Lung function indices for predicting mortality in COPD

Mendelian randomisation studies for causal inference in chronic obstructive pulmonary disease: A narrative review

BACKGROUND AND OBJECTIVE

Most non-randomised controlled trials are unable to establish clear causal relationships in chronic obstructive pulmonary disease (COPD) due to the presence of confounding factors. This review summarises the evidence that the Mendelian randomisation method can be a powerful tool for performing causal inferences in COPD.

METHODS

A non-systematic search of English-language scientific literature was performed on PubMed using the following keywords: 'Mendelian randomisation', 'COPD', 'lung function', and 'GWAS'. No date restrictions were applied. The types of articles selected included randomised controlled trials, cohort studies, observational studies, and reviews.

RESULTS

Mendelian randomisation is becoming an increasingly popular method for identifying the risk factors of COPD. Recent Mendelian randomisation studies have revealed some risk factors for COPD, such as club cell secretory protein-16, impaired kidney function, air pollutants, asthma, and depression. In addition, Mendelian randomisation results suggest that genetically predicted factors such as PM2.5, inflammatory cytokines, growth differentiation factor 15, docosahexaenoic acid, and testosterone may have causal relationships with lung function.

CONCLUSION

Mendelian randomisation is a robust method for performing causal inferences in COPD research as it reduces the impact of confounding factors.

Association between impaired diffusion capacity and small airway dysfunction: a cross-sectional study

Background

Small airway dysfunction (SAD) and impaired diffusion capacity of the lungs for carbon monoxide (D LCO) are positively associated with a worse prognosis. Individuals with both dysfunctions have been identified in clinical practice and it is unknown whether they have worse health status or need management. We conducted this study to explore the association between SAD and impaired D LCO, and the difference between the groups with two dysfunctions, with either one dysfunction and with no dysfunction.

Methods

This study involved subjects partly from those who had returned for the third-year follow-up (up to December 2022) of the Early Chronic Obstructive Pulmonary Disease study and those who newly participated. We assessed diffusion capacity, questionnaire, exacerbations, spirometry, impulse oscillometry (IOS) and computed tomography (CT). Impaired D LCO was defined as D LCO <80% predicted. Spirometry-defined SAD was defined using the percent predicted values of maximal mid-expiratory flow, and forced expiratory flow at 50% and 75% of forced vital capacity, at least two of these three values being <65% predicted after the use of a bronchodilator. IOS-defined SAD was defined when the difference in resistance at 5 and 20 Hz was >0.07 kPa·L-1·s. CT-defined SAD was defined when the percentage of expiratory low-attenuation areas <-856 HU comprised ≥15% of the total lung volume. Covariate analyses and logistic regression were performed to assess the association between impaired D LCO and SAD.

Results

This study involved 581 subjects. The occurrence of both spirometry- and CT-defined SAD was significantly higher in subjects with impaired D LCO than normal D LCO. Subjects with two dysfunctions were associated with worse preceding year's exacerbations than controls.

Conclusions

Impaired diffusion capacity is positively associated with SAD. Subjects with impaired diffusion capacity and SAD may have a worse health status and need additional management.

Respiratory muscle strength can improve the prognostic assessment in COPD

Impaired lung function, respiratory muscle weakness and exercise intolerance are present in COPD and contribute to poor prognosis. However, the contribution of the combination of these manifestations to define prognosis in COPD is still unknown. This study aimed to define cut-off points for both inspiratory and expiratory muscle strength (MIP and MEP, respectively) for mortality prediction over 42-months in patients with COPD, and to investigate its combination with other noninvasive established prognostic measures (FEV1, V̇O2peak and 6MWD) to improve risk identification. Patients with COPD performed pulmonary function, respiratory muscle strength, six-minute walk and cardiopulmonary exercise tests, and were followed over 42 months to analyze all-cause mortality. A total of 79 patients were included. The sample was mostly (91.1%) comprised of severe (n = 37) and very severe (n = 34) COPD, and 43 (54%) patients died during the follow-up period. Cut-points of ≤ 55 and ≤ 80 cmH2O for MIP and MEP, respectively, were associated with increased risk of death (log-rank p = 0.0001 for both MIP and MEP) in 42 months. Furthermore, MIP and MEP substantially improved the mortality risk assessment when combined with FEV1 (log-ranks p = 0.006 for MIP and p < 0.001 for MEP), V̇O2peak (log-rank: p < 0.001 for both MIP and MEP) and 6MWD (log-ranks: p = 0.005 for MIP; p = 0.015 for MEP). Thus, patients severely affected by COPD presenting MIP ≤ 55 and/or MEP ≤ 80 cmH2O are at increased risk of mortality. Furthermore, MIP and MEP substantially improve the mortality risk assessment when combined with FEV1, V̇O2peak and 6MWD in patients with COPD.

Mortality prevention as the centre of COPD management

COPD is a major healthcare problem and cause of mortality worldwide. COPD patients at increased mortality risk are those who are more symptomatic, have lower lung function and lower diffusing capacity of the lung for carbon monoxide, decreased exercise capacity, belong to the emphysematous phenotype and those who have concomitant bronchiectasis. Mortality risk seems to be greater in patients who experience COPD exacerbations and in those who suffer from concomitant cardiovascular and/or metabolic diseases. To predict the risk of death in COPD patients, several composite scores have been created using different parameters. In previous years, large studies (also called mega-trials) have evaluated the efficacy of different therapies on COPD mortality, but until recently only nonpharmaceutical interventions have proven to be effective. However, recent studies on fixed combinations of triple therapy (long-acting β-agonists, long-acting muscarinic antagonists and inhaled corticosteroids) have provided encouraging results, showing for the first time a reduction in mortality compared to dual therapies. The aim of the present review is to summarise available data regarding mortality risk in COPD patients and to describe pharmacological therapies that have shown effectiveness in reducing mortality.

The Validity of Patient-Reported Outcome Measures of Quality of Life in Palliative Care: A Systematic Review

Importance: A recent systematic review and meta-analysis found that palliative care was not associated with improvement in quality of life (QOL) in terminal noncancer illness. Among potential reasons for a null effect, it is unclear if patient-reported outcome measures (PROMs) measuring QOL were derived or validated among populations with advanced life-limiting illness (ALLI). Objective: To systematically review the derivation and validation of QOL PROMs from a recent meta-analysis of randomized controlled trials (RCT) of palliative care interventions in people with terminal noncancer illness. Evidence Review: EMBASE, MEDLINE, and PsycINFO were searched from inception to January 8, 2023 for primary validation studies of QOL PROMs in populations with ALLI, defined as adults with a progressive terminal condition and an estimated median survival of less than or equal to one year. The primary outcome was the proportion of PROMs that were derived or validated in ≥1 ALLI population. Findings: Twenty-one unique studies of derivation (n = 13) and validation (n = 11, 3 studies evaluated both) provided data on 9657 participants (mean age 63 years, 50% female) across 15 unique QOL PROMs and subscales. Among studies of validation, 9 were in people with cancer (n = 2289, n = 5 PROMs), 1 in neurodegenerative disease (n = 23, n = 1 PROM), and 1 with mixed diseases (n = 248, n = 1 PROM). Across 15 QOL PROMs and subscales, 47% (n = 7) were derived or validated in an ALLI population. The majority of these seven PROMs were exclusively derived or validated among people with cancer (57%, n = 4). QOL PROMs such as Quality of Life at End of Life, EuroQoL-5 Dimension 5-level, and 36-item Short Form Survey demonstrated validity in more than one terminal noncancer illness. Conclusions: Most QOL PROMs that measured the effect of palliative care on QOL in RCTs were neither derived nor validated in an ALLI population. These findings raise questions about the inferences that palliative care does not improve QOL among people with terminal noncancer illness.

Diffusing capacity as an independent predictor of acute exacerbations in chronic obstructive pulmonary disease

A weak correlation between diffusing capacity of the lung for carbon monoxide (DLCO) and emphysema has been reported. This study investigated whether impaired DLCO in chronic obstructive pulmonary disease (COPD) is associated with increased risk of acute exacerbation independent of the presence or extent of emphysema. This retrospective cohort study included patients with COPD between January 2004 and December 2019. The participants were divided into four groups based on visually detected emphysema and impaired DLCO. Among 597 patients with COPD, 8.5% had no emphysema and impaired DLCO whereas 36.3% had emphysema without impaired DLCO. Among the four groups, patients with impaired DLCO and emphysema showed a higher risk of moderate-to-severe or severe exacerbation than those with normal DLCO. Impaired DLCO was an independent risk factor for severe exacerbation (hazard ratio, 1.524 [95% confidence interval 1.121-2.072]), whereas the presence of emphysema was not. The risk of moderate-to-severe or severe exacerbation increases with the severity of impaired DLCO. After propensity-score matching for the extent of emphysema, impaired DLCO was significantly associated with a higher risk of moderate-to-severe (p = 0.041) or severe exacerbation (p = 0.020). In patients with COPD and heterogeneous parenchymal abnormalities, DLCO can be considered an independent biomarker of acute exacerbation.

Diffusing Capacity as a Predictor of Hospitalizations in a Clinical Cohort of Chronic Obstructive Pulmonary Disease

Rationale: Chronic obstructive pulmonary disease (COPD) hospitalizations are a major burden on patients. Diffusing capacity of the lung for carbon monoxide (DlCO) is a potential predictor that has not been studied in large cohorts. Objectives: This study used electronic health record data to evaluate whether clinically obtained DlCO predicts COPD hospitalizations. Methods: We performed time-to-event analyses of individuals with COPD and DlCO measurements from the Johns Hopkins COPD Precision Medicine Center of Excellence. Cox proportional hazard methods were used to model time from DlCO measurement to first COPD hospitalization and composite first hospitalization or death, adjusting for age, sex, race, body mass index, smoking status, forced expiratory volume in 1 second (FEV1), history of prior COPD hospitalization, and comorbidities. To identify the utility of including DlCO in risk models, area under the receiver operating curve (AUC) values were calculated for models with and without DlCO. Results were externally validated in a separate analogous cohort. Results: Of 2,793 participants, 368 (13%) had a COPD hospitalization within 3 years. In adjusted analyses, for every 10% decrease in DlCO% predicted, risk of COPD hospitalization increased by 10% (hazard ratio, 1.1; 95% confidence interval, 1.1-1.2; P < 0.001). Similar associations were observed for COPD hospitalizations or death. The model including demographics, comorbidities, FEV1, DlCO, and prior COPD hospitalizations performed well, with an AUC of 0.85 and an AUC of 0.84 in an external validation cohort. Conclusions: Diffusing capacity is a strong predictor of COPD hospitalizations in a clinical cohort of individuals with COPD, independent of airflow obstruction and prior hospitalizations. These findings support incorporation of DlCO in risk assessment of patients with COPD.

Individuals with psychosis present a reduced lung diffusion capacity and early spirometry alterations: Results from a cross-sectional study

OBJECTIVE

Individuals with psychosis present a greater prevalence of chronic lung diseases, including Chronic Obstructive Pulmonary Disease (COPD). These chronic respiratory diseases are preceded by early lung function alterations; such as preserved ratio impaired spirometry (PRISm) or normal spirometry but low diffusion capacity of the lung for carbon monoxide (DLCO). However, there is no previous evidence on these lung function alterations in psychosis. The aim of this study is to evaluate the risk of having spirometry and DLCO alterations in subjects with psychosis compared with a control group.

METHODS

Cross-sectional study on a cohort of 170 individuals including 96 subjects with psychosis and 74 sex-age-and smoking habit matched healthy controls. All subjects were under 60 years-old, and without COPD or asthma. Respiratory function was evaluated through spirometry. Clinical characteristics and DLCO values were recorded.

RESULTS

Patients with psychosis showed lower spirometry results, both in terms of absolute and percentage of Forced Vital Capacity (FVC) and Forced Expiratory Volume in one second (FEV1). Absolute and percentage levels of diffusion were also lower in patients with psychosis. The percentage of individuals with DLCO<80% was higher among patients with psychosis (75% vs. 40%, p < 0.001). And the prevalence of PRISm was higher among patients with psychosis (10.4% vs. 1.4%, p < 0.001). Multivariate logistic regression analysis indicated that psychosis was an independent predictor of DLCO<80% (OR 5.67, CI95% 1.86-17.27).

CONCLUSION

Patients with psychosis and females had early alterations in lung function. These results suggest that early screening for lung disease should be encouraged in psychosis.

Stronger Associations of Centrilobular Than Paraseptal Emphysema With Longitudinal Changes in Diffusing Capacity and Mortality in COPD

BACKGROUND

The factors associated with longitudinal changes in diffusing capacity remain unclear among patients with COPD. Centrilobular emphysema (CLE) and paraseptal emphysema (PSE) are major emphysema subtypes that may have distinct clinical-physiological impacts in these patients.

RESEARCH QUESTION

Are CLE and PSE differently associated with longitudinal changes in diffusing capacity and mortality in patients with COPD?

STUDY DESIGN AND METHODS

This pooled analysis included 399 patients with COPD from two prospective observational COPD cohorts. CLE and PSE were visually assessed on CT scan according to the Fleischner Society statement. The diffusing capacity and transfer coefficient of the lung for carbon monoxide (Dlco and KCO) and FEV1 were evaluated at least annually over a 5-year period. Mortality was recorded over 10 years. Longitudinal changes in FEV1, Dlco, and KCO and mortality were compared between mild or less severe and moderate or more severe CLE and between present and absent PSE in each Global Initiative for Chronic Obstructive Lung Disease (GOLD) stage.

RESULTS

The Dlco and KCO decline was weakly associated with FEV1 and greater in GOLD stage 3 or higher than in GOLD stages 1 and 2. Furthermore, moderate or more severe CLE, but not present PSE, was associated with steeper declines in Dlco for GOLD stages 1 and 3 or higher and KCO for all GOLD stages independent of age, sex, height, and smoking history. The moderate or more severe CLE, but not present PSE, was associated with additional FEV1 decline and higher 10-year mortality among patients with GOLD stage 3 or higher.

INTERPRETATION

A CT scan finding of moderate or more severe CLE, but not PSE, was associated with a subsequent accelerated impairment in diffusing capacity and higher long-term mortality in severe GOLD stage among patients with COPD.

Understanding COPD Etiology, Pathophysiology, and Definition

COPD, one of the leading worldwide health problems, currently lacks truly disease-modifying medical therapies applicable to most patients. Developing such novel therapies has been hampered by the marked heterogeneity of phenotypes between individuals with COPD. Such heterogeneity suggests that, rather than a single cause (particularly just direct inhalation of tobacco products), development and progression of COPD likely involve both complex gene-by-environment interactions to multiple inhalational exposures and a variety of molecular pathways. However, there has been considerable recent progress toward understanding how specific pathological processes can lead to discrete COPD phenotypes, particularly that of small airways disease. Advances in imaging techniques that correlate to specific types of histological damage, and in the immunological mechanisms of lung damage in COPD, hold promise for development of personalized therapies. At the same time, there is growing recognition that the current diagnostic criteria for COPD, based solely on spirometry, exclude large numbers of individuals with very similar disease manifestations. This concise review summarizes current understanding of the etiology and pathophysiology of COPD and provides background explaining the increasing calls to expand the diagnostic criteria used to diagnose COPD and some challenges in doing so.

Prognostic Biomarkers Based on Proteomic Technology in COPD: A Recent Review

Chronic obstructive pulmonary disease (COPD) is a common heterogeneous respiratory disease which is characterized by persistent and incompletely reversible airflow limitation. Due to the heterogeneity and phenotypic complexity of COPD, traditional diagnostic methods provide limited information and pose a great challenge to clinical management. In recent years, with the development of omics technologies, proteomics, metabolomics, transcriptomics, etc., have been widely used in the study of COPD, providing great help to discover new biomarkers and elucidate the complex mechanisms of COPD. In this review, we summarize the prognostic biomarkers of COPD based on proteomic studies in recent years and evaluate their association with COPD prognosis. Finally, we present the prospects and challenges of COPD prognostic-related studies. This review is expected to provide cutting-edge evidence in prognostic evaluation of clinical patients with COPD and to inform future proteomic studies on prognostic biomarkers of COPD.

The Anti-Inflammatory Mechanism of Flaxseed Linusorbs on Lipopolysaccharide-Induced RAW 264.7 Macrophages by Modulating TLR4/NF-κB/MAPK Pathway

Flaxseed linusorbs (FLs), cyclic peptides derived from flaxseed oils, have shown multiple activities such as anticancer, antibacterial, and anti-inflammatory effects. However, the anti-inflammatory monomers of FLs and their mechanisms are still unclear. In this study, we have elucidated that FLs suppress the modulation of NF-κB/MAPK signaling pathways by targeting the inhibition of activating TLR4 in LPS-induced RAW 264.7 cells. Therefore, the transcription and expression of inflammatory cytokines (i.e., TNF-α, IL-1β, and IL-6) and inflammatory mediator proteins (i.e., iNos and Cox-2) were significantly suppressed by FLs. In addition, an in silico study discovered that eight monomers of FLs showed high-affinity bindings with TLR4. In silico data combined with HPLC results indicated that FLA and FLE, accounting for 44%, were likely the major anti-inflammatory monomers in FLs. In summary, FLA and FLE were proposed as the main anti-inflammatory active cyclopeptides via hindering TLR4/NF-κB/MAPK signaling pathways, suggesting the potential use of food-derived FLs as natural anti-inflammatory supplements in a daily diet.

Physiology and Biomarkers for Surveillance of Occupational Lung Disease

Respiratory surveillance is the process whereby a group of exposed workers are regularly tested (or screened) for those lung diseases which occur as a result of a specific work exposure. Surveillance is performed by assessing various measures of biological or pathological processes (or biomarkers) for change over time. These traditionally include questionnaires, lung physiological assessments (especially spirometry), and imaging. Early detection of pathological processes or disease can enable removal of a worker from a potentially harmful exposure at an early stage. In this article, we summarize the physiological biomarkers currently used for respiratory surveillance, while commenting on differences in interpretative strategies between different professional groups. We also briefly review the many new techniques which are currently being assessed for respiratory surveillance in prospective research studies and which are likely to significantly broaden and enhance this field in the near future.

Diffusing Capacity and Mortality in Chronic Obstructive Pulmonary Disease

Rationale: Chronic obstructive pulmonary disease (COPD) mortality risk is often estimated using the BODE (body mass index, obstruction, dyspnea, exercise capacity) index, including body mass index, forced expiratory volume in 1 second, dyspnea score, and 6-minute walk distance. Diffusing capacity of the lung for carbon monoxide (DlCO) is a potential predictor of mortality that reflects physiology distinct from that in the BODE index. Objectives: This study evaluated DlCO as a predictor of mortality using participants from the COPDGene study. Methods: We performed time-to-event analyses of individuals with COPD (former or current smokers with forced expiratory volume in 1 second/forced vital capacity < 0.7) and DlCO measurements from the COPDGene phase 2 visit. Cox proportional hazard methods were used to model survival, adjusting for age, sex, pack-years, smoking status, BODE index, computed tomography (CT) percent emphysema (low attenuation areas below -950 Hounsfield units), CT airway wall thickness, and history of cardiovascular or kidney diseases. C statistics for models with DlCO and BODE scores were used to compare discriminative accuracy. Results: Of 2,329 participants, 393 (16.8%) died during the follow-up period (median = 4.9 yr). In adjusted analyses, for every 10% decrease in DlCO percent predicted, mortality increased by 28% (hazard ratio = 1.28; 95% confidence interval, 1.17-1.41, P < 0.001). When compared with other clinical predictors, DlCO percent predicted performed similarly to BODE (C statistic DlCO = 0.68; BODE = 0.70), and the addition of DlCO to BODE improved its discriminative accuracy (C statistic = 0.71). Conclusions: Diffusing capacity, a measure of gas transfer, strongly predicted all-cause mortality in individuals with COPD, independent of BODE index and CT evidence of emphysema and airway wall thickness. These findings support inclusion of DlCO in prognostic models for COPD.

Combustion-Derived Particulate PAHs Associated with Small Airway Dysfunction in Elderly Patients with COPD

Evidence of the respiratory effects of ambient organic aerosols (e.g., polycyclic aromatic hydrocarbons, PAHs) among patients with chronic diseases is limited. We aimed to assess whether exposure to ambient particle-bound PAHs could worsen small airway functions in patients with chronic obstructive pulmonary disease (COPD) and elucidate the underlying mechanisms involved. Forty-five COPD patients were recruited with four repeated visits in 2014-2015 in Beijing, China. Parameters of pulmonary function and pulmonary/systemic inflammation and oxidative stress were measured at each visit. Linear mixed-effect models were performed to evaluate the associations between PAHs and measurements. In this study, participants experienced an average PAH level of 61.7 ng/m³. Interquartile range increases in exposure to particulate PAHs at prior up to 7 days were associated with reduced small airway functions, namely, decreases of 17.7-35.5% in forced maximal mid-expiratory flow. Higher levels of particulate PAHs were also associated with heightened lung injury and inflammation and oxidative stress. Stronger overall effects were found for PAHs from traffic emissions and coal burning. Exposure to ambient particulate PAHs was capable of impairing small airway functions in elderly patients with COPD, potentially via inflammation and oxidative stress. These findings highlight the importance of control efforts on organic particulate matter from fossil fuel combustion emissions.

Traffic-related air pollution associated pulmonary pathophysiologic changes and cardiac injury in elderly patients with COPD

Traffic-related air pollution (TRAP) has shown enormous environmental toxicity, but its cardiorespiratory health impact on chronic obstructive pulmonary disease (COPD) has been less studied. We followed a panel of 45 COPD patients with 4 repeated clinical visits across 14 months in a traffic-predominated urban area of Beijing, China, with concurrent measurements of TRAP metrics (fine particulate matter, black carbon, oxides of nitrogen and carbon monoxide). Linear mixed-effect models were performed to evaluate the associations and potential pathways linking traffic pollution to indicators of spirometry, cardiac injury, inflammation and oxidative stress. We observed that interquartile range increases in moving averages of TRAP exposures at prior up to 7 days were associated with significant reductions in large and small airway functions, namely decreases in forced vital capacity of 3.1-9.3% and forced expiratory flow 25-75% of 5.9-16.4%. Higher TRAP levels were also associated with worsening of biomarkers relevant to lung injury (hepatocyte growth factor and surfactant protein D) and cardiac injury (high-sensitivity cardiac troponin I, B-type natriuretic peptide and soluble ST2), as well as enhanced airway/systemic inflammation and oxidative stress. Mediation analyses showed that TRAP exposures may prompt cardiac injury, possibly via worsening pulmonary pathophysiology. These findings highlight the importance of traffic pollution control priority in urban areas.

Emphysema-Predominant COPD Had a Greater 5-Year Mortality and a Worse Annual Decline in Lung Function Than Airway Obstruction-Predominant COPD or Asthma at Initial Same Degree of Airflow Obstruction

Background and Objectives: We studied whether the extent of exertional oxygen desaturation and emphysema could cause greater mortality in COPD and asthma independent of airflow obstruction. Materials and Methods: We performed a 5-year longitudinal observational study in COPD and asthma patients who matched for airflow obstruction severity. All subjects performed a 6-min walk test (6MWT) and high-resolution computed tomography (HRCT) and followed spirometry and oxygen saturation (SpO2) during the 6MWT every 3-6 months. Overall survival was recorded. Cumulative survival curves were performed according to the Kaplan-Meier method and compared with the log-rank test. Results: The COPD group had higher emphysema scores, higher Δinspiratory capacities (ICs) and lower SpO2 during the 6MWT, which showed a greater yearly decline in FEV1 (40.6 mL) and forced vital capacity (FVC) (28 mL) than the asthma group (FEV1, 9.6 mL; FVC, 1.2 mL; p < 0.05). The emphysema-predominant COPD group had an accelerated annual decline in lung function and worse survival. The nadir SpO2 ≤ 80% and a higher emphysema score were the strong risk factors for mortality in COPD patients. Conclusions: The greater structural changes with a higher emphysema score and greater desaturation during the 6MWT in COPD may contribute to worse yearly decline in FEV1 and higher five-year mortality than in asthma patients with a similar airflow obstruction. The lowest SpO2 ≤ 80% during the 6MWT and emphysema-predominant COPD were the strong independent factors for mortality in chronic obstructive airway disease patients.

Overcoming Therapeutic Inertia to Reduce the Risk of COPD Exacerbations: Four Action Points for Healthcare Professionals

Background

Therapeutic inertia, defined as failure to escalate or initiate adequate therapy when treatment goals are not met, contributes to poor management of COPD exacerbations.

Methods

A multidisciplinary panel of five expert clinicians actively managing COPD and representative of UK practice developed action points to reduce exacerbation risk, based on evidence, clinical expertise, and experience. The action points are applicable despite changing circumstances (eg, virtual clinics). The panel agreed areas where further evidence is needed.

Results

The four action points were (1) an experienced HCP, such as a GP or member of the multi-professional COPD team should review patients within one month of every exacerbation that requires oral steroids, antibiotics, or hospitalization to address modifiable risk factors, optimize non-pharmacological measures, and evaluate pharmacological therapy. (2) Presenting to hospital with an exacerbation defines an important window of opportunity to reduce the risk of further exacerbations. Follow-up by a GP, or member of the multi-professional specialist COPD team within one month of discharge with a full management review and appropriate escalation of pharmacological treatment is essential. (3) Healthcare professionals (HCPs) in all healthcare settings should be able to recognize COPD exacerbations, refer as appropriate and document the episode accurately in medical records across service boundaries. HCPs should support patients to recognize and report exacerbations. (4) HCPs should intervene proactively based on risk assessments, disease activity and any treatable traits at or as soon as possible after diagnosis and annually thereafter. Delivering these action points needs coordinated action with policymakers, funders, and service providers.

Conclusion

These action points should be a fundamental part of clinical practice to determine if a change in management is necessary to reduce the risk of exacerbations. Policymakers should use these action points to develop systems and initiatives that reduce the risk of further exacerbations.

Influence of reduced diffusing capacity and FEV1 on outcome after cardiac surgery

BACKGROUND

Impaired lung function is a well-known risk factor in cardiac surgery patients and reduced forced expiratory volume in 1 second (FEV₁ ) is associated with increased mortality. However, there is limited knowledge regarding the influence of impaired diffusing capacity of the lungs for carbon monoxide (DLCO) in unselected cardiac surgery patients. The aim of this study was to investigate the association of impaired DLCO and/or reduced FEV₁ on post-operative mortality and morbidity in cardiac surgery patients.

METHODS

In a prospective cohort study, 390 patients scheduled for elective cardiac surgery underwent preoperative lung function test including spirometry and DLCO measurements. We defined reduced FEV₁ as FEV₁ below lower limit of normal (LLN) and impaired DLCO as DLCO <60% of predicted.

RESULTS

Mortality within 1 year (90-570 days) was significantly higher in patients with impaired DLCO (12% vs 3%, P = .010) and with reduced FEV₁ (9% vs 3%, P = .028). Mortality was higher in patients with impaired DLCO both in the presence and absence of FEV₁  < LLN. In multivariate analysis, only impaired DLCO [OR: 3.3, 95% confidence interval (CI) 1.4-7.5; P = .005] and age (OR: 1.1 per year, 95% CI 1.0-1.2; P = .001) were independent predictors of the combined outcome of mortality and prolonged intensive care unit (ICU) stay. Impaired DLCO was also associated with post-operative respiratory complications.

CONCLUSION

In patients undergoing elective cardiac surgery, preoperative impaired FEV₁ and DLCO were associated with increased mortality and morbidity. In multivariate analysis, only DLCO and age were independent predictors of a combined outcome of mortality and prolonged ICU stay.

Comparing hospital admissions, comorbidities and biomarkers between severe asthma and Gold III-IV COPD

INTRODUCTION

In spite of difficulties in differentiating asthma from COPD, physicians should strive for accurate diagnosis because outcomes may be different.

OBJECTIVES

Our aims were to compare the frequency of hospital admissions (HA) between severe asthmatic (SA) and Gold III-IV COPD subjects receiving disease specific guideline recommended therapy, depict the frequency of prevalent chronic disorders and the laboratorial profile suggesting allergic and eosinophilic phenotypes.

METHODS

This cross-sectional study comprises one group of SA subjects and another group of Gold III-IV COPD subjects. Subjects answered standard questionnaires, underwent spirometry and provided a peripheral blood sample. We validated the HA that have occurred during the preceding year by review of the report emitted by the hospital. We detected comorbidities by review of current pharmacological therapies.

RESULTS

We enrolled 160 SA and 41 Gold III-IV COPD subjects. As compared with Gold III-IV COPD subjects, SA subjects had lower odds of HA (OR 0.19, 95CI 0.05-0.74) and higher odds of obesity (OR 9.17, 95CI 2.68-31.37), hypertension (OR 2.54, 95CI 1.16-5.57) and diabetes mellitus (OR 5.71, 95CI 1.56-20.85). The frequency of atopic and eosinophilic phenotypes were similar between study groups.

CONCLUSIONS

Our results demonstrated that Gold III-IV COPD subjects had worse outcomes as compared to SA subjects. We also observed that the frequency of atopy and high peripheral-blood eosinophil count were similar between study groups. Finally, we exposed aspects of comorbidities related to asthma and COPD that indicate the need of close monitoring the cardiovascular risk in SA subjects above 40 years of age.

Household Food Insecurity, Lung Function, and COPD in US Adults

Increasing epidemiological evidence suggests that optimal diet quality helps to improve preservation of lung function and to reduce chronic obstructive pulmonary disease (COPD) risk, but no study has investigated the association of food insecurity (FI) and lung health in the general population. Using data from a representative sample of US adults who participated in the National Health and Nutrition Examination Survey (NHANES) 2007-2012 cycles, we investigated the association between FI with lung function and spirometrically defined COPD in 12,469 individuals aged ≥ 18 years of age. FI (high vs. low) was defined using the US Department of Agriculture's Food Security Scale). Population-weighted adjusted regression models were used to investigate associations between FI, and forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC), their ratio, and spirometrically defined restriction (FVC below the lower limit of normal) and airflow obstruction (COPD). The prevalence of household FI was 13.2%. High household FI was associated with lower FVC (adjusted β-coefficient -70.9 mL, 95% CI -116.6, -25.3), and with higher odds (OR) of spirometric restriction (1.02, 95% CI 1.00, 1.03). Stratified analyses showed similar effect sizes within specific ethnic groups. High FI was associated with worse lung health in a nationally representative sample of adults in the US.

The correlation between quadriceps muscle strength and endurance and exercise performance in patients with COPD

To determine the association between quadriceps muscle strength (QMS) and endurance (QME) and exercise capacity in patients with COPD after stratification for sex and resting lung function (LF). Data were collected from 3,246 patients with COPD (60% men, 64 ± 9 yr), including measures of exercise capacity [peak aerobic capacity (peakV̇o₂), 6-min walk distance (6MWD)] and isokinetic QMS and QME. Patients were stratified for sex, forced expiratory volume in 1 s (>50/≤50% predicted), single breath carbon monoxide diffusing capacity (>50/≤50% predicted), and residual volume (>140/≤140% predicted). After stratification for resting LF, QMS and QME were significantly associated with peakV̇o₂ (r range: 0.47-0.61 and 0.49-0.65 for men and 0.53-0.66 and 0.48-0.67 for women, respectively) and 6MWD (r range: 0.29-0.42 and 0.44-0.55 for men and 0.25-0.54 and 0.34-0.55 for women, respectively) (P < 0.001). Regression models demonstrated that QMS and QME were significant determinants of peakV̇o₂ (explained variance R² range: 35.6%-48.8% for men and 36.8%-49.0% for women) and 6MWD (R² range: 24.3%-43.3% for men and 28.4%-40.3% for women), independent of age and fat-free mass. Quadriceps muscle function was significantly associated with peakV̇o₂ and 6MWD in male and female patients with COPD after stratification for resting LF, in which QME appear to be a more important determinant than QMS. This underlines the importance of systematically evaluating both quadriceps muscle strength and endurance in in all patients with COPD.NEW & NOTEWORTHY Our findings identified quadriceps muscle function as an important determinant of exercise capacity across a wide spectrum of lung function. Quadriceps muscle endurance appears to be a more important determinant than quadriceps muscle strength, underlining the importance of including both the measurement of quadriceps muscle strength and endurance in routine assessment for all patient with COPD.

Lung function and peak oxygen uptake in chronic obstructive pulmonary disease phenotypes with and without emphysema

Previous studies of associations of forced expiratory lung volume in one second (FEV₁) with peak oxygen uptake (VO_2peak) in chronic obstructive pulmonary disease (COPD) have not taken sex, age and height related variance of dynamic lung volumes into account. Nor have such demographic spread of spirometric measures been considered in studies comparing VO_2peak between COPD phenotypes characterized by degree of emphysema. We aimed to assess the association of FEV_1Z-score with VO_2peak in COPD (n = 186) and investigate whether this association differs between emphysema (E-COPD) and non-emphysema (NE-COPD) phenotypes. Corresponding assessments using standardized percent predicted FEV₁ (ppFEV₁) were performed for comparison. Additionally, phenotype related differences in VO_2peak were compared using FEV_1Z-score and ppFEV₁ as alternative expressions of FEV₁. E-COPD and NE-COPD were defined by transfer factor of the lung for carbon monoxide below and above lower limits of normal (LLN), respectively. The associations were assessed in linear regression models. One unit reduction in FEV_1Z-score was associated with 1.9 (95% CI 1.4, 2.5) ml/kg/min lower VO_2peak. In stratified analyses, corresponding estimates were 2.2 (95% CI 1.4, 2.9) and 1.2 (95% CI 0.2, 2.2) ml/kg/min lower VO_2peak in E-COPD and NE-COPD, respectively. The association did not differ statistically by COPD phenotype (p-value for interaction = 0.153). Similar estimates were obtained in analyses using standardized ppFEV₁. Compared to NE-COPD, VO_2peak was 2.2 (95% CI 0.8, 3.6) and 2.1 (95% CI 0.8, 3.5) ml/kg/min lower in E-COPD when adjusted for FEV_1Z-score and ppFEV₁, respectively. In COPD, FEV_1Z-score is positively associated with VO_2peak. This association was stronger in E-COPD but did not differ statistically by phenotype. Both the association of FEV₁ with VO_2peak and the difference in VO_2peak comparing COPD phenotypes seems independent of sex, age and height related variance in FEV₁. Mechanisms leading to reduction in FEV₁ may contribute to lower VO_2peak in E-COPD.

Clinical and Prognostic Impact of Low Diffusing Capacity for Carbon Monoxide Values in Patients With Global Initiative for Obstructive Lung Disease I COPD

BACKGROUND

The Global Initiative for Obstructive Lung Disease (GOLD) does not promote diffusing capacity for carbon monoxide (Dlco) values in the evaluation of COPD. In GOLD spirometric stage I COPD patients, the clinical and prognostic impact of a low Dlco has not been explored.

RESEARCH QUESTION

Could a Dlco threshold help define an increased risk of death and a different clinical presentation in these patients?

STUDY DESIGN AND METHODS

GOLD stage I COPD patients (n = 360) were enrolled and followed over 109 ± 50 months. Age, sex, pack-years' history, BMI, dyspnea, lung function measurements, exercise capacity, BODE index, and history of exacerbations were recorded. A cutoff value for Dlco was identified for all-cause mortality and the clinical and physiological characteristics of patients above and below the threshold compared. Cox regression analysis explored the predictive power of that cutoff value for all-cause mortality.

RESULTS

A Dlco cutoff value of <60% predicted was associated with all-cause mortality (Dlco ≥ 60%: 9% vs Dlco < 60%: 23%, P = .01). At a same FEV₁% predicted and Charlson score, patients with Dlco < 60% had lower BMI, more dyspnea, lower inspiratory capacity (IC)/total lung capacity (TLC) ratio, lower 6-min walk distance (6MWD), and higher BODE. Cox multiple regression analysis confirmed that after adjusting for age, sex, pack-years history, smoking status, and BMI, a Dlco < 60% is associated with all-cause mortality (hazard ratio [HR], 95% CI = 3.37, 1.35-8.39; P = .009) INTERPRETATION: In GOLD I COPD patients, a Dlco < 60% predicted is associated with increased risk of death and worse clinical presentation. What the cause(s) of this association are and whether they can be treated need to be determined.

Natural Course of the Diffusing Capacity of the Lungs for Carbon Monoxide in COPD: Importance of Sex

BACKGROUND

The value of the single-breath diffusing capacity of the lungs for carbon monoxide (Dlco) relates to outcomes for patients with COPD. However, little is known about the natural course of Dlco over time, intersubject variability, and factors that may influence Dlco progression.

RESEARCH QUESTION

What is the natural course of Dlco in patients with COPD over time, and which other factors, including sex differences, could influence this progression?

STUDY DESIGN AND METHODS

We phenotyped 602 smokers (women, 33%), of whom 506 (84%) had COPD and 96 (16%) had no airflow limitation. Lung function, including Dlco, was monitored annually over 5 years. A random coefficients model was used to evaluate Dlco changes over time.

RESULTS

The mean (± SE) yearly decline in Dlco % in patients with COPD was 1.34% ± 0.015%/y. This was steeper compared with non-COPD control subjects (0.04% ± 0.032%/y; P = .004). Sixteen percent of the patients with COPD, vs 4.3% of the control subjects, had a statistically significant Dlco % slope annual decline (4.14%/y). At baseline, women with COPD had lower Dlco values (11.37% ± 2.27%; P < .001) in spite of a higher FEV₁ % than men. Compared with men, women with COPD had a steeper Dlco annual decline of 0.89% ± 0.42%/y (P = .039).

INTERPRETATION

Patients with COPD have an accelerated decline in Dlco compared with smokers without the disease. However, the decline is slow, and a testing interval of 3 to 4 years may be clinically informative. The lower and more rapid decline in Dlco values in women, compared with men, suggests a differential impact of sex in gas exchange function.

TRIAL REGISTRY

ClinicalTrials.gov; No.: NCT01122758; URL: www.clinicaltrials.gov.

Epigenome-wide association study on diffusing capacity of the lung

BACKGROUND

Epigenetics may play an important role in the pathogenesis of lung diseases. However, little is known about the epigenetic factors that influence impaired gas exchange at the lung.

AIM

To identify the epigenetic signatures of the diffusing capacity of the lung measured by carbon monoxide uptake (the diffusing capacity of the lung for carbon monoxide (D LCO)).

METHODS

An epigenome-wide association study (EWAS) was performed on diffusing capacity, measured by carbon monoxide uptake (D LCO) and per alveolar volume (V A) (as D LCO/V A), using the single-breath technique in 2674 individuals from two population-based cohort studies. These were the Rotterdam Study (RS, the "discovery panel") and the Framingham Heart Study (FHS, the "replication panel"). We assessed the clinical relevance of our findings by investigating the identified sites in whole blood and by lung tissue specific gene expression.

RESULTS

We identified and replicated two CpG sites (cg05575921 and cg05951221) that were significantly associated with D LCO/V A and one (cg05575921) suggestively associated with D LCO. Furthermore, we found a positive association between aryl hydrocarbon receptor repressor (AHRR) gene (cg05575921) hypomethylation and gene expression of exocyst complex component 3 (EXOC3) in whole blood. We confirmed that the expression of EXOC3 in lung tissue is positively associated with D LCO/V A and D LCO.

CONCLUSIONS

We report on epigenome-wide associations with diffusing capacity in the general population. Our results suggest EXOC3 to be an excellent candidate, through which smoking-induced hypomethylation of AHRR might affect pulmonary gas exchange.

Diffusing capacity in chronic obstructive pulmonary disease assessment: A meta-analysis

To achieve a multidimensional evaluation of chronic obstructive pulmonary disease (COPD) patients, the spirometry measures are supplemented by assessment of symptoms, risk of exacerbations, and CT imaging. However, the measurement of diffusing capacity of the lung for carbon monoxide (DLCO) is not included in most common used models of COPD assessment. Here, we conducted a meta-analysis to evaluate the role of DLCO in COPD assessment.The studies were identified by searching the terms "diffusing capacity" OR "diffusing capacity for carbon monoxide" or "DLCO" AND "COPD" AND "assessment" in Pubmed, Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, Scopus, and Web of Science databases. The mean difference of DLCO % predict was assessed in COPD patient with different severity (according to GOLD stage and GOLD group), between COPD patients with or without with frequent exacerbation, between survivors and non-survivors, between emphysema dominant and non-emphysema dominant COPD patients, and between COPD patients with or without pulmonary hypertension.43 studies were included in the meta-analysis. DLCO % predicted was significantly lower in COPD patients with more severe airflow limitation (stage II/IV), more symptoms (group B/D), and high exacerbation risk (group C/D). Lower DLCO % predicted was also found in exacerbation patients and non-survivors. Low DLCO % predicted was related to emphysema dominant phenotype, and COPD patients with PH.The current meta-analysis suggested that DLCO % predicted might be an important measurement for COPD patients in terms of severity, exacerbation risk, mortality, emphysema domination, and presence of pulmonary hypertension. As diffusion capacity reflects pulmonary ventilation and perfusion at the same time, the predictive value of DLCO or DLCO combined with other criteria worth further exploration.

Disproportionally Impaired Diffusion Capacity Relative to Airflow Limitation in COPD

Forced expiratory volume in 1 s (FEV₁) is a standard physiological index of chronic obstructive pulmonary disease (COPD), but reflects emphysema and vascular abnormalities less sensitively than diffusion capacity for carbon monoxide (D_LCO). This study tested whether a disproportionally impaired D_LCO relative to FEV₁ (FEV₁ z-score>-3 and D_LCO z-score≤-3) is a common functional COPD phenotype associated with distinct clinical and structural features and the prognosis of two cohorts. The cross-sectional analyses of the Korea COPD Subgroup Study (KOCOSS) cohort (multicenter study in Korea) included 743 males with COPD whose D_LCO was available. The cross-sectional and longitudinal analyses of the Kyoto University Cohort (single-center study in Japan) included 195 males with COPD who were prospectively followed for 10 years. A disproportionally impaired D_LCO relative to FEV₁ was observed in 29% and 31% of patients in the KOCOSS and Kyoto University cohorts, respectively. In the multivariable analysis, the disproportionally impaired D_LCO was associated with worse symptoms, shorter 6-minute walking distance, paraseptal and centrilobular emphysema on computed tomography, and reduced arterial oxygen and carbon dioxide pressures compared to the reference (FEV₁ z-score>-3 and D_LCO z-score>-3). In the multivariable Cox proportional hazard model, a higher long-term mortality was observed in the disproportionally impaired D_LCO group than in the reference group (hazard ratio [95% confidence interval] = 3.09 [1.52-6.29]) and similar to the D_LCO z-score≤-3 and FEV₁ z-score≤-3 group. The disproportionally impaired D_LCO relative to FEV₁ is common and associated with increased symptoms, emphysema, arterial blood gas abnormalities, and increased long-term mortality in patients with COPD.

The effects of lung volume reduction treatment on diffusing capacity and gas exchange

Lung volume reduction (LVR) treatment in patients with severe emphysema has been shown to have a positive effect on hyperinflation, expiratory flow, exercise capacity and quality of life. However, the effects on diffusing capacity of the lungs and gas exchange are less clear. In this review, the possible mechanisms by which LVR treatment can affect diffusing capacity of the lung for carbon monoxide (D _LCO) and arterial gas parameters are discussed, the use of D _LCO in LVR treatment is evaluated and other diagnostic techniques reflecting diffusing capacity and regional ventilation (V')/perfusion (Q') mismatch are considered.A systematic review of the literature was performed for studies reporting on D _LCO and arterial blood gas parameters before and after LVR surgery or endoscopic LVR with endobronchial valves (EBV). D _LCO after these LVR treatments improved (40 studies, n=1855) and the mean absolute change from baseline in % predicted D _LCO was +5.7% (range -4.6% to +29%), with no real change in blood gas parameters. Improvement in V' inhomogeneity and V'/Q' mismatch are plausible explanations for the improvement in D _LCO after LVR treatment.

Assessment of Global Lung Function Initiative (GLI) reference equations for diffusing capacity in relation to respiratory burden in the Swedish CArdioPulmonary bioImage Study (SCAPIS)

The Global Lung Function Initiative (GLI) has recently published international reference values for diffusing capacity of the lung for carbon monoxide (D _LCO). Lower limit of normal (LLN), i.e. the 5th percentile, usually defines impaired D _LCO We examined if the GLI LLN for D _LCO differs from the LLN in a Swedish population of healthy, never-smoking individuals and how any such differences affect identification of subjects with respiratory burden.Spirometry, D _LCO, chest high-resolution computed tomography (HRCT) and questionnaires were obtained from the first 15 040 participants, aged 50-64 years, of the Swedish CArdioPulmonary bioImage Study (SCAPIS). Both GLI reference values and the lambda-mu-sigma (LMS) method were used to define the LLN in asymptomatic never-smokers without respiratory disease (n=4903, of which 2329 were women).Both the median and LLN for D _LCO from SCAPIS were above the median and LLN from the GLI (p<0.05). The prevalence of D _LCO <GLI LLN (and also <SCAPIS LLN) was 3.9%, while the prevalence of D _LCO >GLI LLN but <SCAPIS LLN was 5.7%. Subjects with D _LCO >GLI LLN but <SCAPIS LLN (n=860) had more emphysema (14.3% versus 4.5%, p<0.001), chronic airflow limitation (8.5% versus 3.9%, p<0.001) and chronic bronchitis (8.3% versus 4.4%, p<0.01) than subjects (n=13 600) with normal D _LCO (>GLI LLN and >SCAPIS LLN). No differences were found with regard to physician-diagnosed asthma.The GLI LLN for D _LCO is lower than the estimated LLN in healthy, never-smoking, middle-aged Swedish adults. Individuals with D _LCO above the GLI LLN but below the SCAPIS LLN had, to a larger extent, an increased respiratory burden. This suggests clinical implications for choosing an adequate LLN for studied populations.

Chronic Obstructive Pulmonary Disease and Lung Transplantation

Lung transplantation (LTx) has been a viable option for patients with end-stage chronic obstructive pulmonary disease (COPD), with more than 20,000 procedures performed worldwide. Survival after LTx lags behind most other forms of solid-organ transplantation, with median survival for COPD recipients being a sobering 6.0 years. Given the limited supply of suitable donor organs, not all patients with end-stage COPD are candidates for LTx. We discuss appropriate criteria for accepting patients for LTx, as well as contraindications and exclusionary criteria. In the first year post-LTx, infection and graft failure are the leading causes of death. Beyond this chronic graft rejection-currently referred to as chronic lung allograft dysfunction-represents the leading cause of death at all time points, with infection and over time malignancy also limiting survival. Referral of COPD patients to a lung transplant center should be considered in the presence of progressing disease despite maximal medical therapy. As a rule of thumb, a forced expiratory volume in 1 second < 25% predicted in the absence of exacerbation, hypoxia (PaO₂ < 60 mm Hg/8 kPa), and/or hypercapnia (PaCO₂ > 50 mm Hg/6.6 kPa) and satisfactory general clinical condition should be considered the basic prerequisites for timely referral. We also discuss salient issues post-LTx and factors that impact posttransplant survival and morbidity such as infections, malignancy, renal insufficiency, and complications associated with long-term immunosuppression.

The effect of comorbidity severity on pulmonary rehabilitation outcomes in chronic obstructive pulmonary disease patients

CLINICAL TRIAL NUMBER

NCT03319108.

Ultrasonographic assessment of skeletal muscle mass and diaphragm function in patients with chronic obstructive pulmonary disease: A case-control study

BACKGROUND

Although muscle dysfunction is a major contributor to morbidity in chronic obstructive pulmonary disease (COPD), assessment of skeletal muscle, and diaphragm function is not routinely performed in COPD patients.

OBJECTIVES

(1) The aim is to assess muscle dysfunction in COPD by measuring the zone of apposition of diaphragm, diaphragm excursion, thickness of diaphragm, and rectus femoris cross-sectional area (RFCSA) with ultrasonography.(2) To correlate the above assessments with spirometric parameters; notably forced expiratory volume in 1 s (FEV₁).

METHODS

Twenty-four consecutive stable COPD patients and 18 controls were included after obtaining written informed consent. Demographic and clinical data, spirometric values, 6-min walk distance, and sonographic parameters mentioned above were compiled for the analysis.

RESULTS

All included participants were male with a mean age of 62.5 ± 8.4 years. The mean FEV₁in cases was 1.12 ± 0.4 L versus 2.41 ± 0.5 L in controls. The diaphragm thickness (1.8 ± 0.5 mm vs. 2.2 ± 0.6 mm;P = 0.005) and RFCSA was significantly lower in COPD patients (4.8 ± 1.3 cm^[2] vs. 6.12 ± 1.2 cm^[2];P = 0.02). However, diaphragm excursion (5.35 ± 2.8 cm vs. 7 ± 2.6 cm) although lower in COPD patients, was not significantly different between the groups. Correlation between FEV₁and ultrasound diaphragm measurements and RFCSA by Spearman's Rho correlation was poor (ρ= 0.2).

CONCLUSION

Ultrasonographic assessment of the diaphragm and rectus femoris can be used as markers to assess skeletal muscle dysfunction in COPD as diaphragmatic function and RFCSA were lower in COPD patients.

Cardiopulmonary exercise testing in chronic obstructive pulmonary disease: An update on its clinical value and applications

Chronic obstructive pulmonary disease is a debilitating disorder, characterized by airflow limitation, exercise impairment, reduced functional capacity and significant systemic comorbidity, which complicates the course of the disease. The critical inspiratory constraint to tidal volume expansion during exercise (that may be further complicated by the presence of dynamic hyperinflation), abnormalities in oxygen transportation and gas exchange abnormalities are the major pathophysiological mechanisms of exercise intolerance in COPD patients, and thus, exercise testing has been traditionally used for the functional evaluation of these patients. Compared to various laboratory and field exercise tests, cardiopulmonary exercise testing (CPET) provides a thorough assessment of exercise physiology, involving the integrative respiratory, cardiovascular, muscle and metabolic responses to exercise. This review highlights the clinical utility of CPET in COPD patients, as it provides important information for the determination of the major factors that limit exercise among patients with several comorbidities, allows the assessment of the severity of dynamic hyperinflation, provides valuable prognostic information and can be used to evaluate the response to several therapeutic interventions.

Respiratory surveillance in mineral dust-exposed workers

Recently, there has been a worldwide resurgence in pneumoconiosis, or pulmonary fibrosis due to occupational mineral dust exposure. In Queensland, Australia, there has been a re-emergence of coal workers' pneumoconiosis and silicosis. Some coal mining communities have experienced a resurgence of progressive massive fibrosis in the USA and a worldwide epidemic is occurring of accelerated silicosis due to exposure to artificial stone.

These diseases are all preventable and should not be occurring in the 21st century. Best practice prevention includes reduction of exposure to mineral dusts or, ideally, prevention of exposure altogether. However, where dust exposure has occurred, respiratory surveillance can provide a strategy for early disease detection. It is important to identify early signs of occupational lung disease at a stage where intervention may be beneficial, though it must be acknowledged that progression may occur even after cessation of exposure to dusts. Respiratory surveillance should be distinguished from population screening and case finding, which are different methods used for disease investigation and control. Designing an ideal respiratory surveillance programme is challenging, as there is no single test that accurately identifies early disease. Several different respiratory disorders may occur related to the same exposure(s). Physicians organising and interpreting tests used in respiratory surveillance must be aware of the broad range of potential work-related respiratory conditions, complexities in diagnosis, and appropriate interpretation of the exposure history, as well as current management options. A working knowledge of the compensation and medicolegal avenues available to workers in individual jurisdictions is also useful.

Organising and interpreting respiratory surveillance for mineral dust-exposed workers requires specialist knowledge and understanding of the potential range of diseases, as well as a detailed occupational historyhttp://bit.ly/37KXSE4

Endobronchial Valve Treatment in Emphysema Patients with a Very Low DLCO

BACKGROUND

For selected patients with severe emphysema, bronchoscopic lung volume reduction with endobronchial valves (EBV) is recognized as an additional treatment option. In most trials investigating EBV treatment, patients with a very low diffusing capacity (DLCO) were excluded from participation.

OBJECTIVES

Our goal was to investigate whether EBV treatment in patients with emphysema with a very low DLCO is safe and effective.

METHODS

This was a single-center retrospective analysis including patients with emphysema and a DLCO ≤20%pred who underwent EBV treatment. Follow-up was performed 6 months post-treatment. Outcome parameters were compared to a historical matched control group (DLCO >20%pred, matched for sex, age, forced expiratory volume in 1 s [FEV1], and residual volume [RV]).

RESULTS

Twenty patients (80% female, 64 ± 6 years, FEV1 26 ± 6%pred, RV 233 ± 45%pred, DLCO 18 ± 1.6%pred) underwent EBV treatment. At 6 months follow-up, we found a statistically significant improvement in FEV1 (0.08 ± 0.12 L), RV (-0.45 ± 0.95 L), 6-min walking distance (38 ± 65 m), and St. George's Respiratory Questionnaire (-12 ± 13 points). With the exception of FEV1, all exceeded the minimal clinically important difference. The most common serious adverse event was a pneumothorax requiring intervention (15%). There were no significant differences in outcome compared to the DLCO >20%pred control group.

CONCLUSIONS

In this single-center retrospective analysis, we showed statistically significant and clinically relevant improvements in lung function, exercise capacity, and quality of life up to 6 months after EBV treatment in emphysema patients with a DLCO ≤20% (14-20%) of predicted with no increased risk of serious adverse events.

Physical Activity Is Associated with Attenuated Disease Progression in Chronic Obstructive Pulmonary Disease

INTRODUCTION

Chronic obstructive pulmonary disease (COPD) progression is variable and affects several disease domains, including decline in lung function, exercise capacity, muscle strength, and health status as well as changes in body composition. We aimed to assess the longitudinal association of physical activity (PA) with these a priori selected components of disease progression.

METHODS

We studied 114 COPD patients from the PAC-COPD cohort (94% male, mean [SD], 70 yr [8 yr] of age, 54 [16] forced expiratory volume in 1 s % predicted) at baseline and 2.6 yr (0.6 yr) later. Baseline PA was assessed by accelerometry. Multivariable general linear models were built to assess the association between PA and changes in lung function, functional exercise capacity, muscle strength, health status, and body composition. All models were adjusted for confounders and the respective baseline value of each measure.

RESULTS

Per each 1000 steps higher baseline PA, forced expiratory volume in 1 s declined 7 mL less (P < 0.01), forced vital capacity 9 mL less (P = 0.03) and carbon monoxide diffusing capacity 0.10 mL·min·mm Hg less (P = 0.04), while the St George's Respiratory Questionnaire symptom domain deteriorated 0.4 points less (P = 0.03), per year follow-up. Physical activity was not associated with changes in functional exercise capacity, muscle strength, other domains of health status or body composition.

CONCLUSIONS

Higher PA is associated with attenuated decline in lung function and reduced health status (symptoms domain) deterioration in moderate-to-very severe COPD patients.

Chronic Obstructive Pulmonary Disease and the Optimal Timing of Lung Transplantation

Chronic obstructive pulmonary disease (COPD) accounts for the largest proportion of respiratory deaths worldwide and was historically the leading indication for lung transplantation. The success of lung transplantation procedures is measured as survival benefit, calculated as survival with transplantation minus predicted survival without transplantation. In chronic obstructive pulmonary disease, it is difficult to show a clear and consistent survival benefit. Increasing knowledge of the risk factors, phenotypical heterogeneity, systemic manifestations, and their management helps improve our ability to select candidates and list those that will benefit the most from the procedure.

Diffusing Capacity of Carbon Monoxide in Assessment of COPD

BACKGROUND

Diffusing capacity of the lung for carbon monoxide (Dlco) is inconsistently obtained in patients with COPD, and the added benefit of Dlco testing beyond that of more common tools is unknown.

OBJECTIVE

The goal of this study was to determine whether lower Dlco is associated with increased COPD morbidity independent of emphysema assessed via spirometry and CT imaging.

METHODS

Data for 1,806 participants with COPD from the Genetic Epidemiology of COPD (COPDGene) study 5-year visit were analyzed, including pulmonary function testing, quality of life, symptoms, exercise performance, and exacerbation rates. Dlco percent predicted was primarily analyzed as a continuous variable and additionally categorized into four groups: (1) Dlco and FEV₁ > 50% (reference); (2) only Dlco ≤ 50%; (3) only FEV₁ ≤ 50%; and (4) both ≤ 50% predicted. Outcomes were modeled by using multivariable linear and negative binomial regression, including emphysema and FEV₁ percent predicted among other confounders.

RESULTS

In multivariable analyses, every 10% predicted decrease in Dlco was associated with symptoms and quality of life (COPD Assessment Test, 0.53 [P < .001]; St. George's Respiratory Questionnaire, 1.67 [P < .001]; Medical Outcomes Study Short Form 36 Physical Function, -0.89 [P < .001]), exercise performance (6-min walk distance, -45.35 feet; P < .001), and severe exacerbation rate (rate ratio, 1.14; P < .001). When categorized, severe impairment in Dlco alone, FEV₁ alone, or both Dlco and FEV₁ were associated with significantly worse morbidity compared with the reference group (P < .05 for all outcomes).

CONCLUSIONS

Impairment in Dlco was associated with increased COPD symptoms, reduced exercise performance, and severe exacerbation risk even after accounting for spirometry and CT evidence of emphysema. These findings suggest that Dlco should be considered for inclusion in future multidimensional tools assessing COPD.

Changes in ventilation and perfusion following lower lobe endoscopic lung volume reduction (ELVR) with endobronchial valves in severe COPD

BACKGROUND

We have previously reported significant improvements in ventilation and perfusion (VQ) and V/Q matching in the contralateral lung, especially the non-targeted lower zone in patients with severe COPD following upper lobe ELVR with endobronchial valves. However, V/Q changes after lower lobe ELVR have not been described.

METHODS

Seven patients with lower lobe heterogeneous emphysema underwent unilateral lower lobe ELVR at Macquarie University Hospital. Lung function tests, 6-minute walk tests (6MWT), St George's Respiratory Questionnaire (SGRQ) and planar differential VQ scans were performed at baseline and at 1, 3 and 12 months post-ELVR.

RESULTS

Compared to baseline, patients showed significant improvements in FEV1 (0.83 ± 0.09L-0.97 ± 0.12L, p < 0.05), 6MWD (200.33 ± 56.54 m-274.24 ± 48.03 m, p < 0.05) and SGRQ (61.13 ± 5.33-42.86 ± 6.99, p < 0.05) at 3 months after ELVR. This improvement was maintained at 12 months. There was a corresponding significant improvement in the differential ventilation (30.21 ± 3.04%-37.82 ± 3.76%, p < 0.05) and perfusion (31.77 ± 2.53%-35.60 ± 2.58%, p < 0.05) of the contralateral non-targeted upper zone.

CONCLUSIONS

Within the limitations of a small sample size, we have found that in heterogeneous severe COPD patients undergoing ELVR targeting the lower lobes, there are clinical and PFT improvements similar to that reported in ELVR targeting upper lobes. Contralateral improvement in V/Q matching also occurs following lower lobe ELVR with the greatest improvement in the contralateral upper zone, suggesting the contralateral upper lobe should be the least affected lobe if the lower lobe is targeted in ELVR. These findings need to be confirmed in a study with a larger number of patients.

COPD: The Annual Cost-Of-Illness during the Last Two Decades in Italy, and Its Mortality Predictivity Power

Chronic obstructive pulmonary disease (COPD) is a progressive pathological condition characterized by a huge epidemiological and socioeconomic impact worldwide. In Italy, the actual annual cost of COPD was assessed for the first time in 2002: the mean cost per patient per year was €1801 and ranged from €1500 to €3912, depending on COPD severity. In 2008, the mean annual cost per patient was €2723.7, ranging from €1830.6 in mild COPD up to €5451.7 in severe COPD. In 2015, it was €3291, which is 20.8% and 82.7% higher compared to the costs estimated in 2008 and 2002, respectively. In all these studies, the major cost component was direct costs, in particular hospitalization costs due to exacerbations, which corresponded to 59.9% of the total cost and 67.2% of direct costs, respectively. When the annual healthcare expenditure per patient is related to the length of survival by means of the PRO-BODE Index (PBI, which is the implementation of the well-known BODE Index with costs due to annual exacerbations and/or hospitalizations), the annual cost of care proved much more strictly and inversely proportional to patients' survival at three years, with the highest regression coefficient (r = -0.58) of all the multidimensional indices presently available, including the BODE Index (r = -021). In Italy, even though tobacco smoking has progressively declined by up to 21% in the general population, the economic impact of COPD has shown relentless progression over the last two decades, confirming that the present national health system organization is still insufficient for facing the issue of chronic diseases, in particular COPD, effectively. The periodic assessment of costs is an effective instrument for care providers in predicting COPD mortality, and for decision makers for updating and planning their social, economic, and political strategies.

Cost-effectiveness of physical activity in the management of COPD patients in the UK

Background

While the Global Initiative for Chronic Obstructive Lung Disease (GOLD) guidelines advise exercise to reduce disease progression, little investment in promoting physical activity (PA) is made by health care authorities. The purpose of this study was to estimate the cost-effectiveness of regular PA vs sedentary lifestyle in people with COPD in the UK.

Methods

Efficacy, quality of life, and economic evidence on the PA effects in COPD patients were retrieved from literature to serve as input for a Markov microsimulation model comparing a COPD population performing PA vs a COPD population with sedentary lifestyle. The GOLD classification defined the model health states. For the base case, the cost of PA was estimated at zero, a lifetime horizon was used, and costs and effects were discounted at 3.5%. Analyses were performed from the UK National Health Service (NHS) perspective. Uncertainty around inputs and assumptions were explored via scenario and sensitivity analyses, including a cost threshold analysis. Outcomes were cost/quality-adjusted life year (QALY) gained and cost/year gained.

Results

Based on our model, the effects of PA in the UK COPD population would be lower mortality (−6%), fewer hospitalizations (−2%), gains in years (+0.82) and QALYs (+0.66), and total cost savings of £2,568. The cost/QALY and cost/year gained were dominant. PA was cost-saving at costs <£35/month and cost-effective at cost <£202/month. The main model drivers were age and PA impact on death and hospital-treated exacerbations.

Conclusion

Including PA in the management of COPD leads to long-term clinical benefits. If the NHS promotes only exercise via medical advice, this would lead to health care cost savings. If the NHS chose to fund PA, it would still likely be cost-effective.

Airflow limitation more than doubles the risk for hospitalization/mortality in patients with heart failure

BACKGROUND

Comorbid chronic obstructive pulmonary disease is found in approximately one-third of patients with heart failure. Survival in patients with chronic obstructive pulmonary disease generally decreases as lung function declines. However, the association between lung function, hospitalization and survival is less clear for patients with heart failure.

AIM

The purpose of this study was to determine the predictive power of spirometry measures for event-free survival (combined all-cause hospitalization and/or mortality) in patients with heart failure.

METHODS

In this secondary analysis of data from three prospective, longitudinal studies, we selected patients with a confirmed diagnosis of heart failure who completed airflow limitation assessment using spirometry measures ( n=137): forced vital capacity, forced expiratory volume/second, and forced expiratory volume/second/forced vital capacity. Cox proportional hazards modeling was used to determine the relationship between spirometry and all-cause hospitalization/mortality with and without adjusting for demographic and clinical covariates over a four-year follow-up period.

RESULTS

A majority (74%) exhibited some degree of airflow limitation (forced expiratory volume/second<80% predicted value) and 26 (19%) met the spirometric criterion for chronic obstructive pulmonary disease (forced expiratory volume/second/forced vital capacity⩽0.70). Cox proportional hazards regression models compared all-cause hospitalization/mortality between those with and without airflow limitation. Patients with airflow limitation were 2.2 times more likely to be hospitalized or die compared to those without airflow limitations (hazard ratio: 2.20, 95% confidence interval 1.06-4.53, p=0.03).

CONCLUSION

Patients with comorbid heart failure and airflow limitation were at more than double the risk for an event. Spirometric measures may be useful to patients with heart failure, as tailored management of airflow limitation may impact event-free survival.

Reassessing the BODE score as a criterion for listing COPD patients for lung transplantation

BACKGROUND

The BODE score (incorporating body mass index, airflow obstruction, dyspnea and exercise capacity) is used for the timing of listing for lung transplantation (LTx) in COPD, based on survival data from the original BODE cohort. This has limitations, because the original BODE cohort differs from COPD patients who are candidates for LTx and the BODE does not include parameters that may influence survival. Our goal was to assess whether parameters such as age, smoking status and diffusion indices significantly influence survival in the absence of LTx, independently of the BODE.

METHODS

In the present cohort study, the BODE was prospectively assessed in COPD patients followed in a tertiary care hospital with an LTx program. The files of 469 consecutive patients were reviewed for parameters of interest (age, gender, smoking status and diffusing capacity of the lungs for carbon monoxide [DL,CO]) at the time of BODE assessment, as well as for survival status. Their influence on survival independent of the BODE score was assessed, as well as their ability to predict survival in patients aged less than 65 years.

RESULTS

A Cox regression model showed that the BODE score, age and DL,CO were independently related to survival (P-values <0.001), as opposed to smoking status. Survival was better in patients aged less than 65 in the first (P=0.004), third (P=0.002) and fourth BODE quartiles (P=0.008). The difference did not reach significance in the second quartile (P=0.13). Median survival for patients aged less than 65 in the fourth BODE quartile was 55 months. According to a receiver operating characteristic curve analysis, the BODE score as well as FEV1 and DL,CO fared similarly in predicting survival status at 5 years in patients aged less than 65 years.

CONCLUSION

Age and DL,CO add to the BODE score to predict survival in COPD. Assessing survival using tools tested in cohorts of patients younger than 65 years is warranted for improving the listing of patients for LTx.

The respiratory physiome: Clustering based on a comprehensive lung function assessment in patients with COPD

Background

While spirometry and particularly airflow limitation is still considered as an important tool in therapeutic decision making, it poorly reflects the heterogeneity of respiratory impairment in chronic obstructive pulmonary disease (COPD). The aims of this study were to identify pathophysiological clusters in COPD based on an integrated set of standard lung function attributes and to investigate whether these clusters can predict patient-related outcomes and differ in clinical characteristics.

Methods

Clinically stable COPD patients referred for pulmonary rehabilitation underwent an integrated assessment including clinical characteristics, dyspnea score, exercise performance, mood and health status, and lung function measurements (post-bronchodilator spirometry, body plethysmography, diffusing capacity, mouth pressures and arterial blood gases). Self-organizing maps were used to generate lung function based clusters.

Results

Clustering of lung function attributes of 518 patients with mild to very severe COPD identified seven different lung function clusters. Cluster 1 includes patients with better lung function attributes compared to the other clusters. Airflow limitation is attenuated in clusters 1 to 4 but more pronounced in clusters 5 to 7. Static hyperinflation is more dominant in clusters 5 to 7. A different pattern occurs for carbon monoxide diffusing capacity, mouth pressures and for arterial blood gases. Related to the different lung function profiles, clusters 1 and 4 demonstrate the best functional performance and health status while this is worst for clusters 6 and 7. All clusters show differences in dyspnea score, proportion of men/women, age, number of exacerbations and hospitalizations, proportion of patients using long-term oxygen and number of comorbidities.

Conclusion

Based on an integrated assessment of lung function variables, seven pathophysiological clusters can be identified in COPD patients. These clusters poorly predict functional performance and health status.

Exercise response to oxygen supplementation is not associated with survival in hypoxemic patients with obstructive lung disease

Purpose

Hypoxemia is associated with more severe lung disease and worse outcomes. In some patients with chronic obstructive lung diseases who desaturate on exertion, supplemental oxygen improves exercise capacity. The clinical significance of this exercise response to oxygen supplementation is not known.

Patients and methods

We identified chronic obstructive lung disease patients at our center who underwent a 6-minute walking test (6MWT) for ambulatory oxygen assessment and who desaturated breathing air and therefore had an additional walk test on supplemental oxygen, between August 2006 and June 2016. Responders were defined as walking ≥26 m further with oxygen. Survival was determined up to February 1, 2017. We compared survival in oxygen responders and nonresponders in patients with obstructive lung diseases.

Results

One hundred and seventy-four patients were included in the study, median age 70 years. Seventy-seven (44.3%) of the patients were oxygen responders. Borg dyspnea score improved by 1.4 (±1.4) units (P<0.0005) on oxygen. Median survival was 66 months with death occurring in 84 (48.2%) patients. Kaplan–Meier analysis revealed no survival difference between both responders and nonresponders (P=0.571). Cox regression analysis showed that more 6MWT desaturation, lower 6-minute walking distance on room air, male gender, lower hemoglobin, and body mass index were associated with higher mortality risk.

Conclusion

Acute exercise response to supplemental oxygen is not associated with long-term survival in patients with obstructive lung disease. This supports the use of ambulatory oxygen treatment for symptomatic purposes only.

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.

The effects of interaction between particulate matter and temperature on mortality in Beijing, China

BACKGROUND

the effects of interaction between temperature and inhalable particulate matter (aerodynamic diameter < 10 μm, PM₁₀) on mortality have been examined in some previous studies, but the results were inconsistent. This study aims to explore whether the effects of PM₁₀ on daily non-accidental, cardiovascular and respiratory mortality were modified by temperature levels in Beijing from 2006 to 2009.

METHODS

we applied a bivariate response surface model and temperature-stratified model based on time-series Poisson generalized additive models (GAMs) to examine the interactive effects in single- and two-pollutant models. The modification of age and gender was examined in subgroup analyses.

RESULTS

the median of temperature (15.9 °C) and visualized turning point (20 °C) were chosen as cut-offs to define the temperature strata as two levels (low and high). Results showed that the effect estimates of PM₁₀ were stronger at the high temperature level for non-accidental, cardiovascular and respiratory mortality than at the low temperature level. When controlling the moving average lag of temperature for 14 days, the effect estimates per 10 μg m^-3 increase in PM₁₀ for non-accidental, cardiovascular and respiratory mortality increased 0.14% (95% CI: 0.05, 0.22), 0.12% (95% CI: 0.02, 0.23) and 0.14% (95% CI: -0.06, 0.34) when the temperature was low and 0.24% (95% CI: 0.12, 0.35), 0.17% (95% CI: 0.01, 0.34) and 0.45% (95% CI: 0.13, 0.78) at the high temperature level, respectively. In the two-pollutant model, the effects of PM₁₀ were attenuated at both high and low temperatures at all lags after adjusting SO₂ and NO₂. The PM₁₀ effects were stronger at the high temperature level for females and elderly people (≥65 years old).

CONCLUSION

the findings suggest that daily mortality attributed to PM₁₀ might be modified by temperature. The interaction between air pollution and global climate change has potential strategy and policy implications.