Objective and Subjective Measurement of Cough in Asthma: A Systematic Review of the Literature

Relationships Between Chronic Cough and Asthma Control and Quality of Life in Patients With Severe Asthma: A 6-Month Longitudinal Analysis

BACKGROUND

The prevalence and clinical implications of chronic cough (CC) in patients with severe asthma receiving asthma treatment remain relatively unknown.

OBJECTIVE

This study aimed to evaluate the relationships between CC and asthma control and quality of life (QoL) in patients with severe asthma through longitudinal analysis.

METHODS

Baseline and 6-month follow-up data from the Korean Severe Asthma Registry were analyzed. CC was defined as a cough visual analog scale (VAS) score of ≥40 at both baseline and 6 months. Demographic parameters and clinical outcomes were compared between patients with severe asthma and CC and those without CC. Generalized estimating equation (GEE) analysis was performed to identify associations of CC with asthma control and QoL scores.

RESULTS

Of the total 286 participants with severe asthma, 116 (40.6%) were defined as having CC. Patients with CC had higher baseline cough and wheeze severity VAS scores (all P < .001), poorer asthma control (P < .001), and worse QoL (Severe Asthma Questionnaire [SAQ] and Euro-QoL 5-Dimension [EQ-5D] index, all P < .001) than those without CC. During the follow-up, patients with CC were more frequently exposed to oral corticosteroids (58.6% vs 38.6%, P = .010) and experienced more frequent asthma exacerbations (48.3% vs 28.6%, P = .009) than those without CC. GEE analysis revealed that CC was independently associated with poor asthma control, lower SAQ scores, and a lower EQ-5D index after adjusting for confounders.

CONCLUSION

The presence of CC was associated with worse asthma control and QoL in patients with severe asthma. Further studies are warranted to better evaluate and manage CC in these patients.

Cough Reflex Hypersensitivity as a Key Treatable Trait

Cough reflex hypersensitivity is emerging as a key treatable trait in chronic cough and other cough-associated respiratory conditions. This review examines the neurological basis of cough, highlighting the complex interplay between peripheral and central mechanisms. The concept of cough hypersensitivity aims to address unmet clinical needs by recognizing chronic cough as a distinct disorder rather than merely a symptom. Evidence from clinical trials supports cough hypersensitivity as a treatable trait in chronic cough, with opiates, gabapentinoids, and novel P2X3 antagonists showing efficacy. Cough hypersensitivity is also relevant in conditions presenting with persistent cough, such as asthma, bronchiectasis, and idiopathic pulmonary fibrosis, though more research is needed. Recognizing cough reflex hypersensitivity as a treatable trait offers new avenues for management, particularly for patients with persistent cough despite etiology-targeted therapies. We propose redefining chronic cough as a distinct disease entity in which cough hypersensitivity is a common feature and key therapeutic target, potentially leading to better patient care and the development of novel therapies.

Association of Cough Severity with Asthma Control and Quality of Life in Patients with Severe Asthma

PURPOSE

Symptoms are important components in determining asthma control and in the adjustment of treatment levels. However, clinical relevance of cough in severe asthma is not well-understood. This study aimed to evaluate the severity and association of cough with patient-reported outcomes (PROs) in patients with severe asthma.

METHODS

This study analyzed cross-sectional data from the Korean Severe Asthma Registry. The severity of coughing and wheezing symptoms was assessed using a Visual Analog Scale (VAS) ranging from 0 to 100 for each symptom. Additionally, PROs included the Asthma Control Test (ACT), the Severe Asthma Questionnaire (SAQ), and the EuroQoL 5-Dimension (EQ-5D) index. Multivariate linear regression analysis was employed to explore the relationship between cough severity and other PRO scores.

RESULTS

A total of 498 patients with severe asthma (age: 57.9 ± 13.1 years, females: 60.2%) were analyzed. The cough VAS score was higher than the wheeze score (median 30, [interquartile range 10-50] vs. 20 [0-50]; P < 0.001). Additionally, 22.5% of patients ranked in a higher tertile for cough severity compared to wheezing, while 18.5% ranked higher for wheezing severity than cough. Significant correlations were observed between cough and wheeze VAS scores (r = 0.61, P < 0.05) and between each symptom's VAS score and the SAQ (cough: r = -0.41, P < 0.001; wheeze: r = -0.52, P < 0.001), ACT scores (cough: r = -0.50, P < 0.001; wheeze: r = -0.63, P < 0.001) and EQ-5D index (cough: r = -0.40, P < 0.001; wheeze: r = -0.45, P < 0.001). In univariate regression analysis, the cough VAS score had weaker descriptive power (R2) values than the wheeze VAS score in relation to the PRO measures. Nevertheless, cough severity remained significantly associated with ACT, SAQ scores and EQ-5D index in multivariate analyses adjusted for wheeze severity and other confounders.

CONCLUSION

Cough frequently presents as a severe symptom in patients with severe asthma and could have distinct impact on asthma control and quality of life.

The illness burden of severe asthma contrasted to people with mild-to-moderate asthma: a qualitative study

Background

Disabling symptoms of asthma including breathlessness, cough, wheeze and chest tightness largely impact quality of life; however, how these symptoms impact people with asthma of different severity levels remains unknown. This study aimed to compare and characterise patients' symptom experience and the burden caused, their quality of life, and the medication preferences of people with severe asthma against those of people with mild-to-moderate asthma.

Methods

This was a multisite qualitative study involving two focus groups and semistructured interviews of adults with severe asthma undertaken in Australia and UK. Interviews were also undertaken in people with mild-to-moderate asthma. Audio recordings were transcribed and analysed thematically.

Results

Participants in both severe asthma and mild-to-moderate asthma groups had a mean±sd age of 57±12 years. Between the severe asthma and mild-to-moderate asthma groups, 62% of participants were female and 86% lived with family. Themes were identified: 1) what is asthma and most bothersome symptoms: both groups reported breathlessness as the most bothersome symptom; 2) impacts on life: disease-related impact differed as people with severe asthma reported significant burden in their quality of life, which encompassed emotional, physical, social and financial wellbeing; and 3) personalised and responsive care: severe asthma interviewees preferred injectable biological therapy as a mode of treatment administration.

Conclusions

People with asthma are burdened by breathlessness and cough and other disabling symptoms resulting in impaired quality of life. Understanding the experiences of people with asthma of different severities can improve the patient-clinician partnership.

Patient response to the management during the acute presentation of cough variant Asthma: Retrospective cohort study

The clinical improvement after assessing patients with cough variant asthma in outpatient clinics, and therapy success varied depending on the subjective improvement. Cough could be controlled within appropriate time and subsequent management can consist of inhaled corticosteroids. In this study we used the cough improvement, the only available clinical response, as a predictable factor to determine the effect of different modalities of treatment among patients with cough variant asthma. Retrospective observational analysis was performed in Saudi Arabia's King Saud University Medical City, on the presentation, diagnosis, course of therapy, and responsiveness to oral and inhaled steroids in patients with cough variant asthma. All patients who visited the clinic on multiple occasions with persistent, acute coughing without being pre-screened between September 2021 and September 2022 included based on medical records. Cough resembles cough variant asthma is the term used to describe a cough without a diagnosed etiology. To identify patients eligible for CVA treatment, iindividuals having GERD-associated cough, allergic rhinitis, bronchial asthma, smokers and atopic cough was excluded. For the examination of these findings, IBM SPSS version 28 (Armonk, NY, USA) was employed. As a result of using budesonide-formoterol inhaler, most patients (86.3 %) showed improvement in their cough symptoms (with 95 %CI: 78.3 to 94.9). There was a significant yet weak positive correlation between the frequency of cough symptoms before and after using budesonide-formoterol (r = 0.318, P value < 0.001). The understanding of treatment response and patient selection for budesonide-formoterol inhaler therapy, providing clinicians with valuable information to optimize patient care.

Cough and cough hypersensitivity as treatable traits of asthma

Cough is a common and troublesome symptom in people with asthma and is often associated with poorer asthma control and exacerbations. Apart from asthma, other causes or comorbidities might underlie cough in asthma, such as rhinosinusitis and bronchiectasis. Eosinophilic inflammation and bronchoconstriction can lead to an acute episode of cough or worsen chronic cough. Cough hypersensitivity with laryngeal paraesthesia, allotussia, and hypertussia might underlie the cough of asthma through augmented sensory nerve excitability of upper-airway vagal sensory nerves. Cough associated with bronchoconstriction and type 2 inflammation should respond to inhaled corticosteroids and long-acting β-adrenoceptor agonist therapy. For cough hypersensitivity in adults, speech and language therapy and neuromodulators (eg, gabapentin) could be considered. In children, there is no consistent association of asthma with cough sensitivity or between cough and asthma severity. Further research is needed to realise the potential of cough as a measure of asthma control, to understand the mechanisms of cough in asthma, and to develop safe, effective treatments and a precision-medicine approach to the management of cough in asthma in children and adults.

Antitussive Use in Patients with Inadequately Controlled Moderate-to-Severe Asthma: A Post Hoc Analysis of the Omalizumab EXTRA Trial

Acute and chronic cough are common symptoms in patients with severe allergic asthma. Although asthma-related cough can be controlled by asthma-specific medications, both prescription and over-the-counter antitussives are often also necessary. The anti-immunoglobulin E monoclonal antibody omalizumab is an effective treatment for patients with moderate-to-severe asthma, but little is known about subsequent antitussive use patterns. This post hoc analysis examined data from the Phase 3 EXTRA study that included patients aged 12-75 years with inadequately controlled moderate-to-severe asthma. Baseline antitussive use was low overall (16/427, 3.7% for omalizumab and 18/421, 4.3% for placebo). Among patients with no baseline antitussive use (n = 411 omalizumab, n = 403 placebo), most patients (88.3% omalizumab, 83.4% placebo) reported not using antitussives during the 48-week treatment period. The percentage of patients using 1 antitussive was lower for patients treated with omalizumab than placebo (7.1% vs 13.2%), although the adjusted rate of antitussive use during the treatment period was similar for omalizumab and placebo (0.22 and 0.25). Non-narcotics were used more often than narcotics. In conclusion, this analysis found low use of antitussives in patients with severe asthma and suggests that omalizumab may have the potential to decrease antitussive use.

Evolving Concept of Severe Asthma: Transition From Diagnosis to Treatable Traits

In recent decades, the concept of severe asthma has evolved from an umbrella term encompassing patients with high-intensity treatment needs to a clinical syndrome with heterogeneous, albeit distinct, pathophysiological processes. Biased and unbiased cluster approaches have been used to identify several clinical phenotypes. In parallel, cellular and molecular approaches allow for the development of biological therapies, especially targeting type 2 (T2) cytokine pathways. Although T2-biologics have significantly improved clinical outcomes for patients with severe asthma in real-world practice, questions on the proper use of biologics remain open. Furthermore, a subset of severe asthma patients remains poorly controlled. The unmet needs require a new approach. The “treatable traits” concept has been suggested to address a diversity of pathophysiological factors in severe asthma and overcome the limitations of existing treatment strategies. With a tailored therapy that targets the treatable traits in individual patients, better personalized medical care and outcomes should be achieved.