Characterization of the “Frequent Exacerbator Phenotype” in Bronchiectasis

Bronchiectasis insanity: Doing the same thing over and over again and expecting different results?

Bronchiectasis is an increasingly common disease with a significant impact on quality of life and morbidity of affected patients. It is also a very heterogeneous disease with numerous different underlying etiologies and presentations. Most treatments for bronchiectasis are based on low-quality evidence; consequently, no treatments have been approved by the US Food and Drug Administration or the European Medicines Agency for the treatment of bronchiectasis. The last several years have seen numerous clinical trials in which the investigational agent, thought to hold great promise, did not demonstrate a clinically or statistically significant benefit. This commentary will review the likely reasons for these disappointing results and a potential approach that may have a greater likelihood of defining evidence-based treatment for bronchiectasis.

Help, hinder, hide and harm: what can we learn from the interactions between Pseudomonas aeruginosa and Staphylococcus aureus during respiratory infections?

Recent studies of human respiratory secretions using culture-independent techniques have found a surprisingly diverse array of microbes. Interactions among these community members can profoundly impact microbial survival, persistence and antibiotic susceptibility and, consequently, disease progression. Studies of polymicrobial interactions in the human microbiota have shown that the taxonomic and structural compositions, and resulting behaviours, of microbial communities differ substantially from those of the individual constituent species and in ways of clinical importance. These studies primarily involved oral and gastrointestinal microbiomes. While the field of polymicrobial respiratory disease is relatively young, early findings suggest that respiratory tract microbiota members also compete and cooperate in ways that may influence disease outcomes. Ongoing efforts therefore focus on how these findings can inform more 'enlightened', rational approaches to combat respiratory infections. Among the most common respiratory diseases involving polymicrobial infections are cystic fibrosis (CF), non-CF bronchiectasis, COPD and ventilator-associated pneumonia. While respiratory microbiota can be diverse, two of the most common and best-studied members are Staphylococcus aureus and Pseudomonas aeruginosa, which exhibit a range of competitive and cooperative interactions. Here, we review the state of research on pulmonary coinfection with these pathogens, including their prevalence, combined and independent associations with patient outcomes, and mechanisms of those interactions that could influence lung health. Because P. aeruginosa-S. aureus coinfection is common and well studied in CF, this disease serves as the paradigm for our discussions on these two organisms and inform our recommendations for future studies of polymicrobial interactions in pulmonary disease.

Treatable traits in acute exacerbations of chronic airway diseases

Acute exacerbations of chronic airway disease are common occurrences that cause a major burden of illness. Acute exacerbations are associated with impaired health status, increased lung function decline, hospitalization and increased risk of death. Exacerbation avoidance is a major priority. Despite this goal, exacerbations continue to occur and the need for effective models of care that optimize patient outcomes are urgently needed. 'Treatable Traits' is an approach to personalized medicine that has been proposed for the management of airway diseases. The treatable traits approach allows for the recognition of clinically important, identifiable and treatable disease characteristics, followed by targeted and individualized treatment interventions to address each trait. We review the literature relating to treatable traits in airway diseases; in particular, those traits that can predict exacerbations and approaches to management that aim to prevent exacerbations by using a treatable traits model of care. We propose this approach as a potentially useful model of care to both prevent and manage acute exacerbations.

Paediatric and adult bronchiectasis: Monitoring, cross-infection, role of multidisciplinary teams and self-management plans

Bronchiectasis is a chronic lung disease associated with structurally abnormal bronchi, clinically manifested by a persistent wet/productive cough, airway infections and recurrent exacerbations. Early identification and treatment of acute exacerbations is an integral part of monitoring and annual review, in both adults and children, to minimize further damage due to infection and inflammation. Common modalities used to monitor disease progression include clinical signs and symptoms, frequency of exacerbations and/or number of hospital admissions, lung function (forced expiratory volume in 1 s (FEV₁ )% predicted), imaging (radiological severity of disease) and sputum microbiology (chronic infection with Pseudomonas aeruginosa). There is good evidence that these monitoring tools can be used to accurately assess severity of disease and predict prognosis in terms of mortality and future hospitalization. Other tools that are currently used in research settings such as health-related quality of life (QoL) questionnaires, magnetic resonance imaging and lung clearance index can be burdensome and require additional expertise or resource, which limits their use in clinical practice. Studies have demonstrated that cross-infection, especially with P. aeruginosa between patients with bronchiectasis is possible but infrequent. This should not limit participation of patients in group activities such as pulmonary rehabilitation, and simple infection control measures should be carried out to limit the risk of cross-transmission. A multidisciplinary approach to care which includes respiratory physicians, chest physiotherapists, nurse specialists and other allied health professionals are vital in providing holistic care. Patient education and personalized self-management plans are also important despite limited evidence it improves QoL or frequency of exacerbations.

Bronchiectasis

Bronchiectasis refers to abnormal dilatation of the bronchi. Airway dilatation can lead to failure of mucus clearance and increased risk of infection. Pathophysiological mechanisms of bronchiectasis include persistent bacterial infections, dysregulated immune responses, impaired mucociliary clearance and airway obstruction. These mechanisms can interact and self-perpetuate, leading over time to impaired lung function. Patients commonly present with productive cough and recurrent chest infections, and the diagnosis of bronchiectasis is based on clinical symptoms and radiological findings. Bronchiectasis can be the result of several different underlying disorders, and identifying the aetiology is crucial to guide management. Treatment is directed at reducing the frequency of exacerbations, improving quality of life and preventing disease progression. Although no therapy is licensed for bronchiectasis by regulatory agencies, evidence supports the effectiveness of airway clearance techniques, antibiotics and mucolytic agents, such as inhaled isotonic or hypertonic saline, in some patients. Bronchiectasis is a disabling disease with an increasing prevalence and can affect individuals of any age. A major challenge is the application of emerging phenotyping and endotyping techniques to identify the patient populations who would most benefit from a specific treatment, with the goal of better targeting existing and emerging treatments and achieving better outcomes.

Bronchiectasis

Bronchiectasis is an important clinical syndrome because of its increasing prevalence, substantial economic burden on health care, and associated morbidity. Until recently, the disease was considered an orphan and essentially neglected from a therapeutic standpoint, but many recent advances have been made in the field. Several national registries have formed to provide databases from which to study patients with bronchiectasis. Experts published a consensus definition of a bronchiectasis-specific exacerbation that will serve as a unified definition for future clinical trials. Several inhaled antibiotic trials aimed at reducing exacerbation frequency have been completed. Researchers have investigated nonculture techniques, such as 16S ribosomal RNA (rRNA) and whole genome sequencing, to characterize the microbiological characteristics. Studies of anti-Pseudomonas antibodies are providing interesting insight into varying host responses to chronic Pseudomonas infection. After three successful trials demonstrating that macrolides reduce exacerbations in bronchiectasis, other antiinflammatory agents have been investigated, and a trial of a novel antiinflammatory drug is ongoing. A relatively robust study has been published in airway clearance, a therapy that is accepted universally as beneficial but that has never been accompanied by strong evidence. To build on the successes with bronchiectasis thus far, investigators must develop better definitions of phenotypes of bronchiectasis. In this regard, clinical tools have been developed to quantify disease severity and predict prognosis. Studies of different clinical phenotypes of bronchiectasis in patients with bronchiectasis have been published. With continued advances in the field of bronchiectasis, there is hope that evidenced-based therapies will become available.

Medical management of bronchiectasis

The medical management of bronchiectasis includes confirming the diagnosis of the disease, evaluating the patient for possible underlying etiologies and then properly assessing the patient for appropriate therapies. Patients with bronchiectasis are heterogeneous and a personalized approach to each patient is needed in order to properly formulate an optimal management plan.

The overlap between bronchiectasis and chronic airway diseases: state of the art and future directions

Bronchiectasis is a clinical and radiological diagnosis associated with cough, sputum production and recurrent respiratory infections. The clinical presentation inevitably overlaps with other respiratory disorders such as asthma and chronic obstructive pulmonary disease (COPD). In addition, 4-72% of patients with severe COPD are found to have radiological bronchiectasis on computed tomography, with similar frequencies (20-30%) now being reported in cohorts with severe or uncontrolled asthma. Co-diagnosis of bronchiectasis with another airway disease is associated with increased lung inflammation, frequent exacerbations, worse lung function and higher mortality. In addition, many patients with all three disorders have chronic rhinosinusitis and upper airway disease, resulting in a complex "mixed airway" phenotype.The management of asthma, bronchiectasis, COPD and upper airway diseases has traditionally been outlined in separate guidelines for each individual disorder. Recognition that the majority of patients have one or more overlapping pathologies requires that we re-evaluate how we treat airway disease. The concept of treatable traits promotes a holistic, pathophysiology-based approach to treatment rather than a syndromic approach and may be more appropriate for patients with overlapping features.Here, we review the current clinical definition, diagnosis, management and future directions for the overlap between bronchiectasis and other airway diseases.

Bronchiectasis: Treatment decisions for pulmonary exacerbations and their prevention

Interest in bronchiectasis has increased over the past two decades, as shown by the establishment of disease-specific registries in several countries, the publication of management guidelines and a growing number of clinical trials to address evidence gaps for treatment decisions. This review considers the evidence for defining and treating pulmonary exacerbations, the approaches for eradication of newly identified airway pathogens and the methods to prevent exacerbations through long-term treatments from a pragmatic practice-based perspective. Areas for future studies are also explored. Watch the video abstract.

Advances in bronchiectasis: endotyping, genetics, microbiome, and disease heterogeneity

Bronchiectasis is characterised by pathological dilation of the airways. More specifically, the radiographic demonstration of airway enlargement is the common feature of a heterogeneous set of conditions and clinical presentations. No approved therapies exist for the condition other than for bronchiectasis caused by cystic fibrosis. The heterogeneity of bronchiectasis is a major challenge in clinical practice and the main reason for difficulty in achieving endpoints in clinical trials. Recent observations of the past 2 years have improved the understanding of physicians regarding bronchiectasis, and have indicated that it might be more effective to classify patients in a different way. Patients could be categorised according to a heterogeneous group of endotypes (defined by a distinct functional or pathobiological mechanism) or by clinical phenotypes (defined by relevant and common features of the disease). In doing so, more specific therapies needed to effectively treat patients might finally be developed. Here, we describe some of the recent advances in endotyping, genetics, and disease heterogeneity of bronchiectasis including observations related to the microbiome.

Prognostic Value of Frequent Exacerbations in Bronchiectasis: The Relationship With Disease Severity

INTRODUCTION

Bronchiectasis is a very heterogeneous disease but some homogeneous groups with similar clinical characteristics and prognosis have been identified. Exacerbations have been shown to have a negative impact on the natural history of bronchiectasis. The objective of this study was to identify the definition and characteristics of the "frequent exacerbator patient" with the best prognostic value and its relationship with the severity of bronchiectasis.

METHODS

A historical cohort of 651 patients diagnosed with bronchiectasis was included. They had all received 5 years of follow-up since their radiological diagnosis. Exacerbation was defined as a worsening of the symptoms derived from bronchiectasis that required antibiotic treatment. The main outcome was all-cause mortality at the end of follow-up.

RESULTS

The mean age was 48.2 (16) years (32.9% males). 39.8% had chronic infection by Pseudomonas aeruginosa. Mean BSI, FACED, and E-FACED were 7 (4.12), 2.36 (1.68), and 2.89 (2.03), respectively. There were 95 deaths during follow-up. The definition of the "frequent exacerbator patient" that presented the greatest predictive power for mortality was based on at least two exacerbations/year or one hospitalization/year (23.3% of patients; AUC-ROC: 0.75 [95% CI: 0.69-0.81]). Its predictive power was independent of the patient's initial severity. The clinical characteristics of the frequent exacerbator patient according to this definition varied according to the initial severity of bronchiectasis, presence of systemic inflammation, and treatment.

CONCLUSIONS

The combination of two exacerbations or one hospitalization per year is the definition of frequent exacerbator patient that has the best predictive value of mortality independent of the initial severity of bronchiectasis.

Assessing effects of inhaled antibiotics in adults with non-cystic fibrosis bronchiectasis--experiences from recent clinical trials

INTRODUCTION

Non-cystic fibrosis bronchiectasis (NCFB) results from a permanent and progressive destruction of the airways leading to poor lung function. NCFB is characterized by recurrent lung infection, sputum production, and cough, often requiring long-term antibiotic therapy and hospitalization. At present, there are no approved therapies available. Clinical trials of inhaled antibiotics have shown promise against sputum bacterial load, but mixed results on clinical outcomes. Areas covered: The objective of this review is to provide an overview of NCFB and critically evaluate the evidence supporting the outcome measures used in recent clinical trials of inhaled antibiotics. These include quantitative changes in bacterial load, sputum purulence and yield, inflammatory markers, and lung function, as well as clinical changes in exacerbations, exacerbation frequency, hospitalizations, and health-related quality of life. Expert commentary: Recently completed large trials of inhaled antibiotics in NCFB did not consistently meet pre-specified end points, suggesting that we have not yet found the best enrollment criteria or outcome measures to evaluate efficacy, although reduced exacerbation frequency may be clinically most meaningful. Future trials may focus on specific patient populations at high risk with new information obtained through analyses of large international patient registries.

ABBREVIATIONS

6-MWT: Six-Minute Walk Test; AIR-BX: Aztreonam for Inhalation Solution in Patients with Non-Cystic Fibrosis Bronchiectasis trial; BSI: Bronchiectasis Severity Index; CAT: COPD Assessment Test; CF: Cystic Fibrosis; CFTR: Cystic Fibrosis Transmembrane Conductance Regulator; CFU: Colony-Forming Units; COPD: Chronic Obstructive Pulmonary Disease; CRP: C-Reactive Protein; DPI: Dry Powder for Inhalation; EMA: European Medicines Agency; ERS: European Respiratory Society; FACED: FEV1, Age, Chronic colonization by P. aeruginosa, Extension of bronchiectasis and Dyspnea; FDA: US Food and Drug Administration; FEV₁: Forced Expiration in 1 s; FVC: Forced Vital Capacity; HFCC: High-Frequency Chest Compression; HRCT: High-Resolution Computed Tomography; HRQoL: Health-Related Quality of Life; LCQ: Leicester Cough Questionnaire; MID: Minimal Important Difference; NCFB: Non-Cystic Fibrosis Bronchiectasis; NTM: Nontuberculous Mycobacteria; ORBIT: Once-daily Respiratory Bronchiectasis Inhalation Treatment trial; PRO: Patient-Reported Outcomes; QoL-B: Quality of Life-Bronchiectasis; SGRQ: St. George's Respiratory Questionnaire; SWT: Shuttle Walk Test; TORCH: Towards a Revolution in COPD Health trial; UPLIFT: Understanding Potential Long-term Impacts on Function with Tiotropium trial.

Immunological corollary of the pulmonary mycobiome in bronchiectasis: the CAMEB study

Understanding the composition and clinical importance of the fungal mycobiome was recently identified as a key topic in a “research priorities” consensus statement for bronchiectasis.

Patients were recruited as part of the CAMEB study: an international multicentre cross-sectional Cohort of Asian and Matched European Bronchiectasis patients. The mycobiome was determined in 238 patients by targeted amplicon shotgun sequencing of the 18S–28S rRNA internally transcribed spacer regions ITS1 and ITS2. Specific quantitative PCR for detection of and conidial quantification for a range of airway Aspergillus species was performed. Sputum galactomannan, Aspergillus specific IgE, IgG and TARC (thymus and activation regulated chemokine) levels were measured systemically and associated to clinical outcomes.

The bronchiectasis mycobiome is distinct and characterised by specific fungal genera, including Aspergillus, Cryptococcus and Clavispora. Aspergillus fumigatus (in Singapore/Kuala Lumpur) and Aspergillus terreus (in Dundee) dominated profiles, the latter associating with exacerbations. High frequencies of Aspergillus-associated disease including sensitisation and allergic bronchopulmonary aspergillosis were detected. Each revealed distinct mycobiome profiles, and associated with more severe disease, poorer pulmonary function and increased exacerbations.

The pulmonary mycobiome is of clinical relevance in bronchiectasis. Screening for Aspergillus-associated disease should be considered even in apparently stable patients.

The airway mycobiome in bronchiectasis is associated with clinically significant diseasehttp://ow.ly/MCKj30knVrn

Characteristics and Health-care Utilization History of Patients With Bronchiectasis in US Medicare Enrollees With Prescription Drug Plans, 2006 to 2014

BACKGROUND

Bronchiectasis is an increasingly common chronic inflammatory airway disease. There is an urgent need to understand the epidemiology of bronchiectasis in older adults. We describe the prevalence and characteristics of patients with bronchiectasis within the US Medicare population.

METHODS

Among the 40% of Medicare enrollees with prescription drug plans from 2006 to 2014, we identified patients ≥ 65 years of age with bronchiectasis by International Classification of Diseases, Ninth Revision, Clinical Modification claims (494.0 or 494.1) from a pulmonologist and no claim for cystic fibrosis. We calculated the prevalence from 2012 to 2014. Incident or newly diagnosed patients were those enrolled in Medicare at least 12 months prior to the first bronchiectasis diagnosis. We described clinical and health-care utilization characteristics for this cohort during the prior 12-month (baseline) period, and explored differences between those with and without a COPD diagnosis.

RESULTS

We identified 252,362 patients with bronchiectasis meeting all eligibility criteria. The average annual prevalence from 2012 to 2014 was 701 per 100,000 persons. Newly diagnosed patients were a mean age of 76 years, predominately women (65%), and predominately white, non-Hispanic (84%). During the baseline period, 12% were hospitalized for respiratory infections. Fifty-one percent had a dual diagnosis of COPD. Newly diagnosed patients with bronchiectasis and COPD had significantly different characteristics and utilization, for example were more likely hospitalized for respiratory infections during the baseline period (16% vs 7%) and to have a smoking history (46% vs 17%) compared with those without a dual COPD diagnosis, respectively.

CONCLUSIONS

We confirmed a high prevalence of bronchiectasis in the United States and significant heterogeneity in patients with bronchiectasis with and without COPD that should be further explored.

US Patient-Centered Research Priorities and Roadmap for Bronchiectasis

Noncystic fibrosis bronchiectasis (bronchiectasis) is an increasingly common chronic lung disease that is difficult to manage because of a lack of evidence on which to base treatment decision-making. We sought to develop a practical list of US-based patient-centered research priorities and an associated roadmap to guide bronchiectasis research. We designed and administered a web-based patient needs assessment survey to establish broad research priorities, convened three stakeholder webinars to confirm the top priorities, obtained written stakeholder feedback, and completed a final consensus survey of objectives. The stakeholder panel consisted of clinical research experts in bronchiectasis, a seven-member patient advisory panel, and representatives from the two key patient advocacy organizations: COPD Foundation and NTM Info and Research Inc. Based on survey results from 459 patients with bronchiectasis, the stakeholder panel identified 27 patient-centered research priorities for bronchiectasis in the areas of bronchiectasis treatment and prevention of exacerbations, improving treatment of exacerbations and infections, improving health-related quality of life, predictors of poor prognosis, understanding the impact of underlying conditions, and conducting patient-centered clinical trials. These priorities should further inform the development and evaluation of both new and previously unproven therapies, with particular attention to the inclusion of patient-reported outcomes. We anticipate a great deal of progress will be made in the field of bronchiectasis in the next decade.

The impact of acute air pollution fluctuations on bronchiectasis pulmonary exacerbation: a case-crossover analysis

In bronchiectasis, exacerbations are believed to be triggered by infectious agents, but often no pathogen can be identified. We hypothesised that acute air pollution exposure may be associated with bronchiectasis exacerbations.

We combined a case-crossover design with distributed lag models in an observational record linkage study. Patients were recruited from a specialist bronchiectasis clinic at Ninewells Hospital, Dundee, UK.

We recruited 432 patients with clinically confirmed bronchiectasis, as diagnosed by high-resolution computed tomography. After excluding days with missing air pollution data, the final model for particles with a 50% cut-off aerodynamic diameter of 10 µm (PM10) was based on 6741 exacerbations from 430 patients and for nitrogen dioxide (NO2) it included 6248 exacerbations from 426 patients. For each 10 µg·m−³ increase in PM10 and NO2, the risk of having an exacerbation that same day increased significantly by 4.5% (95% CI 0.9–8.3) and 3.2% (95% CI 0.7–5.8) respectively. The overall (lag zero to four) increase in risk of exacerbation for a 10 μg·m−3 increase in air pollutant concentration was 11.2% (95% CI 6.0–16.8) for PM10 and 4.7% (95% CI 0.1–9.5) for NO2. Subanalysis showed higher relative risks during spring (PM10 1.198 (95% CI 1.102–1.303), NO2 1.146 (95% CI 1.035–1.268)) and summer (PM10 2.142 (95% CI 1.785–2.570), NO2 1.352 (95% CI 1.140–1.602)) when outdoor air pollution exposure would be expected to be highest.

In conclusion, acute air pollution fluctuations are associated with increased exacerbation risk in bronchiectasis.