Is laryngeal hypersensitivity the basis of unexplained or refractory chronic cough?

Laryngeal Dysfunction Manifesting as Chronic Refractory Cough and Dyspnea: Laryngeal Physiology in Respiratory Health and Disease

TOPIC IMPORTANCE

Laryngeal dysfunction as a cause of chronic refractory cough and episodic dyspnea is often missed, which results in unnecessary testing and delays in diagnosis. Understanding laryngeal roles in breathing and airway protection can help to appreciate the propensity to laryngeal dysfunction with aging, chronic lung disease, and sleep apnea.

REVIEW FINDINGS

The human larynx is a complex muscular structure that is responsible for multiple roles of breathing, vocalization, coughing, and swallowing. To undertake these activities, the larynx has a high density of sensory and motor innervation. In addition to common embryological origins with the pharynx and esophagus, with which many laryngeal activities are shared, somatomotor and autonomic pathways regulate emotional, cognitive, and complex motor sequence-planning activities within the larynx. Due to its unique location, the larynx is susceptible to infectious and gastroesophageal reflux-related insults. Couple this with key roles in regulation of airflow and mediation of airway protective reflexes, it is not surprising that neuropathic abnormalities and muscle dysfunction frequently develop. The expression of laryngeal dysfunction as hypersensitivity to mechanical, thermal, chemical, and other stimuli leads to exaggerated airway protective reflexes (laryngeal adductor reflex and cough reflex) manifesting as dyspnea and cough.

SUMMARY

Pulmonologists should incorporate assessment of laryngeal dysfunction during evaluation of chronic refractory cough and dyspnea. Recognition of laryngeal hypersensitivity in the patient with chronic refractory cough can identify patients who may benefit from cough suppression therapies. Similarly, timely identification of inducible laryngeal obstruction may not only resolve episodic dyspnea but lessen the need for unnecessary testing and treatments.

Chronic Cough and Obstructive Sleep Apnea

Chronic cough, defined as a cough lasting more than 8 weeks, is a common medical condition occurring in 5% to 10% of the population. Its overlap with another highly prevalent disorder, obstructive sleep apnea (OSA), is therefore not surprising. The relationship between chronic cough and OSA extends beyond this overlap with higher prevalence of OSA in patients with chronic cough than in the general population. The use of continuous positive airway pressure can result in improvement in chronic cough although further studies are needed to understand which patients will experience benefit in their cough from the treatment of comorbid OSA.

Relevant factors associated with the development of chronic cough after recovery from COVID-19

BACKGROUND

Cough is one of the symptoms of the post-COVID-19 condition. However, the factors associated with its development remain unclear. We evaluated the factors associated with chronic cough in the post-COVID-19 condition.

METHODS

In this survey, 170 individuals who previously had COVID-19 and were admitted to Aichi Hospital between October 2020 and October 2021 were included. Using self-developed questionnaires and visual analog scales, 19 symptoms, including cough, were assessed. Cough-specific quality of life (QoL), reflux-related symptoms, and abnormal laryngeal sensations were also evaluated. The patients' clinical characteristics and indices, including cough-specific QoL, at admission were extracted from their medical records. Multivariate regression analyses were conducted to determine the factors associated with cough-related outcomes, such as prevalence, QoL, and severity, in the post-COVID-19 condition.

RESULTS

The median length (range) of the survey after recovery from COVID-19 was 158 (95-467) days. Cough was prevalent (n = 41, 24 %) and often accompanied by other symptoms, including gastrointestinal symptoms. Cough-specific QoL after recovery was correlated with reflux-related symptoms and abnormal laryngeal sensations. Multivariate analyses revealed that gastrointestinal symptoms, sputum, and chronic cough before contracting COVID-19 are significant predictors of cough-related outcomes in the post-COVID-19 condition. Meanwhile, other indices including cough-specific QoL on the acute phase were not reliable predictors in the post-COVID-19 condition.

CONCLUSIONS

Cough during the post-COVID-19 condition had a negative impact on daily life activities. Gastrointestinal symptoms could play a significant role in the pathophysiology of cough in such a condition.

Factors influencing behavioral cough suppression therapy in children with nonspecific chronic cough

BACKGROUND

Behavioral cough suppression therapy (BCST) with a speech-language pathologist is a common treatment for chronic nonspecific cough (a.k.a., tic cough) in children. Yet, the outcomes and duration of pediatric BCST have eluded formal investigation. This study examined whether BCST improves cough in children with nonspecific cough and factors that predict the course of treatment. Additionally, the cough characteristics and comorbidities associated with the condition were examined.

METHODS

A retrospective, observational cohort design was utilized. Cough characteristics, medical history, and BCST treatment details and outcomes for 151 children were extracted from the electronic medical record of a large outpatient pediatric otolaryngology clinic.

RESULTS

Cough was dry and onset unaccompanied by illness in most cases. Roughly half of patients reported gradual onset and cough proceeded by tickle. On average, patients experienced symptoms for 19 months (SD = 20.09) before diagnosis. Rates of comorbid General Anxiety Disorder were elevated compared to pediatric norms. Additionally, high rates of asthma (22.1%), reflux (62.3%), and disordered sleep breathing (19.2%) were observed. Common findings on laryngoscopy included interarytenoid edema and erythema. Vocal fold changes were observed in 22.9% of children. BCST reduced cough in 92.5% of patients following an average of 1.7 sessions. Comorbid behavioral health diagnoses (p = 0.013) or induced laryngeal obstruction symptoms (p = 0.025) were significant predictors of increased therapy sessions. Cough proceeded by tickle significantly predicted fewer sessions in therapy (p = 0.011).

INTERPRETATION

Although randomized clinical trials are needed, these data suggest that BCST is a low-risk, effective treatment for children with nonspecific cough.

Practical multidisciplinary framework for the assessment and management of patients with unexplained chronic aerodigestive symptoms

OBJECTIVE

Patients experiencing unexplained chronic throat symptoms (UCTS) are frequently referred to gastroenterology and otolaryngology outpatient departments for investigation. Often despite extensive investigations, an identifiable structural abnormality to account for the symptoms is not found. The objective of this article is to provide a concise appraisal of the evidence-base for current approaches to the assessment and management of UCTS, their clinical outcomes, and related healthcare utilisation.

DESIGN

This multidisciplinary review critically examines the current understanding of aetiological theories and pathophysiological drivers in UCTS and summarises the evidence base underpinning various diagnostic and management approaches.

RESULTS

The evidence gathered from the review suggests that single-specialty approaches to UCTS inadequately capture the substantial heterogeneity and pervasive overlaps among clinical features and biopsychosocial factors and suggests a more unified approach is needed.

CONCLUSION

Drawing on contemporary insights from the gastrointestinal literature for disorders of gut-brain interaction, this article proposes a refreshed interdisciplinary approach characterised by a positive diagnosis framework and patient-centred therapeutic model. The overarching aim of this approach is to improve patient outcomes and foster collaborative research efforts.

Evaluation and management of chronic cough in adults

Background: Chronic cough (CC), a cough that lasts > 8 weeks, has an overall prevalence of 5-11% in adults, peaking between 60 and 80 years of age. Of the 15% of patients who remain undiagnosed or refractory to treatment, two thirds are women. Objective: The objective was to present an updated evidence-based algorithmic approach for evaluating and managing CC, with emphasis on treatment modalities for refractory CC. Methods: A literature search was conducted of medical literature data bases for guidelines, position papers, systematic reviews, and clinical trials from January 2022 to June 2023, on the evaluation and management of CC. Results: The initial assessment should be limited to a detailed history, physical examination, chest radiograph, spirometry, exhaled nitric oxide, blood eosinophil count, and measurement of cough severity and quality of life by using validated instruments. The top diagnoses to consider are asthma, chronic obstructive pulmonary disease, nonasthmatic eosinophilic bronchitis, gastroesophageal reflux disease, and upper airway cough syndrome. Additional studies are only obtained when red flags are present or the patient fails to respond after avoidance of high-risk factors, e.g., smoking and angiotensin-converting enzyme inhibitors, and 4-6 weeks of empiric treatment for the most likely respiratory and gastrointestinal diseases. When diagnostic tests and/or specific directed treatments fail to control CC, low-dose morphine (preferred), gabapentin, pregabalin, and/or cough control therapy are recommended. Non-narcotic purinergic 2×3 (P2×3) receptor antagonists, gafapixant and campilixant, are currently being studied for CC. Conclusion: For the evaluation and management of patients with CC, clinicians should use an algorithmic approach and identify "red flags," reduce high-risk factors, and use empiric treatment for the five top diagnoses before extensive diagnostic testing. Current treatment for refractory cough is limited to symptomatic management.

Unravelling vagal hypersensitivity in chronic cough: A distinct disease

Chronic cough (CC) is a common but poorly understood disease that has a negative impact on quality of life. For years, clinicians have been trying to find the underlying diagnosis and using existing disease models to describe the patients' illness. This presents a confusing picture of CC. Most patients with CC present with hypersensitivity of the cough reflex, which is characterised by laryngeal paraesthesia and an increased response to the tussive stimuli or an innocuous stimulus that would not trigger coughing in healthy people. Recently, it has been proposed that CC is a unique disease characterised by vagal hypersensitivity that projects to the central nervous system altering responsiveness. The evidence supports the hypothesis that CC is primarily a neurological disorder, consisting of different phenotypes.

From bench to bedside: The role of cough hypersensitivity in chronic cough

BACKGROUND

Chronic cough is a burdensome condition characterized by persistent cough lasting longer than 8 weeks. Chronic cough can significantly affect quality of life, physical function and productivity, with many people troubled with a cough that lasts for months or even years. People with chronic cough commonly report a persistent urge to cough with frequent bouts of coughing triggered by innocuous stimuli, which has led to the concept of cough hypersensitivity.

MAIN BODY

Both central and peripheral neural pathways regulate cough, and although mechanisms driving development of cough hypersensitivity are not fully known, sensitization of these neural pathways contributes to excessive cough triggering in cough hypersensitivity. Effective therapies that control chronic cough are currently lacking. Recent therapeutic development has focused on several ion channels and receptors involved in peripheral activation of cough (e.g., transient receptor potential channels, P2 × 3 receptors and voltage-gated sodium channels) or central cough processing (e.g., neurokinin-1 [NK-1] receptors and nicotinic acetylcholine receptors).

CONCLUSION

These targeted therapies provide novel insights into mechanisms underlying cough hypersensitivity and may offer new treatment options for people with chronic cough. In this review, we explore preclinical and clinical studies that have improved our understanding of the mechanisms responsible for chronic cough and discuss the most promising targeted approaches to date, including trials of P2 × 3-receptor antagonists and NK-1-receptor antagonists.

Cough Sensitivity to Several External Triggers is Associated with Multiple Non-respiratory Symptoms

PURPOSE

Enhanced responsiveness to external triggers is thought to reflect hypersensitivity of the cough reflex. It may involve an enhanced sensitivity of the afferent nerves in the airways and/or an abnormal processing of the afferent information by the central nervous system (CNS). The CNS processing of cough has been shown to involve the same regions as those in symptom amplification, a phenomenon that often manifests as multiple symptoms. The main purpose of the present study was to define whether the presence of several cough triggers is associated with multiple symptoms.

METHODS

2131 subjects with current cough responding to two email surveys filled in a comprehensive questionnaire about social background, lifestyle, general health, doctors' diagnoses and visits, symptoms, and medication. Multiple symptoms was defined as three or more non-respiratory, non-mental symptoms.

RESULTS

A carefully controlled multiple regression analysis revealed that the number of cough triggers was the only cough characteristic associating with multiple non-respiratory, non-mental symptoms [aOR 1.15 (1.12-1.19) per one trigger, p < 0.001]. Among the 268 subjects with current cough both in the first survey and in the follow-up survey 12 months later, the repeatability of the trigger sum was good with an intraclass correlation coefficient of 0.80 (0.75-0.84).

CONCLUSION

The association between the number of the cough triggers and multiple symptoms suggests that the CNS component of cough hypersensitivity may be a manifestation of non-specific alteration in the CNS interpretation of various body sensations. The number of cough triggers is a repeatable measure of cough sensitivity.

Characterization of Ethyl Butyrate-Induced Cough Before and After Breath Control Techniques in Healthy Adults

PURPOSE

Methods for cough elicitation frequently involve aerosolized tussive agents. Here, we sought to determine whether healthy individuals demonstrate a quantifiable cough response after inhaling a volatile ester and if breath control techniques modify this chemically induced cough response.

METHOD

Sixty adult male and female participants inhaled prepared liquid dilutions of ethyl butyrate dissolved in paraffin oil at 20%, 40%, and 60% v/v concentrations in triplicate, with presentation order randomized. We delivered stimuli through a face mask connected to an olfactometer and respiratory pneumotachograph. Participants rated sensations of their urge to cough and pleasantness of the odor while cough airflow was measured. Following baseline testing, participants were randomized to implement pursed-lip breathing or slow-paced breathing after inhaling ethyl butyrate to determine the effects of breath control on cough measures.

RESULTS

Inhaled ethyl butyrate elicited cough in 70% of participants. Higher concentrations of ethyl butyrate resulted in significantly greater sensation of the urge to cough, F(2, 80) = 10.72, p < .001, and significantly more generated coughs, F(2, 63) = 13.14, p < .001. Compared to baseline, participants rated significantly decreased urge to cough during breath control techniques, F(1, 40) = 11.01, p = .0019. No significant changes were observed in the number of generated coughs between baseline and breath control techniques, F(1, 31) = 7.23, p = .01.

CONCLUSIONS

Airborne ethyl butyrate is a tussigenic agent in humans. Our findings provide opportunities for future research directions in normal and disordered cough responses to volatile compounds.

Mini-review: Hypertussivity and allotussivity in chronic cough endotypes

In recent years our understanding of the neurophysiological basis of cough has increased substantially. In conjunction, concepts around the drivers of chronic coughing in patients have also significantly evolved. Increasingly it is recognised that dysregulation of the neuronal pathways mediating cough play an important role in certain phenotypes of chronic cough and therefore pathological processes affecting the nervous system are likely to represent key endotypes in patients. Taking inspiration from the study of neuropathic pain, the term hypertussia has been employed to describe the phenomenon of abnormal excessive coughing in response to airway irritation and allotussia to describe coughing in response to stimuli not normally provoking cough. This review aims to summarise current clinical evidence supporting a role for the hyperexcitability of neuronal pathways contributing to chronic coughing and suggest how these might align with the clinical features observed in patients.

Cough hypersensitivity and chronic cough

Chronic cough is globally prevalent across all age groups. This disorder is challenging to treat because many pulmonary and extrapulmonary conditions can present with chronic cough, and cough can also be present without any identifiable underlying cause or be refractory to therapies that improve associated conditions. Most patients with chronic cough have cough hypersensitivity, which is characterized by increased neural responsivity to a range of stimuli that affect the airways and lungs, and other tissues innervated by common nerve supplies. Cough hypersensitivity presents as excessive coughing often in response to relatively innocuous stimuli, causing significant psychophysical morbidity and affecting patients' quality of life. Understanding of the mechanisms that contribute to cough hypersensitivity and excessive coughing in different patient populations and across the lifespan is advancing and has contributed to the development of new therapies for chronic cough in adults. Owing to differences in the pathology, the organs involved and individual patient factors, treatment of chronic cough is progressing towards a personalized approach, and, in the future, novel ways to endotype patients with cough may prove valuable in management.

The Evolving Clinical Practice of Chronic Cough

Chronic cough, defined as a cough lasting for greater than 8 weeks, accounts for a substantial number of primary care and specialist consultations in the United States. Although cough can arise from a myriad number of serious respiratory diseases, attention has traditionally focused on diagnosing and treating gastroesophageal reflux, upper airway cough syndrome, and eosinophilic airway inflammation (asthma and nonasthmatic eosinophilic bronchitis) in patients with normal chest imaging. The newly described paradigm and entity of cough hypersensitivity syndrome (CHS) becomes useful when the etiology of cough remains elusive or when the cough remains refractory despite appropriate therapy for underlying causes. We present an update on the evolving understanding of refractory chronic cough and/or unexplained chronic cough as manifestations of laryngeal hypersensitivity and CHS. This includes a focus on understanding the pathophysiology underlying current and novel therapeutics for CHS, while also ensuring that common causes of chronic cough continue to be evaluated and treated in a systematic multidisciplinary manner.

OSA and Chronic Respiratory Disease: Mechanisms and Epidemiology

Obstructive sleep apnea (OSA) is a highly prevalent disorder that has profound implications on the outcomes of patients with chronic lung disease. The hallmark of OSA is a collapse of the oropharynx resulting in a transient reduction in airflow, large intrathoracic pressure swings, and intermittent hypoxia and hypercapnia. The subsequent cytokine-mediated inflammatory cascade, coupled with tractional lung injury, damages the lungs and may worsen several conditions, including chronic obstructive pulmonary disease, asthma, interstitial lung disease, and pulmonary hypertension. Further complicating this is the sleep fragmentation and deterioration of sleep quality that occurs because of OSA, which can compound the fatigue and physical exhaustion often experienced by patients due to their chronic lung disease. For patients with many pulmonary disorders, the available evidence suggests that the prompt recognition and treatment of sleep-disordered breathing improves their quality of life and may also alter the course of their illness. However, more robust studies are needed to truly understand this relationship and the impacts of confounding comorbidities such as obesity and gastroesophageal reflux disease. Clinicians taking care of patients with chronic pulmonary disease should screen and treat patients for OSA, given the complex bidirectional relationship OSA has with chronic lung disease.

Prevalence of chronic cough and patient characteristics in adults in Spain: A population-based cross-sectional survey

Background

Chronic cough (CC) represents a significant health burden. This study assessed the prevalence of CC (defined as per international guidelines as cough duration >8 weeks) in Spanish adults and compared characteristics between CC and non-CC cohorts.

Methods

CC cohorts were compiled using data from adult respondents to the 2020 Spanish cross-sectional online National Health and Wellness Survey (NHWS). Using propensity scores, respondents experiencing CC during their lifetime and the previous 12 months were matched 3:1 to respondents without CC and their health characteristics were compared. The number of Spanish adults affected with CC was estimated using weighted CC prevalence.

Results

CC during their lifetime or the previous 12 months was experienced by 579 (8.2%) and 389 (5.5%) of 7074 NHWS respondents, of whom 233 (38.5%) and 171 (44.0%), respectively, had physician-diagnosed CC. Based on weighted prevalence rates, lifetime and 12-month CC were estimated to affect ≈3.3 million and ≈2.2 million Spanish adults, respectively. Relative to the non-CC cohort, the 12-month CC cohort consistently demonstrated poorer health status, poorer mental health, greater healthcare utilization, and lower productivity at work and home.

Conclusion

This study contributes novel data regarding the prevalence of CC in Spain, suggests that CC is underdiagnosed, and reflects that CC and related comorbidities inflict a significant health burden in the affected population.

Clinical characteristics in adult patients with somatic cough syndrome

Objective:

The data in regard of the clinical characteristics and diagnosis of somatic cough syndrome in adults were limited. The aim of this study was to fill that gap.

Methods:

This was a retrospective analysis of patients with somatic cough syndrome. We described clinical characteristics of adult patients with somatic cough syndrome.

Results:

Twenty-three somatic cough syndrome patients were identified in 543 adult patients with chronic cough. Psychiatric disorder of these patients was identified as anxiety (n = 8), obsessive-compulsive (n = 7), somatoform (n = 6), depression (n = 3), and cognitive bias (n = 1). Twelve patients showed abnormal results of investigations related with common causes of chronic cough, including gastroesophageal reflux, sputum eosinophilia, bronchial hyper-responsiveness, or signs of sinusitis but did not respond to the treatments directed to those conditions. All these patients were ever misdiagnosed as other causes of chronic cough. Compared to 520 non-somatic cough syndrome patients, patients with somatic cough syndrome were younger (32 (29.0–43.0) vs 42.0 (32.0–55.0) years, p = 0.013), longer disease duration (48.0 (19.5–102.0) vs 24.0 (9.0–72.0) months, p = 0.037), more common in dry cough (100% vs 57.6%, p < 0.001), and lower proportion of nocturnal cough (13.0% vs 40.2%, p = 0.009). Common cold (60.9%) was the most common initial trigger of cough and itchy throat (60.9%) was the most common accompanying symptom in patients with somatic cough syndrome. Notably, there were similar distribution in cough triggers and accompanying symptoms between two groups.

Conclusion:

In spite of much higher proportion of dry cough and smaller proportion of nocturnal cough, adult patients with somatic cough syndrome show similar clinical characteristics with other chronic cough patients, in regard of cough triggers, accompanying symptoms as well as abnormal results of investigations, which should be an important reason for misdiagnosis of somatic cough syndrome. Psychiatric disorder should be addressed in clinical management of chronic cough.

The Toxicity of Wiped Dust and Airborne Microbes in Individual Classrooms Increase the Risk of Teachers' Work-Related Symptoms: A Cross-Sectional Study

Background: The causes and pathophysiological mechanisms of building-related symptoms (BRS) remain open. Objective: We aimed to investigate the association between teachers’ individual work-related symptoms and intrinsic in vitro toxicity in classrooms. This is a further analysis of a previously published dataset. Methods: Teachers from 15 Finnish schools in Helsinki responded to the symptom survey. The boar sperm motility inhibition assay, a sensitive indicator of mitochondrial dysfunction, was used to measure the toxicity of wiped dust and cultured microbial fallout samples collected from the teachers’ classrooms. Results: 231 teachers whose classroom toxicity data had been collected responded to the questionnaire. Logistic regression analysis adjusted for age, gender, smoking, and atopy showed that classroom dust intrinsic toxicity was statistically significantly associated with the following 12 symptoms reported by teachers (adjusted ORs in parentheses): nose stuffiness (4.1), runny nose (6.9), hoarseness (6.4), globus sensation (9.0), throat mucus (7.6), throat itching (4.4), shortness of breath (12.2), dry cough (4.7), wet eyes (12.7), hypersensitivity to sound (7.9), difficulty falling asleep (7.6), and increased need for sleep (7.7). Toxicity of cultured microbes was found to be associated with nine symptoms (adjusted ORs in parentheses): headache (2.3), nose stuffiness (2.2), nose dryness (2.2), mouth dryness (2.8), hoarseness (2.2), sore throat (2.8), throat mucus (2.3), eye discharge (10.2), and increased need for sleep (3.5). Conclusions: The toxicity of classroom dust and airborne microbes in boar sperm motility inhibition assay significantly increased teachers’ risk of work-related respiratory and ocular symptoms. Potential pathophysiological mechanisms of BRS are discussed.

The Impact of Functional Laryngoscopy on the Diagnosis of Laryngeal Hypersensitivity Syndromes

BACKGROUND

Chronic cough and vocal cord dysfunction are manifestations of laryngeal hypersensitivity syndrome.

OBJECTIVE

The aim of the study was to determine the clinical utility of functional transnasal laryngoscopy in patients with laryngeal hypersensitivity syndromes.

METHODS

This study was a prospective observational cross-sectional study design of 71 participants with laryngeal hypersensitivity syndrome referred for functional transnasal laryngoscopy. Participants had a clinical assessment with a speech pathologist after which a provisional diagnosis of chronic cough, suspected vocal cord dysfunction, suspected muscle tension dysphonia, or a combination was made. A laryngoscopy with provocation was performed and the diagnosis revised after which the provisional and revised diagnoses were compared.

RESULTS

The diagnosis changed in 67% of participants after laryngoscopy. Vocal cord dysfunction was diagnosed in an additional 17 cases when not expected clinically but discounted when suspected clinically in 12 participants. Muscle tension dysphonia was diagnosed in an additional 31 cases when not suspected clinically and not confirmed when suspected in 2.

CONCLUSION

This study demonstrated that conditions such as muscle tension dysphonia and vocal cord dysfunction cannot be diagnosed based on symptoms alone. In addition to diagnostic accuracy, functional laryngoscopy enhances treatment planning and provides immediate feedback regarding laryngeal movement during respiration and phonation.

Laryngeal hypersensitivity and abnormal cough response during mannitol bronchoprovocation challenge

BACKGROUND AND OBJECTIVE

Inhalational challenge with dry mannitol powder may potentially induce cough by two mechanisms: airway bronchoconstriction or laryngeal irritation. This prospective observational study investigated laryngeal and bronchial components of cough induced by mannitol challenge.

METHODS

We recruited consecutive patients referred for clinical mannitol challenge. The Newcastle Laryngeal Hypersensitivity Questionnaire (LHQ) was administered. Throughout testing, coughs were audio-recorded to derive a cough frequency index per time and dose of mannitol. Relationships between cough indices, laryngeal hypersensitivity and bronchial hyperresponsiveness (BHR) were examined. Participants were classified by cough characteristics with k-means cluster analysis.

RESULTS

Of 90 patients who underwent challenge, 83 completed both the questionnaire and challenge. Cough frequency was greater in patients with abnormal laryngeal hypersensitivity (p = 0.042), but not in those with BHR. There was a moderate negative correlation between coughs per minute and laryngeal hypersensitivity score (r = -0.315, p = 0.004), with lower LHQ scores being abnormal. Cluster analysis identified an older, female-predominant cluster with higher cough frequency and laryngeal hypersensitivity, and a younger, gender-balanced cluster with lower cough frequency and normal laryngeal sensitivity.

CONCLUSION

Cough frequency during mannitol challenge in our cohort reflected laryngeal hypersensitivity rather than BHR. Laryngeal hypersensitivity was more often present among older female patients. With the incorporation of cough indices, mannitol challenge may be useful to test for laryngeal hypersensitivity as well as BHR.