The many "small COPDs": COPD should be an orphan disease

The Impact of Pulmonary Rehabilitation on Mental Health and Quality of Life in Patients With Chronic Obstructive Pulmonary Disease (COPD): A Narrative Review

Chronic obstructive pulmonary disease (COPD) is a complex, prevalent, debilitating, and degenerative disease that affects a large population, and the treatment options for the patients are limited. Although progress has been made in COPD pathogenesis, etiology, and management, there is still an unmet need to develop novel therapies. COPD management has recently seen a focus on a multidisciplinary pulmonary rehabilitation approach to help patients manage the disease better. This review primarily focuses on the role of pulmonary rehabilitation as a novel therapeutic strategy for treating and managing COPD, which is known to decrease patients' quality of life. Disease management and the beneficial effects of pulmonary rehabilitation in COPD are discussed. Subsequently, different methods that are employed in pulmonary rehabilitation are examined, including oxygen therapy, exercise, meditation, and education, emphasizing how they can help patients better manage COPD. Pathophysiology and the effect of pulmonary rehabilitation on the cellular level, such as the release of perforins and Th1 and Th17 cytokines, are also explored. The link between exercise and meditation during pulmonary rehabilitation therapy, which promotes repairing affected organs, is emphasized. Future perspectives on personalized medicine and its use in conjunction with pulmonary rehabilitation are also outlined. In conclusion, pulmonary rehabilitation holds significant promise for the management of COPD by addressing the present limitations of treatment. However, further research is essential to overcome and optimize treatment strategies for COPD patients.

An Update on Outcomes for COPD Pharmacological Trials: A COPD Investigators Report - Reassessment of the 2008 American Thoracic Society/European Respiratory Society Statement on Outcomes for COPD Pharmacological Trials

Background: In 2008, a dedicated American Thoracic Society/European Respiratory Society task force published a paper on the possible use and limitations of clinical outcomes and biomarkers to evaluate the impact of pharmacological therapy in patients with chronic obstructive pulmonary disease. Since then, our scientific understanding of chronic obstructive pulmonary disease has increased considerably; there has been a progressive shift from a one-size-fits-all diagnostic and therapeutic approach to a personalized approach; and many new treatments currently in development will require new endpoints to evaluate their efficacy adequately. Objectives: The emergence of several new relevant outcome measures motivated the authors to review advances in the field and highlight the need to update the content of the original report. Methods: The authors separately created search strategies for the literature, primarily based on their opinions and assessments supported by carefully chosen references. No centralized examination of the literature or uniform criteria for including or excluding evidence were used. Measurements and Main Results: Endpoints, outcomes, and biomarkers have been revisited. The limitations of some of those reported in the American Thoracic Society/European Respiratory Society task force document have been highlighted. In addition, new tools that may be useful, especially in evaluating personalized therapy, have been described. Conclusions: Because the "label-free" treatable traits approach is becoming an important step toward precision medicine, future clinical trials should focus on highly prevalent treatable traits, and this will influence the choice of outcomes and markers to be considered. The use of the new tools, particularly combination endpoints, could help better identify the right patients to be treated with the new drugs.

Identifying chronic obstructive pulmonary disease from integrative omics and clustering in lung tissue

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is a highly morbid and heterogenous disease. While COPD is defined by spirometry, many COPD characteristics are seen in cigarette smokers with normal spirometry. The extent to which COPD and COPD heterogeneity is captured in omics of lung tissue is not known.

METHODS

We clustered gene expression and methylation data in 78 lung tissue samples from former smokers with normal lung function or severe COPD. We applied two integrative omics clustering methods: (1) Similarity Network Fusion (SNF) and (2) Entropy-Based Consensus Clustering (ECC).

RESULTS

SNF clusters were not significantly different by the percentage of COPD cases (48.8% vs. 68.6%, p = 0.13), though were different according to median forced expiratory volume in one second (FEV1) % predicted (82 vs. 31, p = 0.017). In contrast, the ECC clusters showed stronger evidence of separation by COPD case status (48.2% vs. 81.8%, p = 0.013) and similar stratification by median FEV1% predicted (82 vs. 30.5, p = 0.0059). ECC clusters using both gene expression and methylation were identical to the ECC clustering solution generated using methylation data alone. Both methods selected clusters with differentially expressed transcripts enriched for interleukin signaling and immunoregulatory interactions between lymphoid and non-lymphoid cells.

CONCLUSIONS

Unsupervised clustering analysis from integrated gene expression and methylation data in lung tissue resulted in clusters with modest concordance with COPD, though were enriched in pathways potentially contributing to COPD-related pathology and heterogeneity.

Identifying COPD subtypes using multi-trait genetics

Chronic Obstructive Pulmonary Disease (COPD) has a simple physiological diagnostic criterion but a wide range of clinical characteristics. The mechanisms underlying this variability in COPD phenotypes are unclear. To investigate the potential contribution of genetic variants to phenotypic heterogeneity, we examined the association of genome-wide associated lung function, COPD, and asthma variants with other phenotypes using phenome-wide association results derived in the UK Biobank. Our clustering analysis of the variants-phenotypes association matrix identified three clusters of genetic variants with different effects on white blood cell counts, height, and body mass index (BMI). To assess the potential clinical and molecular effects of these groups of variants, we investigated the association between cluster-specific genetic risk scores and phenotypes in the COPDGene cohort. We observed differences in steroid use, BMI, lymphocyte counts, chronic bronchitis, and differential gene and protein expression across the three genetic risk scores. Our results suggest that multi-phenotype analysis of obstructive lung disease-related risk variants may identify genetically driven phenotypic patterns in COPD.

Distinct COPD subtypes in former smokers revealed by gene network perturbation analysis

BACKGROUND

Chronic obstructive pulmonary disease (COPD) varies significantly in symptomatic and physiologic presentation. Identifying disease subtypes from molecular data, collected from easily accessible blood samples, can help stratify patients and guide disease management and treatment.

METHODS

Blood gene expression measured by RNA-sequencing in the COPDGene Study was analyzed using a network perturbation analysis method. Each COPD sample was compared against a learned reference gene network to determine the part that is deregulated. Gene deregulation values were used to cluster the disease samples.

RESULTS

The discovery set included 617 former smokers from COPDGene. Four distinct gene network subtypes are identified with significant differences in symptoms, exercise capacity and mortality. These clusters do not necessarily correspond with the levels of lung function impairment and are independently validated in two external cohorts: 769 former smokers from COPDGene and 431 former smokers in the Multi-Ethnic Study of Atherosclerosis (MESA). Additionally, we identify several genes that are significantly deregulated across these subtypes, including DSP and GSTM1, which have been previously associated with COPD through genome-wide association study (GWAS).

CONCLUSIONS

The identified subtypes differ in mortality and in their clinical and functional characteristics, underlining the need for multi-dimensional assessment potentially supplemented by selected markers of gene expression. The subtypes were consistent across cohorts and could be used for new patient stratification and disease prognosis.

Screening and identification of tissue-infiltrating immune cells and genes for patients with emphysema phenotype of COPD

Objective

To study the tissue-infiltrating immune cells of the emphysema phenotype of chronic obstructive pulmonary disease (COPD) and find the molecular mechanism related to the development of emphysema to offer potential targets for more precise treatment of patients with COPD.

Methods

Combined analyses of COPD emphysema phenotype lung tissue-related datasets, GSE47460 and GSE1122, were performed. CIBERSORT was used to assess the distribution of tissue-infiltrating immune cells. Weighted gene co-expression network analysis (WGCNA) was used to select immune key genes closely related to clinical features. Rt-qPCR experiments were used for the validation of key genes. Emphysema risk prediction models were constructed by logistic regression analysis and a nomogram was developed.

Results

In this study, three immune cells significantly associated with clinical features of emphysema (FEV1 post-bronchodilator % predicted, GOLD Stage, and DLCO) were found. The proportion of neutrophils (p=0.025) infiltrating in the emphysema phenotype was significantly increased compared with the non-emphysema phenotype, while the proportions of M2 macrophages (p=0.004) and resting mast cells (p=0.01) were significantly decreased. Five immune-related differentially expressed genes (DEGs) were found. WGCNA and clinical lung tissue validation of patients with emphysema phenotype were performed to further screen immune-related genes closely related to clinical features. A key gene (SERPINA3) was selected and included in the emphysema risk prediction model. Compared with the traditional clinical prediction model (AUC=0.923), the combined prediction model, including SERPINA3 and resting mast cells (AUC=0.941), had better discrimination power and higher net benefit.

Conclusion

This study comprehensively analyzed the tissue-infiltrating immune cells significantly associated with emphysema phenotype, including M2 macrophages, neutrophils, and resting mast cells, and identified SERPINA3 as a key immune-related gene.

Case-finding and improving patient outcomes for chronic obstructive pulmonary disease in primary care: the BLISS research programme including cluster RCT

Background

Chronic obstructive pulmonary disease is a major contributor to morbidity, mortality and health service costs but is vastly underdiagnosed. Evidence on screening and how best to approach this is not clear. There are also uncertainties around the natural history (prognosis) of chronic obstructive pulmonary disease and how it impacts on work performance.

Objectives

Work package 1: to evaluate alternative methods of screening for undiagnosed chronic obstructive pulmonary disease in primary care, with clinical effectiveness and cost-effectiveness analyses and an economic model of a routine screening programme. Work package 2: to recruit a primary care chronic obstructive pulmonary disease cohort, develop a prognostic model [Birmingham Lung Improvement StudieS (BLISS)] to predict risk of respiratory hospital admissions, validate an existing model to predict mortality risk, address some uncertainties about natural history and explore the potential for a home exercise intervention. Work package 3: to identify which factors are associated with employment, absenteeism, presenteeism (working while unwell) and evaluate the feasibility of offering formal occupational health assessment to improve work performance.

Design

Work package 1: a cluster randomised controlled trial with household-level randomised comparison of two alternative case-finding approaches in the intervention arm. Work package 2: cohort study – focus groups. Work package 3: subcohort – feasibility study.

Setting

Primary care settings in West Midlands, UK.

Participants

Work package 1: 74,818 people who have smoked aged 40–79 years without a previous chronic obstructive pulmonary disease diagnosis from 54 general practices. Work package 2: 741 patients with previously diagnosed chronic obstructive pulmonary disease from 71 practices and participants from the work package 1 randomised controlled trial. Twenty-six patients took part in focus groups. Work package 3: occupational subcohort with 248 patients in paid employment at baseline. Thirty-five patients took part in an occupational health intervention feasibility study.

Interventions

Work package 1: targeted case-finding – symptom screening questionnaire, administered opportunistically or additionally by post, followed by diagnostic post-bronchodilator spirometry. The comparator was routine care. Work package 2: twenty-three candidate variables selected from literature and expert reviews. Work package 3: sociodemographic, clinical and occupational characteristics; occupational health assessment and recommendations.

Main outcome measures

Work package 1: yield (screen-detected chronic obstructive pulmonary disease) and cost-effectiveness of case-finding; effectiveness of screening on respiratory hospitalisation and mortality after approximately 4 years. Work package 2: respiratory hospitalisation within 2 years, and barriers to and facilitators of physical activity. Work package 3: work performance – feasibility and acceptability of the occupational health intervention and study processes.

Results

Work package 1: targeted case-finding resulted in greater yield of previously undiagnosed chronic obstructive pulmonary disease than routine care at 1 year [n = 1278 (4%) vs. n = 337 (1%), respectively; adjusted odds ratio 7.45, 95% confidence interval 4.80 to 11.55], and a model-based estimate of a regular screening programme suggested an incremental cost-effectiveness ratio of £16,596 per additional quality-adjusted life-year gained. However, long-term follow-up of the trial showed that at ≈4 years there was no clear evidence that case-finding, compared with routine practice, was effective in reducing respiratory admissions (adjusted hazard ratio 1.04, 95% confidence interval 0.73 to1.47) or mortality (hazard ratio 1.15, 95% confidence interval 0.82 to 1.61). Work package 2: 2305 patients, comprising 1564 with previously diagnosed chronic obstructive pulmonary disease and 741 work package 1 participants (330 with and 411 without obstruction), were recruited. The BLISS prognostic model among cohort participants with confirmed airflow obstruction (n = 1894) included 6 of 23 candidate variables (i.e. age, Chronic Obstructive Pulmonary Disease Assessment Test score, 12-month respiratory admissions, body mass index, diabetes and forced expiratory volume in 1 second percentage predicted). After internal validation and adjustment (uniform shrinkage factor 0.87, 95% confidence interval 0.72 to 1.02), the model discriminated well in predicting 2-year respiratory hospital admissions (c-statistic 0.75, 95% confidence interval 0.72 to 0.79). In focus groups, physical activity engagement was related to self-efficacy and symptom severity. Work package 3: in the occupational subcohort, increasing dyspnoea and exposure to inhaled irritants were associated with lower work productivity at baseline. Longitudinally, increasing exacerbations and worsening symptoms, but not a decline in airflow obstruction, were associated with absenteeism and presenteeism. The acceptability of the occupational health intervention was low, leading to low uptake and low implementation of recommendations and making a full trial unfeasible.

Limitations

Work package 1: even with the most intensive approach, only 38% of patients responded to the case-finding invitation. Management of case-found patients with chronic obstructive pulmonary disease in primary care was generally poor, limiting interpretation of the long-term effectiveness of case-finding on clinical outcomes. Work package 2: the components of the BLISS model may not always be routinely available and calculation of the score requires a computerised system. Work package 3: relatively few cohort participants were in paid employment at baseline, limiting the interpretation of predictors of lower work productivity.

Conclusions

This programme has addressed some of the major uncertainties around screening for undiagnosed chronic obstructive pulmonary disease and has resulted in the development of a novel, accurate model for predicting respiratory hospitalisation in people with chronic obstructive pulmonary disease and the inception of a primary care chronic obstructive pulmonary disease cohort for longer-term follow-up. We have also identified factors that may affect work productivity in people with chronic obstructive pulmonary disease as potential targets for future intervention.

Future work

We plan to obtain data for longer-term follow-up of trial participants at 10 years. The BLISS model needs to be externally validated. Our primary care chronic obstructive pulmonary disease cohort is a unique resource for addressing further questions to better understand the prognosis of chronic obstructive pulmonary disease.

Trial registration

Current Controlled Trials ISRCTN14930255.

Funding

This project was funded by the National Institute for Health Research (NIHR) Programme Grants for Applied Research programme and will be published in full in Programme Grants for Applied Research; Vol. 9, No. 13. See the NIHR Journals Library website for further project information.

Incorporating Comprehensive Assessment Parameters to Better Characterize and Plan Rehabilitation for Persons with Chronic Obstructive Pulmonary Disease

OBJECTIVES

The current management of chronic obstructive pulmonary disease (COPD) largely ignores its heterogeneous pulmonary and extrapulmonary manifestations in the individual patient. This study aimed to identify clusters of patients with COPD based on a thorough traits assessment.

DESIGN

An observational, prospective, single-center study.

SETTING AND PARTICIPANTS

Patients with COPD referred by chest physicians for a comprehensive pulmonary rehabilitation program to CIRO (Horn, the Netherlands) were eligible to participate. CIRO is a specialized pulmonary rehabilitation center in the southern part of the Netherlands for patients with complex underlying respiratory diseases.

METHODS

Clinically stable patients with COPD underwent a comprehensive assessment, including pulmonary traits (airflow limitation, static hyperinflation, gas transfer, respiratory pressures, and arterial blood gases), extrapulmonary functional traits, and health status (quadriceps muscle strength, physical functioning, body composition, comorbidities, symptoms perception, and social and emotional functioning). Clusters were generated using the SOM-Ward Cluster algorithm, a hybrid algorithm that applies the classical hierarchical method of Ward on top of the self-organizing map topology.

RESULTS

Based on the abovementioned attributes of 518 patients with mild to very severe COPD (44% women, age 64.1 ± 9.1 years, forced expiratory volume in the first second 48.6% ± 20.0% of predicted), 7 clusters were identified. Clusters had unique patterns differing in demographics, pulmonary, extrapulmonary functional, and behavioral traits and/or health status.

CONCLUSION AND IMPLICATIONS

The tremendous heterogeneity in pulmonary, extrapulmonary functional and behavioral traits, and health status in patients with COPD supports the need for an individual comprehensive assessment and a goal-directed personalized management strategy.

Finding relationships among biological entities

Confusion over the concepts of “relationships” and “similarities” lies at the heart of many battles over the direction and intent of research projects. Here is a short story that demonstrates the difference between the two concepts: You look up at the clouds, and you begin to see the shape of a lion. The cloud has a tail, like a lion’s tale, and a fluffy head, like a lion’s mane. With a little imagination the mouth of the lion seems to roar down from the sky. You have succeeded in finding similarities between the cloud and a lion. If you look at a cloud and you imagine a tea kettle producing a head of steam and you recognize that the physical forces that create a cloud and the physical forces that produced steam from a heated kettle are the same, then you have found a relationship. Most popular classification algorithms operate by grouping together data objects that have similar properties or values. In so doing, they may miss finding the true relationships among objects. Traditionally, relationships among data objects are discovered by an intellectual process. In this chapter, we will discuss the scientific gains that come when we classify biological entities by relationships, not by their similarities.

Machine Learning Characterization of COPD Subtypes: Insights From the COPDGene Study

COPD is a heterogeneous syndrome. Many COPD subtypes have been proposed, but there is not yet consensus on how many COPD subtypes there are and how they should be defined. The COPD Genetic Epidemiology Study (COPDGene), which has generated 10-year longitudinal chest imaging, spirometry, and molecular data, is a rich resource for relating COPD phenotypes to underlying genetic and molecular mechanisms. In this article, we place COPDGene clustering studies in context with other highly cited COPD clustering studies, and summarize the main COPD subtype findings from COPDGene. First, most manifestations of COPD occur along a continuum, which explains why continuous aspects of COPD or disease axes may be more accurate and reproducible than subtypes identified through clustering methods. Second, continuous COPD-related measures can be used to create subgroups through the use of predictive models to define cut-points, and we review COPDGene research on blood eosinophil count thresholds as a specific example. Third, COPD phenotypes identified or prioritized through machine learning methods have led to novel biological discoveries, including novel emphysema genetic risk variants and systemic inflammatory subtypes of COPD. Fourth, trajectory-based COPD subtyping captures differences in the longitudinal evolution of COPD, addressing a major limitation of clustering analyses that are confounded by disease severity. Ongoing longitudinal characterization of subjects in COPDGene will provide useful insights about the relationship between lung imaging parameters, molecular markers, and COPD progression that will enable the identification of subtypes based on underlying disease processes and distinct patterns of disease progression, with the potential to improve the clinical relevance and reproducibility of COPD subtypes.

Building toolkits for COPD exacerbations: lessons from the past and present

In the nineteenth century, it was recognised that acute attacks of chronic bronchitis were harmful. 140 years later, it is clearer than ever that exacerbations of chronic obstructive pulmonary disease (ECOPD) are important events. They are associated with significant mortality, morbidity, a reduced quality of life and an increasing reliance on social care. ECOPD are common and are increasing in prevalence. Exacerbations beget exacerbations, with up to a quarter of in-patient episodes ending with readmission to hospital within 30 days. The healthcare costs are immense. Yet despite this, the tools available to diagnose and treat ECOPD are essentially unchanged, with the last new intervention (non-invasive ventilation) introduced over 25 years ago.An ECOPD is 'an acute worsening of respiratory symptoms that results in additional therapy'. This symptom and healthcare utility-based definition does not describe pathology and is unable to differentiate from other causes of an acute deterioration in breathlessness with or without a cough and sputum. There is limited understanding of the host immune response during an acute event and no reliable and readily available means to identify aetiology or direct treatment at the point of care (POC). Corticosteroids, short acting bronchodilators with or without antibiotics have been the mainstay of treatment for over 30 years. This is in stark contrast to many other acute presentations of chronic illness, where specific biomarkers and mechanistic understanding has revolutionised care pathways. So why has progress been so slow in ECOPD? This review examines the history of diagnosing and treating ECOPD. It suggests that to move forward, there needs to be an acceptance that not all exacerbations are alike (just as not all COPD is alike) and that clinical presentation alone cannot identify aetiology or stratify treatment.

Precision health: treating the individual patient with chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is defined based on a reduced ratio of forced expiratory volume in one second (FEV₁ ) to forced vital capacity (FVC) on spirometry. However, within this definition, there is significant heterogeneity of pathophysiological processes that lead to airflow obstruction and variation in phenotypic manifestations across patients. Current pharmacological treatments are based on large randomised clinical trials that apply to an "average" patient. Precision health enables tailoring of treatment for each individual patient by taking into account their unique characteristics. The number needed to treat (NNT) metric is often used to define implementation of precision health for specific interventions, with common endpoints requiring an NNT ≤ 5 to achieve precision therapy. Higher NNTs may be acceptable for rare but important endpoints such as mortality. Long-acting muscarinic antagonists and inhaled corticosteroids, which are commonly used in COPD, have 1-year treatment NNTs between 15 and 20 for exacerbation prevention in unselected patients with COPD. Subgroup identification using biomarkers or clinical traits may enable precision health. For example, NNT for inhaled corticosteroids is 9 in patients with a blood eosinophil count ≥ 300 cells/μL and 8 for long-acting muscarinic antagonists in patients with a body mass index ≤ 20 kg/m² . Lung volume reduction surgery is associated with an NNT of 6 for survival over 5 years in patients with upper lobe-predominant disease and low exercise capacity (whereas the NNT is 245 when no bioimaging or exercise markers are used). Continuous domiciliary oxygen therapy (for at least 15 hours/day) has an NNT of 5 for survival over 5 years in patients with resting hypoxemia (PaO₂  < 60 mmHg on room air). Emerging areas of precision health in COPD with potential for low NNTs in specific circumstances include anti-interleukin-5 therapy for eosinophilic COPD, and immunoglobulin replacement therapy for patients with severe immunoglobulin deficiency.

Introduction to precision medicine in COPD

Although there has been tremendous growth in our understanding of chronic obstructive pulmonary disease (COPD) and its pathophysiology over the past few decades, the pace of therapeutic innovation has been extremely slow. COPD is now widely accepted as a heterogeneous condition with multiple phenotypes and endotypes. Thus, there is a pressing need for COPD care to move from the current “one-size-fits-all” approach to a precision medicine approach that takes into account individual patient variability in genes, environment and lifestyle. Precision medicine is enabled by biomarkers that can: 1) accurately identify subgroups of patients who are most likely to benefit from therapeutics and those who will only experience harm (predictive biomarkers); 2) predict therapeutic responses to drugs at an individual level (response biomarkers); and 3) segregate patients who are at risk of poor outcomes from those who have relatively stable disease (prognostic biomarkers). In this essay, we will discuss the current concept of precision medicine and its relevance for COPD and explore ways to implement precision medicine for millions of patients across the world with COPD.

Therapeutic Approaches to Acquired Cystic Fibrosis Transmembrane Conductance Regulator Dysfunction in Chronic Bronchitis

Chronic obstructive pulmonary disease is a common cause of morbidity and a rising cause of mortality worldwide. Its rising impact indicates the ongoing unmet need for novel and effective therapies. Previous work has established a pathophysiological link between the chronic bronchitis phenotype of chronic obstructive pulmonary disease and cystic fibrosis as well as phenotypic similarities between these two airways diseases. An extensive body of evidence has established that cigarette smoke and its constituents contribute to acquired dysfunction of the cystic fibrosis transmembrane conductance regulator (CFTR) protein in the airways, pointing to a mechanistic link with smoking-related and chronic bronchitis. Recent interest surrounding new drugs that target both mutant and wild-type CFTR channels has paved the way for a new treatment opportunity addressing the mucus defect in chronic bronchitis. We review the clinical and pathologic evidence for modulating CFTR to address acquired CFTR dysfunction and pragmatic issues surrounding clinical trials as well as a discussion of other ion channels that may represent alternative therapeutic targets.

COPD: time to improve its taxonomy?

Due to well-conducted epidemiological studies and advances in genetics, molecular biology, translational research, the advent of computed tomography of the lungs and bioinformatics, the diagnosis of chronic obstructive pulmonary disease (COPD) as a single entity caused by susceptibility to cigarette smoke is no longer tenable. Furthermore, the once-accepted concept that COPD results from a rapid and progressive loss of lung function over time is not true for a sizeable proportion of adults with the disease. Now we know that some genetic predisposition and/or different environmental interactions (nutritional, infectious, pollution and immunological) may negatively modulate post-natal lung development and lead to poorly reversible airflow limitation later in life, consistent with COPD. We believe it is time to rethink the taxonomy of this disease based on the evidence at hand. To do so, we have followed the principles outlined in the 1980s by J.D. Scadding who proposed that diseases can be defined by four key characteristics: 1) clinical description (syndrome), 2) disorder of structure (morbid anatomy), 3) disorder of function (pathophysiology) and 4) causation (aetiology). Here, we propose a pragmatic approach to the taxonomy of COPD based on different processes that result in a similar syndromic presentation. It can accommodate changes over time, as the pathobiology that may lead to COPD expands. We hope that stakeholders in the field may find it useful to better define the patients now boxed into one single entity, so that specific studies can be designed and conducted for each type of COPDs.

Natural history of COPD: gaps and opportunities

Understanding the natural history of a disease is as important as knowing its cause(s) for effective disease prevention and treatment. Yet, our current understanding of the natural history of chronic obstructive pulmonary disease (COPD) is incomplete and often controversial. This article discusses the current gaps, and hence opportunities for research, in this field. In particular, it discusses the following six specific questions. 1) Is COPD a “single” disease? 2) Is COPD “only” a lung disease? 3) When does COPD begin or what is “early” COPD? 4) How does COPD “progress”? 5) How do we assess disease “severity”? 6) Can COPD be prevented (beyond smoking cessation) or its course be modified once detected?

A new review series starts in ERJ Open Research: “Gaps in our understanding of COPD”http://ow.ly/CFSD30gpXs8

Do COPD subtypes really exist? COPD heterogeneity and clustering in 10 independent cohorts

BACKGROUND

COPD is a heterogeneous disease, but there is little consensus on specific definitions for COPD subtypes. Unsupervised clustering offers the promise of 'unbiased' data-driven assessment of COPD heterogeneity. Multiple groups have identified COPD subtypes using cluster analysis, but there has been no systematic assessment of the reproducibility of these subtypes.

OBJECTIVE

We performed clustering analyses across 10 cohorts in North America and Europe in order to assess the reproducibility of (1) correlation patterns of key COPD-related clinical characteristics and (2) clustering results.

METHODS

We studied 17 146 individuals with COPD using identical methods and common COPD-related characteristics across cohorts (FEV₁, FEV₁/FVC, FVC, body mass index, Modified Medical Research Council score, asthma and cardiovascular comorbid disease). Correlation patterns between these clinical characteristics were assessed by principal components analysis (PCA). Cluster analysis was performed using k-medoids and hierarchical clustering, and concordance of clustering solutions was quantified with normalised mutual information (NMI), a metric that ranges from 0 to 1 with higher values indicating greater concordance.

RESULTS

The reproducibility of COPD clustering subtypes across studies was modest (median NMI range 0.17-0.43). For methods that excluded individuals that did not clearly belong to any cluster, agreement was better but still suboptimal (median NMI range 0.32-0.60). Continuous representations of COPD clinical characteristics derived from PCA were much more consistent across studies.

CONCLUSIONS

Identical clustering analyses across multiple COPD cohorts showed modest reproducibility. COPD heterogeneity is better characterised by continuous disease traits coexisting in varying degrees within the same individual, rather than by mutually exclusive COPD subtypes.

Plasma Fibrinogen Qualification as a Drug Development Tool in Chronic Obstructive Pulmonary Disease. Perspective of the Chronic Obstructive Pulmonary Disease Biomarker Qualification Consortium

The COPD Foundation Biomarker Qualification Consortium (CBQC) is a unique public-private partnership established in 2010 between the COPD Foundation, the pharmaceutical industry, and academic chronic obstructive pulmonary disease (COPD) experts with advisors from the U.S. NHLBI and the Food and Drug Administration (FDA). This was a direct response to the 2009 publication of a guidance on qualification of drug development tools by the FDA. Although data were believed to be available from publicly funded and industry-funded studies that could support qualification of several tools, the necessary data resided in disparate databases. The initial intent of the CBQC was to integrate these data and submit a dossier for the qualification. This led to the FDA qualification of plasma fibrinogen as a prognostic or enrichment biomarker for all-cause mortality and COPD exacerbations in July 2015. It is the first biomarker drug development tool qualified for use in COPD under the FDA's drug development tool qualification program. This perspective summarizes the FDA's qualification process, the formation of the CBQC, and the effort that led to a successful outcome for plasma fibrinogen and discusses implications for future biomarker qualification efforts.

Exome Array Analysis Identifies a Common Variant in IL27 Associated with Chronic Obstructive Pulmonary Disease

RATIONALE

Chronic obstructive pulmonary disease (COPD) susceptibility is in part related to genetic variants. Most genetic studies have been focused on genome-wide common variants without a specific focus on coding variants, but common and rare coding variants may also affect COPD susceptibility.

OBJECTIVES

To identify coding variants associated with COPD.

METHODS

We tested nonsynonymous, splice, and stop variants derived from the Illumina HumanExome array for association with COPD in five study populations enriched for COPD. We evaluated single variants with a minor allele frequency greater than 0.5% using logistic regression. Results were combined using a fixed effects meta-analysis. We replicated novel single-variant associations in three additional COPD cohorts.

MEASUREMENTS AND MAIN RESULTS

We included 6,004 control subjects and 6,161 COPD cases across five cohorts for analysis. Our top result was rs16969968 (P = 1.7 × 10(-14)) in CHRNA5, a locus previously associated with COPD susceptibility and nicotine dependence. Additional top results were found in AGER, MMP3, and SERPINA1. A nonsynonymous variant, rs181206, in IL27 (P = 4.7 × 10(-6)) was just below the level of exome-wide significance but attained exome-wide significance (P = 5.7 × 10(-8)) when combined with results from other cohorts. Gene expression datasets revealed an association of rs181206 and the surrounding locus with expression of multiple genes; several were differentially expressed in COPD lung tissue, including TUFM.

CONCLUSIONS

In an exome array analysis of COPD, we identified nonsynonymous variants at previously described loci and a novel exome-wide significant variant in IL27. This variant is at a locus previously described in genome-wide associations with diabetes, inflammatory bowel disease, and obesity and appears to affect genes potentially related to COPD pathogenesis.

Early chronic obstructive pulmonary disease: definition, assessment, and prevention

Chronic obstructive pulmonary disease (COPD) is the third leading cause of death worldwide. COPD, however, is a heterogeneous collection of diseases with differing causes, pathogenic mechanisms, and physiological effects. Therefore a comprehensive approach to COPD prevention will need to address the complexity of COPD. Advances in the understanding of the natural history of COPD and the development of strategies to assess COPD in its early stages make prevention a reasonable, if ambitious, goal.

Potential mechanisms to explain how LABAs and PDE4 inhibitors enhance the clinical efficacy of glucocorticoids in inflammatory lung diseases

Inhaled glucocorticoids acting via the glucocorticoid receptor are a mainstay treatment option for individuals with asthma. There is a consensus that the remedial actions of inhaled glucocorticoids are due to their ability to suppress inflammation by modulating gene expression. While inhaled glucocorticoids are generally effective in asthma, there are subjects with moderate-to-severe disease in whom inhaled glucocorticoids fail to provide adequate control. For these individuals, asthma guidelines recommend that a long-acting β₂-adrenoceptor agonist (LABA) be administered concurrently with an inhaled glucocorticoid. This so-called “combination therapy” is often effective and clinically superior to the inhaled glucocorticoid alone, irrespective of dose. LABAs, and another class of drug known as phosphodiesterase 4 (PDE4) inhibitors, may also enhance the efficacy of inhaled glucocorticoids in chronic obstructive pulmonary disease (COPD). In both conditions, these drugs are believed to work by elevating the concentration of cyclic adenosine-3',5'-monophosphate (cAMP) in target cells and tissues. Despite the success of inhaled glucocorticoid/LABA combination therapy, it remains unclear how an increase in cAMP enhances the clinical efficacy of an inhaled glucocorticoid. In this report, we provide a state-of-the-art appraisal, including unresolved and controversial issues, of how cAMP-elevating drugs and inhaled glucocorticoids interact at a molecular level to deliver enhanced anti-inflammatory benefit over inhaled glucocorticoid monotherapy. We also speculate on ways to further exploit this desirable interaction. Critical discussion of how these two drug classes regulate gene transcription, often in a synergistic manner, is a particular focus. Indeed, because interplay between glucocorticoid receptor and cAMP signaling pathways may contribute to the superiority of inhaled glucocorticoid/LABA combination therapy, understanding this interaction may provide a logical framework to rationally design these multicomponent therapeutics that was not previously possible.

Health and social impacts of COPD and the problem of under-diagnosis

This article deals with the prevalence and the possible reasons of COPD underestimation in the population and gives suggestions on how to overcome the obstacles and make the correct diagnosis in order to provide the patients with the appropriate therapy. COPD is diagnosed in later or very advanced stages. In Italy the rate of COPD under-diagnosis ranges between 25 and 50% and, as a consequence, the patient does not consult his doctor until the symptoms have worsened, mainly due to exacerbations. A missed diagnosis influences the timing of therapeutic intervention, thus contributing to the evolution into more severe stages of the illness. An incisive intervention to limit under-diagnosis cannot act only in remittance (passive diagnosis), but must be the promoter for a series of preventive actions: primary, secondary and rehabilitative. To reduce under-diagnosis, some actions need to be taken, such as screening programs for smokers subjects, use of questionnaires aimed to qualify and monitor the disease severity, spirometry, early diagnosis. There is a consensus regarding diagnoses based on screening of at-risk subjects and symptoms, rather than screening of the general population. In practice, all individuals over 40 years of age with risk factors should make a spirometry test. Screening actions on a national scale can be the following: compilation of questionnaires in waiting rooms of doctor’s offices or performing simple maneuvers to evaluate the expiratory force at pharmacies. It is now widely recognized that COPD is a complex syndrome with several pulmonary and extrapulmonary components; as a result, the airway obstruction as assessed by FEV₁ by itself does not adequately describe the complexity of the disease and FEV₁ cannot be used alone for the optimal diagnosis, assessment, and management of the disease. The identification and subsequent grouping of key elements of the COPD syndrome into clinically meaningful and useful subgroups (phenotypes) can guide therapy more effectively. In conclusion, we firmly believe that an early and correct diagnosis can influence positively the progress of the disease (lowering the lung function impairment), decrease the risk of exacerbations, relieve symptoms and increase the patients’ quality of life leading also to a decrease in costs associated to the exacerbations and hospitalization of the patient.

Genome-wide association identifies regulatory Loci associated with distinct local histogram emphysema patterns

RATIONALE

Emphysema is a heritable trait that occurs in smokers with and without chronic obstructive pulmonary disease. Emphysema occurs in distinct pathologic patterns, but the genetic determinants of these patterns are unknown.

OBJECTIVES

To identify genetic loci associated with distinct patterns of emphysema in smokers and investigate the regulatory function of these loci.

METHODS

Quantitative measures of distinct emphysema patterns were generated from computed tomography scans from smokers in the COPDGene Study using the local histogram emphysema quantification method. Genome-wide association studies (GWAS) were performed in 9,614 subjects for five emphysema patterns, and the results were referenced against enhancer and DNase I hypersensitive regions from ENCODE and Roadmap Epigenomics cell lines.

MEASUREMENTS AND MAIN RESULTS

Genome-wide significant associations were identified for seven loci. Two are novel associations (top single-nucleotide polymorphism rs379123 in MYO1D and rs9590614 in VMA8) located within genes that function in cell-cell signaling and cell migration, and five are in loci previously associated with chronic obstructive pulmonary disease susceptibility (HHIP, IREB2/CHRNA3, CYP2A6/ADCK, TGFB2, and MMP12). Five of these seven loci lay within enhancer or DNase I hypersensitivity regions in lung fibroblasts or small airway epithelial cells, respectively. Enhancer enrichment analysis for top GWAS associations (single-nucleotide polymorphisms associated at P < 5 × 10(-6)) identified multiple cell lines with significant enhancer enrichment among top GWAS loci, including lung fibroblasts.

CONCLUSIONS

This study demonstrates for the first time genetic associations with distinct patterns of pulmonary emphysema quantified by computed tomography scan. Enhancer regions are significantly enriched among these GWAS results, with pulmonary fibroblasts among the cell types showing the strongest enrichment.

Integrative genomics of chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is a complex disease with both environmental and genetic determinants, the most important of which is cigarette smoking. There is marked heterogeneity in the development of COPD among persons with similar cigarette smoking histories, which is likely partially explained by genetic variation. Genomic approaches such as genomewide association studies and gene expression studies have been used to discover genes and molecular pathways involved in COPD pathogenesis; however, these "first generation" omics studies have limitations. Integrative genomic studies are emerging which can combine genomic datasets to further examine the molecular underpinnings of COPD. Future research in COPD genetics will likely use network-based approaches to integrate multiple genomic data types in order to model the complex molecular interactions involved in COPD pathogenesis. This article reviews the genomic research to date and offers a vision for the future of integrative genomic research in COPD.

Cyclic nucleotide-based therapeutics for chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) defines a group of chronic inflammatory disorders of the airways that are characterised by a progressive and largely irreversible decline in expiratory airflow. Drugs used to treat COPD through actions mediated by cyclic AMP (cAMP) are restricted to long-acting and short-acting β2-adrenoceptor agonists and, in a subset of patients with chronic bronchitis, a phosphodiesterase 4 inhibitor, roflumilast. These agents relax airway smooth muscle and suppress inflammation. At the molecular level, these effects in the airways are mediated by two cAMP effectors, cAMP-dependent protein kinase and exchange proteins activated by cAMP. The pharmacology of newer agents, acting through these systems, is discussed here with an emphasis on their potential to interact and increase therapeutic effectiveness.

The path to personalised medicine in COPD

Our understanding of chronic obstructive pulmonary disease (COPD) has changed dramatically over the past two decades. We have moved from an airflow limitation-centric view to the realisation that COPD is a complex and heterogeneous disease, which leads inevitably to the need for personalising the assessment and treatment of patients with COPD. This review provides a brief perspective of the extraordinary transition that the COPD field has experienced in the last two decades, and speculates on how it should/can move forward in the near future in order to really achieve the goal of personalising COPD medicine in the clinic.

Cluster analysis in the COPDGene study identifies subtypes of smokers with distinct patterns of airway disease and emphysema

BACKGROUND

There is notable heterogeneity in the clinical presentation of patients with COPD. To characterise this heterogeneity, we sought to identify subgroups of smokers by applying cluster analysis to data from the COPDGene study.

METHODS

We applied a clustering method, k-means, to data from 10 192 smokers in the COPDGene study. After splitting the sample into a training and validation set, we evaluated three sets of input features across a range of k (user-specified number of clusters). Stable solutions were tested for association with four COPD-related measures and five genetic variants previously associated with COPD at genome-wide significance. The results were confirmed in the validation set.

FINDINGS

We identified four clusters that can be characterised as (1) relatively resistant smokers (ie, no/mild obstruction and minimal emphysema despite heavy smoking), (2) mild upper zone emphysema-predominant, (3) airway disease-predominant and (4) severe emphysema. All clusters are strongly associated with COPD-related clinical characteristics, including exacerbations and dyspnoea (p<0.001). We found strong genetic associations between the mild upper zone emphysema group and rs1980057 near HHIP, and between the severe emphysema group and rs8034191 in the chromosome 15q region (p<0.001). All significant associations were replicated at p<0.05 in the validation sample (12/12 associations with clinical measures and 2/2 genetic associations).

INTERPRETATION

Cluster analysis identifies four subgroups of smokers that show robust associations with clinical characteristics of COPD and known COPD-associated genetic variants.

Acquired cystic fibrosis transmembrane conductance regulator dysfunction in the lower airways in COPD

BACKGROUND

Cigarette smoke and smoking-induced inflammation decrease cystic fibrosis transmembrane conductance regulator (CFTR) activity and mucociliary transport in the nasal airway and cultured bronchial epithelial cells. This raises the possibility that lower airway CFTR dysfunction may contribute to the pathophysiology of COPD. We compared lower airway CFTR activity in current and former smokers with COPD, current smokers without COPD, and lifelong nonsmokers to examine the relationships between clinical characteristics and CFTR expression and function.

METHODS

Demographic, spirometry, and symptom questionnaire data were collected. CFTR activity was determined by nasal potential difference (NPD) and lower airway potential difference (LAPD) assays. The primary measure of CFTR function was the total change in chloride transport (Δchloride-free isoproterenol). CFTR protein expression in endobronchial biopsy specimens was measured by Western blot.

RESULTS

Compared with healthy nonsmokers (n = 11), current smokers (n = 17) showed a significant reduction in LAPD CFTR activity (Δchloride-free isoproterenol, -8.70 mV vs -15.9 mV; P = .003). Similar reductions were observed in smokers with and without COPD. Former smokers with COPD (n = 7) showed a nonsignificant reduction in chloride conductance (-12.7 mV). A similar pattern was observed for CFTR protein expression. Univariate analysis demonstrated correlations between LAPD CFTR activity and current smoking, the presence of chronic bronchitis, and dyspnea scores.

CONCLUSIONS

Smokers with and without COPD have reduced lower airway CFTR activity compared with healthy nonsmokers, and this finding correlates with disease phenotype. Acquired CFTR dysfunction may contribute to COPD pathogenesis.

Variations in FEV₁ decline over time in chronic obstructive pulmonary disease and its implications

PURPOSE OF REVIEW

This article reviews findings from longitudinal observational studies in both general and chronic obstructive pulmonary disease (COPD) populations, as well as from intervention trials in COPD, in which the annual rate of decline in forced expired volume in 1  s (FEV₁) has been measured. The purpose of the review is to describe the individual variability in rates of decline in FEV₁ within these populations, explore the factors contributing to this variability and discuss its implications.

RECENT FINDINGS

Individual rates of decline in FEV₁ have been found to vary considerably across participants with COPD in both observational cohorts and intervention trials from decreases as rapid as 150-200  ml per year to increases of up to approximately 150  ml per year, with mean rates of decline ranging from 33 to 69  ml per year. Aside from technical and biologic (e.g., time of day, season, weather, fatigue) sources of variation, other influential factors have included smoking status (most notably current versus former smoking), baseline smoking intensity, baseline lung function, airway hyperresponsiveness, exacerbation frequency, and, variably, age and sex. The presence of emphysema may also be a determinant, as well as certain biomarkers and gene variants.

SUMMARY

The wide distribution of individual rates of decline in FEV₁ includes especially rapid and slow declines. Future research is needed to identify biomarkers that both are predictive of a rapid decline within individuals who might then be targeted for special intervention and might also serve as surrogate endpoints in interventional trials.

A new approach to grading and treating COPD based on clinical phenotypes: summary of the Spanish COPD guidelines (GesEPOC)

After the development of the COPD Strategy of the National Health Service in Spain, all scientific societies, patient organisations, and central and regional governments formed a partnership to enhance care and research in COPD. At the same time, the Spanish Society of Pneumology and Thoracic Surgery (SEPAR) took the initiative to convene the various scientific societies involved in the National COPD Strategy and invited them to participate in the development of the new Spanish guidelines for COPD (Guía Española de la EPOC; GesEPOC). Probably the more innovative approach of GesEPOC is to base treatment of stable COPD on clinical phenotypes, a term which has become increasingly used in recent years to refer to the different clinical forms of COPD with different prognostic implications. The proposed phenotypes are: (A) infrequent exacerbators with either chronic bronchitis or emphysema; (B) overlap COPD-asthma; (C) frequent exacerbators with emphysema predominant; and (D) frequent exacerbators with chronic bronchitis predominant. The assessment of severity has also been updated with the incorporation of multidimensional indices. The severity of the obstruction, as measured by forced expiratory volume in 1 second, is essential but not sufficient. Multidimensional indices such as the BODE index have shown excellent prognostic value. If the 6-minute walking test is not performed routinely, its substitution by the frequency of exacerbations (BODEx index) provides similar prognostic properties. This proposal aims to achieve a more personalised management of COPD according to the clinical characteristics and multidimensional assessment of severity.

Prevalence and characteristics of three clinical phenotypes of chronic obstructive pulmonary disease (COPD)

AIM

To determine the prevalence and analyze the most relevant clinical characteristics of three clinical phenotypes of COPD: emphysema (type 1), chronic bronchitis (type 2) or COPD-asthma (type 3).

METHOD

Observational, multicenter study performed with 331 COPD patients recruited in pulmonology outpatient services. The stratification in three phenotypes was performed with imaging tests, pulmonary function, and a standardized clinical questionnaire.

RESULTS

The 43.2% presented an emphysematous phenotype, 44.7% were chronic bronchitic and the other 12.1% presented a phenotype showing mixed characteristics with asthma. There were no significant differences in the smoking level, in the gasometric values or time of disease evolution. Type 1 patients showed lower FEV1 values in comparison with types 2 and 3, 46.6% (21.1), 55.2% (21.2) and 54.4% (21.8), respectively (p < 0.05), and greater levels of dyspnea (p < 0.05). No significant differences were observed in the percentage of patients who had at least one exacerbation in the last year (68.8%, 63.9%, 64.9%; p = 0.25), in the number of exacerbations (p = 0.56), in the number of visits to the ER (total and due to COPD), or in the number of hospital admittances. Type 2 patients showed a greater prevalence of cardiovascular comorbidities and of sleep apnea syndrome (4.9%, 23.6% and 12.5%, respectively, p < 0.001).

CONCLUSIONS

In COPD, emphysematous patients present worse pulmonary function and greater dyspnea, although there were no differences in the use of hospital health care resources. The greater comorbidity in Group 2 patients may require specific strategies in this subgroup of patients.

Assessing efficacy of indacaterol in moderate and severe COPD patients: a 12-week study in an Asian population

INTRODUCTION

This post hoc analysis evaluated the efficacy of indacaterol, a novel inhaled once-daily long-acting β(2)-agonist, by disease severity (GOLD 2005) in patients with moderate-to-severe COPD from six Asian countries/areas (Hong Kong, India, Japan, Korea, Singapore, Taiwan).

METHODS

Data from a 12-week, double-blind, placebo-controlled, parallel-group study in patients randomized to indacaterol 150 μg, indacaterol 300 μg or placebo once daily were analyzed based on baseline disease severity (moderate or severe). Endpoints were: trough FEV(1) (average of 23 h 10 min and 23 h 45 min post-dose values), transition dyspnoea index (TDI) and St George's Respiratory Questionnaire (SGRQ) at Week 12. Safety data were collected.

RESULTS

Of 347 patients randomized, 59.7% had moderate, and 40.3% had severe COPD. Least squares means (LSMs) indacaterol-placebo differences in trough FEV(1) at Week 12 exceeded the pre-specified minimal clinically important difference (MCID) of 0.12L and were statistically superior (p < 0.001) for indacaterol (150 μg, 300 μg) versus placebo in the two subgroups [0.19L, 0.20L (moderate); 0.15L, 0.19L (severe) respectively]. LSM TDI scores for both indacaterol doses versus placebo in both subgroups were statistically superior (p < 0.05) and clinically meaningful (≥1 unit). Both indacaterol doses showed improvements in LSM SGRQ total scores at Week 12 which exceeded the MCID (4 units) versus placebo in both subgroups, with indacaterol 300 μg-placebo difference in the severe subgroup being statistically significant (p < 0.01). Overall incidence of adverse events was lower with indacaterol than with placebo across both subgroups.

CONCLUSIONS

Indacaterol demonstrated clinically relevant improvements versus placebo in lung function, dyspnea and health status in Asian COPD patients irrespective of disease severity.

CLINICAL TRIALS IDENTIFIER

NCT00794157.

Functional characterization of the matrix metalloproteinase-1 cigarette smoke-responsive region and association with the lung health study

BACKGROUND

Prior studies have demonstrated that the distal 1.5 kb of the MMP-1 promoter is fundamental in directing the induction of the MMP-1 gene by cigarette smoke.

METHODS

To characterize the genetic variants in the MMP-1 cigarette smoke-responsive element, deep re-sequencing of this element was performed on DNA samples from participants in the Lung Health Study. Furthermore, evidence of Sp1 binding to the MMP-1 promoter was assessed using chromatin immunoprecipitation assays and the influence of cigarette smoke exposure on this interaction was evaluated in cultured human small airway epithelial cells.

RESULTS

Ten polymorphisms (four novel) were detected in the cigarette smoke-responsive element. Chromatin immunoprecipitation assays to assess the protein-DNA interactions at Sp1 sites in the MMP-1 promoter showed increased binding to the Sp1 sites in the cigarette smoke-responsive element in small airway epithelial cells treated with cigarette smoke extract. In contrast, a Sp1 site outside of the element exhibited the opposite effect. None of the polymorphisms were more prevalent in the fast decliners versus the slow decliners (fast decliners = mean -4.14% decline in FEV1% predicted per year vs. decline in FEV1% predicted per year).

CONCLUSIONS

Sequencing analyses identified four novel polymorphisms within the cigarette smoke-responsive element of the MMP-1 promoter. This study identifies functional activity within the cigarette smoke-responsive element that is influenced by cigarette smoke and examines this region of the promoter within a small patient population.

The relationship between lung function impairment and quantitative computed tomography in chronic obstructive pulmonary disease

OBJECTIVES

To determine the relationship between lung function impairment and quantitative computed tomography (CT) measurements of air trapping and emphysema in a population of current and former heavy smokers with and without airflow limitation.

METHODS

In 248 subjects (50 normal smokers; 50 mild obstruction; 50 moderate obstruction; 50 severe obstruction; 48 very severe obstruction) CT emphysema and CT air trapping were quantified on paired inspiratory and end-expiratory CT examinations using several available quantification methods. CT measurements were related to lung function (FEV(1), FEV(1)/FVC, RV/TLC, Kco) by univariate and multivariate linear regression analysis.

RESULTS

Quantitative CT measurements of emphysema and air trapping were strongly correlated to airflow limitation (univariate r-squared up to 0.72, p < 0.001). In multivariate analysis, the combination of CT emphysema and CT air trapping explained 68-83% of the variability in airflow limitation in subjects covering the total range of airflow limitation (p < 0.001).

CONCLUSIONS

The combination of quantitative CT air trapping and emphysema measurements is strongly associated with lung function impairment in current and former heavy smokers with a wide range of airflow limitation.

Biomarkers of therapeutic response in patients with chronic obstructive pulmonary disease: a critical review of the literature

Chronic obstructive pulmonary disease (COPD) is a leading cause of morbidity and mortality across the world. Unfortunately, none of the current therapies, except for smoking cessation and supplemental domiciliary oxygen for hypoxaemic patients, can modify its natural course or alter survival. The pipeline for new compounds is not very promising owing to repeated failures, and many large pharmaceutical companies have abandoned COPD drug discovery altogether. One major barrier to new drug discovery is the lack of modifiable biomarkers that can be used as surrogates of clinical outcomes such as exacerbation and mortality. The only accepted marker in COPD is forced expiratory volume in 1 second (FEV(1)). However, by definition, COPD is a non-reversible or poorly reversible condition with respect to FEV(1). Thus, very few drugs except for bronchodilators have been able to address this endpoint. Of many candidate molecules, sputum neutrophil counts, exhaled corrected alveolar nitric oxide and proline-glycine-proline (PGP) and N-α-PGP, which are breakdown products of collagen, are promising lung-based biomarkers. However, their clinical utility has not been validated in large clinical trials. Promising blood biomarkers include surfactant protein D, and pulmonary- and activation-regulated chemokine (PARC/CCL-18). However, the clinical data have been inconsistent. Non-specific inflammatory biomarkers such as C-reactive protein and interleukin-6 lack specificity for COPD and thus are of limited clinical usefulness.

Clinical phenotypes of COPD: identification, definition and implications for guidelines

The term phenotype in the field of COPD is defined as "a single or combination of disease attributes that describe differences between individuals with COPD as they relate to clinically meaningful outcomes". Among all phenotypes described, there are three that are associated with prognosis and especially are associated with a different response to currently available therapies. There phenotypes are: the exacerbator, the overlap COPD-asthma and the emphysema-hyperinflation. The exacerbator is characterised by the presence of, at least, two exacerbations the previous year, and on top of long-acting bronchodilators, may require the use of antiinflammatory drugs. The overlap phenotype presents symptoms of increased variability of airflow and incompletely reversible airflow obstruction. Due to the underlying inflammatory profile, it uses to have a good therapeutic response to inhaled corticosteroids in addition to bronchodilators. Lastly, the emphysema phenotype presents a poor therapeutic response to the existing antiinflammatory drugs and long-acting bronchodilators together with rehabilitation are the treatments of choice. Identifying the peculiarities of the different phenotypes of COPD will allow us to implement a more personalised treatment, in which the characteristics of the patients, together with their severity will be key to choose the best treatment option.