Idiopathic chronic cough and organ-specific autoimmune diseases: a case–control study

Gabapentin for chronic refractory cough: A system review and meta-analysis

Objective

To evaluate the efficacy and safety of gabapentin in the treatment of chronic refractory cough by Meta-Analysis.

Methods

Literatures were retrieved from PubMed, Embase (OvidIP), Cochrane Library, CNKI, VIP, Wanfang Database and China Biomedical Management System and eligible prospective studies were screened. Data were extracted and analyzed by using RevMan 5.4.1 software.

Results

Six articles (2 RCTs and 4 prospective studies) with 536 participants were finally included. Meta-analysis showed that gabapentin was better than placebo in cough-specific quality of life (LCQ score, MD = 4.02, 95%CI [3.26,4,78], Z = 10.34, P < 0.00001), cough severity (VAS score, MD = -29.36, 95% CI (-39.46, -19.26), Z = 5.7, P < 0.00001), cough frequency (MD = -29.87, 95% CI [- 43.84, -15.91], Z = 4.19, P < 0.0001) and therapeutic efficacy (RR = 1.37,95%CI [1.13,1.65], Z = 3.27, P = 0.001), and equal in safety (RR = 1.32,95%CI [0.47,3.7], Z = 0.53, P = 0.59). Gabapentin was similar to other neuromodulators in therapeutic efficacy (RR = 1.07,95%CI [0.87,1.32], Z = 0.64, P = 0.52), but its safety was better.

Conclusion

Gabapentin is effective in the treatment of chronic refractory cough in both subjective and objective evaluations, and its safety is better than other neuromodulators.

Application of unsupervised deep learning algorithms for identification of specific clusters of chronic cough patients from EMR data

BACKGROUND

Chronic cough affects approximately 10% of adults. The lack of ICD codes for chronic cough makes it challenging to apply supervised learning methods to predict the characteristics of chronic cough patients, thereby requiring the identification of chronic cough patients by other mechanisms. We developed a deep clustering algorithm with auto-encoder embedding (DCAE) to identify clusters of chronic cough patients based on data from a large cohort of 264,146 patients from the Electronic Medical Records (EMR) system. We constructed features using the diagnosis within the EMR, then built a clustering-oriented loss function directly on embedded features of the deep autoencoder to jointly perform feature refinement and cluster assignment. Lastly, we performed statistical analysis on the identified clusters to characterize the chronic cough patients compared to the non-chronic cough patients.

RESULTS

The experimental results show that the DCAE model generated three chronic cough clusters and one non-chronic cough patient cluster. We found various diagnoses, medications, and lab tests highly associated with chronic cough patients by comparing the chronic cough cluster with the non-chronic cough cluster. Comparison of chronic cough clusters demonstrated that certain combinations of medications and diagnoses characterize some chronic cough clusters.

CONCLUSIONS

To the best of our knowledge, this study is the first to test the potential of unsupervised deep learning methods for chronic cough investigation, which also shows a great advantage over existing algorithms for patient data clustering.

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.

An update and systematic review on drug therapies for the treatment of refractory chronic cough

INTRODUCTION

Chronic Cough (CC) is common and often associated with significant comorbidity and decreased quality of life. In up to 50% of cases, the cough is refractory despite extensive investigation and treatment trials. It is likely that the key abnormality in refractory CC is dysfunctional, hypersensitive sensory nerves, similar to conditions such as laryngeal hypersensitivity and neuropathic pain.

AREAS COVERED

The aim of this systematic review is to assess drug therapies for refractory CC. The authors review the current management of CC and provide discussion of the similarities between neuropathic pain and refractory CC. They review repurposed and new pharmacological treatments. Several meta-analyses were performed to compare the efficacy of treatments where possible.

EXPERT OPINION

Repurposed pain medications such as gabapentin and pregabalin reduce the frequency of cough and improve quality of life. Along with speech pathology, they are important and alternate treatments for refractory CC. However, more treatments are needed and the P2X3 ion channel receptor antagonists show the most promise. With a better understanding of neuronal activation and sensitisation and their signal processing in the brain, improved animal models of cough, and the use of validated cough measurement tools, more effective treatments will develop.

COPD and lung cancer in patients with pemphigus- a population based study

BACKGROUND

Recent evidence indicates that autoimmunity may contribute to the pathogenesis of chronic obstructive pulmonary disease (COPD). COPD was observed at higher frequency in patients with several autoimmune diseases. The association between pemphigus and COPD has not been evaluated in the past.

OBJECTIVES

To study the association between pemphigus and COPD using a large-scale real-life computerized database.

METHODS

A cross-sectional study was conducted comparing pemphigus patients with age-, sex- and ethnicity-matched control subjects regarding the prevalence of COPD and lung cancer. Chi-square and t-tests were used for bivariate analysis, and logistic regression model was used for multivariate analysis. The study was performed utilizing the computerized database of Clalit Health Services ensuring 4.4 million subjects.

RESULTS

A total of 1985 pemphigus patients and 9874 controls were included in the study. The prevalence of COPD was greater in patients with pemphigus as compared to the control group (13.4% vs. 10.1%, respectively; P < 0.001). In a multivariate analysis adjusting for smoking and other confounding factors, pemphigus was significantly associated with COPD (OR, 1.312-1. 5) but not with lung cancer. Study findings were robust to sensitivity analysis that included patients under pemphigus-specific treatments.

CONCLUSIONS

A significant association was found between COPD and pemphigus. Physicians treating patients with pemphigus might be aware of this possible association. This observation may further support the hypothesis that COPD has an autoimmune component.

Long-term prognosis of chronic cough: a prospective, observational cohort study

Background

The long-term prognosis of chronic cough and its determinants need to be clarified.

Methods

This is a prospective, observational cohort study. Eighty-nine unselected subjects with chronic (> 8 weeks’ duration) cough were carefully investigated: Clinical examination, symptom questionnaire, Leicester Cough Questionnaire (LCQ), skin prick tests, ambulatory peak expiratory flow monitoring, spirometry before and after 0.4 mgs of salbutamol, exhaled nitric oxide concentration measurement, hypertonic saline cough provocation test, and histamine bronchial provocation test. After five years, a letter was sent to the subjects containing questions about continuation of cough, smoking, indoor exposures, presence of co-morbidities, and current medication. It also contained LCQ and Cough Clinic diagnostic questionnaire. Sixty-eight subjects (76%) responded.

Results

At five years, continuing regular cough was present in 31 (46%) of the subjects and continuing impairment in cough-related quality of life (less than 1.3 points’ improvement in LCQ) in 32 (47%). Continuing regular cough was associated with presence of chronic rhinitis or esophageal reflux disease, baseline mild airway responsiveness to histamine, and baseline strong cough responsiveness to hypertonic saline. Continuing impairment in cough-related quality of life was associated with high body mass index, absence of atopy, absence of pets, and high number of background disorders (esophageal reflux disease, asthma, or chronic rhinitis).

Conclusions

Almost half of subjects with chronic cough suffered of the disorder at five years from initial assessment. Several possible determinants of poor prognosis could be identified.

Physiotherapy, and speech and language therapy intervention for patients with refractory chronic cough: a multicentre randomised control trial

BACKGROUND

Physiotherapy, and speech and language therapy are emerging non-pharmacological treatments for refractory chronic cough. We aimed to investigate the efficacy of a physiotherapy, and speech and language therapy intervention (PSALTI) to improve health-related quality of life (HRQoL) and to reduce cough frequency in patients with refractory chronic cough.

METHODS

In this multicentre randomised controlled trial, patients with refractory chronic cough were randomised to four weekly 1:1 sessions of either PSALTI consisting of education, laryngeal hygiene and hydration, cough suppression techniques, breathing exercises and psychoeducational counselling or control intervention consisting of healthy lifestyle advice. We assessed the change in HRQoL at week 4 with the Leicester Cough Questionnaire (LCQ). Secondary efficacy outcomes included 24-hour objective cough frequency (Leicester Cough Monitor) and cough reflex sensitivity. The primary analysis used an analysis of covariance adjusted for baseline measurements with the intention-to-treat population. This study was registered at UK Clinical Research Network (UKCRN ID 10678).

FINDINGS

Between December 2011 and April 2014, we randomly assigned 75 participants who underwent baseline assessment (34 PSALTI and 41 controls). In the observed case analysis, HRQoL (LCQ) improved on average by 1.53 (95% CI 0.21 to 2.85) points more in PSALTI group than with control (p=0.024). Cough frequency decreased by 41% (95% CI 36% to 95%) in PSALTI group relative to control (p=0.030). The improvements within the PSALTI group were sustained up to 3 months. There was no significant difference between groups in the concentration of capsaicin causing five or more coughs.

INTERPRETATION

Greater improvements in HRQoL and cough frequency were observed with PSALTI intervention. Our findings support the use of PSALTI for patients with refractory chronic cough.

TRIAL REGISTRATION NUMBER

UKCRN ID 10678 and ISRCTN 73039760; Results.

Nonpharmacological interventions for refractory chronic cough patients: systematic review

BACKGROUND

For people with refractory chronic cough, nonpharmacological interventions are emerging as alternatives to antitussive medications. These treatments generally are delivered by physiotherapists and speech and language therapists and consist of education, breathing exercises, cough suppression techniques, and counselling. Although the number of studies investigating these treatment options has increased in recent years there has not been a systematic review of the efficacy of these treatment options.

METHODS

Studies were searched for in EMBASE, AMED, Medline, CINAHL, and PsycINFO databases. Bibliographies of studies and reviews were searched by hand. Critical appraisal was carried out by one reviewer using the SIGN appraisal tools and Cochrane handbook for systematic reviews.

RESULTS

From a total of 184 studies, 5 full-text English language articles were included in the review. Nonpharmacological interventions were found to significantly reduce cough reflex sensitivity, improve quality of life, and lead to reductions in cough severity and frequency. However, few studies used validated and reliable tools to measure cough severity and frequency thereby limiting the robustness of these findings.

CONCLUSION

Present data support the use of two to four sessions of education, cough suppression techniques, breathing exercises, and counselling in order to achieve improvements in cough sensitivity and cough-related quality of life for people with chronic refractory cough. Due to the lack of validated outcome measures, results for other aspects of cough should be interpreted with caution. There is a need for additional larger-powered comparative studies investigating nonpharmacological interventions for refractory chronic cough.

Antitussive drugs--past, present, and future

Cough remains a serious unmet clinical problem, both as a symptom of a range of other conditions such as asthma, chronic obstructive pulmonary disease, gastroesophageal reflux, and as a problem in its own right in patients with chronic cough of unknown origin. This article reviews our current understanding of the pathogenesis of cough and the hypertussive state characterizing a number of diseases as well as reviewing the evidence for the different classes of antitussive drug currently in clinical use. For completeness, the review also discusses a number of major drug classes often clinically used to treat cough but that are not generally classified as antitussive drugs. We also reviewed a number of drug classes in various stages of development as antitussive drugs. Perhaps surprising for drugs used to treat such a common symptom, there is a paucity of well-controlled clinical studies documenting evidence for the use of many of the drug classes in use today, particularly those available over the counter. Nonetheless, there has been a considerable increase in our understanding of the cough reflex over the last decade that has led to a number of promising new targets for antitussive drugs being identified and thus giving some hope of new drugs being available in the not too distant future for the treatment of this often debilitating symptom.

Approach to the patient with presumed extraoesophageal GERD

Reflux related cough, asthma and laryngitis are frequently encountered and are considered part of extraoesophageal syndromes. The diagnosis of extraoesophageal reflux is difficult due to the lack of gold standard diagnostic criteria. Esophagogastroduodenoscopy and esophageal pH monitoring are inadequate diagnostic tools for due to poor sensitivity and specificity. For this reason, empirical PPI therapy is recommended as an initial approach to diagnose and treat the potential underlying cause of these symptoms in patients without alarm symptoms. Diagnostic testing with esophageal pH and/or impedance monitoring and esophageal motility testing is usually reserved for those who continue to be symptomatic despite a trial of therapy with PPIs. Recent developments have increased our understanding of this difficult to treat group of patients but more research into reflux related extraoesophageal symptoms are needed to better diagnose and treat this group.

Phenotyping airways disease: an A to E approach

The airway diseases asthma and chronic obstructive pulmonary disease (COPD) are heterogeneous conditions with overlapping pathophysiological and clinical features. It has previously been proposed that this heterogeneity may be characterized in terms of five relatively independent domains labelled from A to E, namely airway hyperresponsiveness (AHR), bronchitis, cough reflex hypersensitivity, damage to the airways and surrounding lung parenchyma, and extrapulmonary factors. Airway hyperresponsiveness occurs in both asthma and COPD, accounting for variable day to day symptoms, although the mechanisms most likely differ between the two conditions. Bronchitis, or airway inflammation, may be predominantly eosinophilic or neutrophilic, with different treatments required for each. Cough reflex hypersensitivity is thought to underlie the chronic dry cough out of proportion to other symptoms that can occur in association with airways disease. Structural changes associated with airway disease (damage) include bronchial wall thickening, airway smooth muscle hypertrophy, bronchiectasis and emphysema. Finally, a variety of extrapulmonary factors may impact upon airway disease, including rhinosinusitis, gastroesophageal reflux disease, obesity and dysfunctional breathing. This article discusses the A to E concept in detail and describes how this framework may be used to assess and treat patients with airway diseases in the clinic.

The long term outcome of patients with unexplained chronic cough

INTRODUCTION

Up to 40% of patients seen in a cough clinic have unexplained chronic cough. The long term outcome of these patients is uncertain.

OBJECTIVE

To determine the long-term outcome in patients diagnosed with unexplained chronic cough.

METHODS

We have performed a longitudinal study of symptoms, airway inflammation and spirometry in a cohort of patients with unexplained chronic cough diagnosed over 7 years ago. Cough was assessed using a 100 mm visual analogue scale (VAS). At the first and final visit cough reflex sensitivity was assessed as the concentration of inhaled capsaicin at which the volunteer coughed 2 (C2) and 5 times (C5).

RESULTS

We identified 42 patients (32 females) with unexplained chronic cough who had been assessed at least 7 years previously and agreed to a further assessment. The mean (SD) duration of cough was 11.5 (4.5) years at the time of their final assessment. Nine patients (21%) had organ specific autoimmune disease and twenty (48%) had a peripheral blood lymphopaenia. Six (14%) patients had complete resolution of symptoms and 11 (26%) had a significant >10 mm improvement in their cough VAS during follow up. Longitudinal spirometry data was available in 30 patients. The median rate of FEV(1) decline was 44 ml/year and four (13%) patients developed a post-bronchodilator forced expiratory volume in 1 s (FEV(1))/forced vital capacity of less than 0.7. FEV(1) decline was similar in patients with persistent cough and those whose cough improved. No other independent predictors of FEV(1) decline were identified. There were no independent predictors of improvement in cough.

CONCLUSIONS

Cough persists over time in the majority of patients with unexplained chronic cough. Patients have an increased rate of decline in FEV(1) and a significant minority develop fixed airflow obstruction.

Novel antitussive strategies

Acute and chronic cough represent one of the most common symptoms of medical importance but effective pharmacotherapy is, to all intents and purposes, absent. Numerous initiatives targeting the recently discovered tussive pathways are in progress. Here, we review the current antitussive armamentarium and provide an update on the novel strategies and compounds in development.

Chronic cough as a complication of treatment with statins: a case report

Statins are widely used for primary and secondary prevention of cardiovascular disease. For this reason, knowledge of the side effects and interactions pertaining to this class of pharmaceuticals is of utmost importance to all physicians. In this text a case report is presented of an eighty year old gentleman, referred to the respiratory clinic at Mater Dei Hospital Malta after developing dry cough on being treated with simvastatin and fluvastatin. An attempt at switching over to a placebo was made with resolution of symptoms. This is the second described case in the literature of lone cough associated with statin therapy necessitating treatment discontinuation in our patient. Possible hypothesis are discussed as well as suggestions for further research to unravel the underlying mechanisms of this association.

Chronic cough and OSA: a new association?

Chronic cough is defined as cough lasting more than 2 months. Common causes for chronic cough in nonsmokers with normal chest radiographs and pulmonary functions include gastroesophageal reflux disease (GERD), cough-variant asthma (CVA), and upper airway cough syndrome (UACS). Current guidelines recommend diagnosing the etiology of chronic cough based upon the results of therapy for suspected GERD, CVA, and UACS. Despite following current recommendations for diagnosis and treatment, the cause for a significant proportion of chronic cough remains unexplained.Recent reports indicate the resolution of chronic cough following treatment of concomitantly diagnosed obstructive sleep apnea (OSA). Whether this represents a co-occurrence of two commonly prevalent disorders or a pathophysiologic relationship between OSA and cough remains unknown. This review offers insights into a pathophysiologic link between OSA and the commonly purported etiologies for cough, namely, GERD, UACS, and CVA. In addition, evidence for a relationship between airway inflammation that can trigger or perpetuate cough and OSA is discussed. This review explores mechanisms by which nocturnal continuous positive airway therapy resolves cough by improving underlying airway inflammation secondary to OSA and impacts upon GERD, CVA, and UACS.

Cough: an unmet clinical need

Cough is among the most common complaints for which patients worldwide seek medical attention. Thus, the evaluation and treatment of cough result in tremendous financial expenditure and consumption of health care resources. Yet, despite the clinical significance of cough, research efforts aimed at improving diagnostic capabilities and developing more effective therapeutic agents have been, to date, disappointing in their limited scope and outcomes. Acute cough due to the common cold represents the most common type of cough. Currently, available medications for the symptomatic management of acute cough are inadequate due to lack of proven efficacy and/or their association with undesirable or intolerable side effects at anti-tussive doses. Subacute cough, often representing a prolonged post-viral response, is typically refractory to standard anti-tussive therapy. Few clinical trials have evaluated therapeutic options for subacute cough. Diagnostic challenges facing the clinician in the management of chronic cough include the determination of whether symptoms of upper airway cough syndrome (formerly, postnasal drip syndrome) or gastro-oesophageal reflux disease are indeed the underlying cause of cough. Chronic, refractory unexplained (formerly, idiopathic) cough must be distinguished from cough that has not been fully evaluated and treated according to current guideline recommendations. Eagerly awaited are new safe and effective anti-tussive agents for use when cough suppression is desired, regardless of underlying aetiology of cough, as well as practical, validated ambulatory cough counters to aid clinical assessment and future research in the field of cough.

New concepts in the management of chronic cough

There has been significant progress in the field of cough in the past 10 years. Obstructive sleep apnoea, tonsillar enlargement and environmental fungi have recently been described as causes of chronic cough. The advances in the assessment of gastro-oesophageal reflux (GOR) have led to a greater understanding of the relationship between cough and GOR and are likely to change the approach to managing patients with GOR-cough. The investigation of the phenotype of patients with idiopathic chronic cough has provided novel insights. Patients with an idiopathic chronic are predominantly female, have an onset of cough around the menopause and have a high prevalence of organ specific autoimmune disease, particularly hypothyroidism. The presence of bronchoalveolar lymphocytosis suggests there is homing of inflammatory cells from primary sites of autoimmune inflammation to the lungs. A heightened cough reflex is a key feature of most patients with chronic cough and has led some investigators to suggest that chronic cough be recognised as a unique entity called Cough Hypersensitivity Syndrome (CHS). A number of subjective and objective tools have been developed recently to assess cough severity. Antitussive drug development is an emerging and exciting area of cough research.

Controversies in the evaluation and management of chronic cough

Chronic cough that cannot be explained after basic evaluation is a common reason for patients to be referred to respiratory outpatient clinics. Asthma, gastroesophageal reflux, and upper airway disorders frequently coexist with chronic cough. There is some controversy as to whether these conditions are causes or aggravants of cough. Heightened cough reflex sensitivity is an important feature in most patients. There is good evidence that it is reversible when associated with upper respiratory tract infection, angiotensin-converting enzyme inhibitor medications, and chronic cough associated with eosinophilic airway inflammation. In many patients, heightened cough reflex sensitivity is persistent and their cough is unexplained. There are few therapeutic options for patients with unexplained chronic cough. There is a pressing need to understand the genetic, molecular, and physiological basis of unexplained chronic cough and to develop novel antitussive drugs that down-regulate cough reflex sensitivity.

New insights in cough

Chronic cough is common, blights patients' lives and is hard to treat. Chronic cough patients demonstrate high objective cough rates and as a group have increased cough reflex sensitivity. However, conventional cough challenge techniques show substantial overlap with normal subjects. This suggests that other important mechanisms have yet to be determined. For the last two decades, chronic cough has been considered to be caused by gastro-oesophageal reflux, post-nasal drip or asthma. However, many patients with these conditions do not have cough, and in those with cough, the response to specific treatments is unpredictable at best. In addition, many chronic cough patients do not have an identifiable cause. This raises questions about the concept of a triad of treatable causes for chronic cough. Our current understanding of the neurophysiology of the cough reflex is largely derived from animal work with limited data in humans. By analogy with chronic pain syndromes, both peripheral and central sensitization may be important mechanisms in chronic cough, and are under active investigation. We need to understand the mechanisms underlying sensitization, how they interact with cough triggers and their relationship with the sensations that drive the urge to cough, and the subsequent motor cough response in chronic cough. Only then will we develop effective interventions.

Unexplained cough in the adult

Unexplained cough is a diagnosis of exclusion that should not be made until a thorough validated diagnostic evaluation is performed, specific and appropriate validated treatments have been tried and failed, and uncommon causes have been ruled out. When chronic cough remains troublesome after the initial work up, determine that a protocol has been used that has been shown to lead to successful results. If such a protocol has been used, next consider whether or not pitfalls in management have been avoided. If they have been, the frequency of truly unexplained chronic cough usually should not exceed 10%. While patients with truly unexplained coughs have an overly sensitive cough reflex, the mere presence of an overly sensitive cough reflex does not by itself explain why they do not get better, because most patients with chronic cough, even those who respond to treatment and get better, have demonstrable heightened cough sensitivity. Management options include referral to a cough clinic with interdisciplinary expertise, speech therapy, and self-limited trials of drugs, preferentially with those shown to be effective in randomized, double-blind placebo-controlled trials in patients with unexplained chronic cough.

Clinical cough II: therapeutic treatments and management of chronic cough

Chronic cough is a common and frequently disruptive symptom which can be difficult to treat with currently available medicines. Asthma/eosinophilic airway disease and gastro-oesophageal reflux disease are most commonly associated with chronic cough but it may also trouble patients with chronic obstructive pulmonary disease, pulmonary fibrosis and lung cancer. Over the last three decades there have been a number of key advances in the clinical approach to cough and a number of international guidelines on the management of cough have been developed. Despite the undoubted benefit of such initiatives, more effective treatments for cough are urgently needed. The precise pathophysiological mechanisms of chronic cough are unknown but central to the process is sensitization (upregulation) of the cough reflex. One well-recognized clinical consequence of this hypersensitive state is bouts of coughing triggered by apparently trivial provocation such as scents and odours and changes in air temperature. The main objective of new treatments for cough would be to identify ways to downregulate this heightened cough reflex but yet preserve its crucial role in protecting the airway. The combined efforts of clinicians, scientists and the pharmaceutical industry offer most hope for such a treatment breakthrough. The aim of this chapter is to provide some rationale for the current treatment recommendations and to offer some reflections on the management of patients with chronic cough.

Developing antitussives: the ideal clinical trial

Antitussive drugs are amongst the most widely used medications worldwide; however no new class of drugs have been introduced into the market for many years. Trials showing patient benefit are scarce and have been hampered by the lack of objective and validated outcome measures. Recent improvements in the assessment of cough will facilitate better trials and aid the development of antitussive drugs. When conducting a trial, patient selection is of paramount importance. Patients with unexplained chronic cough and sub-acute cough following upper respiratory tract infection are ideal because they represent an unmet clinical need and an untapped market for pharmaceutical companies. Patients with asthma and chronic obstructive pulmonary disease are less suitable since cough suppression is not always desirable and the findings of trials may not be generalisable to all patients with cough. Randomized, placebo-controlled, double-blind clinical trials are obviously the gold standard. The choice of placebo, whether inert or active, depends on the incidence and severity of drug side-effects. The primary outcome measure should be objective and cough monitors are the ideal tool. Subjective outcome measures should be used to assess symptoms and health related quality of life. Properly conducted clinical trials are an opportunity to evaluate the benefits of currently available therapies and aid advances in the antitussive drug market.

Extrathoracic airway hyperresponsiveness as a mechanism of post infectious cough: case report

Post-infectious cough is a common diagnosis in people with chronic cough. However, the specific infectious aetiology and cough mechanisms are seldom identified.We report a case of chronic cough after Mycoplasma pneumoniae lower respiratory tract infection with extrathoracic airway hyperresponsiveness as the cough mechanism. Extrathoracic airway hyperresponsiveness may be a common mechanism in post-infectious cough which may be useful both diagnostically and therapeutically since chronic cough with extrathoracic airway hyperresponsiveness responds to speech pathology treatment.

Management of chronic cough

Cough that remains unexplained after basic clinical assessment is a common reason for referral to secondary care. Much of the evidence about management of isolated chronic cough is derived from case series; this evidence suggests that isolated chronic cough is usually due to asthma, gastro-oesophageal reflux disease, and upper airway conditions, and that it can be cured in most people by treatment of these conditions. However, there is increasing recognition that satisfactory control of chronic cough is not achieved in a substantial number of patients seen in secondary care. Moreover, there is a concern that perpetuation of the belief that chronic cough is solely due to the effects of comorbid conditions is inhibiting research into the pathophysiology of an abnormally heightened cough reflex, and jeopardising development of improved treatments. We advocate a change in emphasis, which makes a clear distinction between cough due to corticosteroid-responsive eosinophilic airway diseases and corticosteroid-resistant non-eosinophilic cough. We recommend that some factors with weak evidence of an association with cough are best viewed as potential aggravating factors of an intrinsic abnormality of the cough reflex, rather than the cause. We call for more research into the basic mechanisms and pharmacological control of an abnormally heightened cough reflex, and recommend ways to assess the effects of potentially antitussive treatments.

Does idiopathic cough exist?

Despite a meticulous protocol involving diagnostic testing and trials of empirical therapy, there may be no obvious cause for a chronic cough in up to 42% of cases referred for specialist evaluation. In some cases, failure to consider causes that include the asthma/eosinophilic airway syndromes such as eosinophilic bronchitis and atopic cough, or nonacid gastroesophageal reflux disease may explain diagnostic failure. However, a distinct group of patients may be considered to have true idiopathic cough. Current published evidence suggests a certain patient phenotype, namely, middle-aged females with prolonged nonproductive cough and cough reflex hypersensitivity. Almost nothing else is known about this clinical entity and currently no specific therapy exists.

Quality of life and psychosocial aspects of cough

Chronic cough is a common condition that causes considerable physical and psychological morbidity. The physical symptoms of cough are readily apparent; however, the psychosocial symptoms are often overlooked. Appreciation of the impact of cough on health-related quality of life has led to the development of three validated, cough-specific, health-related quality-of-life questionnaires that assess cough severity: Leicester Cough Questionnaire (LCQ), Cough-specific Quality of Life Questionnaire (CQLQ), and Chronic Cough Impact Questionnaire (CCIQ). These tools capture additional information not measured with objective tools and can be used to assess therapy. They should be used in conjunction with other cough severity measures such as cough frequency monitors to obtain a more complete assessment of cough severity. Recent cough guidelines endorse the measurement of cough-specific quality of life and these questionnaires are ideal tools to facilitate this.

Acute and chronic cough

Cough is a normal protective mechanism which occurs many times every day. Cough with a viral infection lasts up to 2 weeks in 70-80% of children. Cough present for more than 4 weeks may be due to a recognized specific cause or non specific and considered protracted bronchitis. Chronic cough in children is different to that in adults and rarely due to GE reflux, postnasal drip or asthma. Treatment addresses the specific cause and symptomatic treatment is rarely needed or effective.

Changes in pulmonary function in patients with ulcerative colitis

OBJECTIVES

Information on the occurrence and frequency of pulmonary involvement in patients with ulcerative colitis (UC) is inconsistent. Some authors reported pulmonary impairment with UC by standard pulmonary function tests (PFTs) and documented a reduced diffusing capacity for carbon monoxide (DLCO) especially in patients with active disease, whereas others could not detect differences in routine PFTs between UC patients and controls.

AIM

The aim of this prospective study was to determine the frequency and type of pulmonary dysfunction in patients with UC with respect to disease activity. Furthermore, to evaluate the influence of smoking, nutritional status, sputum cytology and sulphasalazine therapy on PFT parameters.

PATIENTS AND METHODS

Twenty-six patients with UC (20 with active disease, 6 inactive) and 16 age and sex matched healthy controls were investigated with respect to the following pulmonary function tests, forced vital capacity (FVC), forced expiratory volume in the 1s (FEV(1)%) and their ratio (FEV(1)/FVC) and forced expiratory flow 25-75% (FEF25-75%) as well as oxygen saturation. For UC patients, colonoscopy and biopsy were done. Disease activity was assessed by Truelove index for UC. Induced sputum was sampled for cytology. Smoking habit, body mass index (BMI) and medications were recorded.

RESULTS

Fifteen out of 26 patients with UC (57.6%) exhibited at least one pathological pulmonary function test (<80% of predicted value). Small airway obstruction was reported in the 15 patients, restrictive dysfunction in 30.7% and obstructive dysfunction in 11.5%. The impairment of PFTs was significant and more pronounced in patients with active disease, FVC (-14% of predicted), FEV(1) (-9% of predicted) and FEF25-75% (-32% of predicted), P<0.01, 0.05 and 0.01, respectively. There was no significant influence of smoking and medications on PFTs.

CONCLUSIONS

UC patients show significantly decreased lung function tests in comparison to healthy controls. The impairment in active disease exceeded that during the remission. Early recognition is important, as they can be strikingly steroid responsive.

A bronchoscopic scoring system for airway secretions--airway cellularity and microbiological validation

There is currently no validated scoring system for quantification of airway secretions in children. A user friendly, valid scoring system of airway secretions during flexible bronchoscopy (FB) would be useful for comparative purposes in clinical medicine and research. The objective of this study was to validate our bronchoscopic secretion (BS) scoring system by examining the relationship between the amount of secretions seen at bronchoscopy with airway cellularity and microbiology. In 106 children undergoing FB, the relationship of BS grades with bronchocalveolar lavage (BAL) cellularity and infective state (bacterial and viral infections) were examined using receptor operator curves (ROC). BAL was obtained according to European Respiratory Society guidelines; first lavage for microbiology and second lavage for cellularity. Area under the ROC was significant for total cell count (TCC) and neutrophil % but not for lymphocyte %. BS grade significantly related to infection positive state (chi(trend) (2) = 5.85, P = 0.016). The area under the ROC for infection positive state versus BS grade was 0.645, 95% CI 0.527-0.763. The BS scoring system is a valid method for quantifying airway secretions in children undergoing bronchoscopy. The system related well to airway cellularity and neutrophilia, as well as to an airway infective state. However, the system is only complementary to cell counts and cultures and cannot replace these laboratory quantification techniques.

Uncommon causes of cough: ACCP evidence-based clinical practice guidelines

OBJECTIVES

To describe the uncommon causes of cough.

DESIGN/METHODOLOGY

An English language literature search by MEDLINE citations from 1975 through 2004 was used to identify publications on uncommon pulmonary and nonpulmonary disorders in which cough was present as the major or presenting symptom in >50% of those persons affected by the uncommon diseases.

RESULTS

A substantial number of uncommon or rare pulmonary and nonpulmonary disorders were identified. The uncommon occurrence of these diseases made it difficult to develop a meaningful evidence-based guideline to the diagnosis and therapy of many of the uncommon causes of cough. As cough was the major or presenting symptom, it was usually initially attributed to common respiratory diseases (eg, asthma or bronchitis). As a result, a substantial time lag existed from the onset of cough to the diagnosis of the etiologic entity. Diagnostic tests limited to the respiratory system did not always provide clues to the diagnosis of uncommon causes of cough.

CONCLUSIONS

Cough is the major or presenting symptom in many uncommon pulmonary and nonpulmonary disorders. A strong index of suspicion is essential to consider and diagnose the uncommon causes of cough. The diagnosis and management of cough in patients with uncommon causes of cough is dependent on the underlying etiology.

Unexplained (Idiopathic) Cough

OBJECTIVE

To review the literature on unexplained cough, previously referred to as idiopathic cough.

METHODS

Search of MEDLINE (through May 2004) for studies published in the English language since 1980 on human subjects using the medical subject heading terms "cough," "unexplained cough," and "idiopathic cough." We selected case series and prospective descriptive clinical trials. We also obtained any references from these studies that were pertinent to the topic.

RESULTS

The diagnosis of unexplained (idiopathic) cough should only be considered after a thorough diagnostic and treatment approach for the most common causes of cough has been completed and uncommon causes have been adequately evaluated Unless this is done, it is likely that many patients with a definable cause of cough will be misdiagnosed as having "unexplained cough."

CONCLUSION

The diagnosis of unexplained cough is probably made too often based on an inadequate diagnostic workup or treatment course to determine the specific cause of cough. Nevertheless, there may be a group of patients in whom none of the usual explanations for cough may be present. For this group, the committee unanimously recommends using the diagnostic term unexplained cough, rather than idiopathic cough.

Idiopathic chronic cough: a real disease or a failure of diagnosis?

Despite extensive diagnostic evaluation and numerous treatment trials, a number of patients remain troubled by a chronic and uncontrollable cough. Eosinophilic bronchitis, atopic cough and non-acid reflux have been recently added to the diagnostic spectrum for chronic cough. In some cases, failure to consider these conditions may explain treatment failure. However, a subset of patients with persisting symptoms may be regarded as having an idiopathic cough. These individuals are most commonly female, of postmenopausal age and frequently report viral upper respiratory tract infections as an initiating event. This paper seeks to explore the validity of idiopathic cough as a distinct clinical entity.

Airway function and markers of airway inflammation in patients with treated hypothyroidism

BACKGROUND

There is increasing evidence of an association between organ specific autoimmune diseases, particularly autoimmune thyroid disease and respiratory morbidity. A study was undertaken to determine whether patients with autoimmune thyroid disease have objective evidence of airway inflammation and dysfunction.

METHODS

Twenty six non-smoking women with treated hypothyroidism and 19 non-smoking controls completed a symptom questionnaire and underwent full lung function tests, capsaicin cough reflex sensitivity measurement, methacholine challenge test, and sputum induction over two visits.

RESULTS

Symptoms of cough (p = 0.01), dyspnoea (p = 0.01), sputum production (p = 0.004), and wheeze (p = 0.04) were reported more commonly in patients than controls. Patients with hypothyroidism had heightened cough reflex sensitivity compared with controls (geometric mean concentration of capsaicin causing five coughs: 40 v 108 mmol/l; mean difference 1.4 doubling doses; 95% confidence interval of difference 0.4 to 2.5; p = 0.008) and a significantly higher proportion of patients had airway hyperresponsiveness (methacholine provocative concentration (PC(20)) <8 mg/ml: 38% v 0%; p = 0.016). Patients with hypothyroidism also had a significantly higher induced sputum total neutrophil cell count (p = 0.01), total lymphocyte count (p = 0.02), and sputum supernatant interleukin-8 concentrations (p = 0.048).

CONCLUSION

Patients with treated hypothyroidism report more respiratory symptoms and have objective evidence of airway dysfunction and inflammation.

Idiopathic cough, prevalence and underlying mechanisms

A number of authors have reported a significant percentage of patients whose cause of cough remains undetermined despite a systematic evaluation as recommended in a number of International Guidelines. This subset of patients, which may be regarded as having an idiopathic cough, are often female and of peri or postmenopausal age. Sex hormones may influence the cough reflex in disease or contribute to the chronic lymphocytic airway inflammation seen in some cases and to the association with organ specific autoimmune disease reported. This paper seeks to investigate some of the possible causes of idiopathic cough.