UNASSIGNED: Chronic cough, a cough lasting >8 weeks, includes refractory chronic cough (RCC) and unexplained chronic cough (UCC). Patient-reported outcome (PRO) measures are needed to better understand chronic cough impacts that matter most to patients. The 19-item Leicester Cough Questionnaire (LCQ), an existing PRO measure of chronic cough, assesses impacts of cough across physical, psychological, and social domains. However, the content validity of the LCQ evaluating these concepts in patients with RCC/UCC had not been established.
UNASSIGNED: To evaluate the content validity of the LCQ in patients with RCC/UCC.
UNASSIGNED: A cross-sectional, qualitative interview study.
UNASSIGNED: First, previously completed qualitative interview results in adults with RCC/UCC (N = 30) were evaluated and mapped to LCQ concepts. Next, a clinical cough expert reviewed each LCQ item and assessed the salience of its concepts for patients with RCC/UCC. Finally, semistructured interviews-including both concept elicitation and cognitive debriefing-were conducted in adults with RCC/UCC (N = 20) to elicit a comprehensive set of participant experiences and to assess the appropriateness of using the LCQ in this population.
UNASSIGNED: Concepts reported in the past and present qualitative interviews were included across all LCQ items, and most impacts reported to be the \"most bothersome\" were assessed in the LCQ. In the current study, all participants indicated that reduced cough frequency would be an important treatment target. During cognitive debriefing, each LCQ item was endorsed by ⩾70% of participants. Additionally, participants were generally able to understand, recall, and select a response for each LCQ item. All participants and the clinical expert indicated that the LCQ was appropriate and assessed the impacts most relevant to patients with RCC/UCC.
UNASSIGNED: Our findings support the content validity of the LCQ and demonstrate that this measure is fit-for-purpose and includes important cough impacts in adults with RCC/UCC.

BACKGROUND: Refractory and unexplained chronic cough (RCC and UCC) necessitate frequent referral for specialist evaluations, but data on healthcare resource utilisation and costs are lacking.
METHODS: This observational study enrolled adults with RCC or UCC attending a specialist cough clinic and included a control cohort, both from North West England, matched 1:5 for age, gender and smoking history. Primary and secondary care data were obtained for the 5 years prior to and 2 years post initial clinic visit (index). The primary endpoint was the total 5-year healthcare cost to the UK NHS pre-RCC or UCC diagnosis compared to the control cohort.
RESULTS: Mean age at index for the 200 RCC or UCC consented patients was 62.2 ± 11.4 years; 71% were female, and 68% had never smoked. Mean duration of symptoms pre-diagnosis was 8.0 ± 9.4 years. Mean cough severity score was 63.7 ± 23.2 mm at index on a Visual Analog Scale, and Leicester Cough Questionnaire total score was 10.9 ± 4.1. GP data were available for 80 patients and mean total cost over the 5 years pre-diagnosis (index date) was 3.0-fold higher (95% CI 2.3, 3.9) than in the control cohort (p < 0.001). Most excess costs were related to visits and procedures carried out in secondary care. RCC- or UCC-associated costs decreased post-diagnosis, but remained higher than those of controls.
CONCLUSIONS: Diagnosis of RCC or UCC requires significant health resource utilisation in the 5 years prior to a specialist clinic diagnosis. Resource utilisation was less after diagnosis, but remained higher than in a matched control cohort.

BACKGROUND: Cough is one of the most common presenting problems for patients in primary care and is largely managed in primary care clinical settings. Family physicians\' familiarity with chronic cough guidelines and the extent to which these guidelines translate into everyday practice have not been well described. The objective of this study was to characterize current diagnosis, treatment, and referral practices among family physicians and to identify potentially impactful strategies to optimize chronic cough management in primary care.
METHODS: We conducted a cross-sectional survey of 5,000 family physicians to explore diagnosis, treatment, and referral practices related to chronic cough management in adults in primary care. Respondents completed the survey via paper or online. The outcome measures were self-reported numeric ratings and responses related to the survey elements.
RESULTS: 588 surveys were completed (11.8% response rate). About half (49.6%) of respondents defined chronic cough in a manner consistent with the American College of Chest Physicians (ACCP) chronic cough guidelines, with the rest differing in opinion primarily regarding duration of symptom presentation. Respondents reported trying to rule out most common causes of chronic cough themselves before referring (mean 3.41 on a 4-point scale where 4 is \"describes me completely\") and indicated a desire for more resources to help them manage and treat chronic cough. Years in practice and rural/urban setting influenced diagnosis and referral practices.
CONCLUSIONS: Family physicians see chronic cough as a complicated condition that can be and is often diagnosed and treated entirely in a primary care setting. They also value the ability to refer in complex cases. Our results support that family physicians provide evidence-based management of chronic cough.

OBJECTIVE: Cough represents a natural mechanism that plays an important defensive role in the respiratory tract, but in some conditions, it may become persistent, nonproductive, and harmful. In general, refractory chronic cough (RCC) occurs in about 20% of individuals; hence, we aimed to assess the presence of altered gut-lung communication in RCC patients through a compositional and functional characterization of both gut (GM) and oral microbiota (OM).
METHODS: 16S rRNA sequencing was used to characterize both GM and OM composition of RCC patients and healthy controls (HC). PICRUST2 assessed functional changes in microbial communities while gas chromatography was used to evaluate fecal short-chain fatty acid levels and serum-free fatty acid (FFA) abundances.
RESULTS: In comparison with HC, RCC patients reported increased saliva alpha-diversity and statistically significant beta-diversity in both GM and OM. Also, a, respectively, significant increased or reduced Firmicutes/Bacteroidota ratio in stool and saliva samples of RCC patients has been shown, in addition to a modification of the abundances of several taxa in both GM and OM. Moreover, a potential fecal over-expression of lipopolysaccharide biosynthesis and lipoic acid metabolism pathways and several differences in serum FFA levels have been reported in RCC patients than in HC.
CONCLUSIONS: Since differences in both GM and OM of RCC patients have been documented, these findings could provide new information about RCC pathogenesis and also pave the way for the development of novel nutritional or pharmacological interventions for the management of RCC through the restoration of eubiotic gut-lung communication.

BACKGROUND: Refractory or unexplained chronic cough (RCC or UCC) is difficult to manage and is usually treated by the off-label use of drugs approved for other indications.
OBJECTIVE: The objectives of this systematic literature review (SLR) were to identify and characterize the current published body of evidence for the efficacy and safety of treatments for RCC or UCC.
METHODS: The SLR was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The SLRs pre-defined population included patients ≥18 years of age who were diagnosed with chronic cough. The review was not restricted to any intervention type or study comparator, nor by timeframe.
RESULTS: A total of 20 eligible publications from 19 unique trials were included. Seventeen of these trials were randomized controlled trials and most (14/17) were placebo-controlled. There was considerable variability between trials in the definition of RCC or UCC, participant exclusion and inclusion criteria, outcome measurement timepoints, and the safety and efficacy outcomes assessed. Several trials identified significant improvements in cough frequency, severity, or health-related quality of life measures while participants were on treatment, although these improvements did not persist in any of the studies that included a post-treatment follow-up timepoint.
CONCLUSIONS: In the absence of an approved therapy, placebo remains the most common comparator in trials of potential RCC or UCC treatments. The between-study comparability of the published evidence is limited by heterogeneity of study design, study populations, and outcomes measures, as well as by concerns regarding study size and risk of bias.

UNASSIGNED: Cough hypersensitivity is an important part of the neurophysiology of cough, which presents with increased cough response to a lower level of stimuli or triggers. Classification of stimuli might bring about additional insight into the underlying mechanisms and management.
UNASSIGNED: This study investigated the profile of cough triggers in chronic cough patients and their relationship with capsaicin cough sensitivity.
UNASSIGNED: This was a cross-sectional observational study.
UNASSIGNED: We enrolled patients with different causes of chronic cough from 2006 to 2021. Cough triggers were defined as cough response to chemical triggers, mechanical triggers, meal triggers, or thermal trigger. Cough sensitivity to capsaicin was evaluated by the capsaicin challenge test, which was expressed as the lowest concentration of capsaicin inducing 5 or more coughing (C5).
UNASSIGNED: Among 1211 patients with chronic cough, 1107 (91.4%) patients reported at least one cough trigger. Chemical triggers (66.9%) were the most common cough triggers, followed by thermal exposure (50.6%), mechanical triggers (48.2%), and meal triggers (21.2%). There was no difference in the proportion of chemical triggers among different etiologies. Patients with refractory chronic cough reported the highest prevalence of cough triggers (97.1%). A higher number of meal triggers (34.9%) was associated with gastroesophageal reflux-related cough, and meal triggers and mechanical triggers were more common in refractory chronic cough. Among 254 patients who completed capsaicin challenge test, both the number of total triggers and the number of chemical triggers had a significant but mild correlation with capsaicin cough sensitivity.
UNASSIGNED: Cough hypersensitivity as reflected by a variety of cough triggers is a common feature in chronic cough patients, but different etiologies present specific profiles of cough triggers, which could not be evaluated comprehensively by capsaicin cough sensitivity.

In recent years, there has been a substantial increase in the development of antitussive therapies and the first new therapy, gefapixant has been licenced in Europe. This review describes current unlicenced treatments for chronic cough and details treatments currently in development for refractory chronic cough and cough in idiopathic pulmonary fibrosis, as well as compounds previously explored.

Chronic cough (CC) is associated with high healthcare resource utilization (HCRU) due to challenges in diagnosis and treatment and is anticipated to have a substantial economic impact. This systematic literature review (SLR) sought to identify evidence on the cost-effectiveness of treatments and the economic burden associated with CC. Electronic database searches were supplemented with searches of conference proceedings and health technology assessment body websites. Two independent reviewers assessed all citations for inclusion based on predefined inclusion/exclusion criteria. Key inclusion criteria were patient population with CC, and outcomes related to cost-effectiveness and HCRU and costs. After screening, one cost-effectiveness analysis was identified, alongside eight studies reporting HCRU and costs related to CC. Though evidence was limited, studies suggest that patients with CC incur higher costs and use more resources than those with acute cough. Types of resource use reported included healthcare contacts and prescriptions, diagnostic tests, referrals and specialist evaluations, and treatment use. There is a paucity of literature on HCRU and costs in CC, and very limited cost-effectiveness analyses. The economic burden appears higher in these patients however, without direct comparison to the general population it is difficult to determine the total impact. The increased burden is expected to be a result of the challenges with diagnosis and lack of approved treatments. However, limited conclusions can be drawn in the absence of further data. Future studies should endeavor to quantify the HCRU and cost attributable to patients with CC.

UNASSIGNED: Refractory chronic cough (RCC) has a significant impact on patient\'s health-related quality of life and represents a challenge in clinical management. However, the optimal treatment for RCC remains controversial. This study aimed to investigate and compare the efficacy and safety of the current pharmacological therapeutic options for RCC.
UNASSIGNED: A systematic review was performed by searching PubMed, Web of Science, Embase, and Ovid databases from January 1, 2008 to March 1, 2023. All randomised control trials (RCTs) reporting outcomes of efficacy or/and safety were included in the Bayesian network meta-analysis. Here, we compared the effects on Leicester Cough Questionnaire (LCQ), Visual Analogue Scale (VAS), and objective cough frequency of patients with RCC. Besides, we also compared the incidence of adverse events (AEs) for analysis of safety. PROSPERO registration: CRD42022345940.
UNASSIGNED: 19 eligible RCTs included 3326 patients and 7 medication categories: P2X3 antagonist, GABA modulator, Transient Receptor Potential (TRP) modulator, NK-1 agonist, opioid analgesic, macrolide, and sodium cromoglicate. Compared with placebo, mean difference (MD) of LCQ and 24 h cough frequency for P2X3 antagonist relief were 1.637 (95% CI: 0.887-2.387) and -11.042 (P = 0.035). Compared with placebo, effect sizes (MD for LCQ and cough severity VAS) for GABA modulator were 1.347 (P = 0.003) and -7.843 (P = 0.003). In the network meta-analysis, gefapixant is the most effective treatment for patients with RCC (The Surface Under the Cumulative Ranking Curves (SUCRA) is 0.711 in LCQ, 0.983 in 24 h cough frequency, and 0.786 in cough severity VAS). Lesogaberan had better efficacy than placebo (SUCRA: 0.632 vs. 0.472) in 24 h cough frequency. Eliapixant and lesogaberan had better efficacy than placebo in cough severity VAS. However, TRP modulator had worse efficacy than placebo. In the meta-analysis of AEs, the present study found P2X3 antagonist had a significant correlation to AEs (RR: 1.129, 95% CI: 1.012-1.259), especially taste-related AEs (RR: 6.216, P < 0.05).
UNASSIGNED: In this network meta-analysis, P2X3 antagonist showing advantages in terms of efficacy is currently the most promising medication for treatment of RCC. GABA modulator also showed potential efficacy for RCC but with AEs of the central system. Nevertheless, the role of TRP modulator needed to be revisited. Further research is needed to determine the potential beneficiary population for optimizing the pharmacological management of chronic cough.
UNASSIGNED: National Natural Science Foundation of China (81870079), Guangdong Science and Technology Project (2021A050520012), Incubation Program of National Science Foundation for Distinguished Young Scholars (GMU2020-207).

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.
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).
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.