Chronic cough from the patient's perspective

A real world study of cough burden and quality of life of UK patients who have undergone evaluation for chronic cough

OBJECTIVE

Treatment options for adults with chronic cough (CC) are limited. This study reports on the health status and experiences of patients with recent healthcare evaluation for CC.

METHODS

This prospective, UK, cross-sectional study surveyed adults with a CC evaluation within the previous 12 months. All were never smokers (or ex-smokers for ≥12 months). Subjects completed five validated patient-reported outcome measures: cough visual analogue scale (VAS), EuroQoL 5 dimension, 5 level (EQ-5D-5L), EQ-5D VAS, Leicester Cough Questionnaire (LCQ), and Work Productivity and Activity Impairment (WPAI) questionnaire.

RESULTS

A total of 101 participants were recruited: 71% were female, mean age was 54.9 ± 15.2 years. Median (IQR) CC duration was 36 (11, 120) months. Mean self-reported CC severity (Cough-VAS) was 51.3 ± 22.9 over the previous 2 weeks and 62.9 ± 23.7 on the worst day of coughing. EQ-5D values were lower for CC patients than population norms. Subanalyses revealed that EQ-5D and LCQ scores were significantly impacted by CC duration and the number of healthcare providers (HCPs) visited. WPAI analysis showed a 27.6% work time impairment because of participants' CC. The number of HCP attendances ranged from 1 to 10 (3.3 ± 2.8) before diagnosis was confirmed. Treatment was being prescribed to 87% of participants and comprised mainly steroids (nasal [19%] and inhaled [25%]), beta agonists (24%), and proton pump inhibitors (21%); 44% of patients were dissatisfied with treatment efficacy.

CONCLUSION

Real-world data from a nationally representative UK population show significant unmet needs associated with CC, including multiple healthcare visits and limited treatment effectiveness, resulting in inadequate cough control and impaired health status.

Superior Laryngeal Nerve Block Response Rates in 54 Neurogenic Cough Patients

OBJECTIVE

Neurogenic cough related to hypersensitivity of the internal branch of the superior laryngeal nerve (SLN) is often treated with neuromodulating medications, which can cause considerable side effects. An alternative therapy is steroid and local anesthetic injection of the SLN ("SLN block"), initially proposed to benefit those with lateralizing symptoms (tenderness over the thyrohyoid membrane or unilateral cough source). Our objectives are to determine if SLN block produces subjective symptomatic improvements and if repeat injections further improve symptoms, and evaluate clinical factors potentially predictive of response.

METHODS

Retrospective chart review of 54 patients receiving SLN blocks at a tertiary medical academic center from January 2010 to June 2020. Medical history and anticipated predictors of positive response, including stigmata of laryngeal hypersensitivity, were recorded. Outcomes included symptomatic response, number of injections required, and side effects. Response was defined subjectively by asking patients whether the injection was beneficial and objectively by using CSI scores.

RESULTS

Fifty-four patients met the inclusion criteria. Thirty-eight patients (70.4%) endorsed improvement. No variables were identified as positive predictors of response. Thirty-two of the 38 (84.2%) endorsed improvement after one injection. Six of 15 (40%) patients who failed the first injection had positive response to the second. No significant side effects were reported.

CONCLUSION

No localizing symptoms, specific cough features, or aspects of the medical history helped predict response, suggesting that a broader range of patients may be offered the intervention. The majority of patients reported symptomatic improvement and repeat injections may benefit patients with initial nonresponse.

LEVEL OF EVIDENCE

4 Laryngoscope, 133:2647-2653, 2023.

Burden of refractory and unexplained chronic cough on patients' lives: a cohort study

Background

Chronic cough (cough lasting for ≥8 weeks) can lead to significant impairment in quality of life (QoL). Using patient-reported outcomes, this cohort study assessed the perceived impact of chronic cough on QoL and everyday life in patients from outpatient hospital clinics with refractory chronic cough (RCC) or unexplained chronic cough (UCC).

Methods

This was a multicentre, non-interventional survey study. Cough severity was assessed on a 0-100 mm Visual Analogue Scale (VAS). Frequency, intensity and disruptiveness of cough were assessed using an adaptation of the Cough Severity Diary. The impact of cough on QoL was assessed using the Leicester Cough Questionnaire (LCQ). The physical impact of cough and associated impact on everyday life activities were explored using purpose-designed questions.

Results

191 patients responded to the survey; 121 (63.4%) had RCC and 149 were women (78.0%). Mean score on the cough severity VAS was 62.9 mm. Mean LCQ total score of 11.9 indicated reduced QoL. Cough impaired patients' everyday life, including the inability to speak fluently (58.0% of patients) and feeling tired/drained (46.6%). Women perceived poorer chronic cough-related QoL than men, as reflected by lower LCQ scores, and greater impairment of physical health, including cough-related stress urinary incontinence, and psychological health.

Conclusions

Patients with RCC/UCC experience a significant burden in their everyday life, including impaired QoL, and perceive a negative impact on physical and psychological health and everyday activities, affecting work, relationships and leisure activities. The impact appears to be greater in women than men for several of the aspects studied.

The disease burden and quality of life of chronic cough patients in South Korea and Taiwan

Background

Chronic cough (CC) is a common condition, but the burden of CC in general populations remains largely unknown. This study aims to investigate the disease prevalence and burden among community-based CC patients in South Korea and Taiwan, using structured tools.

Methods

A population-based cross-sectional study uses data from the 2020 South Korea and Taiwan National Health and Wellness Survey (NHWS) as well as a CC survey conducted between January–February 2020 and March–April 2020, respectively. Health outcome measures included health-related quality of life (HRQoL), health state utilities, work productivity and activity impairment (WPAI), and measurement of depression, anxiety, and insomnia among CC patients.

Results

The weighted lifetime and 12-month prevalence of CC was 6.20% and 4.34% in South Korea, and 8.27% and 5.55% in Taiwan. Compared to matched non-CC controls, CC patients reported poorer HRQoL (SF-12v2) in terms of physical component summary (PCS) score (South Korea: 47.69 ± 7.68 vs. 50.08 ± 7.29; Taiwan: 48.58 ± 7.15 vs. 50.50 ± 7.30) and mental component summary (MCS) score (44.15 ± 8.85 vs. 46.28 ± 8.50; 42.44 ± 7.78 vs. 44.60 ± 8.08), health state utilities EQ-5D index (0.73 ± 0.23 vs. 0.82 ± 0.16; 0.82 ± 0.13 vs. 0.86 ± 0.14), and more visits to healthcare professionals (7.80 vs. 4.61; 6.09 vs. 4.20) (p < 0.05). In terms of WPAI, CC patients reported higher impairments in presenteeism (32.8% vs. 21.0%; 25.9% vs. 19.4%), total work productivity (36.2% vs. 22.3%; 27.7% vs. 20.6%), and total activity (34.2% vs. 23.2%; 27.7% vs. 20.3%) than non-CC controls (p < 0.001). CC patients in South Korea and Taiwan experienced anxiety, depression, and insomnia more than non-CC controls. Poorer health outcomes were associated with the severity of CC. Patients with severe CC (visual analogue scale [VAS]>4) in both nations reported lower PCS score (45.80 vs. 49.48; 47.41 vs. 49.22) and higher absenteeism (8.5% vs. 3.6%; 5.5% vs. 1.8%) than patients with mild CC (VAS≤4) (p < 0.05).

Conclusions

The findings revealed that the disease burden of CC in general populations of South Korea and Taiwan is considerable with a negative impact on the overall quality of life, social and work life, and psychological comorbidities and is significantly associated with increased severity of the CC. There is an unmet need for further treatment interventions for CC patients to relieve the burden of CC in both nations.

Chronic cough: new insights and future prospects

Chronic cough is defined in adults as a cough that lasts for ≥8 weeks. When it proves intractable to standard-of-care treatment, it can be referred to as refractory chronic cough (RCC). Chronic cough is now understood to be a condition of neural dysregulation. Chronic cough and RCC result in a serious, often unrecognized, disease burden, which forms the focus of the current review.

The estimated global prevalence of chronic cough is 2–18%. Patients with chronic cough and RCC report many physical and psychological effects, which impair their quality of life. Chronic cough also has a significant economic burden for the patient and healthcare systems. RCC diagnosis and treatment are often delayed for many years as potential treatable triggers must be excluded first and a stepwise empirical therapeutic regimen is recommended.

Evidence supporting most currently recommended treatments is limited. Many treatments do not address the underlying pathology, are used off-label, have limited efficacy and produce significant side-effects. There is therefore a significant unmet need for alternative therapies for RCC that target the underlying disease mechanisms. Early clinical data suggest that antagonists of the purinergic P2X3 receptor, an important mediator of RCC, are promising, though more evidence is needed.

Chronic cough exerts a considerable burden on patients and healthcare systems. In addition to effective targeted therapies, further data are needed to understand the pathophysiology, epidemiology and disease burden.https://bit.ly/3Be9JZI

Cough symptom severity in patients with refractory or unexplained chronic cough: a systematic survey and conceptual framework

BACKGROUND

Cough severity represents an important subjective endpoint in assessing the effectiveness of therapies for patients with chronic cough. Although cough-specific quality of life questionnaires exist, a widely available cough severity instrument with established measurement properties remains unavailable.

AIMS

To identify and summarise the results of studies reporting on the experience of patients with chronic cough and, in the process, develop a conceptual framework to inform development of a patient-reported outcome measurement (PROM) addressing cough severity.

RESULTS

We identified 61 eligible studies reporting on patient experience with chronic cough. Studies provided 82 potential items, of which 43 proved unique and relevant to cough severity. The urge-to-cough sensation and the cough symptom itself represented broad domains of cough severity. Two subdomains under urge-to-cough included frequency (1 item) and intensity (1 item). Five subdomains under cough symptoms included control (2 items), frequency (6 items), bout duration (1 item), intensity (8 items), and associated features/sequelae (24 items).

CONCLUSIONS

Our systematic survey and conceptual framework identified items and domains of cough severity in patients with refractory or unexplained chronic cough. The results support item generation and content validity for a PROM assessing cough severity.

A novel automatic cough frequency monitoring system combining a triaxial accelerometer and a stretchable strain sensor

Objective evaluations of cough frequency are considered important for assessing the clinical state of patients with respiratory diseases. However, cough monitors with audio recordings are rarely used in clinical settings. Issues regarding privacy and background noise with audio recordings are barriers to the wide use of these monitors; to solve these problems, we developed a novel automatic cough frequency monitoring system combining a triaxial accelerator and a stretchable strain sensor. Eleven healthy adult volunteers and 10 adult patients with cough were enrolled. The participants wore two devices for 30 min for the cough measurements. An accelerator was attached to the epigastric region, and a stretchable strain sensor was worn around their neck. When the subjects coughed, these devices displayed specific waveforms. The data from all the participants were categorized into a training dataset and a test dataset. Using a variational autoencoder, a machine learning algorithm with deep learning, the components of the test dataset were automatically judged as being a “cough unit” or “non-cough unit”. The sensitivity and specificity in detecting coughs were 92% and 96%, respectively. Our cough monitoring system has the potential to be widely used in clinical settings without any concerns regarding privacy or background noise.

Characterization of Patients With Refractory or Unexplained Chronic Cough Participating in a Phase 2 Clinical Trial of the P2X3-Receptor Antagonist Gefapixant

Purpose

This analysis assesses clinical characteristics of patients with refractory chronic cough (RCC) or unexplained chronic cough (UCC) enrolled in a phase 2 study to better understand this patient population.

Methods

Patients with RCC/UCC lasting for ≥ 1 year and cough severity visual analog scale (VAS) score of > 40 mm at screening were eligible. Demographics, clinical characteristics, and medical history were collected at baseline. Cough-related measures included cough severity VAS, Cough Severity Diary (CSD), Leicester Cough Questionnaire (LCQ), and a structured cough-trigger questionnaire. Medication history included all medications 30 days before screening and chronic cough treatments within 1 year before screening. Data were summarized using descriptive statistics.

Results

Patients (N = 253; female, 76%; mean age, 60 years) had severe (mean cough severity VAS, 57.5 mm) and long-lasting (median duration, 11 years) cough. The most burdensome self-reported aspects included psychological and social factors (LCQ) and cough frequency and intensity (CSD). Patient-reported triggers were consistent with cough hypersensitivity (e.g., 95% to 96% reported irritation or tickle in throat). Common reported comorbidities included gastroesophageal reflux disease (GERD; 56%), allergic rhinitis (47%), and asthma (30%); 12% of patients had been diagnosed with all 3 conditions. The most common prior medications included inhaled or oral steroids (21%), antihistamines (15%), and antacids (15%).

Conclusion

Patients with RCC/UCC had severe, long-lasting, and burdensome cough with clinical features of cough hypersensitivity. Many patients had been diagnosed with GERD, allergic rhinitis, and asthma but had a persistent cough despite treatment of these conditions.

Trial registration: ClinicalTrials.gov, NCT02612610; registered November 20, 2015

Mechanisms and Rationale for Targeted Therapies in Refractory and Unexplained Chronic Cough

Chronic cough, defined as a cough lasting > 8 weeks, is a common medical condition that exerts a substantial physical, mental, and social burden on patients. A subset of patients with chronic cough are troubled with a cough that persists despite optimal treatment of presumed associated common and uncommon conditions (refractory chronic cough; RCC) or in which no diagnosable cause for cough can be identified despite extensive assessment (unexplained chronic cough; UCC). Many of these patients exhibit clinical features of cough hypersensitivity, including laryngeal paresthesia, hypertussia, and allotussia. Over-the-counter cough remedies are ineffective and can lead to intolerable side effects when used for RCC/UCC, and the lack of approved treatments indicated for these conditions reflects a major unmet need. An increased understanding of the anatomy and neurophysiology of protective and pathologic cough has fostered a robust clinical development pipeline of several targeted therapies for RCC/UCC. This manuscript reviews the mechanisms presumed to underly RCC/UCC together with the rationale and clinical evidence for several targeted therapies currently under clinical investigation, including transient receptor potential channel antagonists, P2X3-receptor antagonists, voltage-gated sodium channel blockers, neuromodulators, and neurokinin-1-receptor antagonists. Finally, we provide an overview of targets that have been investigated in preclinical models of cough and other airway diseases that may hold future promise for clinical studies in RCC/UCC. Development of targeted therapies with different sites of action may foster a precision medicine approach to treat this heterogeneous, underserved patient population.

Quantitative measurement properties and score interpretation of the Cough Severity Diary in patients with chronic cough

AIMS

The Cough Severity Diary (CSD) was developed in accordance with the FDA guidance for patient-reported outcome measures and is focused on capturing the patient's perception of cough in terms of frequency, intensity, and disruption due to their cough. The measure includes a series of seven items asking patients to rate the frequency (three items), intensity (two items), and disruptiveness (two items) of their cough. The instrument was designed to be completed daily before bedtime, has a recall period of 'today,' and responses to items are entered on an 11-point numeric rating scale ranging from 0 to 10 with anchors on each end. The objective of this analysis was to confirm the domain structure of the CSD and assess its reliability, validity, and responsiveness in adult patients with refractory or unexplained chronic cough (RCC/UCC). Criteria for defining meaningful changes in mean weekly CSD total and domain scores in the context of a clinical trial were also developed.

METHODS

Pooled data from a phase II randomized controlled trial of an investigational treatment for RCC/UCC were analyzed. Participants were non-smokers, had RCC/UCC for ⩾1 year, and a baseline cough severity visual analogue scale (VAS) ⩾40 mm. CSD scores (baseline, week 4), were analyzed; the Leicester Cough Questionnaire (LCQ), cough severity VAS, Patient Global Impression of Change (PGIC), and objective cough frequency counts were used for validation. CSD domain structure (Total, Frequency, Intensity, Disruption) was assessed for scoring.

RESULTS

A total of 253 participants were included (mean age 60.2; 76% female). Global fit of the three-factor CSD was acceptable. For the CSD total score, internal consistency (α = 0.89) and test-retest reliability (intraclass correlation coefficient = 0.68) were high. CSD total scores were correlated with the LCQ total (r = -0.62) and cough severity VAS (r = 0.84). Participants with a PGIC score of 1 or 2 (most improved groups) had the greatest mean score improvement on the CSD Total (Day 0 to Day 28), supporting responsiveness (similar findings for subscales). A change threshold of ⩾1.3-point reduction on the total and subscale scores is appropriate to define clinically meaningful improvement.

CONCLUSION

The CSD is a reliable, valid, and responsive measure of cough symptom severity in patients with refractory or unexplained chronic cough and fit-for-purpose for assessing changes in cough severity in clinical trials. The reviews of this paper are available via the supplemental material section.

A Cross-sectional Survey of the Clinical Manifestations and Underlying Illness of Cough

AIM

The aim of this study was to identify factors affecting the final diagnosis of cough.

MATERIALS AND METHODS

This study recruited 463 consecutive patients who visited five Japanese general hospitals due to cough from October 2006 to September 2007. Of these, 418 patients (90%) who completed a questionnaire designed to acquire data regarding clinical manifestations of cough were included.

RESULTS

Most patients with bronchial asthma had cough with seasonal variation and wheezing. Patients with gastro esophageal reflux disease suffered from heartburn and cough without daily or seasonal variation. Cough associated with sinobronchial syndrome was only observed in females and was linked to increased sputum. Patients with whooping cough were bothered by cough interrupting sleep and talking. Patients with cardiogenic cough had exertional dyspnea.

CONCLUSION

The specific items on our questionnaire relating to patient characteristics, complications, and triggers of cough, represent useful tools for diagnosing the primary disease producing cough.

The effect of gefapixant, a P2X3 antagonist, on cough reflex sensitivity: a randomised placebo-controlled study

We evaluated the effect of gefapixant on cough reflex sensitivity to evoked tussive challenge.

In this phase 2, double-blind, two-period study, patients with chronic cough (CC) and healthy volunteers (HV) were randomised to single-dose gefapixant 100 mg or placebo in a crossover fashion. Sequential inhalational challenges with ATP, citric acid, capsaicin and distilled water were performed 1, 3 and 5 h after dosing. Mean concentrations evoking ≥2 coughs (C2) and ≥5 coughs (C5) post dose versus baseline were co-primary endpoints. Objective cough frequency (coughs·h−1) over 24 h and a cough severity visual analogue scale (VAS) were assessed in CC patients. Adverse events were monitored.

24 CC patients and 12 HV were randomised (mean age 61 and 38 years, respectively). The cough challenge threshold increased for ATP by 4.7-fold (C2, p≤0.001) and 3.7-fold (C5, p=0.007) for gefapixant versus placebo in CC patients; in HV, C2 and C5 increased 2.4-fold (C2, p=0.113; C5, p=0.003). The distilled water C2 and C5 thresholds increased significantly (p<0.001) by a factor of 1.4 and 1.3, respectively, in CC patients. Gefapixant had no effect on capsaicin or citric acid challenge. Median cough frequency was reduced by 42% and the least squares mean cough severity VAS was 18.0 mm lower for gefapixant versus placebo in CC patients. Dysgeusia was the most frequent adverse event (75% of HV and 67% of CC patients).

ATP-evoked cough was significantly inhibited by gefapixant 100 mg, demonstrating peripheral target engagement. Cough count and severity were reduced in CC patients. Distilled water may also evoke cough through a purinergic pathway.

Treatments for subacute cough in primary care: systematic review and meta-analyses of randomised clinical trials

BACKGROUND

Subacute cough following a non-specific viral infection lasting 3-8 weeks is common. However, despite many treatment options there are no systematic reviews evaluating these.

AIM

To provide a systematic overview of treatment options and outcomes evaluated in randomised clinical trials (RCTs).

DESIGN AND SETTING

Systematic review and meta-analyses assessing the overall effects of any treatment for subacute cough.

METHOD

The authors systematically searched PubMed/MEDLINE and the Cochrane Central Register of Controlled Trials (last search March 2017) for RCTs in adult patients with subacute cough. The authors considered trials evaluating any outcome of any drug or non-drug treatments, apart from traditional Chinese and Asian medicines. They combined treatment effects on cough-related outcomes in random effects meta-analyses.

RESULTS

Six eligible RCTs including 724 patients were identified. These assessed montelukast, salbutamol plus ipratropium bromide, gelatine, fluticasone propionate, budesonide, and nociception opioid 1 receptor agonist and codeine. Five studies reported effects on various cough severity scores at various timepoints. No treatment option was associated with a clear benefit on cough recovery or other patient-relevant outcomes in any of the studies or in meta-analyses for cough outcomes at 14 days and 28 days. Reported adverse events were rather mild and reported for 14% of patients across all treatments.

CONCLUSION

Evidence on treatment options for subacute cough is weak. There is no treatment showing clear patient-relevant benefits in clinical trials.

Influence of baclofen on laryngeal and spinal motor drive during cough in the anesthetized cat

OBJECTIVES/HYPOTHESIS

The antitussive properties of (±) baclofen on laryngeal muscle activities have not been determined. The hypothesis of this study was that administration of (±) baclofen would suppress upper airway muscle motor activity in a dose-dependent manner during cough.

STUDY DESIGN

This is a prospective, preclinical, hypothesis-driven, paired design.

METHODS

Electromyograms of the parasternal, rectus abdominis, thyroarytenoid, posterior cricoarytenoid, and thyrohyoid were measured, along with esophageal pressure. Cough was elicited by mechanical stimulation of the lumen of the intrathoracic trachea in spontaneously breathing cats.

RESULTS

Baclofen (±) (3-10 μg kg(-1) i.a.) induced decreases in the electromyogram amplitude of the rectus abdominis motor drive during coughing, the inspiratory and active expiratory (E1) phases of cough, and cough number per epoch. There was no effect of (±) baclofen on the EMG amplitudes of any of the laryngeal muscles, the parasternal, or the duration of the passive expiratory (E2) phase.

CONCLUSIONS

Results from the present study indicate differential control mechanisms for laryngeal and inspiratory motor drive during cough, providing evidence of a control system regulating laryngeal activity and inspiratory spinal drive that is divergent from the control of expiratory spinal motoneurons.

The objective assessment of cough frequency: accuracy of the LR102 device

Background

The measurement of cough frequency is problematic and most often based on subjective assessment. The aim of the study was to assess the accuracy of the automatic identification of cough episodes by LR102, a cough frequency meter based on electromyography and audio sensors.

Methods

Ten adult patients complaining of cough were recruited in primary care and hospital settings. Participants were asked to wear LR102 for 4 consecutive hours during which they were also filmed.

Results

Measures of cough frequency by LR102 and manual counting were closely correlated (r = 0.87 for number of cough episodes per hour; r = 0.89 for number of single coughs per hour) but LR102 overestimated cough frequency. Bland-Altman plots indicate that differences between the two measurements were not influenced by cough frequency.

Conclusions

LR102 offers a useful estimate of cough frequency in adults in their own environment, while significantly reducing the time required for analysis.

Assessment and management of patients with chronic cough by Certified Respiratory Educators: a randomized controlled trial

BACKGROUND

The value of other health care professionals is increasingly being recognized to compensate for the shortage of physicians in Canada. Chronic cough is one of the most common reasons for consultation with a respirologist. In the present study, a prospective, randomized, controlled study was undertaken to determine whether Certified Respiratory Educators (CREs) could manage screened patients with chronic cough as effectively as respirologists.

METHODS

An eight-week, prospective, parallel-design, randomized, controlled trial of the management of chronic cough patients was conducted. Patients were screened to exclude those with potentially life-threatening conditions. The primary outcome was the number of patients whose cough resolved or subjectively improved.

RESULTS

A total of 198 patients were randomly assigned, and eight-week data were available on 151 patients. Mean age of the patients was 49.8+/-13.4 years, 70.2% were female and median cough duration was 16 months. The screening process was effective and referral wait times decreased from a median of two months to less than four weeks (P<0.0001). The educators averaged 4.9 contacts per patient compared with 2.7 by the physicians over the eight-week study period (P<0.0001). Most patients had had multiple therapeutic trials before referral. Cough resolved or improved in two-thirds of the patients at eight weeks; however, more patients showed improvement in the educator arm than in the physician arm, P<0.02. Cough-specific quality of life improved similarly in the two study arms at eight weeks (physician arm: 61.5+/-14.1 to 52.6+/-14.4, P<0.0001; CRE arm: 58.1+/-14.9 to 50.0+/-15.8, P=0.0003).

CONCLUSIONS

CREs can safely and effectively assess, as well as appropriately treat, screened patients with chronic cough with a resultant reduction in wait times.

Cough: a worldwide problem

Cough is a common and important respiratory symptom that can produce significant complications for patients and be a diagnostic challenge for physicians. An organized approach to evaluating cough begins with classifying it as acute, subacute, or chronic in duration. Acute cough lasting less than 3 weeks may indicate an acute underlying cardiorespiratory disorder but is most commonly caused by a self-limited viral upper respiratory tract infection (eg, common cold). Subacute cough lasting 3 to 8 weeks commonly has a postinfectious origin; among the causes, Bordetella pertussis infection should be included in the differential diagnosis. Chronic cough lasts longer than 8 weeks. When a patient is a nonsmoker, is not taking an angiotensin-converting enzyme inhibitor, and has a normal or near-normal chest radiograph, chronic cough is most commonly caused by upper airway cough syndrome, asthma, nonasthmatic eosinophilic bronchitis, or gastroesophageal reflux disease alone or in combination.

Associations of physical and mental health problems with chronic cough in a representative population cohort

BACKGROUND

Although chronic cough is a common problem in clinical practice, data on the prevalence and characteristics of cough in the general population are scarce. Our aim was to determine the prevalence of chronic cough that is not associated with diagnosed respiratory conditions and examine the impact on health status and psychological health, in a representative adult population cohort

METHODS

North West Adelaide Health Study (n stage 1 = 4060, stage 2 = 3160) is a representative population adult cohort. Clinical assessment included spirometry, anthropometry and skin tests. Questionnaires assessed demographics, lifestyle risk factors, quality of life, mental health and respiratory symptoms, doctor diagnosed conditions and medication use.

RESULTS

Of the 3355 people without identified lung disease at baseline, 18.2% reported chronic cough. In multiple logistic regression models, at follow-up, dry chronic cough without sputum production was significantly more common in males (OR 1.5, 95% CI 1.1, 1.9), current smokers (OR 4.9, 95% CI 3.4, 7.2), obesity (OR 1.9, 95% CI 1.3, 2.9), use of ACE inhibitors (OR 1.8, 95% CI 1.1, 2.9), severe mental health disturbance (OR 2.1, 95% CI 1.4, 3.1) and older age (40-59 years OR 1.7 95% CI 1.2, 2.4; > or = 60 years OR 2.1 95% CI 1.3, 3.5). Among non-smokers only, all cough was significantly more common in men, those with severe mental health disturbance and obesity.

CONCLUSIONS

Chronic cough is a major cause of morbidity. Attention to cough is indicated in patients with obesity, psychological symptoms or smokers. Inquiring about cough in those with mental health problems may identify reversible morbidity.

Nitric oxide measurement in chronic cough

Chronic cough is a common symptom-based diagnostic challenge for primary care physicians and respiratory specialists. Measurement of exhaled nitric oxide is a convenient, reproducible, and inexpensive point-of-service test. It can simplify the evaluation process of chronic cough by providing information regarding the state of airway inflammation. If exhaled nitric oxide is elevated, this is predictive of a favorable response to inhaled corticosteroids. This has the effect of reducing empirical trials for cough-variant asthma or eosinophilic bronchitis. The inclusion of exhaled nitric oxide in the diagnostic approach to chronic cough should be considered.

Taming chronic cough

OBJECTIVE

To review the available evidence on treating chronic cough to relay a thoughtful, evidence-based approach for the diagnosis and treatment of chronic cough.

DATA SOURCES

MEDLINE, PubMed, EMBASE, and CINAHL were searched using the following keywords: cough, asthma, gastroesophageal reflux, sinusitis, rhinitis (allergic, seasonal), postnasal drip, vocal cord dysfunction, lung disease (interstitial), bronchiectasis, and bronchoscopy.

STUDY SELECTION

Studies were selected based on their relevance to the diagnosis and treatment of chronic cough. Because of a lack of randomized prospective studies, nonrandomized and retrospective studies were considered, with their strengths and limitations noted.

RESULTS

Few randomized controlled trials have addressed the diagnosis and treatment of chronic cough. There are several prospective noncontrolled trials for adults with chronic cough that found a high percentage of cough resolution when using an approach that focused on the diagnosis and treatment of the most common causes: asthma, gastroesophageal reflux disease, and upper airway cough syndrome. Preliminary studies in children support an approach that distinguishes between a wet and dry cough, as well as an in-depth investigation of any specific symptoms that point to an underlying chronic illness.

CONCLUSION

Allergists, as experts in treating upper airway and lower airway disorders, are uniquely poised to diagnose and treat chronic cough.