Impact of refractory and unexplained chronic cough on disease burden: a qualitative study

Development and validation of a novel questionnaire to describe and assess sensations and triggers associated with refractory and unexplained chronic cough

INTRODUCTION

Refractory or unexplained chronic cough (RUCC) is a common clinical problem with no effective diagnostic tools. The Sensations and Triggers Provoking Cough questionnaire (TOPIC) was developed to characterise cough in RUCC versus cough in other conditions.

METHODS

Content analysis of participant interviews discussing the sensations and triggers of chronic cough informed TOPIC development. Participants with chronic cough completed the draft-TOPIC (a subset repeating 5-7 days later), St George's Respiratory Questionnaire (SGRQ), Cough Severity Diary (CSD) and Global Rating of Change Scale. The draft-TOPIC item list was reduced in hierarchical and Rasch analysis to refine the questionnaire to the TOPIC.

RESULTS

49 items describing the triggers and sensations of cough were generated from participant interviews (RUCC n=14, chronic obstructive pulmonary disease (COPD) n=11, interstitial lung disease (ILD) n=10, asthma n=11, bronchiectasis n=3, cystic fibrosis n=7). 140 participants (median age 60.0 (19.0-88.0), female 56.4%; RUCC n=39, ILD n=38, asthma n=45, COPD n=6, bronchiectasis n=12) completed draft-TOPIC, where items with poor 'fit' for RUCC were removed to create TOPIC (8 trigger items, 7 sensation items). Median TOPIC score was significantly higher in RUCC (37.0) vs ILD (24.5, p=0.009) and asthma (7.0, p<0.001), but not bronchiectasis (20.0, p=0.318) or COPD (18.5, p=0.238), likely due to small sample sizes. The Rasch model demonstrated excellent fit in RUCC (χ2=22.04, p=0.85; PSI=0.88); as expected. When all participant groups were included, fit was no longer demonstrated (χ2=66.43, p=0.0001, PSI=0.89) due to the increased heterogeneity (CI=0.077). TOPIC correlated positively with SGRQ (r=0.47, p<0.001) and CSD (r=0.63, p<0.001). The test-retest reliability of TOPIC (intraclass correlation coefficient) was excellent (r=0.90, p<0.001).

CONCLUSIONS

High TOPIC scores in the RUCC patients suggest their cough is characterised by specific sensations and triggers. Validation of TOPIC in cough clinics may demonstrate value as an aid to identify features of RUCC versus cough in other conditions.

Chronic Cough and Cerebellar Ataxia With Neuropathy and Bilateral Vestibular Areflexia Syndrome (CANVAS): Screening for Mutations in Replication Factor C Subunit 1 (RFC1)

INTRODUCTION

A common complaint in patients is chronic cough (CC), which may be refractory (RCC) or unexplained (UCC). Recent studies point, as a possible cause of CC, to the hereditary cerebellar ataxia with neuropathy and bilateral vestibular areflexia syndrome (CANVAS), with an estimated carrier prevalence of 1 in 20000.

AIM

In patients with CC, determine the prevalence of the biallelic (AAGGG)exp mutation in replication factor C subunit 1 (RFC1) responsible for CANVAS, test the usefulness of the Rydel-Seiffer fork test, and evaluate patient quality of life (QoL).

METHODS

Clinical and functional data were collected for the 33 included patients undergoing CC studies in our specialized unit. Performed were an etiological study of CC following European Respiratory Society recommendations, a genetic study of RFC1 mutations, and Rydel-Seiffer fork testing to detect possible peripheral vibratory sensitivity impairment. Administered to evaluate QoL were 4 questionnaires.

RESULTS

Prevalence of biallelic (AAGGG)exp in RFC1 was 6.1% (n=2) overall, increasing to 7.1% in the RCC subgroup, and to 33.3% in the Rydel-Seiffer fork altered results subgroup. Prevalence of monoallelic (AAGGG)exp in RFC1 was 18.2% (n=6) overall, rising to 50.0% (n=2) in the UCC subgroup.

CONCLUSION

Genetic screening for (AAGGG)exp in RFC1, and also use of the Rydel-Seiffer fork test, should be considered in specialized CC consultations for patients with RCC and UCC. Detecting possible CANVAS symptoms in CC studies would identify candidates for early genetic screening, of interest in reducing the disease burden for patients and health systems alike.

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.

Clinical and functional characteristics, possible causes, and impact of chronic cough in patients with cerebellar ataxia, neuropathy, and bilateral vestibular areflexia syndrome (CANVAS)

Cerebellar ataxia with neuropathy and bilateral vestibular areflexia syndrome (CANVAS) is an hereditary autosomal recessive disease. Recent studies propose including chronic cough (CC) as a symptom of CANVAS. For 10 patients with CANVAS as genetically confirmed by biallelic expansion of the AAGG repeat motif (AAGGGexp) in intron 2 of replication factor C subunit 1 (RFC1), our aim was, as a multidisciplinary team, to describe clinical and functional characteristics and possible causes of CC following European Respiratory Society (ERS) recommendations, and to evaluate CC impact on quality of life (QoL) using self-administered questionnaires (Cough Severity Diary, Leicester Cough Questionnaire, Discrete Emotions Questionnaire, and EQ-5D-5L). In all 10 patients, the CC was a dry cough that developed several years prior to the neurological symptoms (mean 14.2 years); 7 patients had symptoms compatible with gastroesophageal reflux (GER), 5 with pathological GER diagnosed by 24-h esophageal pH testing, and 6 patients had impaired esophageal motility diagnosed by high-resolution esophageal manometry, most frequently ineffective peristalsis. Although further studies are required for confirmation, we conclude that CC may be a characteristic prodrome of CANVAS and may be related to GER and esophageal disorders. Furthermore, CC affects patients' QoL, especially in the psychosocial sphere.

Machine learning to identify chronic cough from administrative claims data

Accurate identification of patient populations is an essential component of clinical research, especially for medical conditions such as chronic cough that are inconsistently defined and diagnosed. We aimed to develop and compare machine learning models to identify chronic cough from medical and pharmacy claims data. In this retrospective observational study, we compared 3 machine learning algorithms based on XG Boost, logistic regression, and neural network approaches using a large claims and electronic health record database. Of the 327,423 patients who met the study criteria, 4,818 had chronic cough based on linked claims-electronic health record data. The XG Boost model showed the best performance, achieving a Receiver-Operator Characteristic Area Under the Curve (ROC-AUC) of 0.916. We selected a cutoff that favors a high positive predictive value (PPV) to minimize false positives, resulting in a sensitivity, specificity, PPV, and negative predictive value of 18.0%, 99.6%, 38.7%, and 98.8%, respectively on the held-out testing set (n = 82,262). Logistic regression and neural network models achieved slightly lower ROC-AUCs of 0.907 and 0.838, respectively. The XG Boost and logistic regression models maintained their robust performance in subgroups of individuals with higher rates of chronic cough. Machine learning algorithms are one way of identifying conditions that are not coded in medical records, and can help identify individuals with chronic cough from claims data with a high degree of classification value.

Patient-reported experiences with refractory or unexplained chronic cough: a qualitative analysis

BACKGROUND

Chronic cough, defined as a cough lasting 8 or more weeks, affects up to 10% of adults. Refractory chronic cough (RCC) is a cough that is uncontrolled despite comprehensive investigation and treatment of comorbid conditions while unexplained chronic cough (UCC) is a cough with no identifiable cause despite extensive evaluation of comorbid conditions. RCC and UCC are often poorly controlled. Understanding individuals' lived experience of the symptoms and impacts of these conditions may guide therapeutic strategies.

OBJECTIVES

The primary objectives of this study were to assess respondents' perceptions of the key symptoms of RCC and UCC and the impacts of RCC and UCC and their symptoms on well-being, health-related quality of life, work productivity, and social relationships.

DESIGN

Qualitative study.

METHODS

This study enrolled 30 adults with physician-diagnosed RCC or UCC. Two trained qualitative researchers conducted individual, in-depth telephone interviews using a semi-structured interview guide. Interviews were audio-recorded, transcribed, coded, and systematically analyzed to identify content themes.

RESULTS

A total of 15 respondents with RCC and 15 with UCC were included in the study. Many respondents had RCC or UCC for a long duration (median 9 years, range: 0-24). Half of the respondents reported having a coughing episode at least once daily. Only 40% of respondents reported that medication had improved their symptoms. In over half of the respondents, RCC or UCC hindered communication, caused embarrassment, frustration, and worry, and lowered quality of life. Perceptions of meaningful treatment benefits in RCC or UCC varied widely across respondents.

CONCLUSION

RCC and UCC remained poorly managed in many individuals and were associated with a wide range of symptoms and cough triggers that hindered daily activities and reduced emotional well-being. Understanding individuals' lived experiences may inform the development of RCC and UCC therapeutic strategies.

Trajectories and risk factors of persistent cough after pulmonary resection: A prospective two-center study

BACKGROUND

Persistent cough is one of the most frequent complications following lung cancer surgery. To promote optimal recovery, we conducted a study to investigate the trajectories of coughing symptoms and their impact on quality of life (QOL), as well as to identify potential risk factors of persistent cough after pulmonary resection (CAP).

METHODS

This prospective observational study assessed patients who underwent pulmonary resection for lung tumor at two medical centers in China. Persistent CAP was evaluated before surgery, at discharge, and 1, 3, and 6 months following surgery using visual analog scale (VAS), cough symptom score (CSS), and Leicester Cough Questionnaire in Mandarin Chinese (LCQ-MC). Univariate and multivariate logistic regression analyses were conducted to explore independent risk factors for persistent CAP.

RESULTS

Of the 506 enrolled patients, 130 patients were diagnosed with persistent CAP with an incidence of 25.69%. Compared to the noncough group, patients with persistent CAP reported significantly higher VAS (p < 0.001) and CSS scores (p < 0.001) and experienced worse QOL (p < 0.001) for up to 6 months, particularly at 1 month following surgery. Multivariable regression analysis revealed that a duration of anesthesia exceeding 156 min (odds ratio [OR]: 1.847, 95% confidence interval [CI]: 1.156-2.951, p = 0.010) and gastroesophageal acid reflux (GER) (OR: 3.870, 95% CI: 2.376-6.304, p < 0.001) were independent risk factors of persistent CAP.

CONCLUSION

Patients who suffer from persistent CAP face a substantial burden and diminished QOL for an extended period compared to noncough patients. Moreover, prolonged duration of anesthesia and postoperative GER are potential risk factors of persistent CAP.

Relationship Between Asthma Control Status and Health-Related Quality of Life in Japan: A Cross-Sectional Mixed-Methods Study

INTRODUCTION

There is limited information regarding multidimensional relationships between asthma control and health-related quality of life (HRQoL), work productivity, and asthma symptom burden in Japan. Furthermore, systematic qualitative investigations about asthma burden have not been performed.

METHODS

This cross-sectional, mixed-methods study included Japanese patients (≥ 20 years) with asthma adherent to inhaled corticosteroids/long-acting β2-agonists (ICS/LABA). The primary endpoint was impact of asthma on HRQoL, measured using the Asthma Health Questionnaire-33 (AHQ-33). Secondary endpoints were cough burden (Japanese-adapted Leicester Cough Questionnaire [J-LCQ]) and impact of asthma on work/activities (asthma-specific Work Productivity and Activity Impairment Questionnaire [WPAI:Asthma]). Quantitative data were assessed for the overall population and for well-controlled (WC) and not well-controlled (NWC) asthma subgroups. Qualitative verbal interviews further assessed the impact of NWC asthma on patients' HRQoL; emergent themes were extracted using thematic analyses.

RESULTS

Of 454 patients, 45.2% (n = 205) had NWC asthma. Patients with NWC asthma had significantly worse asthma- and cough-related HRQoL across all AHQ-33 and J-LCQ domains and significantly greater work and activity impairment versus patients with WC asthma, across all assessed WPAI:Asthma domains. AHQ-33 total score was highly correlated with J-LCQ total and domain scores (r = - 0.8132 to r = - 0.7407). Nine themes emerged from qualitative interviews and confirmed that patients with NWC asthma had considerable HRQoL impairment due to asthma symptoms.

CONCLUSIONS

Patients with NWC asthma had higher symptom burden and worse HRQoL than patients with WC asthma, despite ICS/LABA adherence. Cough burden correlated with HRQoL, suggesting cough may be one of the key markers to inform treatment strategy for patients with asthma.

The "vicious circle" of chronic cough: the patient experience - qualitative synthesis

Aim

The aim of this study was to systematically search and synthesise findings from peer-reviewed qualitative studies describing the experiences of those living with chronic cough.

Methods

A systematic search was conducted to identify all studies that used qualitative methodology to report on the experiences of adults living with chronic cough. A thematic synthesis of the first-hand narratives was undertaken. Key themes in relation to personal perspectives and experiences of living with chronic cough were identified and grouped into analytical themes.

Results

Six studies met the inclusion criteria. The thematic synthesis generated three analytical themes: 1) "It's just a cough"; 2) "Constant cough and constant worry"; and 3) "No light at the end of the tunnel", highlighting the biopsychosocial nature of chronic cough. The synthesis highlights chronic cough as a heterogeneous experience that may appear idiosyncratic, completely consuming the lives of those living with it.

Conclusion

This is to our knowledge the first qualitative synthesis reporting on the perceptions and experiences of adults living with chronic cough. Our review draws attention to the paucity of literature that utilises qualitative methodology to explore the experience of living with chronic cough. We highlight the missing voice of people living with chronic cough in the contemporary literature. There is now a requirement for research exploring the narratives of those living with chronic cough, to gain an understanding of the condition beyond simple quantification.