Evaluation of COPD Longitudinally to Identify Predictive Surrogate End-points (ECLIPSE)

N-glycosylation patterns of plasma proteins and immunoglobulin G in chronic obstructive pulmonary disease

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is a complex condition, whose diagnosis requires spirometric assessment. However, considering its heterogeneity, subjects with similar spirometric parameters do not necessarily have the same functional status. To overcome this limitation novel biomarkers for COPD have been investigated. Therefore, we aimed to explore the potential value of N-glycans as COPD biomarkers and to examine the individual variation of plasma protein and immunoglobulin G (IgG) glycosylation profiles in subjects with COPD and healthy controls.

METHODS

Both the total plasma protein and IgG N-glycome have been profiled in the total of 137 patients with COPD and 95 matching controls from Croatia. Replication cohort consisted of 61 subjects with COPD and 148 controls recruited at another Croatian medical centre.

RESULTS

Plasma protein N-glycome in COPD subjects exhibited significant decrease in low branched and conversely, an increase in more complex glycan structures (tetragalactosylated, trisialylated, tetrasialylated and antennary fucosylated glycoforms). We also observed a significant decline in plasma monogalactosylated species, and the same change replicated in IgG glycome. N-glycans also showed value in distinguishing subjects in different COPD GOLD stages, where the relative abundance of more complex glycan structures increased as the disease progressed. Glycans also showed statistically significant associations with the frequency of exacerbations and demonstrated to be affected by smoking, which is the major risk factor for COPD development.

CONCLUSIONS

This study showed that complexity of glycans associates with COPD, mirroring also the disease severity. Moreover, changes in N-glycome associate with exacerbation frequency and are affected by smoking. In general, this study provided new insights into plasma protein and IgG N-glycome changes occurring in COPD and pointed out potential novel markers of the disease progression and severity.

Long-term outcomes following first short-term clinically important deterioration in COPD

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is characterized by varying trajectories of decline. Information regarding the prognostic value of preventing short-term clinically important deterioration (CID) in lung function, health status, or first moderate/severe exacerbation as a composite endpoint of worsening is needed. We evaluated post hoc the link between early CID and long-term adverse outcomes.

METHODS

CID was defined as ≥100 mL decrease in forced expiratory volume in 1 s (FEV1), ≥4-unit increase in St George's Respiratory Questionnaire (SGRQ) score from baseline, and/or a moderate/severe exacerbation during enrollment in two 3-year studies. Presence of CID was assessed at 6 months for the principal analysis (TORCH) and 12 months for the confirmatory analysis (ECLIPSE). Association between presence (+) or absence (-) of CID and long-term deterioration in FEV1, SGRQ, future risk of exacerbations, and all-cause mortality was assessed.

RESULTS

In total, 2870 (54%; TORCH) and 1442 (73%; ECLIPSE) patients were CID+. At 36 months, in TORCH, CID+ patients (vs CID-) had sustained clinically significant worsening of FEV1 (- 117 mL; 95% confidence interval [CI]: - 134, - 100 mL; P < 0.001) and SGRQ score (+ 6.42 units; 95% CI: 5.40, 7.45; P < 0.001), and had higher risk of exacerbations (hazard ratio [HR]: 1.61 [95% CI: 1.50, 1.72]; P < 0.001) and all-cause mortality (HR: 1.41 [95% CI: 1.15, 1.72]; P < 0.001). Similar risks post-CID were observed in ECLIPSE.

CONCLUSIONS

A CID within 6-12 months of follow-up was consistently associated with increased long-term risk of exacerbations and all-cause mortality, and predicted sustained meaningful loss in FEV1 and health status amongst survivors.

TRIAL REGISTRATION

NCT00268216 ; NCT00292552 .

Preventing Clinically Important Deterioration of COPD with Addition of Umeclidinium to Inhaled Corticosteroid/Long-Acting β2-Agonist Therapy: An Integrated Post Hoc Analysis

INTRODUCTION

Assessing clinically important measures of disease progression is essential for evaluating therapeutic effects on disease stability in chronic obstructive pulmonary disease (COPD). This analysis assessed whether providing additional bronchodilation with the long-acting muscarinic antagonist umeclidinium (UMEC) to patients treated with inhaled corticosteroid (ICS)/long-acting β2-agonist (LABA) therapy would improve disease stability compared with ICS/LABA therapy alone.

METHODS

This integrated post hoc analysis of four 12-week, randomized, double-blind trials (NCT01772134, NCT01772147, NCT01957163, NCT02119286) compared UMEC 62.5 µg with placebo added to open-label ICS/LABA in symptomatic patients with COPD (modified Medical Research Council dyspnea scale score ≥ 2). A clinically important deterioration (CID) was defined as: a decrease from baseline of ≥ 100 mL in trough forced expiratory volume in 1 s (FEV1), an increase from baseline of ≥ 4 units in St George's Respiratory Questionnaire (SGRQ) total score, or a moderate/severe exacerbation. Risk of a first CID was evaluated in the intent-to-treat (ITT) population and in patients stratified by Global initiative for chronic Obstructive Lung Disease (GOLD) classification, exacerbation history and type of ICS/LABA therapy. Adverse events (AEs) were also assessed.

RESULTS

Overall, 1637 patients included in the ITT population received UMEC + ICS/LABA (n = 819) or placebo + ICS/LABA (n = 818). Additional bronchodilation with UMEC reduced the risk of a first CID by 45-58% in the ITT population and all subgroups analyzed compared with placebo (all p < 0.001). Improvements were observed in reducing FEV1 (69% risk reduction; p < 0.001) and exacerbation (47% risk reduction; p = 0.004) events in the ITT population. No significant reduction in risk of a SGRQ CID was observed. AE incidence was similar between treatment groups.

CONCLUSION

Symptomatic patients with COPD receiving ICS/LABA experience frequent deteriorations. Additional bronchodilation with UMEC significantly reduced the risk of CID and provided greater short-term stability versus continued ICS/LABA therapy in these patients.

FUNDING

GlaxoSmithKline (study number: 202067). Plain language summary available for this article.

High Imminent Vertebral Fracture Risk in Subjects With COPD With a Prevalent or Incident Vertebral Fracture

Subjects with chronic obstructive pulmonary disease (COPD) have an increased risk of vertebral fractures (VFs); however, VF incidence is largely unknown. Therefore, the aim of our study was to determine the incidence of new and/or worsening VF in subjects with COPD. Smokers and subjects with COPD (GOLD II-IV) from the ECLIPSE study with complete set of chest CT scans (baseline and 1- and 3-year follow-up) to evaluate vertebrae T₁ down to L₁ were included. If a VF was diagnosed on the last scan, detailed VF assessment of the previous scans was performed. VFs were scored according to the method of Genant as mild, moderate, or severe. Main outcome measure was the cumulative incidence of new and/or worsening VF at subject level, within 1 and 3 years. Of 1239 subjects (mean age 61 years, 757 males [61%], 999 subjects with COPD), 253 (20.5%) had ≥1 prevalent VF. The cumulative incidence of VFs was 10.1% within 1 year and 24.0% within 3 years. After adjustment for age, sex, body mass index (BMI), pack-years, and smoking status, prevalence and incidence were similar between smokers and COPD GOLD stages. Within 1 year, 29.2% of the subjects with a prevalent VF had an incident VF, compared with 5.1% in absence of prevalent VF (hazard ratio [HR] = 5.1; 95% confidence interval [CI] 3.6-7.4) and 58.5% versus 15.0% within 3 years (HR = 3.6; 95% CI 2.9-4.6). The incidence of VF was higher with increasing number and severity of prevalent VFs. Among subjects having an incident VF within the first year, 57.3% had a subsequent VF within the next 2 years. In this study, more than half of the smokers and subjects with COPD with a prevalent VF or an incident VF within the first year sustained a subsequent VF within 3 years. The 3-year risk was even higher in the presence of multiple or severe prevalent VFs. © 2018 The Authors. Journal of Bone and Mineral Research Published by Wiley Periodicals Inc.

Development of a pulmonary imaging biomarker pipeline for phenotyping of chronic lung disease

We designed and generated pulmonary imaging biomarker pipelines to facilitate high-throughput research and point-of-care use in patients with chronic lung disease. Image processing modules and algorithm pipelines were embedded within a graphical user interface (based on the .NET framework) for pulmonary magnetic resonance imaging (MRI) and x-ray computed-tomography (CT) datasets. The software pipelines were generated using C++ and included: (1) inhaled He3/Xe129 MRI ventilation and apparent diffusion coefficients, (2) CT-MRI coregistration for lobar and segmental ventilation and perfusion measurements, (3) ultrashort echo-time H1 MRI proton density measurements, (4) free-breathing Fourier-decomposition H1 MRI ventilation/perfusion and free-breathing H1 MRI specific ventilation, (5) multivolume CT and MRI parametric response maps, and (6) MRI and CT texture analysis and radiomics. The image analysis framework was implemented on a desktop workstation/tablet to generate biomarkers of regional lung structure and function related to ventilation, perfusion, lung tissue texture, and integrity as well as multiparametric measures of gas trapping and airspace enlargement. All biomarkers were generated within 10 min with measurement reproducibility consistent with clinical and research requirements. The resultant pulmonary imaging biomarker pipeline provides real-time and automated lung imaging measurements for point-of-care and high-throughput research.

Investigating Fractional Exhaled Nitric Oxide in Chronic Obstructive Pulmonary Disease (COPD) and Asthma-COPD Overlap (ACO): A Scoping Review

Chronic obstructive pulmonary disease (COPD) is the most common fixed airflow limitation. Individuals may present with the features of both asthma and COPD called asthma-COPD overlap (ACO) with more severity and worse health-related quality of life than COPD or asthma. One of the promising biomarkers that could be used in clinical practice to differentiate ACO from COPD is fractional exhaled nitric oxide (FENO). The role of Fractional exhaled nitric oxide (FENO) in COPD/ACO remains unknown. This scoping review aims to investigate the role of FENO measurement to differentiate COPD from ACO, to anticipate disease severity/progression and treatment response. A structured comprehensive literature search was performed in major databases including Medline, EMBASE, CINAHL, Cochrane Library, Web of Science, and BIOSIS from 2005 onwards. Thirty-eight studies were retrieved. Based on the synthesis of the reviewed literature, six themes emerged. Thirty-four articles covered more than one theme. From which, 24 articles were on modifying factors in FENO measurement, 18 on FENO in COPD compared with healthy subjects, and seven on FENO in ACO compared with COPD, 22 on FENO and disease severity/progression,12 on FENO and biomarkers, and eight on FENO and treatment response. FENO measurement cannot be used alone in the clinical settings of COPD patients. Although FENO level is higher in ACO patients than COPD-only, it is still unclear if there is a FENO cut-off that can be used to make the diagnosis of ACO and/or to guide therapy with inhaled corticosteroids/glucocorticoids in COPD patients.

Blood eosinophil count thresholds and exacerbations in patients with chronic obstructive pulmonary disease

BACKGROUND

Eosinophilic airway inflammation in patients with chronic obstructive pulmonary disease (COPD) is associated with exacerbations and responsivity to steroids, suggesting potential shared mechanisms with eosinophilic asthma. However, there is no consistent blood eosinophil count that has been used to define the increased exacerbation risk.

OBJECTIVE

We sought to investigate blood eosinophil counts associated with exacerbation risk in patients with COPD.

METHODS

Blood eosinophil counts and exacerbation risk were analyzed in patients with moderate-to-severe COPD by using 2 independent studies of former and current smokers with longitudinal data. The Genetic Epidemiology of COPD (COPDGene) study was analyzed for discovery (n = 1,553), and the Evaluation of COPD Longitudinally to Identify Predictive Surrogate Endpoints (ECLIPSE) study was analyzed for validation (n = 1,895). A subset of the ECLIPSE study subjects were used to assess the stability of blood eosinophil counts over time.

RESULTS

COPD exacerbation risk increased with higher eosinophil counts. An eosinophil count threshold of 300 cells/μL or greater showed adjusted incidence rate ratios for exacerbations of 1.32 in the COPDGene study (95% CI, 1.10-1.63). The cutoff of 300 cells/μL or greater was validated for prospective risk of exacerbation in the ECLIPSE study, with adjusted incidence rate ratios of 1.22 (95% CI, 1.06-1.41) using 3-year follow-up data. Stratified analysis confirmed that the increased exacerbation risk associated with an eosinophil count of 300 cells/μL or greater was driven by subjects with a history of frequent exacerbations in both the COPDGene and ECLIPSE studies.

CONCLUSIONS

Patients with moderate-to-severe COPD and blood eosinophil counts of 300 cells/μL or greater had an increased risk exacerbations in the COPDGene study, which was prospectively validated in the ECLIPSE study.

Is the purinergic pathway involved in the pathology of COPD? Decreased lung CD39 expression at initial stages of COPD

BACKGROUND

Extracellular adenosine triphosphate (ATP) is up-regulated in the airways of patients with chronic obstructive pulmonary disease (COPD), resulting in increased inflammation, bronchoconstriction, and cough. Although extracellular ATP levels are tightly controlled by nucleoside triphosphate diphosphohydrolase-1 (NTPDase1; also known as CD39) in the lungs, the role of CD39 in the pathology of COPD is unknown. We hypothesized that alterations in the expression and activity of CD39 could be part of the mechanisms for initiating and perpetuating the disease.

METHODS

We analyzed CD39 gene and protein expression as well as ATPase enzyme activity in lung tissue samples of patients with COPD (n = 17), non-obstructed smokers (NOS) (n = 16), and never smokers (NS) (n = 13). Morphometry studies were performed to analyze pulmonary vascular remodeling.

RESULTS

There was significantly decreased CD39 gene expression in the lungs of the COPD group (1.17 [0.85-1.81]) compared with the NOS group (1.88 [1.35-4.41]) and NS group (3.32 [1.23-5.39]) (p = 0.037). This attenuation correlated with higher systemic inflammation and intimal thickening of muscular pulmonary arteries in the COPD group. Lung CD39 protein levels were also lower in the COPD group (0.34 [0.22-0.92]) compared with the NOS group (0.67 [0.32-1.06]) and NS group (0.95 [0.4-1.1) (p = 0.133). Immunohistochemistry showed that CD39 was downregulated in lung parenchyma, epithelial bronchial cells, and the endothelial cells of pulmonary muscular arteries in the COPD group. ATPase activity in human pulmonary structures was reduced in the lungs of patients with COPD.

CONCLUSION

An attenuation of CD39 expression and activity is presented in lung tissue of stable COPD patients, which could lead to pulmonary ATP accumulation, favoring the development of pulmonary inflammation and emphysema. This may be a mechanism underlying the development of COPD.

The role of high resolution oesophageal manometry in occult respiratory symptoms

PURPOSE

Cough Hypersensitivity Syndrome is the urge to cough following minimal stimulation, but its mechanism and method of provocation remain unexplained. 121 patients (44 males, 77 females; age range 18-81 years) were evaluated.

PROCEDURES

High resolution manometry was performed on consecutive patients presenting with unexplained respiratory symptoms (Respiratory Group 61). Data were compared with matched controls, i.e. dyspepsia without respiratory symptoms (Dyspepsia Group 60).

MAIN FINDINGS

Results showed increased inspiratory gastro-oesophageal pressure gradient due to significantly lower intra-oesophageal pressure on inspiration (p = 0.001), and reduced oesophageal motility in the Respiratory Group.

CONCLUSIONS

Further research in respiratory conditions characterised by decreased intrathoracic pressure during inspiration is needed.

Current Approaches for Phenotyping as a Target for Precision Medicine in COPD Management

The study of airway diseases continues to present several challenges for modern medicine. The different disease presentations with variables and overlapping features may result in a real challenge for the clinician. In this context, the concept of precision medicine has started to emerge in order to give answers to some of these challenges from a diagnostic and therapeutic point of view. The main reasons to target for precision medicine in chronic obstructive pulmonary disease (COPD) include that there is variability in the clinical presentation, there is no correlation between the different clinical variables at the patient level, there are a number of relevant clinical variables associated with outcomes, we do have specific therapies for specific patient types, and that there is variability in the clinical response to different therapies. To bring precision medicine into clinical practice several approaches have been used, including the use of independent variables to identify subjects, the use of multidimensional indexes, the so-called clinical phenotypes, and the approximation by the so-called treatable traits. All these approaches have their strengths and weaknesses which are reviewed in the present document. Although there is no universally accepted proposal, the available initiatives provide us with a framework on which to start working and move toward precision medicine in COPD, with the ultimate goal of bringing the best possible medicine to each patient in particular.

Prevalence and features of asthma-chronic obstructive pulmonary disease overlap in Northern Italy general population

OBJECTIVE

There is controversy about the diagnostic criteria, prevalence, symptoms, and spirometry characteristics of asthma-chronic obstructive pulmonary disease (COPD) overlap (ACO). Recent data indicate that the fixed method for diagnosing airway obstruction (AO) may overestimate ACO prevalence in the elderly, and a variable method may be more accurate. We aimed at estimating ACO prevalence in a general population sample and comparing patient and clinical features in subjects with ACO, COPD, and asthma.

METHODS

We analyzed data from a cross-sectional study estimating COPD prevalence in randomly selected adults aged 20-79 years in Verona, Italy, and estimated prevalence and analyzed characteristics of asthma, COPD, and ACO. ACO was defined as AO (Forced Expiratory Volume in one second-FEV₁/ Forced Vital Capacity-FVC < Lower Limit of Normal-LLN), highly positive bronchodilator test (≥15% increase in FEV₁ and FVC ≥400 mL), and personal self-reported history of physician diagnosed asthma and atopy.

RESULTS

One thousand two hundred and thirty-six patients were included; 207 (16.7%) had asthma, COPD, or ACO (mean ages: 61.2, 59.7, and 57.2 years, respectively). The 3 groups had similar clinical and demographic variables; however, spirometry revealed differences between ACO and COPD patients, particularly post-bronchodilator FEV₁ reversibility, which was detected in ACO and asthma patients but not in those with COPD.

CONCLUSION

ACO prevalence in Northern Italy was estimated at 2.1%, in the range of values reported by previous studies. Marked differences between ACO and COPD revealed by spirometry may have important clinical implications in terms of treatment for patients with ACO.

Emphysema and extrapulmonary tissue loss in COPD: a multi-organ loss of tissue phenotype

We tested whether emphysema progression accompanies enhanced tissue loss in other body compartments in 1817 patients from the ECLIPSE chronic obstructive pulmonary disease (COPD) cohort.Clinical and selected systemic biomarker measurements were compared in subjects grouped by quantitative tomography scan emphysema quartiles using the percentage of low attenuation area (LAA%). Lowest and highest quartile patients had amino-acid metabolomic profiles. We related LAA% to 3 years decline in lung function (forced expiratory volume in 1 s (FEV₁)), body mass index (BMI), fat-free mass index (FFMI) and exacerbations, hospitalisations and mortality rates.Participants with more baseline emphysema had lower FEV₁, BMI and FFMI, worse functional capacity, and less cardiovascular disease but more osteoporosis. Systemic C-reactive protein and interleukin-6 levels were similar among groups, but club cell protein 16 was higher and interleukin-8, surfactant protein D and soluble receptor for advanced glycation end product were lower with more emphysema. Metabolomics differed between extreme emphysema quartiles. Patients with more emphysema had accelerated FEV₁, BMI and FFMI decline and more exacerbations, hospitalisations and mortality.COPD patients with more emphysema undergo excessive loss of pulmonary and extrapulmonary tissue, which is probably related to abnormal tissue maintenance. Because of worse clinical outcomes, we propose this subgroup be named the multi-organ loss of tissue (MOLT) COPD phenotype.

Disease Staging and Prognosis in Smokers Using Deep Learning in Chest Computed Tomography

RATIONALE

Deep learning is a powerful tool that may allow for improved outcome prediction.

OBJECTIVES

To determine if deep learning, specifically convolutional neural network (CNN) analysis, could detect and stage chronic obstructive pulmonary disease (COPD) and predict acute respiratory disease (ARD) events and mortality in smokers.

METHODS

A CNN was trained using computed tomography scans from 7,983 COPDGene participants and evaluated using 1,000 nonoverlapping COPDGene participants and 1,672 ECLIPSE participants. Logistic regression (C statistic and the Hosmer-Lemeshow test) was used to assess COPD diagnosis and ARD prediction. Cox regression (C index and the Greenwood-Nam-D'Agnostino test) was used to assess mortality.

MEASUREMENTS AND MAIN RESULTS

In COPDGene, the C statistic for the detection of COPD was 0.856. A total of 51.1% of participants in COPDGene were accurately staged and 74.95% were within one stage. In ECLIPSE, 29.4% were accurately staged and 74.6% were within one stage. In COPDGene and ECLIPSE, the C statistics for ARD events were 0.64 and 0.55, respectively, and the Hosmer-Lemeshow P values were 0.502 and 0.380, respectively, suggesting no evidence of poor calibration. In COPDGene and ECLIPSE, CNN predicted mortality with fair discrimination (C indices, 0.72 and 0.60, respectively), and without evidence of poor calibration (Greenwood-Nam-D'Agnostino P values, 0.307 and 0.331, respectively).

CONCLUSIONS

A deep-learning approach that uses only computed tomography imaging data can identify those smokers who have COPD and predict who are most likely to have ARD events and those with the highest mortality. At a population level CNN analysis may be a powerful tool for risk assessment.

An ECLIPSE View of Alpha-1 Antitrypsin Deficiency

Chronic obstructive pulmonary disease (COPD) is a multicomponent condition that is estimated to become the third leading cause of death in 2020. The ECLIPSE (Evaluation of COPD Longitudinally to Identify Predictive Surrogate Endpoints) study, funded by GlaxoSmithKline, is an observational study designed to define outcomes that can be used as endpoints in clinical trials in individuals with COPD. It allowed us to describe the heterogeneity of COPD, the stability of the exacerbation phenotype, and the factors associated with a progressive decline in lung function and the progression of emphysema on computed tomography scans. The cohort was also used to define genetic factors and biomarkers associated with COPD and disease progression. This review considers how the results from ECLIPSE can inform our understanding of the lung disease associated with alpha-1 antitrypsin deficiency.

Chest computed tomography-derived low fat-free mass index and mortality in COPD

Low fat-free mass index (FFMI) is an independent risk factor for mortality in chronic obstructive pulmonary disease (COPD) not typically measured during routine care. In the present study, we aimed to derive fat-free mass from the pectoralis muscle area (FFM_PMA) and assess whether low FFMI_PMA is associated with all-cause mortality in COPD cases. We used data from two independent COPD cohorts, ECLIPSE and COPDGene.Two equal sized groups of COPD cases (n=759) from the ECLIPSE study were used to derive and validate an equation to calculate the FFM_PMA measured using bioelectrical impedance from PMA. We then applied the equation in COPD cases (n=3121) from the COPDGene cohort, and assessed survival. Low FFMI_PMA was defined, using the Schols classification (FFMI <16 in men, FFMI <15 in women) and the fifth percentile normative values of FFMI from the UK Biobank.The final regression model included PMA, weight, sex and height, and had an adjusted R² of 0.92 with fat-free mass (FFM) as the outcome. In the test group, the correlation between FFM_PMA and FFM remained high (Pearson correlation=0.97). In COPDGene, COPD cases with a low FFMI_PMA had an increased risk of death (HR 1.6, p<0.001).We demonstrated COPD cases with a low FFMI_PMA have an increased risk of death.

Estimating drivers of cell state transitions using gene regulatory network models

Background

Specific cellular states are often associated with distinct gene expression patterns. These states are plastic, changing during development, or in the transition from health to disease. One relatively simple extension of this concept is to recognize that we can classify different cell-types by their active gene regulatory networks and that, consequently, transitions between cellular states can be modeled by changes in these underlying regulatory networks.

Results

Here we describe MONSTER, MOdeling Network State Transitions from Expression and Regulatory data, a regression-based method for inferring transcription factor drivers of cell state conditions at the gene regulatory network level. As a demonstration, we apply MONSTER to four different studies of chronic obstructive pulmonary disease to identify transcription factors that alter the network structure as the cell state progresses toward the disease-state.

Conclusions

We demonstrate that MONSTER can find strong regulatory signals that persist across studies and tissues of the same disease and that are not detectable using conventional analysis methods based on differential expression. An R package implementing MONSTER is available at github.com/QuackenbushLab/MONSTER.

Electronic supplementary material

The online version of this article (doi:10.1186/s12918-017-0517-y) contains supplementary material, which is available to authorized users.

Biomarkers of collagen turnover are related to annual change in FEV1 in patients with chronic obstructive pulmonary disease within the ECLIPSE study

Background

Change in forced expiratory volume in one second (FEV₁) is important for defining severity of chronic obstructive pulmonary disease (COPD). Serological neoepitope markers of collagen turnover may predict rate of change in FEV₁.

Methods

One thousand COPD subjects from the observational, multicentre, three-year ECLIPSE (Evaluation of COPD Longitudinally to Identify Predictive Surrogate Endpoints) study (NCT00292552, trial registration in February 2006) were included. Matrix metalloproteinase (MMP)-generated fragments of collagen type I, and type VI (C1M and C6M) were assessed in month six serum samples. A random-coefficient model with both a random intercept and a random slope was used to test the ability of the markers to predict post-dose bronchodilator FEV₁ (PD-FEV₁) change over two years adjusting for sex, age, BMI, smoking, bronchodilator reversibility, prior exacerbations, emphysema and chronic bronchitis status at baseline.

Results

Annual change of PD-FEV₁ was estimated from a linear model for the two-year study period. Serum C1M and C6M were independent predictors of lung function change (p = 0.007/0.005). Smoking, bronchodilator reversibility, plasma hsCRP and emphysema were also significant predictors. The effect estimate between annual change in PD-FEV₁ per one standard deviation (1SD) increase of C1M and C6M was +10.4 mL/yr. and +8.6 mL/yr. C1M, and C6M, had a significant association with baseline FEV₁.

Conclusion

We demonstrated that markers of tissue turnover were significantly associated with lung function change. These markers may function as prognostic biomarkers and possibly as efficacy biomarkers in clinical trials focusing on lung function change in COPD.

Trial registration

NCT00292552, Retrospectively registered, trial registration in February 2006.

Electronic supplementary material

The online version of this article (10.1186/s12890-017-0505-4) contains supplementary material, which is available to authorized users.

Examining the Effects of Age on Health Outcomes of Chronic Obstructive Pulmonary Disease: Results From the Genetic Epidemiology of Chronic Obstructive Pulmonary Disease Study and Evaluation of Chronic Obstructive Pulmonary Disease Longitudinally to Identify Predictive Surrogate Endpoints Cohorts

RATIONALE

The prevalence of chronic obstructive pulmonary disease (COPD) and its associated comorbidities increase with age. However, little is understood about differences in the disease in patients over 65 years of age compared with younger patients.

OBJECTIVES

To determine disease characteristics of COPD and its impact in older patients compared with younger patients.

METHODS

We examined baseline characteristics of patients with COPD (global obstructive lung disease stage II-IV) in 2 large cohorts: Genetic Epidemiology of COPD Study (COPDGene) and Evaluation of COPD Longitudinally to Identify Predictive Surrogate Endpoints (ECLIPSE). We compared demographics, indices of disease severity, prevalence of comorbidities, exacerbation frequency, and quality of life scores in patients ≥65 years of age vs patients <65 years of age. We also tested for associations of age with disease characteristics and health outcomes.

RESULTS

In the COPDGene cohort, older patients (n = 1663) had more severe disease as measured by forced expiratory volume in 1 second (1.22 vs 1.52 L, P < .001), use of long-term oxygen therapy (35% vs 22%, P < .001), 6-minute walk distance (355 vs 375 m, P < .001), and radiographic evidence of emphysema (14% vs 8%, P < .001) and air trapping (47% vs 36%, P < .001) and were more likely to have comorbidities compared with younger patients (n = 2027). Similarly, in the ECLIPSE cohort, older patients (n = 1030) had lower forced expiratory volume in 1 second (1.22 vs 1.34 L, P < .001), greater use of long-term oxygen therapy (7% vs 5%, P = .02), shorter 6- minute walk distance (360 vs 389 m, P < .001), and more radiographic evidence of emphysema (17% vs 14%, P = .009) than younger patients (n = 1131). In adjusted analyses of both cohorts, older age was associated with decreased frequency of exacerbations [odds ratio = 0.52, 95% confidence interval (CI) = 0.43-0.64 in COPDGene, odds ratio = 0.79, 95% CI = 0.64-0.99 in ECLIPSE] and a better quality of life (lower St. Georges respiratory questionnaire score) (β = -8.7, 95% CI = -10.0 to -7.4 in COPDGene, β = -4.4, 95% CI = -6.1 to -3.2 in ECLIPSE).

CONCLUSIONS

Despite greater severity of illness, older patients with COPD had better quality of life and reported fewer exacerbations than younger patients. Although this observation needs to be explored further, it may be related to the fact that older patients change their expectations and learn to adapt to their disease.

A review of current and developing fixed-dose LABA/LAMA combinations for treating COPD

INTRODUCTION

The current GOLD (Global Initiative for Chronic Obstructive Lung Disease) recommendations suggest using long acting β2 agonists (LABA) and long acting muscarinic antagonists (LAMA) in combination for group B COPD patients with persistent symptoms, group C COPD patients with further exacerbations on LAMA therapy alone and for group D COPD patients with or without combination with inhaled corticosteroids (ICS). Thus, there is a lot of interest in developing LABA/LAMA combinations for maintenance therapy of chronic stable COPD. Areas covered: Many LABA/LAMA combinations have successfully been approved through carefully designed pivotal clinical trials. The current clinical use of LABA/LAMA combinations in COPD will continue to evolve as new trials with and without inhaled corticosteroids are completed. Expert opinion: Combining different classes of bronchodilators in a single inhaler is an attractive concept that can potentially improve patient adherence to therapy. Because LABA/LAMA combinations are the preferred treatment option for preventing COPD exacerbations in the updated GOLD guidelines for COPD, they will be clinically used. Future treatment of COPD should revolve around a personalized approach based on characterization of the COPD phenotype.

Prediction models for exacerbations in different COPD patient populations: comparing results of five large data sources

BACKGROUND AND OBJECTIVES

Exacerbations are important outcomes in COPD both from a clinical and an economic perspective. Most studies investigating predictors of exacerbations were performed in COPD patients participating in pharmacological clinical trials who usually have moderate to severe airflow obstruction. This study was aimed to investigate whether predictors of COPD exacerbations depend on the COPD population studied.

METHODS

A network of COPD health economic modelers used data from five COPD data sources - two population-based studies (COPDGene® and The Obstructive Lung Disease in Norrbotten), one primary care study (RECODE), and two studies in secondary care (Evaluation of COPD Longitudinally to Identify Predictive Surrogate Endpoint and UPLIFT) - to estimate and validate several prediction models for total and severe exacerbations (= hospitalization). The models differed in terms of predictors (depending on availability) and type of model.

RESULTS

FEV1% predicted and previous exacerbations were significant predictors of total exacerbations in all five data sources. Disease-specific quality of life and gender were predictors in four out of four and three out of five data sources, respectively. Age was significant only in the two studies including secondary care patients. Other significant predictors of total exacerbations available in one database were: presence of cough and wheeze, pack-years, 6-min walking distance, inhaled corticosteroid use, and oxygen saturation. Predictors of severe exacerbations were in general the same as for total exacerbations, but in addition low body mass index, cardiovascular disease, and emphysema were significant predictors of hospitalization for an exacerbation in secondary care patients.

CONCLUSIONS

FEV1% predicted, previous exacerbations, and disease-specific quality of life were predictors of exacerbations in patients regardless of their COPD severity, while age, low body mass index, cardiovascular disease, and emphysema seem to be predictors in secondary care patients only.

Meta-analysis of peripheral blood gene expression modules for COPD phenotypes

Chronic obstructive pulmonary disease (COPD) occurs typically in current or former smokers, but only a minority of people with smoking history develops the disease. Besides environmental factors, genetics is an important risk factor for COPD. However, the relationship between genetics, environment and phenotypes is not well understood. Sample sizes for genome-wide expression studies based on lung tissue have been small due to the invasive nature of sample collection. Increasing evidence for the systemic nature of the disease makes blood a good alternative source to study the disease, but there have also been few large-scale blood genomic studies in COPD. Due to the complexity and heterogeneity of COPD, examining groups of interacting genes may have more relevance than identifying individual genes. Therefore, we used Weighted Gene Co-expression Network Analysis to find groups of genes (modules) that are highly connected. However, module definitions may vary between individual data sets. To alleviate this problem, we used a consensus module definition based on two cohorts, COPDGene and ECLIPSE. We studied the relationship between the consensus modules and COPD phenotypes airflow obstruction and emphysema. We also used these consensus module definitions on an independent cohort (TESRA) and performed a meta analysis involving all data sets. We found several modules that are associated with COPD phenotypes, are enriched in functional categories and are overrepresented for cell-type specific genes. Of the 14 consensus modules, three were strongly associated with airflow obstruction (meta p ≤ 0.0002), and two had some association with emphysema (meta p ≤ 0.06); some associations were stronger in the case-control cohorts, and others in the cases-only subcohorts. Gene Ontology terms that were overrepresented included “immune response” and “defense response.” The cell types whose type-specific genes were overrepresented in modules (p < 0.05) included natural killer cells, dendritic cells, and neutrophils. Together, this is the largest investigation of gene blood expression in COPD with 469 cases in COPDGene, ECLIPSE and TESRA combined, with 6267 genes common to all data sets. Additional, we have 42 and 83 controls in COPDGene and ECLIPSE, respectively.

Integrative Genomics of Emphysema-Associated Genes Reveals Potential Disease Biomarkers

Chronic obstructive pulmonary disease is the third leading cause of death worldwide. Gene expression profiling across multiple regions of the same lung identified genes significantly related to emphysema. We sought to determine whether the lung and epithelial expression of 127 emphysema-related genes was also related to lung function in independent cohorts, and whether any of these genes could be used as biomarkers in the peripheral blood of patients with chronic obstructive pulmonary disease. To that end, we examined whether the expression levels of these genes were under genetic control in lung tissue (n = 1,111). We then determined whether the mRNA levels of these genes in lung tissue (n = 727), small airway epithelial cells (n = 238), and peripheral blood (n = 620) were significantly related to lung function measurements. The expression of 63 of the 127 genes (50%) was under genetic control in lung tissue. The lung and epithelial mRNA expression of a subset of the emphysema-associated genes, including ASRGL1, LPHN2, and EDNRB, was strongly associated with lung function. In peripheral blood, the expression of 40 genes was significantly associated with lung function. Twenty-nine of these genes (73%) were also associated with lung function in lung tissue, but with the opposite direction of effect for 24 of the 29 genes, including those involved in hypoxia and B cell-related responses. The integrative genomics approach uncovered a significant overlap of emphysema genes associations with lung function between lung and blood with opposite directions between the two. These results support the use of peripheral blood to detect disease biomarkers.

CT imaging of chronic obstructive pulmonary disease: insights, disappointments, and promise

CT imaging is a readily quantifiable tool that can provide in-vivo assessments of lung structure in conditions such as chronic obstructive pulmonary disease (COPD). The information extracted from these data has been used in many clinical, epidemiological, and genetic investigations for patient stratification and prognostication, and to determine intermediate endpoints for clinical trials. Although these efforts have informed our understanding of the heterogeneity of pulmonary disease in smokers, they have not yet translated into new treatments for COPD or the personalisation of patient care. There are a multitude of potential reasons for this, including the lack of insight that static imaging provides for lung function and dysfunction, the limited resolution of clinical CT scanning for microscopic changes to the lung architecture, and the challenges that the biomedical community faces when trying to translate discovery to therapy. Such limitations might be addressed through novel image analysis techniques, up-and-coming CT-based and MRI-based technologies, closer ties between academia and industry, and an expanded endeavour to share data across the biomedical community.

Inhaled Steroids and Active Smoking Drive Chronic Obstructive Pulmonary Disease Symptoms and Biomarkers to a Greater Degree Than Airflow Limitation

RATIONALE

Chronic obstructive pulmonary disease (COPD) is a heterogeneous disease, and development of novel therapeutics requires an understanding of pathophysiologic phenotypes.

OBJECTIVES

The purpose of the Airways Disease Endotyping for Personalized Therapeutics (ADEPT) study was to correlate clinical features and biomarkers with molecular characteristics in a well-profiled COPD cohort.

METHODS

A total of 67 COPD subjects (forced expiratory volume in the first second of expiration [FEV1]: 45%-80% predicted) and 63 healthy smoking and nonsmoking controls underwent multiple assessments including patient questionnaires, lung function, and clinical biomarkers including fractional exhaled nitric oxide (FENO), induced sputum, and blood.

MEASUREMENTS AND MAIN RESULTS

The impact of inhaled corticosteroids (ICSs), and to a lesser extent current smoking, was more associated with symptom control, exacerbation rates, and clinical biomarkers, than severity by FEV1. The ICS-treated smoking subjects were most symptomatic, with significantly elevated scores on patient-reported outcomes and more annual exacerbations (P < .05). Inhaled corticosteroid users had greater airflow obstruction and air trapping compared with non-ICS users, regardless of smoking status. Smoking, regardless of ICS use, was associated with significantly lower FENO (P < .05). Smoking, in non-ICS users, was associated with an elevated proportion of sputum neutrophils and reduced sputum macrophages. Increased serum C-reactive protein was observed in smokers but not in ICS and nonsmoking ICS users (P < .05). In contrast, only air trapping and neutrophilic inflammation increased with severity, defined by postbronchodilator FEV1.

CONCLUSIONS

Compared with COPD severity by FEV1, ICS use and current smoking were better determinants of clinical characteristics and biomarkers. Use of the ADEPT COPD data promises to prove useful in defining biological phenotypes to facilitate personalized therapeutic approaches.

Chronic obstructive pulmonary disease with mild airflow limitation: current knowledge and proposal for future research - a consensus document from six scientific societies

Chronic obstructive pulmonary disease (COPD) is a leading cause of mortality and morbidity worldwide, with high and growing prevalence. Its underdiagnosis and hence under-treatment is a general feature across all countries. This is particularly true for the mild or early stages of the disease, when symptoms do not yet interfere with daily living activities and both patients and doctors are likely to underestimate the presence of the disease. A diagnosis of COPD requires spirometry in subjects with a history of exposure to known risk factors and symptoms. Postbronchodilator forced expiratory volume in 1 second (FEV₁)/forced vital capacity <0.7 or less than the lower limit of normal confirms the presence of airflow limitation, the severity of which can be measured by FEV₁% predicted: stage 1 defines COPD with mild airflow limitation, which means postbronchodilator FEV₁ ≥80% predicted. In recent years, an elegant series of studies has shown that "exclusive reliance on spirometry, in patients with mild airflow limitation, may result in underestimation of clinically important physiologic impairment". In fact, exercise tolerance, diffusing capacity, and gas exchange can be impaired in subjects at a mild stage of airflow limitation. Furthermore, growing evidence indicates that smokers without overt abnormal spirometry have respiratory symptoms and undergo therapy. This is an essential issue in COPD. In fact, on one hand, airflow limitation, even mild, can unduly limit the patient's physical activity, with deleterious consequences on quality of life and even survival; on the other hand, particularly in younger subjects, mild airflow limitation might coincide with the early stage of the disease. Therefore, we thought that it was worthwhile to analyze further and discuss this stage of "mild COPD". To this end, representatives of scientific societies from five European countries have met and developed this document to stimulate the attention of the scientific community on COPD with "mild" airflow limitation. The aim of this document is to highlight some key features of this important concept and help the practicing physician to understand better what is behind "mild" COPD. Future research should address two major issues: first, whether mild airflow limitation represents an early stage of COPD and what the mechanisms underlying the evolution to more severe stages of the disease are; and second, not far removed from the first, whether regular treatment should be considered for COPD patients with mild airflow limitation, either to prevent progression of the disease or to encourage and improve physical activity or both.

Interdependence of physical inactivity, loss of muscle mass and low dietary intake: Extrapulmonary manifestations in older chronic obstructive pulmonary disease patients

AIM

Extrapulmonary manifestations, such as reductions in skeletal muscle and physical inactivity, are important clinical features of patients with chronic obstructive pulmonary disease (COPD), and might depend on the severity of COPD. As it is still unclear whether the relationship between muscle loss and physical inactivity is dominated by a disease-specific relationship or caused by patient factors, including physiological aging, we aimed to investigate the pulmonary or extrapulmonary factors associated with physical inactivity among older COPD patients.

METHODS

A total of 38 older male COPD patients (aged ≥65 years) were enrolled, and were evaluated cross-sectionally. Skeletal muscle mass was measured using bioelectrical impedance, and physical activity and energy intake were recorded for 2 weeks using a pedometer and diary.

RESULTS

Daily step counts were successfully evaluated in 28 participants (mean forced expiratory volume in 1 s [%predicted; %FEV₁ ]; 49.5%), and ranged widely. The mean step counts was 5166 steps/day, and found to have a significant relationship with dyspnea (r = -0.46), diffusing capacity (r = 0.47), %FEV1 (r = 0.44), skeletal muscle index (r = 0.59) and total dietary intake (r = 0.47), but not with age (P = 0.14). A stepwise multivariate analysis showed that the skeletal muscle index (β = 0.50) and total dietary intake (β = 0.35) were significant determinants of the daily step count (R² = 0.46, p < 0.01).

CONCLUSIONS

Although various pulmonary factors are associated with daily physical activity, skeletal muscle mass and dietary intake are more closely correlated with physical activity in COPD patients. Because physical inactivity might be the strongest predictor of prognosis, the present results suggest that a comprehensive treatment strategy must be considered for older COPD patients to improve their extrapulmonary manifestations and pulmonary dysfunction. Geriatr Gerontol Int 2018; 18: 88-94.

The association of tidal EFL with exercise performance, exacerbations, and death in COPD

BACKGROUND

Tidal expiratory flow limitation (EFL_T) is frequently found in patients with COPD and can be detected by forced oscillations when within-breath reactance of a single-breath is ≥0.28 kPa·s·L^-1. The present study explored the association of within-breath reactance measured over multiple breaths and EFL_T with 6-minute walk distance (6MWD), exacerbations, and mortality.

METHODS

In 425 patients, spirometry and forced oscillation technique measurements were obtained on eight occasions over 3 years. 6MWD was assessed at baseline and at the 3-year visit. Respiratory symptoms, exacerbations, and hospitalizations were recorded. A total of 5-year mortality statistics were retrieved retrospectively. We grouped patients according to the mean within-breath reactance [Formula: see text], measured over several breaths at baseline, calculated as mean inspiratory-mean expiratory reactance over the sampling period. In addition to the established threshold of EFL_T, an upper limit of normal (ULN) was defined using the 97.5th percentile of [Formula: see text], of the healthy controls in the study; 6MWDs were compared according to [Formula: see text], as normal, ≥ ULN < EFL_T, or ≥ EFL_T. Annual exacerbation rates were analyzed using a negative binomial model in the three groups, supplemented by time to first exacerbation analysis, and dichotomizing patients at the ULN.

RESULTS

In patients with COPD and baseline [Formula: see text] below the ULN (0.09 kPa·s·L^-1), 6MWD was stable. 6MWD declined significantly in patients with [Formula: see text]. Worse lung function and more exacerbations were found in patients with COPD with [Formula: see text], and patients with [Formula: see text] had shorter time to first exacerbation and hospitalization. A significantly higher mortality was found in patients with [Formula: see text] and FEV₁ >50%.

CONCLUSION

Patients with baseline [Formula: see text] had a deterioration in exercise performance, more exacerbations, and greater hospitalizations, and, among those with moderate airway obstruction, a higher mortality. [Formula: see text] is a novel independent marker of outcome in COPD.

Undiagnosed Chronic Obstructive Pulmonary Disease Contributes to the Burden of Health Care Use. Data from the CanCOLD Study

RATIONALE

Chronic obstructive pulmonary disease (COPD) remains undiagnosed in many individuals with persistent airflow limitation. These individuals may be susceptible to exacerbation-like respiratory events that consume health care resources.

OBJECTIVES

To compare exacerbation-like respiratory events, event prevalence, and differences in the odds of using medication and/or health services between subjects with diagnosed and undiagnosed COPD.

METHODS

Subjects sampled from the general population participating in the CanCOLD (Canadian Cohort Obstructive Lung Disease) study, with at least 12 months of exacerbation-event follow-up who were classified as having physician-diagnosed or undiagnosed COPD were assessed. Exacerbation-like respiratory events were captured using a questionnaire administered every 3 months.

MEASUREMENTS AND MAIN RESULTS

A total of 355 subjects were undiagnosed and 150 were diagnosed with COPD. Undiagnosed subjects were less symptomatic and functionally impaired, had been prescribed fewer respiratory medications, and had better health status. The incidence of reported exacerbation-like events was higher in diagnosed subjects and increased in both groups with the severity of airflow obstruction. Although subjects with diagnosed COPD were more often prescribed medication for exacerbation events, health service use for exacerbation events was similar in both groups.

CONCLUSIONS

Most subjects with COPD in Canada remain undiagnosed. These subjects are less symptomatic and impaired, which may partly explain lack of diagnosis. Although patients with undiagnosed COPD experience fewer exacerbations than those with diagnosed COPD, they use a similar amount of health services for exacerbation events; thus, the overall health system burden of exacerbations in those with undiagnosed COPD is considerable.

Genetic Association and Risk Scores in a Chronic Obstructive Pulmonary Disease Meta-analysis of 16,707 Subjects

The heritability of chronic obstructive pulmonary disease (COPD) cannot be fully explained by recognized genetic risk factors identified as achieving genome-wide significance. In addition, the combined contribution of genetic variation to COPD risk has not been fully explored. We sought to determine: (1) whether studies of variants from previous studies of COPD or lung function in a larger sample could identify additional associated variants, particularly for severe COPD; and (2) the impact of genetic risk scores on COPD. We genotyped 3,346 single-nucleotide polymorphisms (SNPs) in 2,588 cases (1,803 severe COPD) and 1,782 control subjects from four cohorts, and performed association testing with COPD, combining these results with existing genotyping data from 6,633 cases (3,497 severe COPD) and 5,704 control subjects. In addition, we developed genetic risk scores from SNPs associated with lung function and COPD and tested their discriminatory power for COPD-related measures. We identified significant associations between SNPs near PPIC (P = 1.28 × 10^-8) and PPP4R4/SERPINA1 (P = 1.01 × 10^-8) and severe COPD; the latter association may be driven by recognized variants in SERPINA1. Genetic risk scores based on SNPs previously associated with COPD and lung function had a modest ability to discriminate COPD (area under the curve, ∼0.6), and accounted for a mean 0.9-1.9% lower forced expiratory volume in 1 second percent predicted for each additional risk allele. In a large genetic association analysis, we identified associations with severe COPD near PPIC and SERPINA1. A risk score based on combining genetic variants had modest, but significant, effects on risk of COPD and lung function.

Sex-Based Genetic Association Study Identifies CELSR1 as a Possible Chronic Obstructive Pulmonary Disease Risk Locus among Women

Chronic obstructive pulmonary disease (COPD) is a complex disease with strong environmental and genetic influences and sexually dimorphic features. Although genetic risk factors for COPD have been identified, much of the heritability remains unexplained. Sex-based genetic association studies may uncover additional COPD genetic risk factors. We studied current and former smokers from COPD case-control cohorts (COPDGene non-Hispanic whites and African Americans, Evaluation of COPD Longitudinally to Identify Predictive Surrogate End-Points, and Genetics of Chronic Obstructive Lung Disease). COPD was defined as post-bronchodilator forced expiratory volume in 1 second/forced vital capacity less than 0.70 and forced expiratory volume in 1 second percent predicted less than 80. Testing was performed across all cohorts and combined in a meta-analysis adjusted for age, pack-years, and genetic ancestry. We first performed genome-wide single-nucleotide polymorphism (SNP)-by-sex interaction testing on the outcome of COPD affection status. We performed sex-stratified association testing for SNPs with interaction P less than 10^-6. We examined over 8 million SNPs in four populations, including 6,260 subjects with COPD (40.6% female) and 5,269 smoking control subjects (47.3% female). The SNP rs9615358 in the cadherin gene CELSR1 approached genome-wide significance for an interaction with sex (P = 1.24 × 10^-7). In the sex-stratified meta-analysis, this SNP was associated with COPD among females (odds ratio, 1.37 [95% confidence interval, 1.25-1.49]; P = 3.32 × 10^-7) but not males (odds ratio, 0.90 [95% confidence interval, 0.79-1.01]; P = 0.06). CELSR1 is involved in fetal lung development. In a human fetal lung tissue dataset, we observed greater CELSR1 expression in female compared with male samples. This SNP-by-sex genome-wide association analysis identified the fetal lung development gene, CELSR1, as a potential sex-specific risk factor for COPD. Identifying sex-specific genetic risk factors may reveal new insights into sexually dimorphic features of COPD.

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.

Multiple biomarkers predict disease severity, progression and mortality in COPD

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is a heterogeneous disease characterized by multiple subtypes and variable disease progression. Blood biomarkers have been variably associated with subtype, severity, and disease progression. Just as combined clinical variables are more highly predictive of outcomes than individual clinical variables, we hypothesized that multiple biomarkers may be more informative than individual biomarkers to predict subtypes, disease severity, disease progression, and mortality.

METHODS

Fibrinogen, C-Reactive Protein (CRP), surfactant protein D (SP-D), soluble Receptor for Advanced Glycation Endproducts (sRAGE), and Club Cell Secretory Protein (CC16) were measured in the plasma of 1465 subjects from the COPDGene cohort and 2746 subjects from the ECLIPSE cohort. Regression analysis was performed to determine whether these biomarkers, individually or in combination, were predictive of subtypes, disease severity, disease progression, or mortality, after adjustment for clinical covariates.

RESULTS

In COPDGene, the best combinations of biomarkers were: CC16, sRAGE, fibrinogen, CRP, and SP-D for airflow limitation (p < 10^-4), SP-D, CRP, sRAGE and fibrinogen for emphysema (p < 10^-3), CC16, fibrinogen, and sRAGE for decline in FEV₁ (p < 0.05) and progression of emphysema (p < 10^-3), and all five biomarkers together for mortality (p < 0.05). All associations except mortality were validated in ECLIPSE. The combination of SP-D, CRP, and fibrinogen was the best model for mortality in ECLIPSE (p < 0.05), and this combination was also significant in COPDGene.

CONCLUSION

This comprehensive analysis of two large cohorts revealed that combinations of biomarkers improve predictive value compared with clinical variables and individual biomarkers for relevant cross-sectional and longitudinal COPD outcomes.

Chronic obstructive pulmonary disease is independently associated with hypertension in men: A survey design analysis using nationwide survey data

Although studies have shown that chronic obstructive pulmonary disease (COPD) and hypertension are linked as comorbidities, it remains unclear whether COPD is independently associated with the risk of hypertension or is caused by common risk factors such as age and smoking. The objective of this study was to investigate the relationship between COPD and hypertension by using nationally representative data.This cross-sectional study analyzed data from the Korea National Health and Nutrition Examination Survey V conducted during 2010 to 2012. Hypertension was defined as a mean systolic blood pressure ≥ 140 mm Hg and/or a diastolic blood pressure ≥ 90 mm Hg, or current consumption of antihypertensive medications. A diagnosis of COPD was defined as a smoking history of at least 10 pack-years with airflow limitation on spirometry. Multivariate logistic regression was performed to investigate the independent association between COPD and hypertension after adjusting for covariates. Survey design analyses were conducted for all analyses.Among 4043 men (aged ≥ 40 years) who underwent spirometry, 2190 (54.2%) had hypertension. Even after adjusting for age, body mass index, smoking status, diabetes, metabolic syndrome, and stroke, COPD was independently associated with hypertension (adjusted odds ratio, 1.71; 95% confidence interval, 1.37-2.13; P < .001). Adjusted pulse pressure significantly increased as the ratio of forced expiratory volume in 1 s (FEV1) to forced vital capacity and FEV1 decreased.COPD is independently associated with hypertension, and this could explain the link between the risk of cardiovascular diseases and COPD.

Development of a Conceptual Model of Disease Progression for Use in Economic Modeling of Chronic Obstructive Pulmonary Disease

BACKGROUND

To develop and validate a new conceptual model (CM) of chronic obstructive pulmonary disease (COPD) for use in disease progression and economic modeling. The CM identifies and describes qualitative associations between disease attributes, progression and outcomes.

METHODS

A literature review was performed to identify any published CMs or literature reporting the impact and association of COPD disease attributes with outcomes. After critical analysis of the literature, a Steering Group of experts from the disciplines of health economics, epidemiology and clinical medicine was convened to develop a draft CM, which was refined using a Delphi process. The refined CM was validated by testing for associations between attributes using data from the Evaluation of COPD Longitudinally to Identify Predictive Surrogate Endpoints (ECLIPSE).

RESULTS

Disease progression attributes included in the final CM were history and occurrence of exacerbations, lung function, exercise capacity, signs and symptoms (cough, sputum, dyspnea), cardiovascular disease comorbidities, 'other' comorbidities (including depression), body composition (body mass index), fibrinogen as a biomarker, smoking and demographic characteristics (age, gender). Mortality and health-related quality of life were determined to be the most relevant final outcome measures for this model, intended to be the foundation of an economic model of COPD.

CONCLUSION

The CM is being used as the foundation for developing a new COPD model of disease progression and to provide a framework for the analysis of patient-level data. The CM is available as a reference for the implementation of further disease progression and economic models.

Percent Emphysema and Daily Motor Activity Levels in the General Population: Multi-Ethnic Study of Atherosclerosis

BACKGROUND

COPD is associated with reduced physical capacity. However, it is unclear whether pulmonary emphysema, which can occur without COPD, is associated with reduced physical activity in daily life, particularly among people without COPD and never smokers. We hypothesized that greater percentage of emphysema-like lung on CT scan is associated with reduced physical activity assessed by actigraphy and self-report.

METHODS

The Multi-Ethnic Study of Atherosclerosis (MESA) enrolled participants free of clinical cardiovascular disease from the general population. Percent emphysema was defined as percentage of voxels < -950 Hounsfield units on full-lung CT scans. Physical activity was measured by wrist actigraphy over 7 days and a questionnaire. Multivariable linear regression was used to adjust for age, sex, race/ethnicity, height, weight, education, smoking, pack-years, and lung function.

RESULTS

Among 1,435 participants with actigraphy and lung measures, 47% had never smoked, and 8% had COPD. Percent emphysema was associated with lower activity levels on actigraphy (P = .001), corresponding to 1.5 hour less per week of moderately paced walking for the average participant in quintile 2 vs 4 of percent emphysema. This association was significant among participants without COPD (P = .004) and among ever (P = .01) and never smokers (P = .03). It was also independent of coronary artery calcium and left ventricular ejection fraction. There was no evidence that percent emphysema was associated with self-reported activity levels.

CONCLUSIONS

Percent emphysema was associated with decreased physical activity in daily life objectively assessed by actigraphy in the general population, among participants without COPD, and nonsmokers.

Network-based analysis reveals novel gene signatures in peripheral blood of patients with chronic obstructive pulmonary disease

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is currently the third leading cause of death and there is a huge unmet clinical need to identify disease biomarkers in peripheral blood. Compared to gene level differential expression approaches to identify gene signatures, network analyses provide a biologically intuitive approach which leverages the co-expression patterns in the transcriptome to identify modules of co-expressed genes.

METHODS

A weighted gene co-expression network analysis (WGCNA) was applied to peripheral blood transcriptome from 238 COPD subjects to discover co-expressed gene modules. We then determined the relationship between these modules and forced expiratory volume in 1 s (FEV1). In a second, independent cohort of 381 subjects, we determined the preservation of these modules and their relationship with FEV1. For those modules that were significantly related to FEV1, we determined the biological processes as well as the blood cell-specific gene expression that were over-represented using additional external datasets.

RESULTS

Using WGCNA, we identified 17 modules of co-expressed genes in the discovery cohort. Three of these modules were significantly correlated with FEV1 (FDR < 0.1). In the replication cohort, these modules were highly preserved and their FEV1 associations were reproducible (P < 0.05). Two of the three modules were negatively related to FEV1 and were enriched in IL8 and IL10 pathways and correlated with neutrophil-specific gene expression. The positively related module, on the other hand, was enriched in DNA transcription and translation and was strongly correlated to CD4+, CD8+ T cell-specific gene expression.

CONCLUSIONS

Network based approaches are promising tools to identify potential biomarkers for COPD.

TRIAL REGISTRATION

The ECLIPSE study was funded by GlaxoSmithKline, under ClinicalTrials.gov identifier NCT00292552 and GSK No. SCO104960.

Stability of the frequent COPD exacerbator in the general population: A Danish nationwide register-based study

Exacerbation frequency is central in treatment strategies for chronic obstructive pulmonary disease. However, whether chronic obstructive pulmonary disease patients from the general population with frequent exacerbations continue to have frequent exacerbations over an extended period of time is currently unknown. In this study, we aimed to investigate the stability of the frequent exacerbator in a population-based setting. To this end, we conducted a nationwide register-based descriptive study with a 10-year follow-up period of chronic obstructive pulmonary disease patients with at least one medically treated exacerbation in 2003. Each subsequent year, we divided the population into frequent, infrequent and non-exacerbators and quantified the flow between categories. Further, we estimated the percentage of frequent exacerbators at baseline who stayed in this category each year during a 5-year follow-up. We identified 19,752 patients with chronic obstructive pulmonary disease and an exacerbation in 2003. Thirty percent were frequent exacerbators. Overall, the majority of exacerbators in 2003 were non-exacerbators in the following years (60% in 2004 increasing to 68% in 2012). Approximately half of frequent exacerbators in one year experienced a decrease in exacerbation frequency and had either zero or one exacerbation in the subsequent year. This pattern was stable throughout follow-up. During a 5-year follow-up period, a substantial proportion (42%) of frequent exacerbators in 2003 had no additional years as frequent exacerbators, while the minority (6%) remained in this category each year. In conclusion, the rate of exacerbations shows considerable variation over time among chronic obstructive pulmonary disease patients in the general population. This might hold implications for chronic obstructive pulmonary disease treatment guidelines and their practical application.

Patients with chronic obstructive pulmonary disease (COPD) who suffer from frequent exacerbations do not necessarily persist with such severity over time. Exacerbations in COPD are defined by worsening respiratory symptoms that result in changes to treatment, hospitalization and, at worst, death. However, clarity is needed on whether frequent exacerbations is a stable feature of some patients’ disease. Mette Reilev at the University of Southern Denmark and co-workers followed, over 10 years, 19,752 COPD patients living in Denmark who suffered at least one exacerbation in 2003. By 2004, 60% of patients were classed as infrequent or non-exacerbators, rising to 68% by 2012. Very few patients remained “frequent exacerbators”, suggesting the rate of exacerbations changes considerably over time. This could hold implications for COPD treatment and challenge assumptions made about disease progression.

Neutrophil-mediated IL-6 receptor trans-signaling and the risk of chronic obstructive pulmonary disease and asthma

The Asp358Ala variant in the interleukin-6 receptor (IL-6R) gene has been implicated in asthma, autoimmune and cardiovascular disorders, but its role in other respiratory conditions such as chronic obstructive pulmonary disease (COPD) has not been investigated. The aims of this study were to evaluate whether there is an association between Asp358Ala and COPD or asthma risk, and to explore the role of the Asp358Ala variant in sIL-6R shedding from neutrophils and its pro-inflammatory effects in the lung. We undertook logistic regression using data from the UK Biobank and the ECLIPSE COPD cohort. Results were meta-analyzed with summary data from a further three COPD cohorts (7,519 total cases and 35,653 total controls), showing no association between Asp358Ala and COPD (OR = 1.02 [95% CI: 0.96, 1.07]). Data from the UK Biobank showed a positive association between the Asp358Ala variant and atopic asthma (OR = 1.07 [1.01, 1.13]). In a series of in vitro studies using blood samples from 37 participants, we found that shedding of sIL-6R from neutrophils was greater in carriers of the Asp358Ala minor allele than in non-carriers. Human pulmonary artery endothelial cells cultured with serum from homozygous carriers showed an increase in MCP-1 release in carriers of the minor allele, with the difference eliminated upon addition of tocilizumab. In conclusion, there is evidence that neutrophils may be an important source of sIL-6R in the lungs, and the Asp358Ala variant may have pro-inflammatory effects in lung cells. However, we were unable to identify evidence for an association between Asp358Ala and COPD.

Screening for interaction effects in gene expression data

Expression quantitative trait (eQTL) studies are a powerful tool for identifying genetic variants that affect levels of messenger RNA. Since gene expression is controlled by a complex network of gene-regulating factors, one way to identify these factors is to search for interaction effects between genetic variants and mRNA levels of transcription factors (TFs) and their respective target genes. However, identification of interaction effects in gene expression data pose a variety of methodological challenges, and it has become clear that such analyses should be conducted and interpreted with caution. Investigating the validity and interpretability of several interaction tests when screening for eQTL SNPs whose effect on the target gene expression is modified by the expression level of a transcription factor, we characterized two important methodological issues. First, we stress the scale-dependency of interaction effects and highlight that commonly applied transformation of gene expression data can induce or remove interactions, making interpretation of results more challenging. We then demonstrate that, in the setting of moderate to strong interaction effects on the order of what may be reasonably expected for eQTL studies, standard interaction screening can be biased due to heteroscedasticity induced by true interactions. Using simulation and real data analysis, we outline a set of reasonable minimum conditions and sample size requirements for reliable detection of variant-by-environment and variant-by-TF interactions using the heteroscedasticity consistent covariance-based approach.

Incidence and relative risk for developing cancer among patients with COPD: a nationwide cohort study in Taiwan

OBJECTIVES

This observational study aimed to examine the incidence of malignant diseases, including specific cancer types, after the diagnosis of chronic obstructive pulmonary disease (COPD) in Taiwanese patients.

SETTING

Taiwan's National Health Insurance Research Database.

PARTICIPANTS

The definition of a patient with COPD was a patient with a discharge diagnosis of COPD or at least 3 ambulatory visits for COPD. The index date was the date of the first COPD diagnosis. Patients with a history of malignancy disorders before the index date were excluded. After matching age and gender, 13 289 patients with COPD and 26 578 control participants without COPD were retrieved and analysed. They were followed from the index date to malignancy diagnosis, death or the end of study follow-up (31 December 2011), whichever came first.

PRIMARY OUTCOME MEASURES

Patients were diagnosed with cancer (n=1681, 4.2%; 973 (7.3%) for patients with COPD and 728 (2.7%) for patients without COPD). The risk of 7 major cancer types, including lung, liver, colorectal, breast, prostate, stomach and oesophagus, between patients with COPD and patients without COPD was also estimated.

RESULTS

The mean age of all study participants was 57.9±13.5 years. The average length of follow-up to cancer incidence was 3.9 years for patients with COPD and 5.0 years for patients without COPD (p<0.01). Patients with COPD were diagnosed with cancer (n=973, 73%) at a significantly higher rate than patients without COPD (n=708, 2.7%; p<0.01). The HR for developing cancer in patients with COPD was 2.8 (95% CI 2.6 to 3.1) compared with patients without COPD after adjusting for age, sex and comorbidities. The most common cancers in patients with COPD include lung, liver, colorectal, breast, prostate and stomach cancers.

CONCLUSIONS

The risk of developing cancer is higher in patients with COPD compared with patients without COPD. Cancer screening is warranted in patients with COPD.