Feasibility and clinical utility of ambulatory cough monitoring in an outpatient clinical setting: a real-world retrospective evaluation

Methods of Cough Assessment and Objectivization

Cough is one of the most important airway defensive reflexes aimed at removing foreign particles or endogenously produced materials from the airways and provides protection against aspiration. Generally considered, cough is a vital physiological defensive mechanism for lung health. However, in case of cough dysregulation this reflex can become pathological and leads to an adverse influence on daily life. Therefore, it is necessary to effectively evaluate the severity of cough for its diagnosis and treatment. There are subjective and objective methods for assessing cough. These methods should help describe the heterogeneity of cough phenotypes and may establish better treatment by monitoring response to nonpharmacological or pharmacological therapies. It is important to keep in mind that the clinical assessment of cough should include both tools that measure the amount and severity of the cough. The importance of a combined subjective and objective evaluation for a comprehensive assessment of cough has been advocated in the guidelines of the European Respiratory Society on cough evaluation. This review article provides an overview of subjective and objective methods for assessing and monitoring cough in children and adults comparing to animal models. Key words Cough frequency; Cough intensity; Cough reflex sensitivity; Cough monitors; Cough assessment.

Feasibility and Utility of a Smartphone Application-Based Longitudinal Cough Monitoring in Chronic Cough Patients in a Real-World Setting

PURPOSE

This study evaluated the feasibility and utility of longitudinal cough frequency monitoring with the Hyfe Cough Tracker, a mobile application equipped with cough-counting artificial intelligence algorithms, in real-world patients with chronic cough.

METHODS

Patients with chronic cough (> 8-week duration) were monitored continuously for cough frequency with the Hyfe app for at least one week. Cough was also evaluated using the Leicester Cough Questionnaire (LCQ) and daily cough severity scoring (0-10). The study analyzed adherence rate, the correlation between objective cough frequency and subjective scores, day-to-day variability, and patient experience.

RESULTS

Of 65 subjects consecutively recruited, 43 completed the study. The median cough monitoring duration was 13.9 days, with a median adherence of 91%. Study completion was associated with baseline cough severity, and the adherence rate was higher in younger subjects. Cross-sectional correlation analyses showed modest correlations between objective and subjective cough measures at the group level. However, in time series correlation analyses, correlations between objective and subjective measures widely varied across individuals. Cough frequency had greater day-to-day variability than daily cough severity scores in most subjects. A patient experience survey found that 70% of participants found the cough monitoring helpful, 86% considered it acceptable, and 84% felt it was easy to use.

CONCLUSION

Monitoring cough frequency longitudinally for at least one week may be feasible. The substantial day-to-day variability in objective cough frequency highlights the need for continuous monitoring. Grasping the implications of daily cough variability is crucial in both clinical practice and clinical trials.

Present and future perspectives in early diagnosis and monitoring for progressive fibrosing interstitial lung diseases

Progressive fibrosing interstitial lung diseases (PF-ILDs) represent a group of conditions of both known and unknown origin which continue to worsen despite standard treatments, leading to respiratory failure and early mortality. Given the potential to slow down progression by initiating antifibrotic therapies where appropriate, there is ample opportunity to implement innovative strategies for early diagnosis and monitoring with the goal of improving clinical outcomes. Early diagnosis can be facilitated by standardizing ILD multidisciplinary team (MDT) discussions, implementing machine learning algorithms for chest computed-tomography quantitative analysis and novel magnetic-resonance imaging techniques, as well as measuring blood biomarker signatures and genetic testing for telomere length and identification of deleterious mutations in telomere-related genes and other single-nucleotide polymorphisms (SNPs) linked to pulmonary fibrosis such as rs35705950 in the MUC5B promoter region. Assessing disease progression in the post COVID-19 era also led to a number of advances in home monitoring using digitally-enabled home spirometers, pulse oximeters and other wearable devices. While validation for many of these innovations is still in progress, significant changes to current clinical practice for PF-ILDs can be expected in the near future.

Home monitoring in interstitial lung diseases

The widespread use of smartphones and the internet has enabled self-monitoring and more hybrid-care models. The COVID-19 pandemic has further accelerated remote monitoring, including in the heterogenous and often vulnerable group of patients with interstitial lung diseases (ILDs). Home monitoring in ILD has the potential to improve access to specialist care, reduce the burden on health-care systems, improve quality of life for patients, identify acute and chronic disease worsening, guide treatment decisions, and simplify clinical trials. Home spirometry has been used in ILD for several years and studies with other devices (such as pulse oximeters, activity trackers, and cough monitors) have emerged. At the same time, challenges have surfaced, including technical, analytical, and implementational issues. In this Series paper, we provide an overview of experiences with home monitoring in ILD, address the challenges and limitations for both care and research, and provide future perspectives. VIDEO ABSTRACT.

An observational study to determine the relationship between cough frequency and markers of inflammation in severe asthma

BACKGROUND

The relationship between objectively measured cough and type 2 (T2) biomarkers and other measures of asthma control and severity is poorly understood. The objective of this study was to assess the relationship between objective and subjective cough measurement tools and clinical biomarkers of asthma.

METHODS

Patients with severe asthma and mild-to-moderate asthma completed validated asthma and cough-related measurement tools (including ambulatory cough monitoring) and measurement of spirometry and T2 biomarkers (exhaled nitric oxide fraction (F ENO) and peripheral blood eosinophil count). Patients were classified according to T2 status based on T2-low (F ENO <20 ppb and peripheral blood eosinophils <150 cells·µL-1), T2-intermediate (F ENO ≥20 ppb or peripheral blood eosinophils ≥150 cells·µL-1) or T2-high (F ENO ≥20 ppb and peripheral blood eosinophils ≥150 cells·µL-1).

RESULTS

61 patients completed the study measurements (42 severe asthma and 19 mild-to-moderate asthma). Patients with severe asthma had higher rates of cough than those with mild-to-moderate asthma in terms of total 24-h cough counts (geometric mean±sd 170.3±2.7 versus 60.8±4.1; p=0.002) and cough frequency (geometric mean±sd 7.1±2.7 versus 2.5±4.1 coughs·h-1; p=0.002). T2-low patients with severe asthma had significantly lower 24-h cough frequency compared with T2-intermediate and T2-high patients.

CONCLUSIONS

In patients with low biomarkers of T2 inflammation, cough frequency measurements were not elevated, suggesting that the mechanism for cough in asthma is underlying T2 eosinophilic inflammation and the logical first step for treating cough in asthma may be to achieve adequate suppression of T2 inflammation with currently available therapies.

Chronic cough-the limitation and advances in assessment techniques

Accurate and consistent assessments of cough are essential to advance the understanding of the mechanisms of cough and individualised the management of patients. Considerable progress has been made in this work. Here we reviewed the currently available tools for subjectively and objectively measuring both cough sensitivity and severity. We also provided some opinions on the new techniques and future directions. The simple and practical Visual Analogue Scale (VAS), the Leicester Cough Questionnaire (LCQ), and the Cough Specific Quality of Life Questionnaire (CQLQ) are the most widely used self-reported questionnaires for evaluating and quantifying cough severity. The Hull Airway Reflux Questionnaire (HARQ) is a tool to elucidate the constellation of symptoms underlying the diagnosis of chronic cough. Chemical excitation tests are widely used to explore the pathophysiological mechanisms of the cough reflex, such as capsaicin, citric acid and adenosine triphosphate (ATP) challenge test. Cough frequency is an ideal primary endpoint for clinical research, but the application of cough counters has been limited in clinical practice by the high cost and reliance on aural validation. The ongoing development of cough detection technology for smartphone apps and wearable devices will hopefully simplify cough counting, thus transitioning it from niche research to a widely available clinical application.

Residual Dyspnea May Predict Small Airways Dysfunction and Poor Responsiveness to Single-Inhaler Triple Therapy in Asthmatic Patients

PURPOSE

Recently, single-inhaler triple therapy (SITT) has demonstrated efficacy in patients with uncontrolled asthma who were symptomatic despite treatment with inhaled corticosteroids/long-acting β2 agonists. However, the characteristics of patients who benefit from SITT remain unclear in the real-world. The aim of this study was to examine the predictors of responsiveness to SITT in patients with asthma.

PATIENTS AND METHODS

A total of 45 patients with asthma who had regularly visited our respiratory clinic and were started on SITT from March 2019 to March 2021 were retrospectively analyzed. Patients' demographic characteristics, residual respiratory symptoms, type 2 biomarkers, and lung function before SITT were assessed from the patients' medical records. Predictors of responsiveness to four-week SITT were evaluated in these patients. The definition of responders was based on the physician-assessed global evaluation of treatment effectiveness.

RESULTS

Thirty-four (75%) of 45 patients were identified as responders to SITT. Non-responders showed significantly lower forced vital capacity (FVC) (%predicted) values, and complained of dyspnea more frequently than responders before SITT (p = 0.01 and p = 0.02, respectively). There were no significant differences in demographic characteristics and type 2 biomarkers between responders and non-responders. Clinical predictors of poor response to SITT were residual dyspnea (OR = 0.14, p = 0.02), low FVC (%predicted) values (OR = 1.05, p = 0.01), and FVC (%predicted) <80% (OR = 0.11, p = 0.02). Multivariate analysis showed that poor response to SITT was associated with residual dyspnea before SITT (OR = 0.14, p = 0.02). On the other hand, patients with residual dyspnea had significantly lower FEF_25-75 (%predicted) values than patients without residual dyspnea before SITT (p = 0.04).

CONCLUSION

Residual dyspnea, reflecting small airways dysfunction, may predict poor responsiveness to short-term SITT in patients with asthma.

Assessing cough symptom severity in refractory or unexplained chronic cough: findings from patient focus groups and an international expert panel

Background

Cough symptom severity represents an important subjective end-point to assess the impact of therapies for patients with refractory or unexplained chronic cough (RCC/UCC). As existing instruments assessing the severity of cough are neither widely available nor tested for measurement properties, we aim to develop a new patient-reported outcome measure addressing cough severity.

Objective

The aim of this study was to establish items and domains that would inform development of a new cough severity instrument.

Methods

Three focus groups involving 16 adult patients with RCC/UCC provided data that we analysed using directed content analysis. Discussions led to consensus among an international panel of 15 experts on candidate items and domains to assess cough severity.

Results

The patient focus group provided 48 unique items arranged under broad domains of urge-to-cough sensations and cough symptom. Feedback from expert panel members confirmed the appropriateness of items and domains, and provided an additional subdomain related to cough triggers. The final conceptual framework comprised 51 items in the following domains: urge-to-cough sensations (subdomains: frequency and intensity) and cough symptom (subdomains: triggers, control, frequency, fit/bout duration, intensity, quality and associated features/sequelae).

Conclusions

Consensus findings from patients and international experts established domains of urge-to-cough and cough symptom with associated subdomains and relevant items. The results support item generation and content validity for a novel patient-reported outcome measure for use in health research and clinical practice.

The urge-to-cough (subdomains: frequency and intensity) and cough symptom (subdomains: triggers, control, frequency, fit/bout duration, intensity, quality, and associated features/sequelae) represent domains to assess cough severity in RCC/UCChttps://bit.ly/3fI6qkC

History Taking as a Diagnostic Tool in Children With Chronic Cough

Chronic cough is a common symptom of many underlying respiratory and non-respiratory disorders and may be associated with less serious causes, such as gastroesophageal reflux and nasal diseases. Chronic cough in children differs from that in adults with respect to its etiologies and management since it can indicate a symptom of an underlying disease in children. Guidelines for managing chronic cough in children are based on recording the history, followed by physical examination, chest radiography, and spirometry. Thus, taking accurate respiratory history for coughing helps delineate the pathophysiological basis of the cause of chronic cough. Detailed history taking enhances the evaluation and treatment, and facilitates a tailored diagnostic identification of likely diagnoses. While studies have described evidence-based red flags in children with chronic cough, the value of skilled physicians regarding history taking has received less attention for the best patient care. In the present article, we outline the major questions comprising a detailed history taking for chronic cough in children.

Objective cough frequency monitoring in real-world practice

There are possibilities and obstacles to the use of objective cough monitoring in real-world practice. Advances in technology will overcome the difficulties and continuous real-time cough monitoring will then provide a valuable tool in cough management. https://bit.ly/3lu5cfk.