Health-Related Quality of Life and Its Determinants in Chronic Cough: The Korean Chronic Cough Registry Study

How Will a Treatable Traits Approach Reshape Clinical Practice in Chronic Cough?

Chronic cough, which affects 5%-18% of adults, has traditionally been considered a symptom defined by its duration. However, recent advances in understanding the pathophysiology of chronic cough have prompted the concept that chronic cough may exist as a distinct clinical entity driven by neuronal dysregulation and cough hypersensitivity. This evolving perspective recognizes various treatable traits and clinical characteristics which support the notion of cough as a disease entity and beyond that of a symptom-based classification. Initially developed for asthma and chronic obstructive pulmonary disease, the treatable traits approach has now been extended to chronic cough management, offering a more personalized treatment model. It focuses on identifying modifiable traits that significantly impact patient outcomes. However, challenges remain in implementing this model, including the need for trait validation, biomarker development, staff training, and the integration of new therapies. Despite these challenges, the treatable traits approach provides a promising framework for refining chronic cough management strategies and improving patient care.

Could cough hypersensitivity symptom profile differentiate phenotypes of chronic cough?

Background

Recently, cough reflex hypersensitivity has been proposed as a common underlying feature of chronic cough in adults. However, symptoms and clinical characteristics of cough hypersensitivity have not been studied amongst phenotypes of chronic cough. This study aimed to compare symptom features, such as cough triggers and associated throat sensations, of cough hypersensitivity in patients with asthmatic chronic cough and those with refractory chronic cough (RCC).

Methods

Patients with chronic cough from the Korean Chronic Cough Registry were prospectively evaluated over 6 months. Physicians determined the aetiological diagnosis based on clinical evaluations and responses to treatment at the 6-month follow-up visit. Symptoms of cough hypersensitivity and cough-specific quality of life were assessed using the Cough Hypersensitivity Questionnaire (CHQ) and the Leicester Cough Questionnaire (LCQ), respectively.

Results

The analysis included 280 patients who completed the follow-up: 79 with asthmatic cough (cough variant asthma or eosinophilic bronchitis) and 201 with RCC. Baseline CHQ scores were similar between the groups (8.3±3.7 in asthmatic cough versus 8.9±3.9 in RCC; p=0.215, adjusted for age, sex and LCQ score). There were no significant between-group differences in the LCQ and cough severity Visual Analog Scale scores. Both groups showed a similar negative correlation with LCQ scores (asthmatic cough: r=-0.427, p<0.001; RCC: r=-0.306, p<0.001).

Conclusions

The symptoms of cough hypersensitivity may not distinguish between asthmatic cough and RCC. This suggests that chronic cough is the primary diagnosis in both phenotypes. It indicates a shared mechanism in their cough pathogenesis, despite having potentially different treatable traits.

Exploring Traits Associated With Central Sensitization Features in Patients With Chronic Cough

The concept of cough hypersensitivity suggests that central sensitization plays a role in the pathophysiology of chronic cough. However, it remains unclear which traits are associated with central sensitization features in patients with chronic cough. A cohort of 317 Korean patients with newly referred chronic cough underwent clinical evaluations. The Central Sensitization Inventory (CSI), a questionnaire originally developed as a screening tool to identify patients with Central Sensitization Syndrome, was also administered. Other patient-reported outcomes (PROs), such as the cough severity visual analogue scale, Leicester Cough Questionnaire (LCQ), Cough Hypersensitivity Questionnaire (CHQ), and the Center for Epidemiological Studies Depression (CES-D) scale, were also administered. Follow-up assessments were conducted one month later. At baseline, the presence of CSI scores of ≥ 40 was associated with being female (89.6% vs. 63.4%; P < 0.001), older age, concomitant symptoms, and cough-related complications. CSI scores correlated with PRO scores, including LCQ (r = -0.424, P < 0.001), CHQ (r = 0.373, P < 0.001), and CES-D (r = -0.660, P < 0.001). Their patterns of correlations were similar in the 1-month longitudinal follow-up data analysis. In conclusion, CSI scores in patients with chronic cough correlated with cough-specific and depression-related PROs, suggesting the potential relevance of central sensitization in certain phenotypes of chronic cough.

Exploring the concept of disease control in chronic cough

Background

Disease control in chronic diseases is an overarching concept that reflects the degree to which the goals of therapy are met. However, to date, there is no consensus on the definition of disease control in chronic cough. This study aimed to provide a conceptual exploration of patient-reported cough control in chronic cough.

Methods

This research is comprised of two subanalyses. First, patients with chronic cough receiving care at referral clinics were evaluated. Correlation analyses were performed between patient-reported cough control (a 5-point Likert scale), cough-specific patient-reported outcomes (PROs) and generic health PRO scores. Second, a survey was conducted among patients with refractory chronic cough and physicians to identify factors pertinent to cough control.

Results

The analysis of 341 patients (mean age: 55.5±15.1 years; female: 66.6%) revealed that cough control rating was moderately correlated with cough severity visual analogue scale and Leicester Cough Questionnaire scores, while demonstrating weaker correlations with cough-associated throat symptoms, cough-related complications or general health-related quality of life (QoL). In the survey of patients and physicians, both groups considered certain factors, such as cough frequency, severity and impact on QoL, to be relevant to the concept of cough control. However, patients rated "need for cough rescue drug" notably higher than physicians.

Conclusion

Patient-reported cough control was associated with cough severity or impact on QoL; however, cough control may not be fully captured by conventional cough PRO measurement tools. Further studies are warranted to define the consensus and tools to measure disease control in chronic cough.

Burden of Disease Associated with Refractory and Unexplained Chronic Cough in Canada: Results from a National Survey

INTRODUCTION

Chronic cough (persisting for ≥ 8 weeks) is a common disorder that includes refractory chronic cough (RCC; cough that persists despite treatment of underlying disease) and unexplained chronic cough (UCC; cough with no identifiable cause). We evaluated self-reported health-related quality of life (HR-QoL) and work/activity impairment associated with RCC/UCC in Canada.

METHODS

Our exploratory study included Canadians in the Leger Opinion Panel with RCC or UCC. Key entry criteria were ≥ 18 years of age, cough for ≥ 8 weeks, not currently smoking/quit ≥ 1 year ago, no serious respiratory disease or lung cancer, and not taking angiotensin-converting enzyme inhibitors. Respondents completed a 30-min online survey with general and cough-specific HR-QoL questionnaires, including the EuroQol (EQ) visual analogue scale (VAS), EQ-5-dimension 5-level (EQ-5D-5L), cough severity VAS, Leicester Cough Questionnaire (LCQ), and Work Productivity and Activity Impairment-Specific Health Problem (WPAI-SPH).

RESULTS

Of 49,076 individuals who completed the chronic cough screening questionnaire (July 30-September 1, 2021), 1,620 (3.3%) met entry criteria for RCC/UCC and 1,046 (2.1%) completed the survey. The mean age of respondents was 45 years and 61% were female. Respondents reported impairments in global HR-QoL (EQ-VAS 73.8, 61% with anxiety/depression on the EQ-5D-5L) and cough-specific HR-QoL (mean cough severity VAS score 29.7, LCQ index 15.2). Work and non-work activities were reduced by 34% and 30%, respectively, on the WPAI-SPH.

CONCLUSION

RCC/UCC is prevalent in Canada and associated with impaired HR-QoL, particularly in mental health domains. Additional support and management options may be required to fully address this burden.

Cough Response to High-Dose Inhaled Corticosteroids in Patients with Chronic Cough and Fractional Exhaled Nitric Oxide Levels ≥ 25 ppb: A Prospective Study

This study aimed to investigate the effects of high-dose inhaled corticosteroids (ICS) on chronic cough patients with elevated fractional exhaled nitric oxide (FeNO) levels. In a prospective study, adults with chronic cough and FeNO ≥ 25 ppb, without any other apparent etiology, received fluticasone furoate (200 mcg) for three weeks. Outcomes were evaluated using FeNO levels, cough severity, and Leicester Cough Questionnaire (LCQ) before and after treatment. Of the fifty participants (average age: 58.4 years; 58% female), the treatment responder rate (≥ 1.3-point increase in LCQ) was 68%, with a significant improvement in cough and LCQ scores and FeNO levels post-treatment. However, improvements in cough did not significantly correlate with changes in FeNO levels. These findings support the guideline recommendations for a short-term ICS trial in adults with chronic cough and elevated FeNO levels, but the lack of correlations between FeNO levels and cough raises questions about their direct mechanistic link.

Mediating role of health literacy in relationship between frailty and health-related quality of life in community-dwelling older adults

PURPOSE

The aim of this study was to investigate the mediating effects of health literacy on the relationship between frailty and health-related quality of life (HRQOL) among community-dwelling older adults.

METHODS

This study used the Korean Frailty and Aging Cohort Database (KFACD) for secondary data analysis. We selected data from 1,631 people without missing main variable values for analysis. Frailty was determined based on the modified Fried's phenotype [MFP], and HRQOL was measured using the Korean version of the 5-level EuroQol questionnaire (EQ-5D-5L). Health literacy was assessed using the questions on the Behavioral Risk Factor Surveillance System (BRFSS) used by the U.S. Center for Disease Control and Prevention. To examine the mediating role of health literacy in the relationship between frailty and HRQOL, Baron & Kenny's three-step mediating effect verification method was utilized.

RESULTS

The participants had a mean frailty score of 1.37±1.02, health literacy score of 8.56±2.59, and HRQOL score of 0.84±0.10. Frailty was negatively correlated with health literacy (r = -0.27, p < .001) and HRQOL (r = -0.32, p < .001), while health literacy was positively correlated with HRQOL (r = 0.34, p < .001). We observed that health literacy played a partial mediating role in the relationship between frailty and HRQOL.

CONCLUSION

To increase older adults' HRQOL, measures that directly prevent and manage frailty as well as interventions that target the enhancement of health literacy are needed.

Baseline Cohort Profile of the Korean Chronic Cough Registry: A Multicenter, Prospective, Observational Study

PURPOSE

The Korean Chronic Cough Registry study was initiated to characterize patients with chronic cough (CC) and investigate their outcomes in real-world clinical practice. This report aims to describe the baseline cohort profile and study protocols.

METHODS

This multicenter, prospective observational cohort study included newly referred CC patients and those already being treated for refractory or unexplained chronic cough (RUCC). Cough status was assessed using a visual analog scale, the Leicester Cough Questionnaire (LCQ), and the Cough Hypersensitivity Questionnaire (CHQ).

RESULTS

A total of 610 patients (66.9% women; median age 59.0 years) were recruited from 18 centers, with 176 being RUCC patients (28.9%). The median age at CC onset was 50.1 years, and 94.4% had adult-onset CC (≥ 19 years). The median cough duration was 4 years. Compared to newly referred CC patients, RUCC patients had a longer cough duration (6.0 years vs. 3.0 years) but had fewer symptoms and signs suggesting asthma, rhinosinusitis, or gastroesophageal acid reflux disease. Subjects with RUCC had lower LCQ scores (10.3 ± 3.3 vs. 11.6 ± 3.6; P < 0.001) and higher CHQ scores (9.1 ± 3.9 vs. 8.4 ± 4.1; P = 0.024). There were no marked differences in the characteristics of cough between refractory chronic cough and unexplained chronic cough.

CONCLUSIONS

Chronic cough typically develops in adulthood, lasting for years. Cough severity and quality of life impairment indicate the presence of unmet clinical needs and insufficient cough control in real-world clinical practice. Longitudinal follow-up is warranted to investigate the natural history and treatment outcomes.

Effects of bepotastine, a nonsedating H1-antihistamine, for the treatment of persistent cough and allergic rhinitis: a randomised, double-blind, placebo-controlled trial

Background

Empirical therapy with oral histamine-1 receptor antagonists (H1RAs) is often used for patients with suspected upper airway cough syndrome. No placebo-controlled trials with nonsedating H1RAs (nsH1RAs) have evaluated validated cough outcomes. The objective of the present study was to assess the effect of an nsH1RA, bepotastine, on cough outcomes in patients with allergic rhinitis and persistent cough.

Methods

A randomised, double-blind, placebo-controlled trial was conducted. Adult patients with persistent cough (>3 weeks in duration) and symptomatic allergic rhinitis were recruited and randomly assigned to receive either bepotastine or placebo at a 1:1 ratio. The primary outcome was cough-specific quality of life assessed using the Leicester Cough Questionnaire (LCQ). Secondary outcomes included cough severity visual analogue scale (VAS), throat VAS, Cough Hypersensitivity Questionnaire, Sinonasal Outcome Test-22 score and drug adverse events.

Results

Between October 2021 and September 2022, 50 participants (43 females; mean age 46.28 years; median cough duration 3 months) were assigned to either the bepotastine 10 mg twice daily or placebo group in a 1:1 ratio. After 2 weeks of treatment, both bepotastine and placebo groups showed significant improvements in the LCQ scores, but there was no significant difference in the magnitude of change between the groups (3.45±2.10 versus 3.04±2.94, p=0.576). Secondary outcomes were also comparable.

Conclusions

Despite the relatively small sample size, our study clearly demonstrated that a 2-week treatment with bepotastine did not provide therapeutic benefits for cough outcomes. These findings suggest against the use of nsH1RAs with the intention of improving cough outcomes, even in patients with persistent cough and allergic rhinitis.