimed to identify the characteristics and the differences associated with its cause to develop a clinical prediction model. Adult subjects with chronic cough who completed both Korean version of the Leicester Cough Questionnaire (K-LCQ) and COugh Assessment Test (COAT) were enrolled. Clinical characteristics of each etiology were compared using features included in questionnaires. Decision tree models were built to classify the causes. A total of 246 subjects were included for analysis. Subjects with asthma including cough variant asthma (CVA) suffered from more severe cough in physical and psychological domains. Subjects with eosinophilic bronchitis (EB) presented less severe cough in physical domain. Those with gastro-esophageal reflux disease (GERD) displayed less severe cough in all 3 domains. In logistic regression, voice hoarseness was an independent feature of upper airway cough syndrome (UACS), whereas female sex, tiredness, and hypersensitivity to irritants were predictors of asthma/CVA; less hoarseness was a significant feature of EB, and feeling fed-up and hoarseness were less common characteristics of GERD. The decision tree was built to classify the causes and the accuracy was relatively high for both K-LCQ and COAT, except for UACS. Voice hoarseness, degree of tiredness, hypersensitivity to irritants and feeling fed-up are important features in determining the etiologies. The decision tree may further assists classifying the causes of chronic cough.

Perspectives on chronic cough in Korea

Chronic cough is a common condition, and generally affects about 3% of Korean adults with a significant influence on quality of life (QoL). Despite continued clinical and academic efforts, there are unmet needs for chronic cough prevention and management in Korea. Epidemiologically, there are two major challenges: an aging population and air pollution. Korea is one of the most rapidly aging countries, and the relative proportion of elderly to younger people is expected to double within the next two decades. Air pollution is a major concern, but there is very limited evidence on the effects of air pollutant on cough in Korean patients. Clinically, upper and lower airway diseases, such as rhinitis/rhinosinusitis and cough variant asthma/eosinophilic bronchitis, are reported to account for about 75% of chronic cough in Korean adults, which formed the basis in formulating clinical practice guidelines. However, further studies are warranted to resolve clinical uncertainty, particularly for the evaluation and treatment of upper airway conditions in chronic cough. The prevalence of gastroesophageal reflux disease (GERD) is increasing, thus its relevance to cough among Koreans may warrant re-evaluation. Infection-associated chronic cough, such as tuberculosis, is another continuing concern. The proportion of chronic refractory or unexplained cough is assumed to be 10–20% among patients visiting referral clinics for chronic cough. This review presents our perspectives on current epidemiological and clinical issues of chronic cough in Korea, and addresses major knowledge gaps and future research priorities.

Cluster analysis in 975 patients with current cough identifies a phenotype with several cough triggers, many background disorders, and low quality of life

BACKGROUND

Recognition of disorder phenotypes may help to estimate prognosis and to guide the clinical management. Current cough management guidelines classify patients according to the duration of the cough episode. However, this classification is not based on phenotype analyses. The present study aimed to identify cough phenotypes by clustering.

METHODS

An email survey among employed, working-age subjects identified 975 patients with current cough. All filled in a comprehensive 80-item questionnaire including the Leicester Cough Questionnaire. Phenotypes were identified utilizing K-means partitional clustering. A subgroup filled in a follow-up questionnaire 12 months later to investigate the possible differences in the prognosis between the phenotypes.

RESULTS

Two clusters were found. The cluster A included 608 patients (62.4% of the population) and the cluster B 367 patients (37.6%). The three most important variables to separate the clusters were the number of the triggers of cough (mean 2.63 (SD 2.22) vs. 6.95 (2.30), respectively, p < 0.001), the number of the cough background disorders (chronic rhinosinusitis, current asthma, gastroesophageal reflux disease, 0.29 (0.50) vs. 1.28 (0.75), respectively, p < 0.001), and the Leicester Cough Questionnaire physical domain (5.33 (0.76) vs. 4.25 (0.84), respectively, p < 0.001). There were significant interrelationships between these three variables (each p < 0.001). Duration of the episode was not among the most important variables to separate the clusters. At 12 months, 27.0% of the patients of the cluster A and 46.1% of the patients of the cluster B suffered from cough that had continued without interruptions from the first survey (p < 0.001).

CONCLUSIONS

Two cough phenotypes could be identified. Cluster A represents phenotype A, which includes the majority of patients and has a tendency to heal by itself. The authors propose that cluster B represents phenotype TBQ (Triggers, Background disorders, Quality of life impairment). Given the poor prognosis of this phenotype, it urges a prompt and comprehensive clinical evaluation regardless of the duration of the cough episode.

Dispensing Antibiotics without a Prescription for Acute Cough Associated with Common Cold at Community Pharmacies in Shenyang, Northeastern China: A Cross-Sectional Study

: The inappropriate use of antibiotics is a major health issue in China. We aimed to assess nonprescription antibiotic dispensing and assess pharmacy service practice at community pharmacies in Shenyang, northeastern China, and to compare these practices between pediatric and adult cases. A cross-sectional study was performed from March to May 2018 using the standardized client method. Two different simulated scenarios were presented at pharmacies, namely, pediatric and adult acute cough associated with a common cold. Of 150 pharmacy visits, 147 visits were completed (pediatric case: 73, adult case: 74). A total of 130 (88.4%) community pharmacies dispensed antibiotics without a prescription, with a significant difference between pediatric and adult cases (pediatric case, 79.5% versus adult case, 97.3%, p = 0.005). Symptoms were asked in most visits (pediatric case: 82.2%, adult case 82.4%). Patients' previous treatment and history of allergies were both inquired more frequently in the pediatric cases than in the adult cases. Medication advice was provided more often in the adult cases than in pediatric cases. Antibiotics were easily obtained without a prescription in Shenyang, especially for adult patients. Adequate inquiries and counseling had not occurred in most pharmacies.

Psychiatric comorbidity in children with psychogenic and functional breathing disorders

BACKGROUND

The present study aims to assess psychiatric diagnoses in children with psychogenic and functional breathing disorders (PFBD), which consist of children with psychogenic cough, throat-clearing tics, and sighing dyspnea, and compare them to a control group without any diagnosis of chronic medical problems.

METHODS

The participants consist of 52 children with PFBD and 42 children without any chronic medical problems. Psychiatric diagnoses were assessed via semistructured psychiatric interviews in both groups.

RESULTS

The two groups did not differ on age (PFBD group 11.25 ± 2.61, control group 11.17 ± 2.58; t = 0.14, P = .88) or sex (48.1% of the PFBD group were female, 61.9% of the control group were female; χ²  = 1.79, P = .18). 55.8% of the PFBD group and 28.6% of the control group had at least one psychiatric diagnosis according to the semistructured interviews (χ²  = 6.99, P = .008). The most common psychiatric diagnoses in the PFBD group were attention deficit hyperactivity disorder (ADHD; 17.3%), tic disorders, (15.4%), and specific phobia (15.4%). 11.5% of the cases in the PFBD group were diagnosed with somatic symptom disorder and more than half of the patients (n = 27 (51.9%)) showed clinical characteristics of tic disorders.

CONCLUSION

Psychiatric diagnoses are common in children with PFBD, and teamwork involving child psychiatrists may be essential for the management of children with PFBD.

HL301 in the treatment of acute bronchitis: a phase 2b, randomized, double-blind, placebocontrolled, multicenter study

BACKGROUND/AIMS

There is insufficient quality data to recommend the use of herbs for the treatment of acute bronchitis. Small number of randomized trials of plant extracts for this purpose were determined to be low quality and there are concerns for the safety. HL301 is a combined product of seven medicinal plants. In the present study, we tried to evaluate the efficacy and safety of HL301 for the treatment of acute bronchitis with a randomized, double-blind, placebo-controlled, multicenter trial design.

METHODS

A total of 166 patients with acute bronchitis were randomized to receive placebo or HL301 (600 mg/day) for 7 days. The primary endpoint was change in bronchitis severity score (BSS) from baseline visit (visit 2) to the end of treatment (visit 3). Other efficacy variables were the change of each component of the BSS (cough, sputum, dyspnea, chest pain, and crackle) with treatment, response rate, improvement rate, satisfaction rate and number of rescue medications taken.

RESULTS

Changes in the BSS from visit 2 to visit 3 were higher in the HL301 group than in the placebo group both in the full analysis set (4.57 ± 1.82 vs. 3.15 ± 3.08, p < 0.01) and in the per protocol set (4.62 ± 1.81 vs. 3.30 ± 3.03, p < 0.01). Four BSS components (cough, sputum, dyspnea, and chest pain) improved more with HL301 treatment than with placebo treatment. Participants treated with HL301 showed higher response, improvement, and satisfaction rates and less use of rescue medication than the placebo group.

CONCLUSION

HL301 (600 mg/day) was effective and safe for symptomatic treatment of acute bronchitis.

Clinical Characteristics of Chronic Cough in Korea

BACKGROUND

Chronic cough is defined as a cough lasting more than 8 weeks and socio-economic burden of chronic cough is enormous. The characteristics of chronic cough in Korea are not well understood. The Korean Academy of Tuberculosis and Respiratory Diseases (KATRD) published guidelines on cough management in 2014. The current study evaluated the clinical characteristics of chronic cough in Korea and the efficacy of the KATRD guidelines.

METHODS

This was a multi-center, retrospective observational study conducted in Korea. The participants were over 18 years of age. They had coughs lasting more than 8 weeks. Subjects with current pulmonary diseases, smokers, ex-smokers with more than 10 pack-years or who quit within the past 1 year, pregnant women, and users of cough-inducing medications were excluded. Evaluation and management of cough followed the KATRD cough-management guidelines.

RESULTS

Participants with chronic cough in Korea showed age in the late forties and cough duration of more than 1 year. Upper airway cough syndrome was the most common cause of cough, followed by cough-variant asthma (CVA). Gastro-esophageal reflux diseases and eosinophilic bronchitis were less frequently observed. Following the KATRD cough-management guidelines, 91.2% of the subjects improved after 4 weeks of treatment. Responders were younger, had a longer duration of cough, and an initial impression of CVA. In univariate and multivariate analyses, an initial impression of CVA was the only factor related to better treatment response.

CONCLUSION

The causes of chronic cough in Korea differed from those reported in other countries. The current Korean guidelines proved efficient for treating Korean patients with chronic cough.

Development and validation of the COugh Assessment Test (COAT)

BACKGROUND AND OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Efficacy and safety of HL301 in the treatment of acute bronchitis and acute exacerbation of chronic bronchitis: a phase 2, randomized, double-blind, placebo-controlled, multicenter study

PURPOSE

The efficacy and safety of Chinese herbs for symptomatic treatment of bronchitis is not well established. We evaluated the efficacy and safety of a combination product of seven herbs (HL301) for the treatment of acute bronchitis (AB) and acute exacerbation of chronic bronchitis (AECB) using a randomized, double-blind, placebo-controlled, multicenter trial design.

METHODS

A total of 160 patients with AB or with AECB were randomized to receive placebo or one of three doses of HL301 (0.6 g/day, 1.2 g/day, or 1.8 g/day) for a total of 7 days. The primary study endpoint was the change in bronchitis severity score (BSS) from the baseline visit (visit 2) to the end of treatment visit (visit 3). Other efficacy variables were percentage BSS systemic sign efficacy after treatment and change in individual BSS parameters after treatment.

FINDINGS

Changes in BSS from visit 2 to visit 3 in the three treatment groups (4.63 ± 2.24, 4.08 ± 1.63, and 4.15 ± 1.74 in the HL301 0.6 g/day, 1.2 g/day, and 1.8 g/day groups, respectively) were higher than that of the placebo group (2.88 ± 2.57) in the per protocol set (PPS) (P < .05), and it was also valid in the full analysis set (FAS). The number of participants whose symptoms (measured by BSS) improved at least 30% after treatment was higher in all three treatment groups compared to the placebo group in both the FAS and the PPS (P < .05, for all).

IMPLICATIONS

Three different doses of HL301 (0.6 g/day, 1.2 g/day, and 1.8 g/day) were effective in decreasing the BSS index compared to placebo. HL301 may be effective for symptomatic treatment of both AB and AECB.

LIMITATIONS

Essential components of HL301 have not been delineated in the study and patients with AB and AECB were indiscriminately enrolled in the present study. Respective evaluation of the efficacy of HL301 for AB and AECB will be necessary in the future.

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.

Prevalence of chronic cough and possible causes in the general population based on the Korean National Health and Nutrition Examination Survey

Although chronic cough is very common, its prevalence and causes have been rarely reported in the large general population including smokers. This study aimed to identify the prevalence of possible causes of chronic cough and their clinical impact.From Korean National Health and Nutrition Examination Survey (KNHANES) data including 119,280 adults aged over 40 years, 302 individuals with chronic cough were recruited irrespective of smoking status. Data from questionnaire, laboratory tests including spirometry, chest radiographs, and otorhinolaryngologic examination were analyzed.The prevalence of chronic cough in adults was 2.5% ± 0.2%. Current smokers occupied 47.7% ± 3.8% of study population and 46.8% ± 3.9% of the subjects showed upper airway cough syndrome (UACS). Based on spirometry, chronic obstructive pulmonary disease (COPD) was identified in 26.4% ± 3.5%. Asthma explained for 14.5% ± 2.8% of chronic cough. Only 4.1% ± 1.6% showed chronic laryngitis suggesting gastro-esophageal reflux-related cough. Abnormalities on chest radiography were found in 4.0% ± 1.2%. Interestingly, 50.3% ± 4.5% of study subjects had coexisting causes. In multivariate analysis, only current smoking (odds ratio [OR] 3.16, P < 0.001), UACS (OR 2.50, P < 0.001), COPD (OR 2.41, P < 0.001), asthma (OR 8.89, P < 0.001), and chest radiographic abnormalities (OR 2.74, P = 0.003) were independent risk factor for chronic cough. This pattern was not different according to smoking status excepting the prevalence of COPD.Smoking, COPD, and chest radiographic abnormalities should be considered as causes of chronic cough, along with UACS and asthma. Gastro-esophageal reflux-related cough is not prevalent in study population.