Identification of a predominant COPD phenotype in clinical practice

Single-Breath Simultaneous Measurement of DLNO and DLCO as Predictor of the Emphysema Component in COPD - A Retrospective Observational Study

Background

Chronic Obstructive Pulmonary Disease (COPD) is a respiratory condition characterized by heterogeneous abnormalities of the airways and lung parenchyma that cause different clinical presentations. The assessment of the prevailing pathogenetic components underlying COPD is not usually pursued in daily practice, also due to technological limitations and cost.

Aim

To assess non-invasively the lung emphysema component of COPD by the simultaneous measurement of DLNO and DLCO via a single-breath (sDLNO and sDLCO).

Methods

COPD patients aged ≥40 years of both genders were recruited consecutively and labelled by computed tomography as "with significant" emphysema (>10% of CT lung volume) or "with negligible" emphysema otherwise. Current lung function tests such as sDLNO, sDLCO and Vc (the lung capillary blood volume) were measured. All possible subsets of independent spirometric and diffusive parameters were tested as predictors of emphysema, and their predicted power compared to each parameter alone by ROC analysis and area under the curve (AUC).

Results

Thirty-one patients with "significant emphysema" were compared to thirty-one with "negligible emphysema". FEV1 and FEV1/FVC seemed to be the best spirometric predictors (AUC 0.80 and 0.81, respectively), while sDLCO and Vc had the highest predicted power among diffusive parameters (AUC 0.92 and 0.94, respectively). sDLCO and Vc values were the parameters most correlated to the extent of CT emphysema. Six subsets of independent predictors were identified and included at least one spirometric and one diffusive parameter. According to goodness-to-fit scores (AIC, BIC, log-likelihood and pseudo R2), RV coupled with sDLCO or Vc proved the best predictors of emphysema.

Conclusion

When investigating the parenchymal destructive component due to emphysema occurring in COPD, sDLNO, sDLCO and Vc do enhance the predictive power of current spirometric measures substantially. sDLNO, sDLCO and Vc contribute to phenotype of the main pathogenetic components of COPD easily and with high sensitivity. Organizational problems, radiation exposure, time and costs could be reduced, while personalized and precision medicine could be noticeably implemented.

Exacerbation Burden in COPD and Occurrence of Mortality in a Cohort of Italian Patients: Results of the Gulp Study

Objective

To describe the burden of moderate to severe exacerbations and all-cause mortality; the secondary objectives were to analyze treatment patterns and changes over follow-up.

Design

Observational, multicenter, retrospective, cohort study with a three year follow-up period.

Setting

Ten Italian academic secondary- and tertiary-care centers.

Participants

Patients with a confirmed diagnosis of COPD referring to the outpatient clinics of the participating centers were retrospectively recruited.

Primary and Secondary Outcome Measures

Annualized frequency of moderate and severe exacerbations stratified by exacerbation history prior to study enrollment. Patients were classified according to airflow obstruction, GOLD risk categories, and divided in 4 groups: A = no exacerbations; B = 1 moderate exacerbation; C = 1 severe exacerbation; D = ≥2 moderate and/or severe exacerbations. Overall all-cause mortality stratified by age, COPD category, and COPD therapy. A logistic regression model assessed the association of clinical characteristics with mortality.

Results

1111 patients were included (73% males), of which 41.5% had a history of exacerbations. As expected, the proportion of patients experiencing ≥1 exacerbation during follow-up increased according to pre-defined study risk categories (B: 79%, C: 84%, D: 97.4%). Overall, by the end of follow-up, 45.5% of patients without a history of exacerbation experienced an exacerbation (31% of which severe), and 13% died. Deceased patients were significantly older, more obstructed and hyperinflated, and more frequently active smokers compared with survivors. Severe exacerbations were more frequent in patients that died (23.5%, vs 10.2%; p-value: 0.002). Chronic heart failure and ischemic heart disease were the only comorbidities associated with a higher odds ratio (OR) for death (OR: 2.2, p-value: 0.001; and OR: 1.9, p-value: 0.007). Treatment patterns were similar in patients that died and survivors.

Conclusion

Patients with a low exacerbation risk are exposed to a significant future risk of moderate/severe exacerbations. Real life data confirm the strong association between mortality and cardiovascular comorbidities in COPD.

Heterogeneity and Progression of Chronic Obstructive Pulmonary Disease: Emphysema-Predominant and Non-Emphysema-Predominant Disease

While variation in emphysema severity between patients with chronic obstructive pulmonary disease (COPD) is well-recognized, clinically applicable definitions of the emphysema-predominant disease (EPD) and non-emphysema-predominant disease (NEPD) subtypes have not been established. To study the clinical relevance of the EPD and NEPD subtypes, we tested the association of these subtypes with prospective decline in forced expiratory volume in 1 second (FEV1) and mortality among 3,427 subjects with Global Initiative for Chronic Obstructive Lung Disease (GOLD) spirometric grade 2-4 COPD at baseline in the Genetic Epidemiology of COPD (COPDGene) Study, an ongoing national multicenter study that started in 2007. NEPD was defined as airflow obstruction with less than 5% computed tomography (CT) quantitative densitometric emphysema at -950 Hounsfield units, and EPD was defined as airflow obstruction with 10% or greater CT emphysema. Mixed-effects models for FEV1 demonstrated larger average annual FEV1 loss in EPD subjects than in NEPD subjects (-10.2 mL/year; P < 0.001), and subtype-specific associations with FEV1 decline were identified. Cox proportional hazards models showed higher risk of mortality among EPD patients versus NEPD patients (hazard ratio = 1.46, 95% confidence interval: 1.34, 1.60; P < 0.001). To determine whether the NEPD/EPD dichotomy is captured by previously described COPDGene subtypes, we used logistic regression and receiver operating characteristic (ROC) curve analysis to predict NEPD/EPD membership using these previous subtype definitions. The analysis generally showed excellent discrimination, with areas under the ROC curve greater than 0.9. The NEPD and EPD COPD subtypes capture important aspects of COPD heterogeneity and are associated with different rates of disease progression and mortality.

Unsupervised Learning Identifies Computed Tomographic Measurements as Primary Drivers of Progression, Exacerbation, and Mortality in Chronic Obstructive Pulmonary Disease

Rationale: Chronic obstructive pulmonary disease (COPD) is a heterogeneous syndrome with phenotypic manifestations that tend to be distributed along a continuum. Unsupervised machine learning based on broad selection of imaging and clinical phenotypes may be used to identify primary variables that define disease axes and stratify patients with COPD. Objectives: To identify primary variables driving COPD heterogeneity using principal component analysis and to define disease axes and assess the prognostic value of these axes across three outcomes: progression, exacerbation, and mortality. Methods: We included 7,331 patients between 39 and 85 years old, of whom 40.3% were Black and 45.8% were female smokers with a mean of 44.6 pack-years, from the COPDGene (Genetic Epidemiology of COPD) phase I cohort (2008-2011) in our analysis. Out of a total of 916 phenotypes, 147 continuous clinical, spirometric, and computed tomography (CT) features were selected. For each principal component (PC), we computed a PC score based on feature weights. We used PC score distributions to define disease axes along which we divided the patients into quartiles. To assess the prognostic value of these axes, we applied logistic regression analyses to estimate 5-year (n = 4,159) and 10-year (n = 1,487) odds of progression. Cox regression and Kaplan-Meier analyses were performed to estimate 5-year and 10-year risk of exacerbation (n = 6,532) and all-cause mortality (n = 7,331). Results: The first PC, accounting for 43.7% of variance, was defined by CT measures of air trapping and emphysema. The second PC, accounting for 13.7% of variance, was defined by spirometric and CT measures of vital capacity and lung volume. The third PC, accounting for 7.9% of the variance, was defined by CT measures of lung mass, airway thickening, and body habitus. Stratification of patients across each disease axis revealed up to 3.2-fold (95% confidence interval [CI] 2.4, 4.3) greater odds of 5-year progression, 5.4-fold (95% CI 4.6, 6.3) greater risk of 5-year exacerbation, and 5.0-fold (95% CI 4.2, 6.0) greater risk of 10-year mortality between the highest and lowest quartiles. Conclusions: Unsupervised learning analysis of the COPDGene cohort reveals that CT measurements may bolster patient stratification along the continuum of COPD phenotypes. Each of the disease axes also individually demonstrate prognostic potential, predictive of future forced expiratory volume in 1 second decline, exacerbation, and mortality.

Correlation between TNF-α -308 and +489 Gene Polymorphism and Acute Exacerbation of Chronic Obstructive Pulmonary Diseases

Acute exacerbation of chronic obstructive pulmonary disease (AECOPD) is becoming a common respiratory disease, leading to increased morbidity and mortality worldwide. Tumor necrosis factor-alpha (TNF-α) is a powerful proinflammatory cytokine involved in the pathogenesis of AECOPD. Therefore, we proposed a close correlation between the TNF-α polymorphism [-308G/A (rs1800629), +489G/A (rs1800610)] and the disease progress of patients with AECOPD. Comparison of the TNF-α genotypes between the 198 AECOPD diagnosed patients groups and 195 healthy peoples suggested their significant differences of the three genotypes (AA, GA, GG) distribution for TNF-α -308 (P < 0.05), but no differences of that for TNF-α +489. We found that patients with TNF-α -308 GA/AA genotypes showed smaller adjacent arterial diameter, thicker bronchial wall, higher bronchial artery ratio, higher bronchial wall grading, and higher frequency of acute exacerbations than those with TNF-α -308 GG genotype. Patients with TNF-α +489 GA/AA genotypes showed the same AECOPD properties as patients with TNF-α -308 except for the high frequency of acute exacerbations. Further experiment showed that the TNF-α -308 and+489 gene polymorphisms could affect the expression level of TNF-α in macrophages, suggesting the involvement of the macrophage population in disease regulation of AECOPD patients with TNF-α -308G/A and+489G/A genotype heterogeneity. In conclusion, the TNF-α -308 G/A genotype was related to AECOPD susceptibility and progress, while the TNF-α +489G/A genotype was related to AECOPD progress, but not AECOPD susceptibility.

Standard spirometry to assess emphysema in patients with chronic obstructive pulmonary disease: the Emphysema Severity Index (ESI)

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is a generic term identifying a condition characterized by variable changes in peripheral airways and lung parenchyma. Standard spirometry cannot discriminate the relative role of conductive airways inflammatory changes from destructive parenchymal emphysema changes. The aim of this study was to quantify the emphysema component in COPD by a simple parameter (the Emphysema Severity Index - ESI), previously proved to reflect CT-assessed emphysema.

METHODS

ESI was obtained by fitting the descending limb of MEFV curves by a fully automated procedure providing a 0 to 10 score of emphysema severity. ESI was computed in COPD patients enrolled in the CLIMA Study.

RESULTS

The vast majority of ESI values ranged from 0 to 4, compatible with no-to-mild/moderate emphysema component. A limited proportion of patients showed ESI values >4, compatible with severe-to-very severe emphysema. ESI values were greatly dispersed within each GOLD class indicating that GOLD classification cannot discriminate emphysema and conductive airways changes in patients with similar airflow limitation. ESI and diffusing capacity (DLCO) were significantly correlated (p<0.001). However, the great dispersion in their correlation suggests that ESI and DLCO reflect partially different anatomo-functional determinants in COPD.

CONCLUSIONS

Airflow limitation has heterogenous determinants in COPD. Inflammatory and destructive changes may combine in CT densitometric alterations that cannot be detected by standard spirometry. ESI computation from spirometric data helps to define the prevailing pathogenetic mechanism underlying the measured airflow limitation. ESI could be a reliable advancement to select large samples of patients in clinical or epidemiological trials, and to compare different pharmacological treatments.

Comprehensive Cluster Analysis for COPD Including Systemic and Airway Inflammatory Markers

Chronic obstructive pulmonary disease (COPD) is a complex, multidimensional and heterogeneous disease. The main purpose of the present study was to identify clinical phenotypes through cluster analysis in adults suffering from COPD. A retrospective study was conducted on 178 COPD patients in stable state recruited from ambulatory care at University hospital of Liege. All patients were above 40 years, had a smoking history of more than 20 pack years, post bronchodilator FEV1/FVC <70% and denied any history of asthma before 40 years. In this study, the patients were described by a total of 84 mixed sets of variables with some missing values. Hierarchical clustering on principal components (HCPC) was applied on multiple imputation. In the final step, patients were classified into homogeneous distinct groups by consensus clustering. Three different clusters, which shared similar smoking history were found. Cluster 1 included men with moderate airway obstruction (n = 67) while cluster 2 comprised men who were exacerbation-prone, with severe airflow limitation and intense granulocytic airway and neutrophilic systemic inflammation (n = 56). Cluster 3 essentially included women with moderate airway obstruction (n = 55). All clusters had a low rate of bacterial colonization (5%), a low median FeNO value (<20 ppb) and a very low sensitization rate toward common aeroallergens (0-5%). CAT score did not differ between clusters. Including markers of systemic airway inflammation and atopy and applying a comprehensive cluster analysis we provide here evidence for 3 clusters markedly shaped by sex, airway obstruction and neutrophilic inflammation but not by symptoms and T2 biomarkers.

The value of bronchial and cavity contraction rates in differentiating benign and malignant pulmonary cavities

BACKGROUND

The present study aimed to assess the value of bronchial and cavity contraction percentages in differentiating benign and malignant pulmonary cavities.

METHODS

Forty-two patients with pulmonary cavities were scanned by dual-phase computed tomography (CT). Then, the cavity and bronchial contraction percentages were respectively measured, the differences between the benign and malignant cavities were compared, and the best diagnostic critical point for differentiating benign and malignant cavities was obtained through the receiver operator characteristic (ROC) curve of the diagnostic test.

RESULTS

The contraction percentage of the bronchial end with benign cavities was significantly higher than that of the bronchial end with malignant cavities (P < 0.001). The contraction percentage was significantly higher in the benign group than in the malignant group (P < 0.001). The ROC analysis revealed that the sensitivity and specificity of the bronchial contraction percentage was 90.50 and 86.40%, respectively, while the sensitivity and specificity of the cavity contraction percentage was 90.50 and 90.90%, respectively.

CONCLUSION

The dual-phase CT scanning of the bronchial and cavity contraction percentage can distinguish between benign and malignant cavities.

COPD phenotypes and machine learning cluster analysis: A systematic review and future research agenda

Chronic Obstructive Pulmonary Disease (COPD) is a highly heterogeneous condition projected to become the third leading cause of death worldwide by 2030. To better characterize this condition, clinicians have classified patients sharing certain symptomatic characteristics, such as symptom intensity and history of exacerbations, into distinct phenotypes. In recent years, the growing use of machine learning algorithms, and cluster analysis in particular, has promised to advance this classification through the integration of additional patient characteristics, including comorbidities, biomarkers, and genomic information. This combination would allow researchers to more reliably identify new COPD phenotypes, as well as better characterize existing ones, with the aim of improving diagnosis and developing novel treatments. Here, we systematically review the last decade of research progress, which uses cluster analysis to identify COPD phenotypes. Collectively, we provide a systematized account of the extant evidence, describe the strengths and weaknesses of the main methods used, identify gaps in the literature, and suggest recommendations for future research.

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.

Prediction of Treatment Response in Patients with Chronic Obstructive Pulmonary Disease by Determination of Airway Dimensions with Baseline Computed Tomography

Objective

To determine the predictive factors for treatment responsiveness in patients with chronic obstructive pulmonary disease (COPD) at 1-year follow-up by performing quantitative analyses of baseline CT scans.

Materials and Methods

COPD patients (n = 226; 212 men, 14 women) were recruited from the Korean Obstructive Lung Disease cohort. Patients received a combination of inhaled long-acting beta-agonists and corticosteroids twice daily for 3 months and subsequently received medications according to the practicing clinician's decision. The emphysema index, air-trapping indices, and airway parameter (Pi10), calculated using both full-width-half-maximum and integral-based half-band (IBHB) methods, were obtained with baseline CT scans. Clinically meaningful treatment response was defined as an absolute increase of ≥ 0.225 L in the forced expiratory volume in 1 second (FEV₁) at the one-year follow-up. Multivariate logistic regression analysis was performed to investigate the predictors of an increase in FEV₁, and receiver operating characteristic (ROC) analysis was performed to evaluate the performance of the suggested models.

Results

Treatment response was noted in 47 patients (20.8%). The mean FEV₁ increase in responders was 0.36 ± 0.10 L. On univariate analysis, the air-trapping index (ATI) obtained by the subtraction method, ATI of the emphysematous area, and IBHB-measured Pi10 parameter differed significantly between treatment responders and non-responders (p = 0.048, 0.042, and 0.002, respectively). Multivariate analysis revealed that the IBHB-measured Pi10 was the only independent variable predictive of an FEV₁ increase (p = 0.003). The adjusted odds ratio was 1.787 (95% confidence interval: 1.220–2.619). The area under the ROC curve was 0.641.

Conclusion

Measurement of standardized airway dimensions on baseline CT by using a recently validated quantification method can predict treatment responsiveness in COPD patients.

Clinical and Functional Characteristics of COPD Patients Across GOLD Classifications: Results of a Multicenter Observational Study

Chronic obstructive pulmonary disease (COPD) is a heterogeneous disease. The severity grading systems proposed by the Global initiative for Chronic Obstructive Lung Disease (GOLD) have changed over time. The aim of the study was to evaluate if the different GOLD classifications can capture the complexity of the disease by investigating the distribution of lung function and clinical parameters across the GOLD classification systems. This was an observational, retrospective, multicentre study. COPD patients were stratified according to the GOLD severity grading proposed in the 2007, and to the ABCD assessment tool present in the 2011, and 2017 versions of the initiative. Data from body plethysmography, DLCO, comorbidities, exacerbation history, pharmacological therapy and eosinophil counts were collected. A total of 1360 patients (73.4% males) were included in the analysis. Overall, 37% of the patients were severe-very severe according to GOLD 2007. Compared with GOLD 2011, applying the GOLD 2017 criteria, the proportion of the at risk categories (C and D) was reduced by ∼23%. Impairment in inspiratory capacity, DLCO and the prevalence of emphysema paralleled the GOLD 2007 classification only. The proportion of patients with ≥ 200 eosinophils/µL was higher in GOLD 2007 stages 3-4 compared with stages 1-2 (P = 0.008). Eosinophil levels were similar across risk classes in GOLD 2011 and 2017. Overall, 41.8% and 52.4% of the patients in the low risk groups according to GOLD 2011 and 2017 were exposed to inhaled corticosteroids. The GOLD 2011 and 2017 classifications, despite exploring symptoms and exacerbations, might miss other relevant patients' clinical characteristics such as lung function and phenotypes, which have a significant impact on outcomes and disease severity.

Competence in bronchoscopic treatments in emphysema

Bronchoscopic lung volume reduction (BLVR) has been proven to be effective in patients with severe emphysema. These techniques are divided into two groups: non-blocking devices that are independent of collateral ventilation and blocking devices that are dependent on collateral ventilation so the choice of the target lobe with inadequate scissors is crucial for the success of the treatment. Current evidences suggest that not all classes and phenotypes of emphysema will benefit from BLVR, and that each technique appears to provide a greater benefit to specific sub-groups of patients. Careful patient selection is imperative to prevent insertion in patients unlikely to gain clinical benefits as well as wasteful expenditure. The Chartis system represents the gold standard for measuring fissure integrity and is a direct measurement method. Indirect method is instead the TC study which, thanks to the development of software for quantitative analysis, allows us to obtain reliable measurements of regional density of parenchyma, airway thickness and scissor integrity. BLVR is a highly complex procedure: a first-level competence is a pre-requisite for admission to training. The practical training must be based on discussion of clinical cases and the insertion techniques of the different devices on plastic or animal models, or on cadavers. A specific course, offering final certification, has been developed on the use of Zephyr valves.

Blood MCP-1 levels are increased in chronic obstructive pulmonary disease patients with prevalent emphysema

Background and aims

Chronic obstructive pulmonary disease (COPD) is a heterogeneous disease characterized by different phenotypes with either bronchial airways alterations or emphysema prevailing. As blood biomarkers could be clinically useful for COPD stratification, we aimed at investigating the levels of blood biomarkers in COPD patients differentiated by phenotype: prevalent chronic airway disease versus emphysema.

Methods

In 23 COPD patients with prevalent airway disease (COPD-B), 22 COPD patients with prevalent emphysema (COPD-E), 9 control smokers (CSs), and 18 control nonsmokers (CNSs), we analyzed the expression levels of interleukin (IL)-1α, IL-1β, IL-2, IL-4, IL-6, IL-8, IL-10, tumor necrosis factor (TNF)-α, interferon (IFN)-γ, epidermal growth factor (EGF), monocyte chemotactic protein (MCP)-1, and vascular endothelial growth factor by enzyme-linked immunosorbent assay in plasma/serum; glutathione peroxidase and superoxide dismutase (SOD)-1 by immunochemical kits in plasma; and free F2-isoprostanes (F2-IsoPs) by gas chromatography in plasma.

Results

F2-IsoPs level was increased in COPD-B and COPD-E compared with CSs and CNSs; in addition, CS showed higher levels than CNSs; SOD1 level was lower in COPD-B and COPD-E than that in CNSs. Interestingly, MCP-1 level was higher only in COPD-E versus CSs and CNSs; EGF and IL-8 levels were higher in COPD-B and COPD-E versus CNSs; IL-6 level was increased in all three smoking groups (COPD-B, COPD-E, and CSs) versus CNS; IFN-γ and IL-1α levels were higher in CSs than in CNSs; and IL-1α level was also higher in CSs versus COPD-B and COPD-E. In all subjects, F2-IsoPs level correlated positively and significantly with MCP-1, IL-2, IL-1β, IFN-γ, and TNF-α and negatively with SOD1. When correlations were restricted to COPD-E and COPD-B groups, F2-IsoPs maintained the positive associations with IFN-γ, TNF-α, and IL-2.

Conclusion

We did not find any specific blood biomarkers that could differentiate COPD patients with prevalent airway disease from those with prevalent emphysema. The MCP-1 increase in COPD-E, associated with the imbalance of oxidant/antioxidant markers, may play a role in inducing emphysema.

A cluster analysis of chronic obstructive pulmonary disease in dusty areas cohort identified three subgroups

Background

Chronic obstructive pulmonary disease (COPD) is a heterogeneous disease with variable clinical manifestations, structural changes, and treatment responses. In a cohort study, we performed a baseline cluster analysis to identify the subgroups of COPD and to assess the clinical outcomes of each subgroup during a 1-year follow-up.

Methods

We analyzed dusty areas cohort comprising 272 patients with COPD. The main factors with the highest loading in 15 variables were selected using principal component analysis (PCA) at baseline. The COPD patients were classified by hierarchical cluster analysis using clinical, physiological, and imaging data based on PCA-transformed data. The clinical parameters and outcomes during the 1-year follow-up were evaluated among the subgroups.

Results

PCA revealed that six independent components accounted for 77.3% of variance. Three distinct subgroups were identified through the cluster analysis. Subgroup 1 included younger subjects with fewer symptoms and mild airflow obstruction, and they had fewer exacerbations during the 1-year follow-up. Subgroup 2 comprised subjects with additional symptoms and moderate airflow obstruction, and they most frequently experienced exacerbations requiring hospitalization during the 1-year follow-up. Subgroup 3 included subjects with additional symptoms and mild airflow obstruction; this group had more female patients and a modest frequency of exacerbations requiring hospitalization.

Conclusions

Cluster analysis using the baseline data of a COPD cohort identified three distinct subgroups with different clinical parameters and outcomes. These findings suggest that the identified subgroups represent clinically meaningful subtypes of COPD.

Electronic supplementary material

The online version of this article (10.1186/s12890-017-0553-9) contains supplementary material, which is available to authorized users.

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.

Lung densitometry: why, how and when

Lung densitometry assesses with computed tomography (CT) the X-ray attenuation of the pulmonary tissue which reflects both the degree of inflation and the structural lung abnormalities implying decreased attenuation, as in emphysema and cystic diseases, or increased attenuation, as in fibrosis. Five reasons justify replacement with lung densitometry of semi-quantitative visual scales used to measure extent and severity of diffuse lung diseases: (I) improved reproducibility; (II) complete vs. discrete assessment of the lung tissue; (III) shorter computation times; (IV) better correlation with pathology quantification of pulmonary emphysema; (V) better or equal correlation with pulmonary function tests (PFT). Commercially and open platform software are available for lung densitometry. It requires attention to technical and methodological issues including CT scanner calibration, radiation dose, and selection of thickness and filter to be applied to sections reconstructed from whole-lung CT acquisition. Critical is also the lung volume reached by the subject at scanning that can be measured in post-processing and represent valuable information per se. The measurements of lung density include mean and standard deviation, relative area (RA) at -970, -960 or -950 Hounsfield units (HU) and 1st and 15th percentile for emphysema in inspiratory scans, and RA at -856 HU for air trapping in expiratory scans. Kurtosis and skewness are used for evaluating pulmonary fibrosis in inspiratory scans. The main indication for lung densitometry is assessment of emphysema component in the single patient with chronic obstructive pulmonary diseases (COPD). Additional emerging applications include the evaluation of air trapping in COPD patients and in subjects at risk of emphysema and the staging in patients with lymphangioleiomyomatosis (LAM) and with pulmonary fibrosis. It has also been applied to assess prevalence of smoking-related emphysema and to monitor progression of smoking-related emphysema, alpha1 antitrypsin deficiency emphysema, and pulmonary fibrosis. Finally, it is recommended as end-point in pharmacological trials of emphysema and lung fibrosis.

Cross-Sectional Study of Chronic Obstructive Pulmonary Disease Prevalence Among Smokers, Ex-Smokers, and Never-Smokers in Almaty, Kazakhstan: Study Protocol

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is significantly underdiagnosed in Kazakhstan, and there is no previously conducted study on COPD prevalence in the country.

OBJECTIVE

The purpose of this study is to assess the prevalence of COPD among individuals aged 40 to 59 years based on results of spirometry before and after bronchodilator, presence of structural changes in the lungs (emphysema, inflammatory changes, and thickening of the walls of the large and small airways) detected by computer tomography, and the symptoms of COPD. The study has 3 study groups: smokers of conventional cigarettes, those who had quit smoking 1 to 5 years ago, and those who haven't smoked cigarettes.

METHODS

This is an observational study with a cross-sectional design among individuals aged 40 to 59 years in Almaty, Kazakhstan. The sample of 900 individuals of both sexes contains 500 smokers, 200 ex-smokers, and 200 never-smokers. Study measures include spirometry, chest computed tomography, electrocardiography, physical exams, laboratory testing of serum, anthropometry, and 6-minute walk test. Data are collected by computer-assisted personal interviewing with tablets. The questionnaire was designed to explore possible COPD risk factors including history of smoking, current smoking, level of smoking exposure (in pack-years), passive smoking, occupational and environmental hazards, and covariates: age, gender, ethnicity, education, occupation, and self-reported morbidity. COPD Assessment Test (CAT) is used to collect information about COPD symptoms.

RESULTS

We have completed the participant recruitment and study procedures. Currently, we are working on data processing and data analysis. The authors anticipate the preliminary results should be available by September 2017. Study results will be published in peer-reviewed scientific journals.

CONCLUSIONS

This is the first study in Kazakhstan that assesses prevalence of COPD and its comorbidities in the adult population aged 40 to 59 years. The results of the study will be useful for improving COPD preventive measures, better COPD screening, identification, and registration. Findings of the study will also contribute to global knowledge on the epidemiology of COPD.

TRIAL REGISTRATION

ClinicalTrials.gov NCT02926534; https://clinicaltrials.gov/ct2/show/NCT02926534 (Archived by WebCite at http://www.webcitation.org/6rjwGsPOZ).

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.

Phenotyping Before Starting Treatment in COPD?

Chronic Obstructive Pulmonary Disease (COPD) is a heterogeneous and complex disease with great morbidity and mortality. Despite the new developments in the managements of COPD, it was recognized that not all patients benefit from the available medications. Therefore, efforts to identify subgroups or phenotypes had been made in order to predict who will respond to a class of drugs for COPD. This review will discuss phenotypes, endotypes, and subgroups such as the frequent exacerbator, the one with systemic inflammation, the fast decliner, ACOS, and the one with co-morbidities and their impact on therapy. It became apparent, that the "inflammatory" phenotypes: frequent exacerbator, chronic bronchitic, and those with a number of co-morbidities need inhaled corticosteroids; in contrast, the emphysematous type with dyspnea and lung hyperinflation, the fast decliner, need dual bronchodilation (deflators). However, larger, well designed studies clustering COPD patients are needed, in order to identify the important subgroups and thus, to lead to personalize management in COPD.

Phenotyping emphysema and airways disease: Clinical value of quantitative radiological techniques

The pathophysiology of chronic obstructive pulmonary disease (COPD) and Alpha one antitrypsin deficiency is increasingly recognised as complex such that lung function alone is insufficient for early detection, clinical categorisation and dictating management. Quantitative imaging techniques can detect disease earlier and more accurately, and provide an objective tool to help phenotype patients into predominant airways disease or emphysema. Computed tomography provides detailed information relating to structural and anatomical changes seen in COPD, and magnetic resonance imaging/nuclear imaging gives functional and regional information with regards to ventilation and perfusion. It is likely imaging will become part of routine clinical practice, and an understanding of the implications of the data is essential. This review discusses technical and clinical aspects of quantitative imaging in obstructive airways disease.

Body height as risk factor for emphysema in COPD

Pulmonary emphysema is a phenotypic component of chronic obstructive pulmonary disease (COPD) which carries substantial morbidity and mortality. We explored the association between emphysema and body height in 726 patients with COPD using computed tomography as the reference diagnostic standard for emphysema. We applied univariate analysis to look for differences between patients with emphysema and those without, and multivariate logistic regression to identify significant predictors of the risk of emphysema. As covariates we included age, sex, body height, body mass index, pack-years of smoking, and forced expiratory volume in one second (FEV₁) as percent predicted. The overall prevalence of emphysema was 52%. Emphysemic patients were significantly taller and thinner than non-emphysemic ones, and featured significantly higher pack-years of smoking and lower FEV₁ (P < 0.001). The prevalence of emphysema rose linearly by 10-cm increase in body height (r² = 0.96). In multivariate analysis, the odds of emphysema increased by 5% (95% confidence interval, 3 to 7%) along with one-centimeter increase in body height, and remained unchanged after adjusting for all the potential confounders considered (P < 0.001). The odds of emphysema were not statistically different between males and females. In conclusion, body height is a strong, independent risk factor for emphysema in COPD.

Clinical phenotypes of obstructive airway diseases in an outpatient population

BACKGROUND AND OBJECTIVES

Historically, obstructive airway diseases such as asthma and COPD are classified as different diseases. Although the definitions are clearly described, classification of patients into these traditional, clinical disease entity can be difficult. Recent evidence that there are complex, overlapping phenotypes of obstructive lung disease. Our aim was to capture clinical phenotypes of obstructive diseases through the use of cluster analysis in a representative patient population at a common Dutch pulmonary outpatient clinic. Clinical physiological and cellular/ molecular markers were used in the analysis.

METHODS

To carry out the cluster analysis, an imputed dataset was created from a random sample of 191 adult patients chosen from a pulmonary outpatient clinic. The selection criteria from the sample included patients with a doctor's diagnosis for asthma or COPD. Detailed assessment of patient pulmonary function, blood eosinophil counts, allergic sensitisation and smoking history was collected.

RESULTS

We observed four distinct clusters with different clinical characteristics of obstructive lung diseases. Cluster 1: patients with a history of extensive cigarette smoking, airway obstruction without signs of emphysema; cluster 2: patients with features of the emphysematous type of COPD; cluster 3: patients with characteristics of allergic asthma; cluster 4: patients with features suggesting an overlap syndrome of atopic asthma and COPD.

CONCLUSION

Four phenotypes of obstructive lung disease were identified amongst patients clinically labelled as asthma or COPD. These findings emphasize the concept that there are different phenotypes of obstructive lung diseases, including overlapping and complementary disease entities. These phenotypes of chronic airways disease can serve to tailor disease management.

Emphysema- and airway-dominant COPD phenotypes defined by standardised quantitative computed tomography

EvA (Emphysema versus Airway disease) is a multicentre project to study mechanisms and identify biomarkers of emphysema and airway disease in chronic obstructive pulmonary disease (COPD). The objective of this study was to delineate objectively imaging-based emphysema-dominant and airway disease-dominant phenotypes using quantitative computed tomography (QCT) indices, standardised with a novel phantom-based approach.441 subjects with COPD (Global Initiative for Chronic Obstructive Lung Disease (GOLD) stages 1-3) were assessed in terms of clinical and physiological measurements, laboratory testing and standardised QCT indices of emphysema and airway wall geometry.QCT indices were influenced by scanner non-conformity, but standardisation significantly reduced variability (p<0.001) and led to more robust phenotypes. Four imaging-derived phenotypes were identified, reflecting "emphysema-dominant", "airway disease-dominant", "mixed" disease and "mild" disease. The emphysema-dominant group had significantly higher lung volumes, lower gas transfer coefficient, lower oxygen (PO2 ) and carbon dioxide (PCO2 ) tensions, higher haemoglobin and higher blood leukocyte numbers than the airway disease-dominant group.The utility of QCT for phenotyping in the setting of an international multicentre study is improved by standardisation. QCT indices of emphysema and airway disease can delineate within a population of patients with COPD, phenotypic groups that have typical clinical features known to be associated with emphysema-dominant and airway-dominant disease.

Identification of five chronic obstructive pulmonary disease subgroups with different prognoses in the ECLIPSE cohort using cluster analysis

RATIONALE

Chronic obstructive pulmonary disease (COPD) is a heterogeneous disease that likely includes clinically relevant subgroups.

OBJECTIVES

To identify subgroups of COPD in ECLIPSE (Evaluation of COPD Longitudinally to Identify Predictive Surrogate Endpoints) subjects using cluster analysis and to assess clinically meaningful outcomes of the clusters during 3 years of longitudinal follow-up.

METHODS

Factor analysis was used to reduce 41 variables determined at recruitment in 2,164 patients with COPD to 13 main factors, and the variables with the highest loading were used for cluster analysis. Clusters were evaluated for their relationship with clinically meaningful outcomes during 3 years of follow-up. The relationships among clinical parameters were evaluated within clusters.

MEASUREMENTS AND MAIN RESULTS

Five subgroups were distinguished using cross-sectional clinical features. These groups differed regarding outcomes. Cluster A included patients with milder disease and had fewer deaths and hospitalizations. Cluster B had less systemic inflammation at baseline but had notable changes in health status and emphysema extent. Cluster C had many comorbidities, evidence of systemic inflammation, and the highest mortality. Cluster D had low FEV1, severe emphysema, and the highest exacerbation and COPD hospitalization rate. Cluster E was intermediate for most variables and may represent a mixed group that includes further clusters. The relationships among clinical variables within clusters differed from that in the entire COPD population.

CONCLUSIONS

Cluster analysis using baseline data in ECLIPSE identified five COPD subgroups that differ in outcomes and inflammatory biomarkers and show different relationships between clinical parameters, suggesting the clusters represent clinically and biologically different subtypes of COPD.

Wheezing, a significant clinical phenotype of COPD: experience from the Taiwan Obstructive Lung Disease Study

BACKGROUND

COPD is an important public health challenge with significant heterogeneity of clinical presentation and disease progression. Clinicians have been trying to find phenotypes that may be linked to distinct prognoses and different therapeutic choices. Not all patients with COPD present with wheezing, a possible clinical phenotype that can help differentiate patient subgroups.

METHODS

The Taiwan Obstructive Lung Disease study was a retrospective, multicenter research study to investigate the treatment patterns of COPD after the implementation of the Global Initiative for Chronic Obstructive Lung Disease 2011 guidelines. Between November 2012 and August 2013, medical records were retrieved from patients with COPD aged ≥40 years; patients diagnosed with asthma were excluded. Demographic data, lung function, symptom scores, and acute exacerbation were recorded and analyzed, and the differences between patients with and without wheezing were evaluated.

RESULTS

Of the 1,096 patients with COPD, 424 (38.7%) had the wheezing phenotype. The wheezing group had significantly higher COPD Assessment Test scores (12.4±7.8 versus 10.5±6.7, P<0.001), higher modified Medical Research Council grade (2.0±1.0 versus 1.7±0.9, P<0.001), and more acute exacerbations within the past year (0.9±1.3 versus 0.4±0.9, P<0.001) than the nonwheezing group. The postbronchodilator forced expiratory volume in 1 second was lower in wheezing patients (1.2±0.5 L versus 1.5±0.6 L, P<0.001). Even in patients with maintenance treatment fitting the Global Initiative for Chronic Obstructive Lung Disease 2011 guidelines, the wheezing group still had worse symptom scores and more exacerbations.

CONCLUSION

Wheezing is an important phenotype in patients with COPD. Patients with COPD having the wheezing phenotype are associated with worse symptoms, more exacerbations, and worse lung function.

LAMA/LABA vs ICS/LABA in the treatment of COPD in Japan based on the disease phenotypes

In the combined use of bronchodilators of different classes, ie, long-acting β2-agonists (LABAs) and long-acting muscarinic antagonists (LAMAs), bronchodilation is obtained both directly, through LABA-mediated stimulation of β2-adrenergic receptors, and indirectly, through LAMA-mediated inhibition of acetylcholine action at muscarinic receptors. The clinical trial data for LABAs/LAMAs in the treatment of chronic obstructive pulmonary disease (COPD) continue to be promising, and these combinations will provide the convenience of delivering the two major bronchodilator classes, recommended as first-line maintenance options in COPD treatment guidelines. COPD is a complex condition that has pulmonary and extrapulmonary manifestations. These clinical manifestations are highly variable, and several are associated with different responses to currently available therapies. The concept of a COPD phenotype is rapidly evolving from one focusing on the clinical characteristics to one linking the underlying biology to the phenotype of the disease. Identification of the peculiarities of the different COPD phenotypes will permit us to implement a more personalized treatment in which the patient's characteristics, together with his or her genotype, will be key to choosing the best treatment option. At present in Japan, fixed combinations of inhaled corticosteroids (ICSs) and LABAs are frequently prescribed in the earlier stages of COPD. However, ICSs increase the risk of pneumonia. Notably, 10%-30% of patients with COPD with or without a history of asthma have persistent circulating and airway eosinophilia associated with an increased risk of exacerbations and sensitivity to steroids. Thus, sputum or blood eosinophil counts might identify a subpopulation in which ICSs could have potentially deleterious effects as well as a subpopulation that benefits from ICSs. In this review, I propose one plausible approach to position ICSs and LABAs/LAMAs in clinical practice, based on both the extent of airflow obstruction and the presence of an asthma component or airway eosinophilic inflammation. This approach is a tentative move toward personalized treatment for COPD patients, and with progress in knowledge and developments in physiology, lung imaging, medical biology, and genetics, identification of COPD phenotypes that provide prognostic and therapeutic information that can affect clinically meaningful outcomes is an urgent medical need.

Derivation and validation of clinical phenotypes for COPD: a systematic review

BACKGROUND

The traditional classification of COPD, which relies solely on spirometry, fails to account for the complexity and heterogeneity of the disease. Phenotyping is a method that attempts to derive a single or combination of disease attributes that are associated with clinically meaningful outcomes. Deriving phenotypes entails the use of cluster analyses, and helps individualize patient management by identifying groups of individuals with similar characteristics. We aimed to systematically review the literature for studies that had derived such phenotypes using unsupervised methods.

METHODS

Two independent reviewers systematically searched multiple databases for studies that performed validated statistical analyses, free of definitive pre-determined hypotheses, to derive phenotypes among patients with COPD. Data were extracted independently.

RESULTS

9156 citations were retrieved, of which, 8 studies were included. The number of subjects ranged from 213 to 1543. Most studies appeared to be biased: patients were more likely males, with severe disease, and recruited in tertiary care settings. Statistical methods used to derive phenotypes varied by study. The number of phenotypes identified ranged from 2 to 5. Two phenotypes, with poor longitudinal health outcomes, were common across multiple studies: young patients with severe respiratory disease, few cardiovascular co-morbidities, poor nutritional status and poor health status, and a phenotype of older patients with moderate respiratory disease, obesity, cardiovascular and metabolic co-morbidities.

CONCLUSIONS

The recognition that two phenotypes of COPD were often reported may have clinical implications for altering the course of the disease. This review also provided important information on limitations of phenotype studies in COPD and the need for improvement in future studies.

A prospective multicentric study of pulmonary rehabilitation in patients with chronic obstructive pulmonary disease and different clinical phenotypes

BACKGROUND

Recently, it has been proposed that different clinical phenotypes can be recognized in patients with chronic obstructive disease (COPD), namely predominant airway disease or parenchymal destructive changes.

OBJECTIVES

The aim of this prospective multicenter study was to evaluate whether these two phenotypes may influence outcomes following a pulmonary rehabilitation program (PRP).

METHODS

We have prospectively evaluated 364 consecutive COPD patients (70 ± 8 years, 76.3% males) admitted to a standard hospital-based PRP in 6 Italian centers. According to their phenotype, the study cohort was divided into two groups: patients with airway obstructive (group 1, n = 208) or parenchymal destructive COPD (group 2, n = 156). Before and after PRP, values of 6-min walking distance, perceived breathlessness (Medical Research Council), health-related quality of life (St. George's Respiratory Questionnaire) and respiratory muscle function (maximal inspiratory and expiratory pressure) were recorded.

RESULTS

PRP resulted in significant improvements in all outcome measures without any significant differences between groups.

CONCLUSIONS

Our study confirms that COPD patients may benefit from pulmonary rehabilitation independent of their clinical phenotype.

Severity grading of chronic obstructive pulmonary disease: the confounding effect of phenotype and thoracic gas compression

Current guidelines recommend severity of chronic obstructive pulmonary disease be graded by using forced expiratory volume in 1 s (FEV1). But this measurement is biased by thoracic gas compression depending on lung volume and airflow resistance. The aim of this study was to test the hypothesis that the effect of thoracic gas compression on FEV1 is greater in emphysema than chronic bronchitis because of larger lung volumes, and this influences severity classification and prognosis. FEV1 was simultaneously measured by spirometry and body plethysmography (FEV1-pl) in 47 subjects with dominant emphysema and 51 with dominant chronic bronchitis. Subjects with dominant emphysema had larger lung volumes, lower diffusion capacity, and lower FEV1 than those with dominant chronic bronchitis. However, FEV1-pl, patient-centered variables (dyspnea, quality of life, exercise tolerance, exacerbation frequency), arterial blood gases, and respiratory impedance were not significantly different between groups. Using FEV1-pl instead of FEV1 shifted severity distribution toward less severe classes in dominant emphysema more than chronic bronchitis. The body mass, obstruction, dyspnea, and exercise (BODE) index was significantly higher in dominant emphysema than chronic bronchitis, but this difference significantly decreased when FEV1-pl was substituted for FEV1. In conclusion, the FEV1 is biased by thoracic gas compression more in subjects with dominant emphysema than in those with chronic bronchitis. This variably and significantly affects the severity grading systems currently recommended.

Non-emphysematous chronic obstructive pulmonary disease is associated with diabetes mellitus

BACKGROUND

Chronic obstructive pulmonary disease (COPD) has been classically divided into blue bloaters and pink puffers. The utility of these clinical subtypes is unclear. However, the broader distinction between airway-predominant and emphysema-predominant COPD may be clinically relevant. The objective was to define clinical features of emphysema-predominant and non-emphysematous COPD patients.

METHODS

Current and former smokers from the Genetic Epidemiology of COPD Study (COPDGene) had chest computed tomography (CT) scans with quantitative image analysis. Emphysema-predominant COPD was defined by low attenuation area at -950 Hounsfield Units (LAA-950) ≥10%. Non-emphysematous COPD was defined by airflow obstruction with minimal to no emphysema (LAA-950 < 5%).

RESULTS

Out of 4197 COPD subjects, 1687 were classified as emphysema-predominant and 1817 as non-emphysematous; 693 had LAA-950 between 5-10% and were not categorized. Subjects with emphysema-predominant COPD were older (65.6 vs 60.6 years, p < 0.0001) with more severe COPD based on airflow obstruction (FEV1 44.5 vs 68.4%, p < 0.0001), greater exercise limitation (6-minute walk distance 1138 vs 1331 ft, p < 0.0001) and reduced quality of life (St. George's Respiratory Questionnaire score 43 vs 31, p < 0.0001). Self-reported diabetes was more frequent in non-emphysematous COPD (OR 2.13, p < 0.001), which was also confirmed using a strict definition of diabetes based on medication use. The association between diabetes and non-emphysematous COPD was replicated in the ECLIPSE study.

CONCLUSIONS

Non-emphysematous COPD, defined by airflow obstruction with a paucity of emphysema on chest CT scan, is associated with an increased risk of diabetes. COPD patients without emphysema may warrant closer monitoring for diabetes, hypertension, and hyperlipidemia and vice versa.

TRIAL REGISTRATION

Clinicaltrials.gov identifiers: COPDGene NCT00608764, ECLIPSE NCT00292552.

AIMAR survey on COPD phenotypes

BACKGROUND

COPD is characterized by considerable diversity in terms of clinical signs and symptoms, physiopathological mechanisms, response to treatment and disease progression. For this reason, the identification of different patient subgroups (or possible phenotypes) is important both for prognosis and for therapeutic objectives. Based on the foregoing, AIMAR has decided to conduct a survey on the perception of the prevalence of the different clinical COPD phenotypes/subtypes in the clinical practice of physicians who treat patients with chronic obstructive pulmonary disease, and on their therapeutic objectives.

METHODS

The survey consisted of 19 multiple-choice questions, compiled through a form published online. All the data and answers entered into the system were checked for consistency and completeness directly online at the time they were entered, and each respondent could only complete the questionnaire once.

RESULTS

The survey took place from May through October 2012. A total of 1,434 questionnaires (60% of the sample approached) were eligible for analysis, broken down as follows: 537 pulmonologists, 666 general practitioners (GPs), 72 internal medicine specialists, 36 allergists, 30 geriatricians, 93 other specialists. The results show that a significant proportion of GPs (33%) identified more than 50 patients in their practices with a diagnosis of COPD. Although most patients are or have been in treatment with a long-acting bronchodilator, the most common reasons for seeing a GP or a specialist were exacerbations and worsening of the symptoms, suggesting the importance of an appropriate background therapy in order to reduce the risk of disease instability. The frequent exacerbator phenotype was the most commonly found phenotype in clinical practice (by 75% of specialists and 66% of GPs); patients with a prevalent phenotype of chronic bronchitis were reported more often by GPs, while specialists reported a higher number of patients with a prevalent phenotype of emphysema.A medical history of exacerbations and the extent of deterioration of the spirometry parameters were considered to be the major indicators for COPD severity and clinical risk. In managing the frequent exacerbator phenotype, the therapeutic objectives - both for GPs and for specialists - included reducing airway inflammation, improving bronchial dilation, and reducing pulmonary hyperinflation. For this type of patients at high clinical risk, specialists selected a first-line therapeutic option based on a predetermined combination of an inhaled corticosteroid (ICS) and a long-acting β2-agonist bronchodilator (LABA) and a second-line three-drug therapy (combination of ICS and two long-acting bronchodilators), while GPs' choices are more diversified, without a clear-cut prevalence of one type of treatment. In patients with COPD and concomitant cardiovascular diseases, frequently observed in clinical practice by all physicians, the combination of ICS and LABA was considered the first-choice option by the highest proportion of GPs (43%) and specialists (37%), while a smaller number of specialists (35%) opted for the long acting muscarinic antagonists (LAMA). Both GPs and specialists believe that therapeutic continuity is of primary importance for the achievement of clinical outcomes with all classes of drugs.

CONCLUSIONS

A good knowledge of COPD has been observed in a high percentage of GPs, indicating an increased awareness of this disease in Primary Health Care. The frequent exacerbator phenotype is viewed by all physicians as the most prevalent in clinical practice, bearing a high risk of hospitalization. For specialists, therapeutic measures aimed at reducing the number and severity of exacerbations are primarily based on the combination of inhaled corticosteroid and bronchodilator, presumably because of the complementary pharmacological action of its components, whereas while GPs' choices tend to be more diversified. Adherence to medication regimens is of the essence for the achievement of clinical outcomes.

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.

Identification of clinical phenotypes using cluster analyses in COPD patients with multiple comorbidities

Chronic obstructive pulmonary disease (COPD) is characterized by persistent airflow limitation, the severity of which is assessed using forced expiratory volume in 1 sec (FEV1, % predicted). Cohort studies have confirmed that COPD patients with similar levels of airflow limitation showed marked heterogeneity in clinical manifestations and outcomes. Chronic coexisting diseases, also called comorbidities, are highly prevalent in COPD patients and likely contribute to this heterogeneity. In recent years, investigators have used innovative statistical methods (e.g., cluster analyses) to examine the hypothesis that subgroups of COPD patients sharing clinically relevant characteristics (phenotypes) can be identified. The objectives of the present paper are to review recent studies that have used cluster analyses for defining phenotypes in observational cohorts of COPD patients. Strengths and weaknesses of these statistical approaches are briefly described. Description of the phenotypes that were reasonably reproducible across studies and received prospective validation in at least one study is provided, with a special focus on differences in age and comorbidities (including cardiovascular diseases). Finally, gaps in current knowledge are described, leading to proposals for future studies.

Exercise performance after standard rehabilitation in COPD patients with lung hyperinflation

The role of pulmonary rehabilitation (PR) in COPD patients with lung hyperinflation has not yet been fully investigated. We retrospectively evaluated the effect of a standard PR course on exercise tolerance and symptoms according to the presence or absence of associated lung hyperinflation, as defined by lung function parameters in three Italian rehabilitation centres. In a cohort of 823 COPD patients (age 71 ± 8 years, FEV1 56 ± 18% pred.) we have systematically recorded: changes (∆) in 6-minute walking test (6MWD) as the primary outcome; dyspnoea (D); muscle fatigue (F); SO2nadir during effort; perceived breathlessness score (MRC); and specific health-related quality of life (SGRQ). Outcomes were compared between patients with lung hyperinflation (n = 283, LH) or without (n = 540 No-LH). Groups were comparable for age, body mass index, baseline exercise tolerance, and breathlessness. ∆-6MWD (+72 ± 47 vs. +62 ± 42 m, p < 0.05); ∆-D (-2.3 ± 1.7 vs. -1.9 ± 1.3 point, p < 0.05) and ∆-SO2nadir (+1.4 ± 3.0 and +0.5 ± 3.3 point, p < 0.05) were greater in LH than in No-LH. Using a multivariate linear regression model, ∆-6MWD in the LH group significantly correlated with lower functional residual capacity (p = 0.021) and baseline 6MWD (p = 0.004). Tolerance, gas exchange and perceived symptoms during effort are the parameters that gain a significant benefit from standard rehabilitation in COPD patients with a lung hyperinflation condition.

Challenges of COPD diagnosis

INTRODUCTION

Chronic obstructive pulmonary disease (COPD) is a leading cause of death worldwide and this burden is predicted to increase unless exposure to risk factors is addressed. Diagnosis of COPD is a challenge: COPD is underdiagnosed and frequently misdiagnosed for asthma or other respiratory conditions. Although spirometry is only one parameter for establishing a clinical diagnosis of COPD, lack of routine spirometry is a key cause of COPD misdiagnosis. Differential diagnosis from asthma is essential because the treatment strategies for, and progression and outcomes of, the two conditions vary greatly.

AREAS COVERED

Here the authors review methods for the differential diagnosis of COPD and asthma; approaches to improve diagnosis, including case-finding and screening; the identification of specific COPD phenotypes and targeted therapy; and the potential role of exhaled biomarkers in the diagnosis of COPD.

EXPERT OPINION

Methods to diagnose COPD, specifically differential diagnosis from asthma, have improved in recent years. To translate these into clinical practice will require the development of combined guidelines for COPD and asthma that include COPD-asthma overlap syndrome and are based on evidence from randomized controlled trials.

Computerized analysis of respiratory sounds during COPD exacerbations

Acute exacerbation of chronic obstructive pulmonary disease (AECOPD) is a major event in the natural course of the disease, and is associated with significant mortality and socioeconomic impact. Abnormal respiratory sounds are commonly present in patients with AECOPD. Computerized analysis of these sounds can assist in diagnosis and in evaluation during follow-up. Exploratory data analysis methods were applied to respiratory sounds in these patients when they were hospitalized because of exacerbation. Two different patterns of presentation and evolution of respiratory sounds in AECOPD were found and described from the method of computerized respiratory sound analysis and unsupervised clustering that was devised. Based on the findings of the study, remote monitoring of respiratory sounds may be useful for the detection and/or follow-up of COPD exacerbation.

Chronic obstructive pulmonary disease diagnosis: the simpler the better? Not always

The acronym chronic obstructive pulmonary disease (COPD) has been introduced in the early 1960s to describe a disease characterized by largely irreversible airflow obstruction, due to a combination of airway disease and pulmonary emphysema, without defining their respective contribution to the pathology. COPD is a disorder that causes considerable morbidity and mortality. Currently, it represents the fourth leading cause of death in the world, and it is expected to increase both in prevalence and in mortality over the next decades. The most widely adopted definition of COPD is that of the Global Initiative for Chronic Obstructive Lung Disease (GOLD), that recommends the use of the post-bronchodilator forced expiratory volume in the first second to forced vital capacity ratio (FEV1/FVC)<0.7 to define irreversible airflow obstruction. This approach, called "fixed ratio", has been introduced to provide a simple tool for COPD diagnosis, as it is easy to remember. Even if modern medicine and research seem to prefer rigid cut-offs and classifications, this often contrasts with the complex nature of the disease. The aim of the present review is to explain that such a fixed cut-off failed to increase COPD diagnosis, and furthermore often leads to inescapable misclassification of patients, with the risk of an excessive simplification of a clinical approach necessarily complex.

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.

Effects of emphysema on oxygen uptake during maximal exercise in COPD

The objective of the study is to assess the effects of emphysema on peak oxygen uptake ([Formula: see text]) during a cardiopulmonary exercise test in patients with chronic obstructive pulmonary disease (COPD). We measured [Formula: see text] and oxygen pulse in 80 patients with stable COPD exercising maximally. Oxygen saturation was measured by pulse oximetry (SpO(2)), and the ventilatory response assessed by the ratio of tidal volume (V (T)) at peak to slow vital capacity (SVC) at baseline, and by the percent increase of peak V (T) over baseline. Computed tomography imaging (CT scan) served as the reference diagnostic standard for emphysema. Based on the panel-grading (PG) method, emphysema was rated absent or mild (PG ≤ 30, n = 54), or moderate to severe (PG > 30, n = 26). Multiple quantile regression was applied to estimate the effects of PG > 30 on [Formula: see text]. At peak exercise, the patients with PG > 30 had significantly lower [Formula: see text], oxygen pulse and SpO(2), and featured a blunted ventilatory response with respect to those with PG ≤ 30 (p < 0.001). With multiple quantile regression, the effects of PG > 30 on [Formula: see text] were only partially explained by the degree of lung hyperinflation, a substantial component being imputable to impairment of lung diffusing capacity. In conclusion, chronic obstructive pulmonary disease patients with moderate to severe emphysema feature significantly lower exercise tolerance than those with no or mild emphysema. Our findings underscore the need of tailoring therapeutic interventions for COPD to the predominant clinical phenotype to improve exercise capacity.

The rapid FEV(1) decline in chronic obstructive pulmonary disease is associated with predominant emphysema: a longitudinal study

BACKGROUND

Early identification of patients with COPD and prone to more rapid decline in lung function is of particular interest from both a prognostic and therapeutic point of view. The aim of this study was to identify the clinical, functional and imaging characteristics associated with the rapid FEV(1) decline in COPD.

METHODS

Between 2001 and 2005, 131 outpatients with moderate COPD in stable condition under maximum inhaled therapy underwent clinical interview, pulmonary function tests and HRCT imaging of the chest and were followed for at least 3 years.

RESULTS

Twenty-six percent of patients had emphysema detected visually using HRCT. The FEV(1) decline was 42 ± 66 mL/y in the total sample, 88 ± 76 mL/y among rapid decliners and 6 ± 54 mL/y among the other patients. In the univariable analysis, the decline of FEV(1) was positively associated with pack-years (p < 0.05), emphysema at HRCT (p < 0.001), RV (p < 0.05), FRC (p < 0.05), FEV(1) (p < 0.01) at baseline and with number of hospitalizations per year (p < 0.05) during the follow-up. Using multivariable analysis, the presence of emphysema proved to be an independent prognostic factor of rapid decline (p = 0.001). When emphysema was replaced by RV, the model still remained significant.

CONCLUSIONS

The rapid decline in lung function may be identified by the presence of emphysema at HRCT or increased RV in patients with a long smoking history.

BODE-index, modified BODE-index and ADO-score in chronic obstructive pulmonary disease: relationship with COPD phenotypes and CT lung density changes

COPD is a heterogeneous disorder whose assessment is going to be increasingly multidimensional. Grading systems such as BODE (Body-Mass Index, Obstruction, Dyspnea, Exercise), mBODE (BODE modified in grading of walked distance), ADO (Age, Dyspnea, Obstruction) are proposed to assess COPD severity and outcome. Computed tomography (CT) is deemed to reflect COPD lung pathologic changes. We studied the relationship of multidimensional grading systems (MGS) with clinically determined COPD phenotypes and CT lung density. Seventy-two patients underwent clinical and chest x-ray evaluation, pulmonary function tests (PFT), 6-minute walking test (6MWT) to derive: predominant COPD clinical phenotype, BODE, mBODE, ADO. Inspiratory and expiratory CT was performed to calculate mean lung attenuation (MLA), relative area with density below-950 HU at inspiration (RAI(-950)), and below -910 HU at expiration (RAE(-910)). MGS, PFT, and CT data were compared between bronchial versus emphysematous COPD phenotype. MGS were correlated with CT data. The prediction of CT density by means of MGS was investigated by direct and stepwise multivariate regression. MGS did not differ in clinically determined COPD phenotypes. BODE was more closely related and better predicted CT findings than mBODE and ADO; the better predictive model was obtained for CT expiratory data; stepwise regression models of CT data did not include 6MWT distance; the dyspnea score MRC was included only to predict RA-950 and RA-910 which quantify emphysema extent. BODE reflect COPD severity better than other MGS, but not its clinical heterogeneity. 6MWT does not significantly increase BODE predictivity of CT lung density changes.

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.