Cough. 1: Chronic cough in adults

An observational study to understand burden and cost of care in adults diagnosed with refractory chronic cough (RCC) or unexplained chronic cough (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.

CONCLUSION

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.

Exposure limits for indoor volatile substances concerning the general population: The role of population-based differences in sensory irritation of the eyes and airways for assessment factors

Assessment factors (AFs) are essential in the derivation of occupational exposure limits (OELs) and indoor air quality guidelines. The factors shall accommodate differences in sensitivity between subgroups, i.e., workers, healthy and sick people, and occupational exposure versus life-long exposure for the general population. Derivation of AFs itself is based on empirical knowledge from human and animal exposure studies with immanent uncertainty in the empirical evidence due to knowledge gaps and experimental reliability. Sensory irritation in the eyes and airways constitute about 30-40% of OELs and is an abundant symptom in non-industrial buildings characterizing the indoor air quality and general health. Intraspecies differences between subgroups of the general population should be quantified for the proposal of more 'empirical' based AFs. In this review, we focus on sensitivity differences in sensory irritation about gender, age, health status, and vulnerability in people, based solely on human exposure studies. Females are more sensitive to sensory irritation than males for few volatile substances. Older people appear less sensitive than younger ones. However, impaired defense mechanisms may increase vulnerability in the long term. Empirical evidence of sensory irritation in children is rare and limited to children down to the age of six years. Studies of the nervous system in children compared to adults suggest a higher sensitivity in children; however, some defense mechanisms are more efficient in children than in adults. Usually, exposure studies are performed with healthy subjects. Exposure studies with sick people are not representative due to the deselection of subjects with moderate or severe eye or airway diseases, which likely underestimates the sensitivity of the group of people with diseases. Psychological characterization like personality factors shows that concentrations of volatile substances far below their sensory irritation thresholds may influence the sensitivity, in part biased by odor perception. Thus, the protection of people with extreme personality traits is not feasible by an AF and other mitigation strategies are required. The available empirical evidence comprising age, lifestyle, and health supports an AF of not greater than up to 2 for sensory irritation. Further, general AFs are discouraged for derivation, rather substance-specific derivation of AFs is recommended based on the risk assessment of empirical data, deposition in the airways depending on the substance's water solubility and compensating for knowledge and experimental gaps. Modeling of sensory irritation would be a better 'empirical' starting point for derivation of AFs for children, older, and sick people, as human exposure studies are not possible (due to ethical reasons) or not generalizable (due to self-selection). Dedicated AFs may be derived for environments where dry air, high room temperature, and visually demanding tasks aggravate the eyes or airways than for places in which the workload is balanced, while indoor playgrounds might need other AFs due to physical workload and affected groups of the general population.

[Chronic cough]

Coughing is an important protective reflex of the respiratory tract and primarily serves clearance of the bronchial system. It is also an exceptionally common symptom in outpatient care that can be an expression of a variety of diseases. Coughing duration of longer than 8 weeks is referred to as chronic cough. A structured, often interdisciplinary diagnostic process is essential. The aim here is to identify causal treatment options, avoiding overdiagnosis and simultaneously not overlooking severe illness. This article discusses current diagnostic procedures, important differential diagnoses and possible treatment options.

A systematic review and meta-analysis of neuromodulators to treat chronic airway hypersensitivity

OBJECTIVES

Chronic laryngitis can present with numerous symptoms, including chronic cough. Patients who do not respond to standard treatment are sometimes diagnosed with chronic airway hypersensitivity (CAH). In many centers, neuromodulators are prescribed off-label despite limited evidence of efficacy. A previous meta-analysis suggested neuromodulator therapy improved cough-related quality-of-life (QoL). This current updated and expanded meta-analysis examined whether neuromodulators reduced cough frequency, reduced cough severity, and/or improved QoL in CAH patients.

DATA SOURCES

PubMed, Embase, Medline, Cochrane Review, and publication bibliographies were searched from 01/01/2000 to 07/31/2021 using MESH terms.

REVIEW METHODS

PRISMA guidelines were followed. 999 abstracts were identified/screened, 28 studies were fully reviewed, and 3 met inclusion criteria. Only randomized controlled trials (RCT) investigating CAH patients with comparable cough-related outcomes were included. Three authors reviewed potentially eligible papers. Fixed-effect models and calculated pooled estimates using the Inverse-Variance method were used.

RESULTS

The estimated difference in change in log coughs per hour (from baseline to intervention end) between treatment and control groups was -0.46, 95%CI [-0.97; 0.05]. Estimated change-from-baseline in VAS scores was -12.24, 95 % CI [-17.84; -6.65] lower for patients who received treatment vs placebo. Estimated change-from-baseline for LCQ scores was 2.15, 95 % CI [1.49-2.80] higher for patients who receive treatment vs placebo. Only change in LCQ score was clinically significant.

CONCLUSIONS

This study tentatively suggests that neuromodulators have the potential to reduce cough symptoms associated with CAH. However, high-quality evidence is lacking. This could be due to limited treatment effect or significant limitations in the design and comparability of existing trials. A well-designed and properly powered RCT is needed to authoritatively test the efficacy of neuromodulators for the treatment of CAH.

LEVEL OF EVIDENCE

Level I, evidence from a systematic review or meta-analysis of all relevant RCTs (randomized controlled trial) or evidence-based clinical practice guidelines based on systematic reviews of RCTs or three or more RCTs of good quality that have similar results.

The risk factors for urinary incontinence in female adults with chronic cough

Background

Female patients with chronic cough are more likely to suffer from urinary incontinence (UI). However, there are few data in regard of risks related with UI in female adults with chronic cough.

Method

We recruited female adult patients with chronic cough from the cough specialist clinic. Demographic information and clinical characteristics including age, BMI, duration of cough, severity of cough, nature and timing of cough, cough triggers, concomitant symptoms, comorbidities and UI condition were collected. The demographics and clinical features of patients with UI and those without UI were compared.

Result

A total of 700 female patients with the main symptom of chronic cough were included, of whom 351 (50.1%) presented with UI. As compared with patients without UI, patients with UI showed a longer mean age (years) (49.5 vs. 42.4, p < 0.001), a more severe cough symptom (median of cough Visual Analogue Scale: 65 vs. 50, p < 0.001), a higher prevalence of chronic sinusitis (17.6% vs. 8.6%, p = 0.002), and combined with a higher incidence of abdominal muscle pain due to cough (39.6% vs. 18.7%, p < 0.001).In addition, patients in UI group whose cough were more easily triggered by exercise (28.2% vs. 17.2%, p = 0.048). Multivariate logistic regression analysis indicated the above five variables were risk factors for UI in female adult patients with chronic cough.

Conclusion

Urinary incontinence is a common complication in female patients with chronic cough. Older age, severe cough, combing with a higher proportion of chronic sinusitis and abdominal muscle pain, a cough easily triggered by exercise are identified as risk factors for urinary incontinence. We should pay more attention to female chronic coughers with these risk factors in clinics.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12890-022-02069-w.

Development of a natural language processing algorithm to detect chronic cough in electronic health records

BACKGROUND

Chronic cough (CC) is difficult to identify in electronic health records (EHRs) due to the lack of specific diagnostic codes. We developed a natural language processing (NLP) model to identify cough in free-text provider notes in EHRs from multiple health care providers with the objective of using the model in a rules-based CC algorithm to identify individuals with CC from EHRs and to describe the demographic and clinical characteristics of individuals with CC.

METHODS

This was a retrospective observational study of enrollees in Optum's Integrated Clinical + Claims Database. Participants were 18-85 years of age with medical and pharmacy health insurance coverage between January 2016 and March 2017. A labeled reference standard data set was constructed by manually annotating 1000 randomly selected provider notes from the EHRs of enrollees with ≥ 1 cough mention. An NLP model was developed to extract positive or negated cough contexts. NLP, cough diagnosis and medications identified cough encounters. Patients with ≥ 3 encounters spanning at least 56 days within 120 days were defined as having CC.

RESULTS

The positive predictive value and sensitivity of the NLP algorithm were 0.96 and 0.68, respectively, for positive cough contexts, and 0.96 and 0.84, respectively, for negated cough contexts. Among the 4818 individuals identified as having CC, 37% were identified using NLP-identified cough mentions in provider notes alone, 16% by diagnosis codes and/or written medication orders, and 47% through a combination of provider notes and diagnosis codes/medications. Chronic cough patients were, on average, 61.0 years and 67.0% were female. The most prevalent comorbidities were respiratory infections (75%) and other lower respiratory disease (82%).

CONCLUSIONS

Our EHR-based algorithm integrating NLP methodology with structured fields was able to identify a CC population. Machine learning based approaches can therefore aid in patient selection for future CC research studies.

Efficacy and Safety of Ojeok-San Plus Saengmaek-San for Gastroesophageal Reflux-Induced Chronic Cough: A Pilot, Randomized, Double-Blind, Placebo-Controlled Trial

Introduction: Gastroesophageal reflux-induced chronic cough (GERC) is one of the most common etiologies of chronic cough. Despite the growing prevalence and interest in GERC, no effective treatment is currently available. In our study, we used a combination of herbal medicines, Ojeok-san (OJS) plus Saengmaek-san (SMS), for the treatment of GERC. Methods: We conducted a pilot, randomized, placebo-controlled, parallel-arm, single-center clinical trial to assess the feasibility of our study protocol, as our study is the first herbal medicine trial for GERC. All enrolled participants were randomly assigned to either the intervention or placebo group in a 1:1 ratio and were administered trial drugs three times a day for 6 weeks, with an evaluation visit performed every 2 weeks for their efficacy and safety assessment until the follow-up visit (week 8). We evaluated the severity and frequency of cough, cough-specific quality of life, airway hypersensitivity, and reflux-related gastrointestinal symptoms, as well as pattern identification, to investigate the complex mechanisms of reflux cough syndrome. Results: A total of 30 participants were enrolled, and 25 completed the study at Kyung Hee University Korean Medicine Hospital from 26 December 2018 to 31 May 2021. OJS plus SMS significantly improved the cough diary score (CDS), cough visual analog scale, Korean version of the Leicester Cough Questionnaire, Hull Airway Reflux Questionnaire, and Gastrointestinal Symptom Rating Scale after the treatment compared to the baseline. Notably, OJS plus SMS showed significant efficacy in the daytime and total CDS compared with the placebo. Only one adverse event was observed during the trial, and no serious adverse events occurred. Additionally, we achieved successful results in feasibility outcomes by exceeding the ratio of 80%. Conclusion: We confirmed the feasibility of our trial design and demonstrated the potential of OJS plus SMS in relieving the severity of cough and GI symptoms in GERC patients with safe and successful feasibility results. We anticipate that our study results will be used as the basis for further large-scale, well-designed, confirmatory trials to evaluate the safety and efficacy of OJS plus SMS in GERC. Clinical Trial Registration: [https://cris.nih.go.kr], identifier WHO International Clinical Trials Registry Platform, Clinical Research Information Service [KCT0003115].

Burden and impact of chronic cough in UK primary care: a dataset analysis

OBJECTIVE

Chronic cough (CC) is a debilitating respiratory symptom, now increasingly recognised as a discrete disease entity. This study evaluated the burden of CC in a primary care setting.

DESIGN

Cross-sectional, retrospective cohort study.

SETTING

Discover dataset from North West London, which links coded data from primary and secondary care. The index date depicted CC persisting for ≥8 weeks and was taken as a surrogate for date of CC diagnosis.

PARTICIPANTS

Data were extracted for individuals aged ≥18 years with a cough persisting ≥8 weeks or cough remedy prescription, between Jan 2015 and Sep 2019.

MAIN OUTCOME MEASURES

Demographic characteristics, comorbidities and service utilisation cost, including investigations performed and treatments prescribed were determined.

RESULTS

CC was identified in 43 453 patients from a total cohort of 2 109 430 (2%). Median (IQR) age was 64 years (41-87). Among the cohort, 31% had no recorded comorbidities, 26% had been given a diagnosis of asthma, 17% chronic obstructive pulmonary disease, 12% rhinitis and 15% reflux. Prevalence of CC was greater in women (57%) and highest in the 65-74 year age range. There was an increase in the number of all investigations performed in the 12 months before and after the index date of CC diagnosis, and in particular for primary care chest X-ray and spirometry which increased from 6535 to 12 880 and from 5791 to 8720, respectively. This was accompanied by an increase in CC-associated healthcare utilisation costs.

CONCLUSION

One-third of individuals had CC in the absence of associated comorbidities, highlighting the importance of recognising CC as a condition in its own right. Overall outpatient costs increased in the year after the CC index date for all comorbidities, but varied significantly with age. Linked primary-care datasets may enable earlier detection of individuals with CC for specialist clinic referral and targeted treatment.

The financial burden of treating patients presenting with acute and chronic cough

OBJECTIVE

Coughing is a common symptom and responsible for a large number of healthcare visits. This study aimed to characterize healthcare resource use and associated financial costs in people with acute or chronic cough.

METHODS

A retrospective cohort study using routine data from the UK National Health Service. Adults (≥18 years) were selected if they had a cough record between 1 March 2014 and 28 February 2015 and were classified by duration.

RESULTS

A cohort of 150,231 patients was identified, of whom 12,513 (8.3%) had chronic cough, 38,599 (25.7%) had an acute cough with more than one cough event, and 99,119 (66.0%) had acute cough with one event in the study year. Resource use and combined costs of all healthcare contacts differed between cough groups. The healthcare cost per person-year in patients with a single record of acute cough was £739; for those with chronic cough, the cost was £3,663.

CONCLUSIONS

Patients with cough represented a substantial financial burden to the NHS. It was difficult to discern the specific portion of treatment associated with cough itself. However, people with chronic cough were associated with substantially increased healthcare use and costs than were those with acute cough.

Randomised trial of the P2X3 receptor antagonist sivopixant for refractory chronic cough

Background

The purinoceptor subtype P2X₃ has been shown to have significant involvement in the cough reflex; the heterotrimer version of the purinoceptor (P2X_2/3) has been implicated in taste disturbance. The most advanced clinical candidate antagonist gefapixant has low selectivity among P2X₃ receptors and induced taste disturbance, whereas newly developed sivopixant has high selectivity towards P2X₃versus P2X_2/3.

Methods

In a phase 2a, randomised, double-blind, placebo-controlled, crossover, multicentre study, adult patients with refractory or unexplained chronic cough received oral sivopixant 150 mg or placebo once daily for 2 weeks, followed by a 2–3-week washout period, and then crossed over to placebo or sivopixant for 2 weeks. Efficacy and safety of sivopixant were evaluated.

Results

Of 31 randomised patients, 15 in the sivopixant-first group and 15 in the placebo-first group completed the study. After 2 weeks of treatment, the placebo-adjusted ratios of the average hourly number of coughs to baseline during daytime (primary end-point) and over 24 h (secondary end-point) were −31.6% (p=0.0546) and −30.9% (p=0.0386), respectively. Sivopixant also improved health-related quality of life. Treatment-related adverse events occurred in 12.9% and 3.2% of patients during sivopixant and placebo administration, respectively. Mild taste disturbance occurred in two patients (6.5%) during sivopixant administration.

Conclusions

Sivopixant reduced objective cough frequency and improved health-related quality of life, with a low incidence of taste disturbance, among patients with refractory or unexplained chronic cough.

This study shows the efficacy of a highly selective P2X₃ receptor antagonist to reduce cough frequency, with low incidence of taste disturbance. Sivopixant may be a promising therapeutic option for refractory or unexplained chronic cough.https://bit.ly/3awojQH

Chronic cough caused by choledochoduodenal fistula: a case report

Background

Chronic cough is characterized by cough as the only or main symptom, with a duration of more than 8 weeks and no obvious abnormality in chest X-ray examination. Its etiology is complex, including respiratory disease, digestive system disease, circulation system disease, and psychological disease. Although a set of etiological diagnosis procedures for chronic cough have been established, it is still difficult to diagnose chronic cough and there are still some patients with misdiagnosis.

Case presentation

We present a case of a 54-year-old female patient who had chronic cough for 28 years. Physical examination had no positive signs and she denied any illness causing cough like tuberculosis, rhinitis. Recurrent clinic visits and symptomatic treatment didn’t improve the condition. Finally, gastroscopy identified the possible etiology of choledochoduodenal fistula that was proved by surgery. And after surgery, the patient's cough symptoms were significantly improved.

Conclusion

We report a rare case of chronic cough caused by choledochoduodenal fistula which demonstrates our as yet inadequate recognition of the etiology and pathogenesis. Written informed consent was obtained from the patient.

How We Do It: Managing Cough in Idiopathic Pulmonary Fibrosis

In many studies, more than one-half of patients with idiopathic pulmonary fibrosis (IPF) endorse cough. In IPF (as in other conditions), when chronic, cough may be frustrating and lead to significant impairments in quality of life. In patients with IPF, comorbid conditions such as gastroesophageal reflux can cause or contribute to cough; when stemming from IPF itself, chronic cough likely arises from multiple mechanisms including mechanical and neurosensory changes. In this article, we review our approach at attempting to identify causes of chronic cough in patients with IPF; these include gastroesophageal reflux disease or upper airway cough syndrome and IPF itself. We cursorily summarize the current evidence for the treatment of chronic cough in IPF, briefly review data on the treatment of unexplained chronic cough and extrapolate it to the treatment of refractory cough in IPF, but we focus our attention on our approaches to evaluation and management, recognizing that some may not be supported by a robust cache of data.

Irritant-Induced Chronic Cough Triggers: A Scoping Review and Clinical Checklist

Purpose The primary aim of this review was to identify environmental irritants known to trigger chronic cough through the life span and develop a comprehensive clinically useful irritant checklist. Method A scoping review was conducted using the Preferred Reporting Items for Systematic Review and Meta-Analysis Extension for Scoping Reviews, checklist, and explanation. English-language, full-text resources were identified through Medline, PsycINFO, SPORTDiscus, Web of Science, and ProQuest Dissertations and Theses Global. Results A total of 1,072 sources were retrieved; of these, 109 were duplicates. Titles of abstracts of 963 articles were screened, with 295 selected for full-text review. Using the exclusion and inclusion criteria listed, 236 articles were considered eligible and 214 different triggers were identified. Triggers were identified from North America, Europe, Africa, Asia, and Australia. Occupational exposures were also delineated. Conclusions A clinically useful checklist of both frequently encountered triggers and idiosyncratic or rare triggers was developed. The clinical checklist provides a unique contribution to streamline and standardize clinical assessment of irritant-induced chronic cough. The international scope of this review extends the usefulness of the clinical checklist to clinicians on most continents.

Exploring the role of nerves in asthma; insights from the study of cough

Cough in asthma predicts disease severity, prognosis, and is a common and troublesome symptom. Cough is the archetypal airway neuronal reflex, yet little is understood about the underlying neuronal mechanisms. It is generally assumed that symptoms arise because of airway hyper-responsiveness and/or airway inflammation, but despite using inhaled corticosteroids and bronchodilators targeting these pathologies, a large proportion of patients have persistent coughing. This review focuses on the prevalence and impact of cough in asthma and explores data from pre-clinical and clinical studies which have explored neuronal mechanisms of cough and asthma. We present evidence to suggest patients with asthma have evidence of neuronal dysfunction, which is further heightened and exaggerated by both bronchoconstriction and airway eosinophilia. Identifying patients with excessive coughing with asthma may represent a neuro-phenotype and hence developing treatment for this symptom is important for reducing the burden of disease on patients' lives and currently represents a major unmet clinical need.

Exploring the clinical relevance of cough hypersensitivity syndrome

Introduction: Knowledge of the pathophysiology of cough has continued to advance over recent decades. Establishing anatomic-diagnostic protocols, based on the anatomy and distribution of vagus nerve pathways regulating the cough reflex, was the first breakthrough in modern clinical medicine for chronic cough. The unmet clinical need has prompted revised thinking regarding the pathophysiology of and the clinical approach to chronic cough.Areas covered: The paradigm of cough hypersensitivity syndrome (CHS) has been recently proposed, wherein aberrant neuro-pathophysiology is a common etiology. This review covers major findings on chronic cough and cough hypersensitivity, particularly focused on recently-published studies and explores the clinical relevance and applicability of CHS based on current knowledge and discuss knowledge gaps and future research directions.Expert opinion: This paradigm has provided new opportunities in managing chronic cough and evidence is accumulating to support the validity of CHS. It also warrants the re-appraisal of existing clinical evidence and investigation of how to refine our clinical strategy. While CHS highlights the importance of clinical thinking from the viewpoint of cough, the value of anatomic-diagnostic protocols should remain. Moreover, given the considerable heterogeneity in clinical presentation, cough-associated disease conditions, and treatment responses across different patients, precise molecular endotyping remains key to making further to advancing clinical practice .

Allergic and Mixed Rhinitis: Diagnosis and Natural Evolution

Chronic rhinitis (CR) is divided into two main categories: allergic rhinitis (AR) and nonallergic rhinitis (NAR). These conditions are more recognizable to an experienced clinician, as they can be more clearly demarcated diagnostically. However, an additional 30% to 50% of patients with CR might have an overlap of NAR and AR, referred to as mixed rhinitis (MR). Progress in elucidating the pathophysiologic mechanisms behind MR and NAR has been made in the past several years, and there are now several guidelines published to assist the clinician in accurately diagnosing AR, NAR, and MR. Clinical history and subjective symptoms can provide clues for differentiating AR from MR and NAR, but allergy testing is recommended to confirm these conditions. Progress in accurately diagnosing patients with CR will be made as studies incorporate subjective (i.e., validated questionnaires such as the irritant index questionnaire (IIQ), medication responsiveness, and quality-of-life tools) and objective (i.e., nasal cytologic testing, nasal provocation, and biomarkers) methods characterizing rhinitis subtypes.

Bronchiectasis and cough: An old relationship in need of renewed attention

Bronchiectasis is an increasingly recognised respiratory condition with limited therapeutic options and a complex spectrum of clinical manifestations that invariably includes chronic cough. As the primary presentation of bronchiectasis in most cases, chronic cough and its mechanistic underpinnings are of central importance but remain poorly understood in this setting. Bronchiectasis is also increasingly identified as an underlying cause of chronic cough highlighting the interrelationship between the two conditions that share overlapping clinical features. Several therapeutic approaches have illustrated positive effects on bronchiectasis-associated cough, however, more focused treatment of heterogeneous cough subtypes may yield better outcomes for patients. A current challenge is the identification of bronchiectasis and cough endophenotypes that may allow improved patient stratification and more targeted therapeutic matching of the right treatment to the right patient. Here we discuss the complex disease phenotypes of bronchiectasis and their interrelationship with cough while considering current and emerging treatment options. We discuss some key cough promoters in bronchiectasis including infection, allergy and immune dysfunction.

Etiologies associated with chronic cough and its clinical characteristics in school-age children

Background

To comprehensively evaluate the etiology of chronic cough and the value of clinical feature in school age children in Suzhou, China.

Methods

School-age (6-14 years) children newly referred with chronic cough (>4 weeks) were prospectively evaluated by utilizing a diagnostic algorithm in this study. Clinical features of different etiologies of chronic cough were also investigated.

Results

In total, 118 patients were enrolled in the study. The cough duration ranged from 1 to 76 months. Upper airway cough syndrome (UACS) was found in 77 (65.3%) patients with chronic cough, cough-variant asthma (CVA) in 57 (48.3%) patients, protracted bronchitis (PB) in 15 (12.7%) patients, gastroesophageal reflux disease (GERD) in 7 (5.9%) patients, tic disorders (TD) in 3 (2.5%) patients and eosinophilic bronchitis (EB) in 2 (1.7%) patients. A single etiology was present in 75 patients and multiple etiologies were present in 43 patients. The three most common single etiologies were UACS (31.4%), CVA (14.4%), and PB (10.2%), followed by GERD (5.9%), and EB (1.7%). The most common multiple etiology was CVA + UACS (31.4%), followed by CVA + PB (2.5%), and TD + UACS (2.5%).

Conclusions

The common etiologies of chronic cough in school-age children were UACS, CVA, and PB, while EB and GERD were rare.

Age and Sex Distribution of Chinese Chronic Cough Patients and Their Relationship With Capsaicin Cough Sensitivity

PURPOSE

An older female predominance has been reported among chronic cough patients in Western countries, which is considered to be associated with a higher cough sensitivity in females. However, the characteristics of Chinese chronic cough patients remain unclear. This study aimed to explore the age and sex distribution as well as their relationship with cough reflex sensitivity to capsaicin in Chinese chronic cough patients.

METHODS

We analyzed the demographic features of 1,882 consecutive chronic cough patients who attended our cough clinic in Guangzhou, China. Cough sensitivity to capsaicin, which was defined as the lowest concentration of capsaicin causing 5 coughs or more (C5), was measured in 539 of the 1,882 patients and 68 healthy volunteers.

RESULTS

The mean age of the patients was 43.0 ± 13.7 years and patients aged <50 years accounted for more than two-thirds of the study population. Around 87% of the patients were never-smokers. The proportion of females (51.5%) was almost equal to that of males (48.5%). The pattern of the age and sex distribution was consistently reflected within most common causes of chronic cough, while a female predominance was shown in patients with cough-variant asthma and patients aged ≥50 years. Female patients had higher cough sensitivity to capsaicin than male patients (log C5: 1.58 ± 0.84 vs. 2.04 ± 0.84 μmol/L, P = 0.001), and patients aged ≥50 years had higher cough sensitivity to capsaicin than patients aged <50 years.

CONCLUSIONS

In China, patients with chronic cough have a roughly equal sex distribution and a middle-aged predominance, irrespective of a higher cough sensitivity to capsaicin in females and older patients.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02591550.

XII AIST 2018 Conference: “The thousand faces of cough: clinical and therapeutic updates”

This paper summarizes the presentations submitted for publication of the 12^th AIST National Congress (Associazione Italiana Studio Tosse/Italian Association for Cough Study) entitled “The thousand facets of cough. A clinical and therapeutic update”, which occurred last February 2^nd-3^rd, 2018 in Bologna (Italy). It summarizes the contributions from leading experts of the sector, who, as in the previous editions, also this year have analyzed a problem too often underestimated which still has many dark sides as regards both the diagnosis and the therapy of cough. The Scientific Committee has chosen topics that had less space in previous editions and these are topical subjects representing a concrete opportunity for learning and comparison of opinions, as well as indispensable elements for the correct management of the symptoms.

Hereby we report the abstracts of the works submitted for publication in this Meeting report.

The main topics have covered Cough relationship with nerve vagus, ATP, air pollution, GERD, imaging, COPD, pediatric and therapy. Of particular interest it is the preliminary data on cough hydration ratio that shows a highly significant correlation between dehydration and cough.

Towards understanding and managing chronic cough

Chronic cough is a common and troublesome condition affecting approximately 12% of the general population. It is associated with poor quality of life with psychological, social and physical consequences. Patients typically complain of a dry irritating cough, driven by a strong urge to cough associated with a sensation or irritation located in the throat. Treatment of potential 'causes', ie asthma, gastro-oesophageal reflux disease and rhino-sinusitis, may produce a complete or partial response, but the response of some patients to opiates and alpha-2-delta ligand antagonists (gabapentin and pregabalin) supports the concept that this is primarily a neurological disorder, characterised by hyper-responsiveness of the nerves. Novel and highly effective neuronal treatments are in development and offer hope of better symptom control with fewer side effects within a few years. This review focuses on understanding the mechanism of chronic cough, current management approaches and research that may lead to novel therapies.

Towards understanding and managing chronic cough

Chronic cough is a common and troublesome condition affecting approximately 12% of the general population. It is associated with poor quality of life with psychological, social and physical consequences. Patients typically complain of a dry irritating cough, driven by a strong urge to cough associated with a sensation or irritation located in the throat. Treatment of potential 'causes', ie asthma, gastro-oesophageal reflux disease and rhino-sinusitis, may produce a complete or partial response, but the response of some patients to opiates and alpha-2-delta ligand antagonists (gabapentin and pregabalin) supports the concept that this is primarily a neurological disorder, characterised by hyper-responsiveness of the nerves. Novel and highly effective neuronal treatments are in development and offer hope of better symptom control with fewer side effects within a few years. This review focuses on understanding the mechanism of chronic cough, current management approaches and research that may lead to novel therapies.

Assessment of five different guideline indication criteria for spirometry, including modified GOLD criteria, in order to detect COPD: data from 5,315 subjects in the PLATINO study

BACKGROUND

Spirometry is the gold standard for diagnosing chronic obstructive pulmonary disease (COPD). Although there are a number of different guideline criteria for deciding who should be selected for spirometric screening, to date it is not known which criteria are the best based on sensitivity and specificity.

AIMS

Firstly, to evaluate the proportion of subjects in the PLATINO Study that would be recommended for spirometry testing according to Global initiative for Obstructive Lung Disease (GOLD)-modified, American College of Chest Physicians (ACCP), National Lung Health Education Program (NLHEP), GOLD and American Thoracic Society/European Respiratory Society (ATS/ERS) criteria. Secondly, we aimed to compare the sensitivity, specificity, and positive predictive and negative predictive values, of these five different criteria.

METHODS

Data from the PLATINO study included information on respiratory symptoms, smoking and previous spirometry testing. The GOLD-modified spirometry indication criteria are based on three positive answers out of five questions: the presence of cough, phlegm in the morning, dyspnoea, age over 40 years and smoking status.

RESULTS

Data from 5,315 subjects were reviewed. Fewer people had an indication for spirometry (41.3%) according to the GOLD-modified criteria, and more people had an indication for spirometry (80.4%) by the GOLD and ATS/ERS criteria. A low percentage had previously had spirometry performed: GOLD-modified (14.5%); ACCP (13.2%); NLHEP (12.6%); and GOLD and ATS/ERS (12.3%). The GOLD-modified criteria showed the least sensitivity (54.9) and the highest specificity (61.0) for detecting COPD, whereas GOLD and ATS/ERS criteria showed the highest sensitivity (87.9) and the least specificity (20.8).

CONCLUSION

There is a considerable difference in the indication for spirometry according to the five different guideline criteria. The GOLD-modified criteria recruit less people with the greatest sum of sensitivity and specificity.

A novel diagnostic algorithm for chronic and subacute cough

BACKGROUND

Cough remains the most common reason for patients to seek medical attention. We practised a novel diagnostic algorithm for chronic and subacute cough.

METHODS

Chronic and subacute cough patients with normal chest X-ray results and without respiratory tract infections in the preceding eight weeks were recruited. The patients were divided into two groups: Group A, patients with typical symptoms and signs of postnasal drip syndrome (PNDS), asthma syndromes (AS) and gastroesophageal reflux disease (GERD); Group B, patients without the typical symptoms and signs. The two groups received targeted or sequential empirical trials of therapy according to the algorithm.

RESULTS

Among the 524 patients available for analysis in Groups A and B, 436 (83.6%) were diagnosed to have PNDS (34.2%), AS (44.5%) and/or GERD (10.1%), among which 26 had two causes (6.0%) and 6 had three causes (1.4%). After empirical trials of therapy, 81.5% of the patients were diagnosed. The mean time for diagnosis was considerably shorter in Group A (13.1 ± 5.6 d) than in Group B (23.4 ± 7.2 d) (p < 0.01). The diagnosis rate of the first trial in Group A (54.1%) was significantly higher than that in Group B (28.6%, p < 0.01).

CONCLUSIONS

The proposed algorithm is a promising and practical approach to diagnose chronic and subacute cough.

Altitude-related cough

Altitude-related cough is a troublesome condition of uncertain aetiology that affects many visitors to high altitude. The traditionally held belief that it was due solely to the inspiration of cold, dry air was refuted by observations and experiments in long duration hypobaric chamber studies. It is likely that altitude-related cough is a symptom of a number of possible perturbations in the cough reflex arc that may exist independently or together. These include loss of water from the respiratory tract; respiratory tract infections and sub-clinical high altitude pulmonary oedema. The published work on altitude-related cough is reviewed and possible aetiologies for the condition are discussed.

The effects of antitussive treatment of ACE inhibitor-induced cough on therapy compliance: a prescription sequence symmetry analysis

BACKGROUND

A common adverse effect of angiotensin-converting enzyme inhibitors (ACEI) is a persistent dry cough. Physicians and pharmacists who fail to recognise dry cough to be ACEI related may prescribe antitussives, instead of recommended ACEI substitution.

OBJECTIVE

The aim of this study was to determine the influence of antitussive treatment of ACEI-induced cough on ACEI therapy compliance.

METHODS

Prescription data from community pharmacies between 2000 and 2012 were retrieved from the IADB.nl database (InterAction Database) in The Netherlands. A prescription sequence symmetry analysis was used to determine whether antitussive agents were prescribed more often following ACEI initiation (cases) than the other way around (controls). ACEI therapy compliance was assessed using the proportion of days covered (PDC) method; patients with a PDC of at least 80 % were considered compliant. Compliance was compared between patients receiving antitussives for ACEI-induced cough and patients receiving antitussives for other reasons and patients who did not receive antitussives.

RESULTS

A total of 1,898 starters of ACEI and antitussives within a half-year time span were included. A significant excess of patients received antitussives after ACEI initiation compared with before ACEI initiation (1,269 cases vs. 629 controls), yielding a sequence ratio of 2.0 (95 % CI 1.8-2.2). The estimated proportion of patients with ACEI-induced cough receiving antitussives decreased over time: from 20.4 % in 2000-2004 to 8.0 % in 2008-2012. ACEI therapy compliance in patients receiving antitussives due to ACEI initiation was 52.4 %, significantly lower than compliance in control patients receiving antitussives for cough unrelated to ACEI (75.5 %, P < 0.001) and control patients who did not receive antitussives (75.2 %, P < 0.001).

CONCLUSIONS

Many patients receive antitussives after ACEI initiation. This suggests that ACEI-induced cough is often either not recognized as being ACEI related or is symptomatically treated. Such prescription behaviour may decrease ACEI therapy compliance.

Chronic cough: an update

Cough persisting beyond 8 weeks (ie, chronic cough) is one of the most common reasons for an outpatient visit. A protracted cough can negatively affect one's quality of life by causing anxiety, physical discomfort, social isolation, and personal embarrassment. Herein, the anatomy and physiology of the cough reflex are reviewed. Upper airway cough syndrome, asthma, eosinophilic bronchitis, and gastroesophageal reflux disease account for most chronic cough after excluding smoking, angiotensin-converting enzyme inhibitor use, and chronic bronchitis. Many patients have more than one reason for chronic cough. Treating the underlying cause(s) resolves cough in most instances. There are some coughs that seem refractory despite an extensive work-up. The possibility of a hypersensitive cough reflex response has been proposed to explain these cases. Several clinical algorithms to evaluate chronic cough are presented.

Chronic cough: relationship between microaspiration, gastroesophageal reflux, and cough frequency

BACKGROUND

Microaspiration is often considered a potential cause of cough. The aim of this study was to investigate the relationship between microaspiration, the degree and type of gastroesophageal reflux, and the frequency of coughing in patients with chronic cough.

METHODS

One hundred patients with chronic cough (mean [± SD] age, 55.8 years [± 11.0 years]; 65 women) and 32 healthy volunteers (median age, 43.5 years [interquartile range (IQR), 30-50.8 years]; 16 women) were recruited. Patients with chronic cough performed 24-h objective cough frequency with simultaneous esophageal impedance/pH monitoring and measurement of pepsin concentrations in sputum and BAL. Twelve healthy volunteers underwent bronchoscopy/BAL, and 20 underwent impedance/pH monitoring.

RESULTS

Patients with chronic cough had significantly more reflux episodes than healthy volunteers (median, 63.5 reflux episodes [IQR, 52.5-80.0] vs 59.0 [IQR, 41.8-66.0]; P = .03), although the absolute difference was small, and there was no difference in numbers of events extending into the proximal esophagus (median, 17.2% [IQR, 8.0%-26.0%] vs 20.3% [IQR, 5.1%-32.1%]; P = .36). BAL pepsin levels were also similar in chronic cough to control subjects (median, 18.2 ng/mL [range, 0-56.4 ng/mL] vs 9.25 ng/mL [range, 0-46.9 ng/mL]; P = .27). Sputum but not BAL pepsin weakly correlated with the number of proximally occurring reflux events (r = 0.33, P = .045) but was inversely related to cough frequency (r = −0.52, P = .04). Sputum pepsin was, therefore, best predicted by combining the opposing influences of cough and proximal reflux (r = 0.50, P = .004).

CONCLUSIONS

Proximal gastroesophageal reflux and microaspiration into the airways have limited roles in provoking chronic cough. Indeed, coughing appears to be protective, reducing pepsin concentration in the larger airways of patients with chronic cough.

The larynx in cough

About 40% of the population will experience chronic cough at some point during their lives and it tends to be more common in women (Thorax 58:901-7, 2003). Post-nasal drip (or upper airway cough syndrome), gastro-esophageal reflux disease and asthma are considered the most common causes. Yet only a small percentage of patients with these common conditions experience chronic cough. Also there is no agreed measure of post-nasal drip and controversy exists about the diagnosis of reflux above the upper esophageal sphincter (laryngopharyngeal reflux) based on observable changes to the larynx. The approach of the otolaryngologist is to consider the upper and lower airways as a continuum and that a common pathology can have an impact on all these anatomical sites.A multidisciplinary approach is advocated, utilising the skills of the respiratory physician, otolaryngologist, gastroenterologist and speech pathologist.

Chronic cough in subjects with upper airway diseases - analysis of mechanisms and clinical applications

Cough is the commonest respiratory symptom leading to a medical consultation. Although acute cough which is usually associated with respiratory viral infection is not a problem to manage, chronic cough is frequently a diagnostic and therapeutic challenge as it does not respond to usual treatments. Specific group of chronic coughers are considered to have upper airway diseases, lately categorized as having upper airway cough syndrome. There is an increasing pool of evidence that upper airway diseases have significant involvements in the regulation of cough reflex, indicating that they must be taken into considerations as major triggers of coughing in the patients. Here we summarize current literature and experiences on the pathogenesis of upper airway cough syndrome, and discuss further clinical applications.

Capsaicin sensitivity in patients with chronic cough- results from a cross-sectional study

Background

A subgroup of patients with chronic cough is recognised as having airway symptoms resulting exposure to chemicals and scents related to enhanced cough sensitivity to inhaled capsaicin. Sensory hyperreactivity, which has an estimated prevalence of more than 6%, is one possible explanation for the symptoms experienced by these patients. We hypothesized that a number of patients diagnosed with chronic unexplained cough also have coughing provoked by chemical irritants associated with augmented capsaicin cough reaction, but the extent of such a relation is not known. One aim of the present study was to analyse cough sensitivity to inhaled capsaicin in patients with chronic unexplained cough. Another aim was to compare capsaicin sensitivity in individuals with chemically induced coughing (the chemical-sensitive group) to capsaicin sensitivity in those without such chemical sensitivity (non-sensitive group).

Methods

Fifty-six participants from an earlier cross-sectional study of 62 patients with chronic unexplained cough were asked to participate in this study: 33 were chemical-sensitive and 23 were non-sensitive. Each participant visited the clinic once and performed a capsaicin inhalation test with one of two inhalation devices. The number of coughs, induced airway symptoms, and spirometry results were recorded.

Results

Thirty-nine of the invited patients participated in the study, with 32 in the chemical-sensitive group (21 women, 11 men), and 7 in the non-sensitive group (4 women, 3 men). The chemical-sensitive patients coughed significantly more on inhaling capsaicin, and had significantly more other airway symptoms compared to those in the non-sensitive group. Women coughed significantly more than men after receiving the higher concentration of capsaicin.

Conclusions

Environmental irritants often trigger chronic unexplained cough. The current findings confirm that this sensitivity is related to enhanced capsaicin cough sensitivity and indicates more involvement of airway sensory nerves in the pathophysiology of the disease than in cough without evident trigger factors.

Management of patients with chronic cough using a clinical protocol: a prospective observational study

Background and aims

Chronic cough is a common symptom the aetiology of which can be challenging to diagnose. Diagnostic protocols for chronic cough have required the use of specialist investigations which are not always easily available. We wanted to determine whether patients with chronic cough can be successfully managed using a clinical algorithm.

Methods

112 consecutive patients with chronic cough were prospectively recruited into this study. They were assessed by history, physical examination, chest radiograph, spirometry and reversibility to nebulised salbutamol. A clinical diagnosis was made and the patient had an 8-week trial of appropriate therapy. Further therapeutic trials were carried out depending on response to treatment and the possible differential diagnoses. Investigations were carried out in cases of failed clinical trials and to exclude specific pathology. The “clinical arm” comprised patients managed on the basis of clinical assessment and without any investigations. The “investigative arm” comprised those who needed further investigations.

Results

81 (72%) were managed in the clinical arm. Of these 74 (66%) were discharged following response to therapy. 31 (28%) patients were converted to the investigative arm after failure of diagnosis in the clinical protocol. The commonest causes of cough were gastroesophageal reflux, asthma and chronic rhinitis. 51 (45.5%) patients responded to therapy based on diagnosis at initial assessment while a further 23 (20.5%) patients responded to sequential clinical trials for the commonest causes of cough. Cough severity score improved by a mean of 3.6 points on a numeric response score (from 0–10, p < 0.0001).

Conclusion

It is possible to manage a majority of chronic cough patients successfully using a protocol based on presenting symptoms and therapeutic trials for the common causes of cough.

Chronic cough: a multidisciplinary approach

BACKGROUND AND METHODS

Chronic cough is defined as a cough persisting for more than eight weeks. This condition generates significant healthcare and economic costs. It is associated with a spectrum of disorders across multiple medical specialties and can provide significant challenges for effective evaluation and management. The current literature was reviewed to gain further insight into chronic cough, including its relationship with sinonasal disease.

RESULTS

Within the reviewed literature, there was strong emphasis on post-nasal drip syndrome as a major causative factor.

CONCLUSION

Cough is the most common complaint for which adult patients seek medical consultation in primary care settings. Chronic cough is associated with a deterioration in the quality of patients' lives. Thorough assessment of a patient with a chronic cough relies on a multidisciplinary approach.

Cough response to isocapnic hyperpnoea of dry air and hypertonic saline are interrelated

Background

Mechanisms behind asthmatic cough are largely unknown. It is known that hyperosmolar challenges provoke cough in asthmatic but not in the healthy subjects. It has been postulated that isocapnic hyperpnea of dry air (IHDA) and hypertonic aerosols act via similar mechanisms in asthma to cause bronchoconstriction. We investigated whether there is an association between cough response induced by IHDA and hypertonic saline (HS) challenges.

Methods

Thirty-six asthmatic and 14 healthy subjects inhaled HS solutions with increasing osmolalities administered via ultrasonic nebuliser until 15 cumulative coughs were recorded. The IHDA consisted of three three-minute ventilation steps: 30%, 60% and 100% of maximal voluntary ventilation with an end-point of 30 cumulative coughs. The challenges were performed on separate days at least 48 hours between them and within one week. Inhaled salbutamol (400 mcg) was administered before the challenges to prevent bronchoconstriction. The cough response was expressed as the cough-to-dose ratio (CDR) which is the total number of coughs divided by the maximal osmolality inhaled or the maximal ventilation achieved.

Results

Cough response to IHDA correlated with the HS challenge (Rs = 0.59, p < 0.001). Cough response to IHDA was at its strongest during the first minute after the challenge. IHDA induced more cough among asthmatic than healthy subjects CDR being (mean ± SD) 0.464 ± 0.514 and 0.011 ± 0.024 coughs/MVV%, p < 0.001, respectively. Salbutamol effectively prevented bronchoconstriction to both challenges.

Conclusions

Asthmatic patients are hypersensitive to the cough-provoking effect of hyperpnoea, as they are to hypertonicity. Cough response induced by IHDA and HS correlated well suggesting similar mechanisms behind the responses.

GERD-related cough: pathophysiology and diagnostic approach

Chronic cough is a common problem resulting in significant impairment of quality of life. Along with cough variant asthma and nasal disease, gastroesophageal reflux is considered one of three main causes of cough. Despite this, acid suppression therapy is often far from effective. This review aims to explore whether reflux can lead to cough, the circumstances in which this is most likely to occur, and the potential mechanisms linking these processes. Particular mechanisms to be explored include laryngopharyngeal reflux, microaspiration, and neuronal cross-organ sensitization. Finally, diagnostic approaches are considered.

Unusual asthma syndromes and their management

Asthma usually presents with symptoms of wheeze, dyspnoea and cough. However, clinicians should be aware of atypical presentation of this disorder when cough is the main or only symptom in conditions such as cough-variant asthma, nonasthmatic eosinophilic bronchitis and atopic cough. Early diagnosis and treatment of these conditions with inhaled corticosteroids improves symptoms in the majority of patients. Up to 10% of patients with asthma remain poorly controlled in spite of optimal standard therapy. These patients have been encompassed under the term 'treatment-refractory asthma' (TRA), have the greatest morbidity and are responsible for more than 50% of healthcare costs. In this review we discuss investigations, management and pathophysiology of the various phenotypes of atypical presentations of asthma as well as novel biological agents licensed and those that have been reported in clinical trials in terms of their efficacy and safety in TRA.

Misdiagnosis and mistreatment of a common side-effect--angiotensin-converting enzyme inhibitor-induced cough

AIMS

Angiotensin-converting enzyme inhibitors (ACEi) are frequently prescribed for various cardiovascular and renal diseases. A common side-effect of these drugs is a persistent dry cough. Physicians who fail to recognize a dry cough to be ACEi-related may attempt to treat it with antitussive agents instead of recommended ACEi substitution. Prescription behaviour in the general population considering treatment of the side-effect with antitussive agents has not been studied before.

METHODS

Drug dispensing data between 2000 and 2007 were retrieved from the IADB.nl database. A prescription sequence symmetry analysis was used to determine whether antitussive agents were prescribed more often following ACEi initiation than the other way around. A logistic regression model was fitted to determine predictors.

RESULTS

We identified 27 446 incident users of ACEi therapy. One thousand and fifty-four patients were incident users of both ACEi and antitussives within a half-year time span. There was an excess of patients being prescribed antitussive agents after ACEi initiation (703 vs. 351), adjusted sequence ratio 2.2 [confidence interval (CI) 1.9, 2.4]. Female patients were more likely to be prescribed antitussive agents following ACEi therapy initiation, odds ratio 1.4 (CI 1.1, 1.9), age and co-medications were not significant predictors.

CONCLUSIONS

There was a significant and clinically relevant excess of patients receiving antitussives after ACEi initiation. The results suggest that cough as a side-effect of ACEi is not recognized as being ACEi-related or is symptomatically treated with antitussive agents instead of ACEi substitution. The estimated frequency of antitussive treatment of ACEi-induced dry cough is 15%.

Chronic cough: Stepwise application in primary care practice of the ACCP guidelines for diagnosis and management of cough

PURPOSE

To illustrate decision points encountered when using evidence-based guidelines for diagnosis and management of chronic cough by means of a composite case study based on primary care practice.

DATA SOURCE

The American College of Chest Physicians (ACCP) Evidence-Based Clinical Practice Guidelines for Diagnosis and Management of Cough, and review of the scientific literature on cough and related topics.

CONCLUSIONS

The ACCP guidelines offer a systematic approach that uses trials of empirical therapies to diagnose and resolve the very common, often perplexing complaint of chronic cough. The major diagnoses reached are upper airway cough syndrome, cough-variant asthma, gastroesophageal reflux disease, and nonasthmatic eosinophilic bronchitis.

IMPLICATIONS FOR PRACTICE

Cough is the most common reason that patients seek an office visit. Many coughs resolve spontaneously, but coughs that persist significantly impair the quality of life. Use of the ACCP guidelines allows a stepwise empirical approach to the problem of unexplained chronic cough. This approach greatly increases the percentage of chronic coughs that are accurately diagnosed and effectively treated, and avoids unnecessary diagnostic testing.

Inter-observer agreement for multichannel intraluminal impedance-pH testing

Twenty-four-hour ambulatory multichannel intraluminal impedance (MII)-pH detects both acid and nonacid reflux (NAR). A computer-based program (Autoscan™, Sandhill Scientific, Highlands Ranch, CO, USA) automates the detection of reflux episodes, increasing the ease of study interpretation. Inter-observer agreement between multiple reviewers and with Autoscan™ for the evaluation of significant NAR with MII-pH has not been studied in the adult population. Twenty MII-pH studies on patients taking a proton pump inhibitor twice daily were randomly selected. Autoscan™ analyzed all studies using the same pre-programmed parameters. Four reviewers interpreted the MII-pH studies, adding or deleting reflux episodes detected by Autoscan™. Positive studies for NAR and total reflux episodes were based on published criteria. Cohen's kappa statistic (κ) evaluated inter-observer agreement between reviewers and Autoscan™ analysis. The average κ for pathologic NAR between reviewers was 0.57 (0.47-0.70), and between reviewers and Autoscan™ was 0.56 (0.4-0.8). When using the total reflux episode number as a marker for pathologic reflux (acid and NAR), the κ score was 0.72 (0.61-0.89) between reviewers, and 0.74 (0.53-0.9) when evaluating total reflux episodes. Two reviewers agreed more often with each other and with Autoscan™ on the number of NAR episodes, while the other two reviewers agreed with each other, but did not agree with either Autoscan™ or the first two reviewers. Inter-observer agreement between reviewers and Autoscan™ for detecting pathologic NAR is moderate, with reviewers either excluding more of the Autoscan™-defined events or excluding fewer events and therefore agreeing with Autoscan™.

Chronic cough and obstructive sleep apnea in a community-based pulmonary practice

BACKGROUND

Recent reports suggest an association between unexplained chronic cough and obstructive sleep apnea (OSA). Current guidelines provide an empiric integrative approach to the management of chronic cough, particularly for etiologies of gastroesophageal reflux (GERD), upper airway cough syndrome (UACS) and cough variant asthma (CVA) but do not provide any recommendations regarding testing for OSA. This study was done to evaluate the prevalence of OSA in patients referred for chronic cough and examine the impact of treating OSA in resolution of chronic cough.

METHODS

A retrospective review of chronic cough patients seen over a four-year period in a community-based pulmonary practice was done. Patients with abnormal chest radiographs, abnormal pulmonary function tests, history of known parenchymal lung disease, and inadequate followup were excluded. Clinical data, treatments provided and degree of resolution of cough was evaluated based on chart review. Specifically, diagnostic testing for OSA and impact of management of OSA on chronic cough was assessed.

RESULTS

75 patients with isolated chronic cough were identified. 44/75 had single etiologies for cough (GERD 37%, UACS 12%, CVA 8%). 31/75 had multiple etiologies for their chronic cough (GERD-UACS 31%, GERD-CVA 5%, UACS-CVA 3%, GERD-UACS-CVA 3%). 31% patients underwent further diagnostic testing to evaluate for UACS, GERD and CVA. Specific testing for OSA was carried out in 38/75 (51%) patients and 33/75 (44%) were found to have obstructive sleep apnea. 93% of the patients that had interventions to optimize their sleep-disordered breathing had improvement in their cough.

CONCLUSIONS

OSA is a common finding in patients with chronic cough, even when another cause of cough has been identified. CPAP therapy in combination with other specific therapy for cough leads to a reduction in cough severity. Sleep apnea evaluation and therapy needs to considered early during the management of chronic cough and as a part of the diagnostic workup for chronic cough.

New developments in reflux-associated cough

Gastro-oesophageal reflux disease (GORD) is generally considered one of the three main causes of chronic cough, along with asthma and nasal disease. The diagnosis of GORD is often based upon a successful trial of anti-acid treatment however GORD is a complex condition taking many forms. Only recently have studies started to address the different types of GORD in patients with chronic cough and how these may infer the mechanisms linking these common conditions. GORD can be assessed in a number of ways; whilst endoscopy provides evidence of oesophagitis (i.e. erosive disease), 24-h ambulatory oesophageal pH monitoring may demonstrate abnormal oesophageal acid exposure in the absence of oesophageal damage (i.e. non-erosive disease). The development of oesophageal impedance monitoring now allows the assessment of all reflux events (regardless of degree of acidity) and further classification of reflux by the proximal extension e.g. to upper oesophagus or even pharynx. Chronic cough patients may still be considered to have GORD if there is a significant temporal association between reflux events and coughing. Recent studies have examined the relationships between cough and reflux events, the roles of distal and proximal/pharyngeal reflux and also micro-aspiration in chronic cough patients. Increasing evidence suggests a significant proportion of patients display statistical associations between reflux and cough events, in the absence of an excessive numbers of reflux events either within or outside of the oesophagus.

Modulation of sensory nerve function and the cough reflex: understanding disease pathogenesis

To cough is a protective defence mechanism that is vital to remove foreign material and secretions from the airways and which in the normal state serves its function appropriately. Modulation of the cough reflex pathway in disease can lead to inappropriate chronic coughing and an augmented cough response. Chronic cough is a symptom that can present in conjunction with a number of diseases including chronic obstructive pulmonary disease (COPD) and asthma, although often the cause of chronic cough may be unknown. As current treatments for cough have proved to exhibit little efficacy and are largely ineffective, there is a need to develop novel, efficacious and safe antitussive therapies. The underlying mechanisms of the cough reflex are complex and involve a network of events, which are not fully understood. It is accepted that the cough reflex is initiated following activation of airway sensory nerves. Therefore, in the hope of identifying novel antitussives, much research has focused on understanding the neural mechanisms of cough provocation. Experimentally this has been undertaken using chemical or mechanical tussive stimuli in conjunction with animal models of cough and clinical cough assessments. This review will discuss the neural mechanisms involved in the cough, changes that occur under pathophysiological conditions and and how current research may lead to novel therapeutic opportunities for the treatment of cough.