Treatment Trials in Young Patients with Chronic Obstructive Pulmonary Disease and Pre-Chronic Obstructive Pulmonary Disease Patients: Time to Move Forward

Epidemiological trends and risk factors of chronic obstructive pulmonary disease in young individuals based on the 2021 global burden of disease data (1990-2021)

OBJECTIVE

Recent studies have shown that chronic obstructive pulmonary disease (COPD) in young individuals cannot be ignored. This study aims to investigate the burden of COPD and its associated risk factors in individuals aged 15 to 49 years, with a particular focus on health inequities across different levels of socioeconomic development.

METHODS

By analyzing data from the Global Burden of Disease (GBD) 2021, we utilized statistical methods such as Joinpoint regression, frontier analysis, and health inequality analysis to evaluate the changes in the age-standardized disability-adjusted life year (DALY) rates (ASDR) and incidence rates (ASIR) of COPD among the global population aged 15-49 years from 1990 to 2021. We specifically examined the disparities in health across countries and regions with varying levels of socioeconomic development. Key risk factors, including particulate matter pollution, smoking, and occupational exposure, were analyzed.

RESULTS

The number of COPD cases among young people globally has significantly increased.While the global ASDR and ASIR of COPD in the 15-49 age group showed an overall declining trend, the burden of COPD remained high in low Sociodemographic Index (SDI) regions and there were significant health inequalities between countries. Particulate matter pollution (41.79%), smoking (19.81%), and occupational exposure (11.73%) were identified as the primary contributors to the burden of COPD in younger individuals. In low SDI regions, particulate matter pollution had a particularly significant impact, accounting for 58.65% of attributable proportion of DALYs, and remained at a persistently high level. Smoking continued to contribute significantly to the burden of COPD in high-income regions, notably in North America, where smoking accounted for 34.26% of DALYs in 2021.

CONCLUSION

Although there is a global downward trend in the burden of COPD among young people, significant health inequities persist in low SDI regions. The findings emphasize the need for more effective public health activities targeting younger populations and low SDI countries and regions, particularly in improving air quality, reducing smoking, and mitigating occupational exposures.

CLINICAL TRIAL NUMBER

Not applicable.

The Causal Relationship Between Gut and Skin Microbiota and Chronic Obstructive Pulmonary Disease:A Bidirectional Two-Sample Mendelian Randomization Analysis

Background

Recently, numerous studies have explored the potential impact of gut microbiota on Chronic Obstructive Pulmonary Disease (COPD). However, the causal relationship between skin microbiota and COPD, as well as the differences and similarities between the relationships of gut microbiota and COPD, has not been thoroughly studied.

Methods

We conducted a comprehensive two-sample Mendelian randomization (MR) analysis to investigate the relationships between gut and skin microbiota and COPD. The inverse variance weighted (IVW) method was used as the primary approach. MR-Egger, weighted median, and MR-PRESSO methods were used as supplementary approaches. Various sensitivity and stability analyses were conducted to validate the results. Genetic variations of gut microbiota were obtained from the FR02 cohort study. Genetic variations of skin microbiota were derived from the KORA FF4 and PopGen cohorts, with a total of 1,656 skin samples. GWAS data for COPD were obtained from the FinnGen consortium, including 18,266 COPD cases and 311,286 controls from European cohorts.

Results

The results of IVW method of MR analysis showed that 10 gut microbiotas and 4 skin microbiotas were negatively associated with COPD [p < 0.05, odds ratio (OR) < 1]; 3 gut microbiotas and 6 skin microbiotas were positively associated with COPD (p < 0.05, OR > 1). None of them were heterogeneous or horizontally pleiotropic (p > 0.05) or reverse causality.

Conclusion

This study revealed the causal relationships between gut and skin microbiota and COPD, offering fresh perspectives for the prevention, diagnosis, and management of COPD.

Paradigm shift in early detection: Lung cancer screening to comprehensive CT screening

Large-scale lung cancer screening implementation combined with improvements in early detection techniques for three major tobacco-related diseases presents a rare opportunity to markedly improve population health outcomes for millions of people. Chest CT enables routine detection of early lung cancer as well as characterizing coronary calcium and detecting early emphysema in the course of lung cancer screening. Integrated preventive care centered on comprehensive chest CT screening has the potential to bring large benefits across co-morbid diseases with a common etiology. The current one-disease/ silo paradigm of medical practice is an obstacle to maximizing chest CT screening's benefits. The large potential for improved health outcomes across the world demands careful public health, quality assurance, and health policy considerations. A systematic analysis of imaging and health data from ongoing chest CT screening could accelerate this paradigm shift through sustained optimization of screening detection, quantitation and management for the three most lethal tobacco-related co-morbidities. To coordinate this effort to advance progress with implementing the full benefit of comprehensive chest CT screening, a new multi- disciplinary professional and advocacy consortium has been developed to foster collaboration to realize the future of multi-disease chest CT screening.

Efficacy of nutrient supplements in managing malnutrition and sarcopenia in Chronic Obstructive Pulmonary Disease (COPD) patients: a protocol for systematic review and meta-analysis

BACKGROUND

COPD patients suffering from malnutrition or sarcopenia often incur higher healthcare costs and experience adverse clinical outcomes. Despite this, the effectiveness of nutrient supplements in this population remains uncertain.

METHODS AND ANALYSIS

Two reviewers will independently search seven databases-PubMed, Embase, Web of Science, China National Knowledge Infrastructure, Wanfang, Chinese Biomedical Literature Database, and the Cochrane Library-for randomized controlled trials (RCTs) published before August 31, 2024. These RCTs should compare the effects of nutrient supplements against either a standard diet or placebo supplements in patients with COPD. The risk of bias in the included studies will be evaluated using the modified Jadad scale and the Cochrane Collaboration's risk of bias tool. Data synthesis will be conducted using RevMan software. Trial sequential analysis (TSA) will be applied to the primary outcomes. Additionally, subgroup and sensitivity analyses will be performed to assess the robustness of the findings.

ETHICS AND DISSEMINATION

Ethical approval is not required because this study is a secondary analysis of existing data. We will disseminate the findings through peer- reviewed publications.

SYSTEMATIC REVIEW REGISTRATION

CRD42024585694.

STRENGTHS AND LIMITATIONS OF THIS STUDY

This systematic review and meta-analysis provides a thorough assessment of the efficacy of nutrient supplements in COPD patients, covering a wide range of studies. ·The use of the modified Jadad scale and the Cochrane Collaboration's risk of bias tool ensures a robust evaluation of study quality. Additionally, trial sequential analysis and subgroup analyses are employed to enhance the robustness of the findings. ·The credibility of the evidence may be compromised due to the potential for uncertain study quality and limited sample sizes in some included trials.

AI integrations with lung cancer screening: Considerations in developing AI in a public health setting

Lung cancer screening implementation has led to expanded imaging of the chest in older, tobacco-exposed populations. Growing numbers of screening cases are also found to have CT-detectable emphysema or elevated levels of coronary calcium, indicating the presence of coronary artery disease. Early interventions based on these additional findings, especially with coronary calcium, are emerging and follow established protocols. Given the pace of diagnostic innovation and the potential public health impact, it is timely to review issues in developing useful chest CT screening infrastructure as chest CT screening will soon involve millions of participants worldwide. Lung cancer screening succeeds because it detects curable, early primary lung cancer by characterizing and measuring changes in non-calcified, lung nodules in the size-range from 3mm to 15 mm in diameter. Therefore, close attention to imaging methodology is essential to lung screening success and similar image quality issues are required for reliable quantitative characterization of early emphysema and coronary artery disease. Today's emergence of advanced image analysis using artificial intelligence (AI) is disrupting many aspects of medical imaging including chest CT screening. Given these emerging technological and volume trends, a major concern is how to balance the diverse needs of parties committed to building AI tools for precise, reproducible, and economical chest CT screening, while addressing the public health needs of screening participants receiving this service. A new consortium, the Alliance for Global Implementation of Lung and Cardiac Early Disease Detection and Treatment (AGILEDxRx) is committed to facilitate broad, equitable implementation of multi-disciplinary, high quality chest CT screening using advanced computational tools at accessible cost.

Quantitative CT and COPD: cluster analysis reveals five distinct subtypes with varying exacerbation risks

BACKGROUND

The heterogeneity of chronic obstructive pulmonary disease (COPD) is increasingly recognized. To characterize the heterogeneity of COPD, we aimed to identify subtypes related to quantitative CT by using principal component analysis (PCA) and cluster analysis.

METHODS

The data of 1879 participants in the SPIROMICS study were obtained from the NHLBI Biologic Specimen and Data Repository Information Coordinating Center. A combination of PCA and k-means clustering was used to analyze the data from these participants in the SPIROMICS study. We randomly split the samples into training and validation sets. Clusters were evaluated for their relationship with acute exacerbation risk throughout the entire follow-up period. The results of the training set were confirmed in the validation set. To avoid sampling errors, we conducted 10 random sampling cycles. Normalized mutual information (NMI) was applied in every cycle to evaluate the stability of clustering.

RESULTS

We identified five clusters related to quantitative CT characterized as follows: (1) male-dominated low disease impact cluster, (2) obesity with relatively high symptom burden cluster, (3) airway wall lesion cluster, (4) lung upper region zone-predominant emphysema cluster, (5) severe emphysema cluster. There are significant differences in acute exacerbation risk among these five clusters.

CONCLUSIONS

Cluster analysis identified 5 clusters related to quantitative CT of all participants in the SPIROMICS cohort with significant differences in baseline characteristics and acute exacerbation risk. The stability of clustering results was validated through NMI in 10 sampling cycles. In addition, dimensionality reduction results showed high reproducibility in different studies.

Skeletal Muscle Function in Relation to COPD Severity and Its Predictive Significance for Disease Progression

Purpose

To compare skeletal muscle function levels in different COPD severities and explore their relationship with COPD severity and progression.

Patients and Methods

The study included COPD patients from the First People's Hospital of Shuangliu District, Chengdu between May 2021 and May 2022, categorized into mild, moderate, severe and very severe groups based on FEV1%. Skeletal muscle function (quadriceps strength, respiratory muscle strength, 6MWD) was compared among these groups. Patients were followed up to assess disease progression, and logistic regression was used to analyze the predictive value of skeletal muscle function for COPD progression.

Results

Among the 400 subjects, respiratory muscle strength, quadriceps strength, and 6MWD were all higher in the nonsmoking group than in the smoking group, with the mild group better than the moderate group, the moderate group better than the severe group, males stronger than females, the MMRC score ≤ 2 group better than the >2 group, and strength greater in the age ≤ 70 group than in the age >70 group. The mild group had a higher 6MWD than the moderate group, the moderate group was better than the severe group, non-smokers had a higher 6MWD than smokers, and the difference between males and females was greater with statistical significance. There are differences in quadriceps strength, respiratory strength, and 6MWD within the progression group. Logistic regression analysis showed that respiratory muscle strength, quadriceps strength, 6MWD, and COPD severity were risk factors for COPD progression (P < 0.05).

Conclusion

COPD patients show skeletal muscle dysfunction that worsens with disease severity. Respiratory muscle strength, quadriceps strength, 6MWD, and COPD severity predict COPD prognosis.

Associations between life-course FEV1/FVC trajectories and respiratory symptoms up to middle age: analysis of data from two prospective cohort studies

BACKGROUND

Life-course lung function trajectories leading to airflow obstruction, as measured by impaired FEV1/FVC (forced vital capacity), precede the onset of chronic obstructive pulmonary disease (COPD). We aimed to investigate whether individuals on impaired FEV1/FVC trajectories have an increased burden of respiratory symptoms, including those who do not meet the spirometric criteria for COPD.

METHODS

We analysed serial life-course data from two population-based cohort studies separately, which included respiratory symptoms and spirometry: the Tasmanian Longitudinal Health Study (TAHS, Australia) cohort was recruited at age 6-7 years and followed up until middle age (mean age 53 years; range 51-55); and the Coronary Artery Risk Development in Young Adults (CARDIA, USA) cohort was recruited at a mean age of 25 years (range 18-30) and followed up to a mean age of 55 years (range 47-64). Participants' symptom profiles at ages 53 and 55 years were derived by latent class analysis. Symptom profiles were compared across pre-bronchodilator FEV1/FVC trajectories derived by group-based modelling, then restricted to those without COPD defined by post-bronchodilator airflow obstruction (FEV1/FVC <5th percentile) at ages 51-55 years and 47-64 years.

FINDINGS

Six FEV1/FVC trajectories previously derived for TAHS were replicated in CARDIA. Optimal models identified five symptom profiles in TAHS (n=2421) and six in CARDIA (n=3153). For both cohorts, the most impaired FEV1/FVC trajectory (early low, rapid decline in TAHS; low peak, rapid decline in CARDIA) was associated with predominant wheeze (multinomial odds ratio [mOR] 6·71 [95% CI 4·10-10·90] in TAHS and 9·90 [4·52-21·70] in CARDIA) and nearly all respiratory symptoms (4·95 [2·52-9·74] and 14·80 [5·97-36·60]) at age 51-55 years in TAHS and age 47-64 years in CARDIA, compared with the average trajectory. Among individuals belonging to the three most impaired trajectories, the associations with predominant wheeze increased with worsening FEV1/FVC impairment and persisted when considering only those without spirometry-defined COPD. Additionally, for those belonging to the two rapid decline trajectories, both wheezing and usual phlegm or bronchitis were reported by 54 (20%) of 265 participants younger than 14 years in TAHS and by 31 (25%) of 123 participants aged 30 years or younger in CARDIA.

INTERPRETATION

In two independent cohorts that collected similar data, people on impaired FEV1/FVC trajectories often had a longstanding history of both wheeze and phlegm or bronchitis, and wheeze was the predominant symptom in individuals aged 47-64 years among those who had not already progressed to COPD.

FUNDING

National Health and Medical Research Council (Australia); The University of Melbourne; Clifford Craig Medical Research Trust; Victorian, Queensland & Tasmanian Asthma Foundations; Royal Hobart Hospital Research Foundation; Helen MacPherson Smith Trust; GlaxoSmithKline; National Heart, Lung, and Blood Institute of the US National Institutes of Health.

Preserved ratio impaired spirometry: clinical, imaging and artificial intelligence perspective

Preserved ratio impaired spirometry (PRISm) is a pulmonary function pattern characterized by a forced expiratory volume in one second (FEV1) to forced vital capacity ratio greater than 0.70, with an FEV1 that is below 80% of the predicted value, even after the use of bronchodilators. PRISm is considered a form of "Pre-Chronic Obstructive Pulmonary Disease (Pre-COPD)" within the broader scope of COPD. Clinically, it presents with respiratory symptoms and is more commonly observed in individuals with high body mass index, females, and those who are current smokers. Additionally, it is frequently associated with metabolic disorders and cardiovascular diseases. Regarding prognosis, PRISm shows considerable variation, ranging from improvement in lung function to the development of COPD. In this article, we review the epidemiology, comorbidities, and clinical outcomes of PRISm, with a particular emphasis on the crucial role of imaging assessments, especially computed tomography scans and magnetic resonance imaging (MRI) technology, in diagnosing, evaluating, and predicting the prognosis of PRISm. Comprehensive imaging provides a quantitative evaluation of lung volume, density, airways, and vasculature, while MRI technology can directly quantify ventilation function and pulmonary blood flow. We also emphasize the future potential of X-ray technology in this field. Moreover, the article discusses the application of artificial intelligence, including its role in predicting PRISm subtypes and modeling ventilation function.

Global, regional, and national burden of young COPD, 1990-2021, with forecasts to 2050: a systematic analysis for the global burden of disease study 2021

BACKGROUND

Young chronic obstructive pulmonary disease (COPD) refers to people with COPD between the ages of 20 and 50 years. Current epidemiological studies focus on local geography, and there is a lack of global-level analysis. This study provides in-depth analyses of the disease burden of young COPD at global, regional, and national levels.

METHODS

This study used the Global Burden of Disease Study 2021 (GBD). The age-standardised prevalence rate (ASPR), age-standardised incidence rate (ASIR), age-standardised death rate (ASDR), and age-standardised disability-adjusted life years (DALYs) rate were used to describe the disease burden. The estimated annual percentage change (EAPC) during the study period was calculated. Joinpoint regression analysis examined the time trend from 1990 to 2021. Annual percentage change (APC) and average annual percentage change (AAPC) were calculated. Risk factors were reported by region and sex.

RESULTS

In 2021, the global number of young COPD cases was 30,384,539, and the ASPR, ASIR, ASDR, and age-standardised DALYs rates fell slightly. Oceania reported the highest ASPR, ASDR, and age-standardised DALYs rate. High-income North America has the highest ASIR. In 2021, the prevalence, incidence, death, and DALYs rates exhibited similar trends, increasing with age. From 1990 to 2021, both the prevalence and death rates showed a consistent downward trend across all age groups. Joinpoint regression analysis indicated a slight increase in both the ASPR (APC: 0.13; 95% CI: 0.06 to 0.19) and the ASIR (APC: 0.17; 95% CI: 0.10 to 0.24) during the period from 1990 to 1994. The leading DALYs attributable to risk factors for young COPD are household air pollution from solid fuels (20.4%), ambient particulate matter pollution (17.9%), and smoking (13.5%).

CONCLUSIONS

The global burden of ASPR, ASIR, ASDR, and age-standardised DALYs rates in young COPD has decreased, however, the absolute number of patients has increased. The global burden shows noticeable regional differences, with particularly high burdens observed in Oceania. Improving air quality, promoting smoking cessation, and increasing access to lung function tests, raising awareness of young COPD are key strategies for alleviating the burden of young COPD.

Quantitative assessment of lung structure changes in low-intensity smokers: a retrospective study in a Chinese male cohort

Background

With an increasing number of smokers who consume fewer cigarettes, it is crucial to understand the lung structure changes of low-intensity smoking. This study aimed to investigate the lung structure changes in low-intensity smokers in a Chinese male cohort.

Methods

Chest computed tomography (CT) examinations of 465 asymptomatic healthy male participants were divided into non-smoking (n=256), light-smoking (n=84), intermediate-smoking (n=85), and heavy-smoking (n=40) groups. Low-intensity smokers (fewer than 10 cigarettes per day) were included (n=32), and a new group of non-smokers was generated using propensity score matching according to age. Quantitative CT parameters, including the volume of the intrapulmonary vessel (IPVV), the volume of the lung, mean lung density (MLD), the low-attenuation areas below -910 Hounsfield units (LAA-910), and the volume ratio of intrapulmonary vessel to the lung for the total lung and each lobe were measured. Quantitative CT parameters were compared among the four smoking groups and also between the low-intensity smokers and non-smokers. Binary logistic regression was used to determine the independent quantitative CT measurements of smoking intensity.

Results

Compared with that in non-smokers, the IPVV and the MLD of the total lung and five lobes was significantly higher in light smokers (P<0.05); meanwhile, the LAA-910 of the total lung and five lobes of the light and intermediate smokers were significantly lower (P<0.05). The IPVV of the total lung and five lobes was significantly higher in the low-intensity smoking group (P<0.05). The IPVV of the total lung was the independent factor for discriminating between the non-smokers and light smokers (odds ratio =1.040; 95% confidence interval: 1.027-1.053) and between the non-smokers and low-intensity smokers (odds ratio =1.034; 95% confidence interval: 1.013-1.055).

Conclusions

CT-quantified measurements of the IPVVs and MLD increased in light and intermediate smokers. The IPVV of the total lung was selected as the independent factor between non-smokers and light smokers and between non-smokers and low-intensity smokers.

Contrasting the clinical and biological characteristics of young and old COPD patients

Background

The ECLIPSE study was a large, international, prospective, controlled, observational study that included COPD patients (Global Initiative for Chronic Obstructive Lung Disease (GOLD) grades 2-4), as well as smoking and non-smoking participants with normal spirometry, aged 40-75 years, who were followed-up regularly for 3 years. Here we sought to contrast the clinical and biological characteristics of young COPD versus controls of similar age and older COPD patients included in ECLIPSE.

Methods

We compared 106 young (<50 years) and 488 old (>70 years) COPD patients, as well as 119 young smokers and 92 nonsmoker controls (<50 years) with normal spirometry.

Results

Young COPD patients: 1) were more symptomatic than young controls, often reported a family history of chronic bronchitis, emphysema and asthma, as well as a personal history of asthma and bronchitis, and suffered from a similar disease burden to older patients; 2) were at higher risk of substantial forced expiratory volume in 1 s decline over time; and 3) had reduced serum levels of CC16 (a lung-derived anti-inflammatory protein that relates to lung damage) and, at the same time, reduced pro-inflammatory markers compared to older COPD patients.

Conclusions

Young COPD patients suffer from significant disease burden, display an altered biomarker and disease progression profile reflected by an accelerated risk of lung function decline highlighting the need for early life diagnosis, prevention approaches and treatment.

Prevalence and characteristics of adults with preserved ratio impaired spirometry (PRISm): Data from the BOLD Australia study

Background: Individuals with Preserved Ratio Impaired Spirometry (PRISm), defined as FEV1/FVC ≥0.7 and FEV1 <80% predicted, are at higher risk of developing COPD. However, data for Australian adults are limited. We aimed to describe prevalence of PRISm and its relationship with clinical characteristics in Australia. Method: Data from the Burden of Lung Disease (BOLD) Australia study of randomly selected adults aged ≥40 years from six sites was classified into airflow limitation, PRISm, or normal spirometry groups. Demographic, clinical characteristics, and lung function were compared between groups. Results: Of the study sample (n = 3518), 387 (11%) had PRISm, 549 (15.6%) had airflow limitation, and 2582 (73.4%) had normal spirometry. PRISm was more common in Indigenous Australian adults. Adults with PRISm had more frequent respiratory symptoms, more comorbidities, greater health burden and poorer quality of life than those with normal spirometry. Pre- and post-bronchodilator FEV1 and FVC were lower in adults with PRISm than those with airflow limitation. Adults with PRISm were less likely to use respiratory medicine than those with airflow limitation (OR = 0.56, 95% CI 0.38-0.81). Conclusions: PRISm was present in 11% of adults in this study and they had similar respiratory symptoms and health burden as adults with airflow limitation.

Disease Severity and Activity in Bronchiectasis: A Paradigm Shift in Bronchiectasis Management

Bronchiectasis has an increasing prevalence and substantial clinical and economic burden. Therefore, physicians should identify patients with bronchiectasis at high risk of disease progression to ensure optimal management in advance. The heterogeneity of bronchiectasis means it is unlikely that any single parameter could identify highrisk patients; therefore, disease severity is usually assessed using validated composite tools, such as the Bronchiectasis Severity Index, FACED, and Bronchiectasis Aetiology Comorbidity Index, to predict long-term outcomes in bronchiectasis. Disease severity, however, implies an advanced process with lung destruction. Earlier intervention may prevent disease progression and improve outcomes. To identify patients at risk, rather than patients with established advanced disease, we need to shift our focus from disease severity to disease activity. Disease activity denotes the activation level of underlying pathophysiological processes and can be measured using clinical presentations and biomarkers. This review discusses a paradigm shift in bronchiectasis management, focusing on disease activity rather than severity, to prevent disease progression.

Machine Learning for Enhanced COPD Diagnosis: A Comparative Analysis of Classification Algorithms

Background: In the United States, chronic obstructive pulmonary disease (COPD) is a significant cause of mortality. As far as we know, it is a chronic, inflammatory lung condition that cuts off airflow to the lungs. Many symptoms have been reported for such a disease: breathing problems, coughing, wheezing, and mucus production. Patients with COPD might be at risk, since they are more susceptible to heart disease and lung cancer. Methods: This study reviews COPD diagnosis utilizing various machine learning (ML) classifiers, such as Logistic Regression (LR), Gradient Boosting Classifier (GBC), Support Vector Machine (SVM), Gaussian Naïve Bayes (GNB), Random Forest Classifier (RFC), K-Nearest Neighbors Classifier (KNC), Decision Tree (DT), and Artificial Neural Network (ANN). These models were applied to a dataset comprising 1603 patients after being referred for a pulmonary function test. Results: The RFC has achieved superior accuracy, reaching up to 82.06% in training and 70.47% in testing. Furthermore, it achieved a maximum F score in training and testing with an ROC value of 0.0.82. Conclusions: The results obtained with the utilized ML models align with previous work in the field, with accuracies ranging from 67.81% to 82.06% in training and from 66.73% to 71.46% in testing.

Demographic and Clinical Characteristics of Mild, Young and Early COPD: A Cross-Sectional Analysis of 5468 Patients

Early, mild and young COPD concepts are not clearly defined and are often used interchangeably to refer to the onset of the disease. Objective: To describe and compare the characteristics of mild, young and early COPD in a large sample of COPD from primary and secondary care. Methods: Pooled analysis of individual data from four multicenter observational studies of patients with stable COPD (≥40 years, FEV1/FVC < 0.7, smoking ≥ 10 pack-years). Mild COPD was defined as FEV1% ≥ 65%; young COPD as <55 years; and early COPD as <55 years and smoking ≤ 20 pack-years. The relationship between FEV1(%), age and pack-years was analyzed with linear regression equations. Results: We included 5468 patients. Their mean age was 67 (SD: 9.6) years, and 85% were male. A total of 1158 (21.2%) patients had mild COPD; 636 (11.6%) had young COPD and 191 (3.5%) early COPD. The three groups shared common characteristics: they were more frequently female, younger and with less tobacco exposure compared with the remaining patients. Early COPD had fewer comorbidities and fewer COPD admissions, but no significant differences were found in ambulatory exacerbations. In linear regression analysis, the decline in FEV1(%) was more pronounced for the first 20 pack-years for all age groups and was even more important in younger patients. Conclusions: Mild, young and early COPD patients were more frequently women. The steepest decline in FEV1(%) was observed in individuals <55 years and smoking between 10 and 20 pack-years (early COPD), which highlights the importance of an early detection and implementation of preventive and therapeutic measures.

Occupational Exposure to Charcoal Smoke and Dust, a Major Risk Factor for COPD: A Multiregional Cross-Sectional Study in the Democratic Republic of Congo

BACKGROUND

Occupational exposure to charcoal smoke and dust is a threat to workers' respiratory systems.

RESEARCH QUESTION

What is the prevalence of COPD in charcoal workers compared with that of farmers in rural areas of Democratic Republic of Congo (DRC)?

STUDY DESIGN AND METHODS

This cross-sectional, comparative, and multisite study was performed in the charcoal-producing provinces of southwestern DRC. We randomly included charcoal workers and compared them with farmers (age range, 18-70 years). Air quality indexes, anthropometric features, physical activity, sociodemographic characteristics, and related medical events data were recorded. A lung function questionnaire was used to assess respiratory symptoms and spirometry was performed. COPD was defined as the presence of respiratory symptoms for > 3 months with an FEV1 to FVC ratio less than the lower limit of normal. The prevalence of COPD was calculated, and logistic regression was used to identify COPD-associated factors.

RESULTS

We included 485 participants between August 2020 and July 2021. Charcoal producers (CPs; n = 229) were compared with farmers (n = 118), and charcoal saleswomen (n = 72) were compared with vegetable saleswomen (n = 66). Respective groups were similar in age, job seniority, height, and weight. The air was more polluted at charcoal workplaces. The prevalence of COPD was higher in CPs than in farmers (39.7% vs 14.4%; P < .0001) and higher in charcoal saleswomens compared with vegetable saleswomen (40.3% vs 13.6%; P < .0001). Being a charcoal worker was associated independently with COPD in the CP and farmers groups (adjusted OR, 3.54; 95% CI, 1.94-6.46) and in the saleswomen group (adjusted OR, 7.85; 95% CI, 2.85-21.5), where it was also associated independently with young age (adjusted OR, 0.85; 95% CI, 0.80-0.93) and monthly income (adjusted OR, 0.88; 95% CI, 0.83-0.96).

INTERPRETATION

In rural areas of DRC, producing or selling charcoal is associated with a higher risk of COPD.

Polygenic and transcriptional risk scores identify chronic obstructive pulmonary disease subtypes in the COPDGene and ECLIPSE cohort studies

BACKGROUND

Genetic variants and gene expression predict risk of chronic obstructive pulmonary disease (COPD), but their effect on COPD heterogeneity is unclear. We aimed to define high-risk COPD subtypes using genetics (polygenic risk score, PRS) and blood gene expression (transcriptional risk score, TRS) and assess differences in clinical and molecular characteristics.

METHODS

We defined high-risk groups based on PRS and TRS quantiles by maximising differences in protein biomarkers in a COPDGene training set and identified these groups in COPDGene and ECLIPSE test sets. We tested multivariable associations of subgroups with clinical outcomes and compared protein-protein interaction networks and drug repurposing analyses between high-risk groups.

FINDINGS

We examined two high-risk omics-defined groups in non-overlapping test sets (n = 1133 NHW COPDGene, n = 299 African American (AA) COPDGene, n = 468 ECLIPSE). We defined "high activity" (low PRS, high TRS) and "severe risk" (high PRS, high TRS) subgroups. Participants in both subgroups had lower body-mass index (BMI), lower lung function, and alterations in metabolic, growth, and immune signalling processes compared to a low-risk (low PRS, low TRS) subgroup. "High activity" but not "severe risk" participants had greater prospective FEV1 decline (COPDGene: -51 mL/year; ECLIPSE: -40 mL/year) and proteomic profiles were enriched in gene sets perturbed by treatment with 5-lipoxygenase inhibitors and angiotensin-converting enzyme (ACE) inhibitors.

INTERPRETATION

Concomitant use of polygenic and transcriptional risk scores identified clinical and molecular heterogeneity amongst high-risk individuals. Proteomic and drug repurposing analysis identified subtype-specific enrichment for therapies and suggest prior drug repurposing failures may be explained by patient selection.

FUNDING

National Institutes of Health.

Identification and experimental validation of PYCARD as a crucial PANoptosis-related gene for immune response and inflammation in COPD

Chronic inflammatory and immune responses play key roles in the development and progression of chronic obstructive pulmonary disease (COPD). PANoptosis, as a unique inflammatory cell death modality, is involved in the pathogenesis of many inflammatory diseases. We aim to identify critical PANoptosis-related biomarkers and explore their potential effects on respiratory tract diseases and immune infiltration landscapes in COPD. Total microarray data consisting of peripheral blood and lung tissue datasets associated with COPD were obtained from the GEO database. PANoptosis-associated genes in COPD were identified by intersecting differentially expressed genes (DEGs) with genes involved in pyroptosis, apoptosis, and necroptosis after normalizing and removing the batch effect. Furthermore, GO, KEGG, PPI network, WGCNA, LASSO-COX, and ROC curves analysis were conducted to screen and verify hub genes, and the correlation between PYCARD and infiltrated immune cells was analyzed. The effect of PYCARD on respiratory tract diseases and the potential small-molecule agents for the treatment of COPD were identified. PYCARD expression was verified in the lung tissue of CS/LPS-induced COPD mice. PYCARD was a critical PANoptosis-related gene in all COPD patients. PYCARD was positively related to NOD-like receptor signaling pathway and promoted immune cell infiltration. Moreover, PYCARD was significantly activated in COPD mice mainly by targeting PANoptosis. PANoptosis-related gene PYCARD is a potential biomarker for COPD diagnosis and treatment.

Mechanism underlying the therapeutic effects of effective component compatibility of Bufei Yishen formula III combined with exercise rehabilitation on chronic obstructive pulmonary disease

OBJECTIVE

To explore the mechanism underlying the therapeutic effect of Bufei Yishen Formula III combined with exercise rehabilitation (ECC-BYF III + ER) on chronic obstructive pulmonary disease (COPD) and further identify hub genes.

MATERIALS AND METHODS

Gene Set Enrichment Analysis was used to identify the COPD-associated pathways and reversal pathways after ECC-BYF III + ER treatment. Protein-protein interaction network analysis and cytoHubba were used to identify the hub genes. These genes were verified using independent datasets, molecular docking and quantitative real-time polymerase chain reaction experiment.

RESULTS

Using the high-throughput sequencing data of COPD rats from our laboratory, 49 significantly disturbed pathways were identified in COPD model compared with control group via gene set enrichment analysis (false discovery rate < 0.05). The 34 pathways were reversed after ECC-BYF III + ER treatment. In the 2306 genes of these 34 pathways, 121 of them were differentially expressed in COPD rats compared with control samples. A protein-protein interaction network comprising 111 nodes and 274 edges was created, and 34 candidate genes were identified. Finally, seven COPD hub genes (Il1b, Ccl2, Cxcl1, Apoe, Ccl7, Ccl12, and Ccl4) were well identified and verified in independent COPD rat data from our laboratory and the public dataset GSE178513. The area under the receiver operating characteristic curve values ranged from 0.86 to 1 and from 0.67 to 1, respectively. The reliability of the mentioned genes, which can bind to the active ingredients of ECC-BYF III through molecular docking, were further verified through qRT-PCR experiments.

CONCLUSION

Thirty-four COPD-related pathways and seven hub genes that may be regulated by ECC-BYF III + ER were identified and well verified. The findings of this study may provide insights into the treatment and mechanism underlying COPD.

Assessment of Metabolic Syndrome in Patients with Chronic Obstructive Pulmonary Disease: A 6-Month Follow-Up Study

BACKGROUND/OBJECTIVES

The association between chronic obstructive pulmonary disease (COPD) and metabolic syndrome (MetS) is a common one, with long-term therapeutic and prognostic impact. In view of the high pulmonary and cardiovascular morbidity and mortality, self-management contributes to decreasing the risk of an acute cardiac event or pulmonary decompensation.

METHODS

We conducted a prospective cohort study on 100 patients admitted to Iasi Clinical Rehabilitation Hospital who were divided into two groups according to the presence (67 patients) or absence (33 patients) of MetS. All patients benefited from multidisciplinary counseling sessions on their active role in improving modifiable cardiovascular risk factors and thus increasing quality of life. The aim of this study was to examine the impact of metabolic syndrome on lung function and the role of self-management in a 6-month follow-up period. The demographic, anthropometric, cardiovascular risk factors, and respiratory function were analyzed at baseline and at 6 months.

RESULTS

The presence of MetS was associated with higher fasting blood glucose (p = 0.004) and triglycerides (p = 0.003) but not with higher levels of interleukins or TNF-alpha. At the 6-month follow-up, abdominal circumference, forced expiratory volume in one second (FEV1), dyspnea severity, and blood pressure values improved in male patients with COPD. Systolic and diastolic blood pressure decreased in the COPD group as a whole, but especially in male patients with and without associated MetS. BMI was positively correlated with FEV1 (r = 0.389, p = 0.001) and the FEV1/forced vital capacity (FVC) ratio (r = 0.508, p < 0.001) in all COPD patients and in the MetS subgroup. In the COPD group as a whole. the six-minute walk test (6MWT) results (m) were positively correlated with FEV1 and FVC. The correlation remained significant for FVC in COPD patients with and without MetS. An increase in BMI by one unit led to an increase in TG values by 3.358 mg/dL, and the presence of metabolic syndrome led to an increase in TG values by 17.433 mg/dL.

CONCLUSIONS

In our study, MetS is a common comorbidity in patients with COPD and is associated with higher BMI, fasting glucose, and triglycerides but not with the inflammatory parameters. A mixed pulmonary-cardiovascular rehabilitation intervention leads to improvement in various parameters in both female and male COPD patients.

CT Radiomics Features Predict Change in Lung Density and Rate of Emphysema Progression

Rationale Emphysema progression is heterogeneous. Predicting temporal changes in lung density and detecting rapid progressors may facilitate selection of individuals for targeted therapies. Objective To test whether computed tomography (CT) radiomics can be used to predict changes in lung density and detect rapid progressors. Methods We extracted radiomics features from inspiratory chest CT in 4,575 subjects with and without airflow obstruction at enrollment, who completed a follow-up visit at approximately 5 years. We quantified emphysema using adjusted lung density (ALD) and estimated emphysema progression as the annualized change in ALD (∆ALD/year) between visits. We categorized participants into rapid progressors (>1% ∆ALD/year) and stable disease (≤1% ∆ALD/year). A gradient boosting model was used (1) to predict ALD at 5-years and (2) to identify rapid progressors. Four models using demographics (base clinical model); CT density; radiomics; and combined features (clinical, radiomics, and CT density) were evaluated and tested. Results There were 1,773 (38.8%) rapid progressors. For predicting ALD at 5-years in the 20% held-out data, the base model explained 31% of the variance (adjusted R2 = 0.31) whereas R2 was 0.74 for the CT density model, 0.66 for the radiomics-only model, and 0.77 for the combined features model. For detecting rapid progressors, the base model (AUC = 0.57, 95%CI 0.53-0.61) was outperformed by the radiomics-only model (AUC = 0.73, 95%CI 0.69-0.76, ∆ =0.0003, p < 0.001) and the combined model (AUC = 0.74, 95%CI 0.71-0.77, ∆ = 0.0003, p < 0.001). Conclusions Parenchymal and airway radiomics features derived from inspiratory scans can be used to predict temporal changes in lung density and help identify rapid progressors.

Proteomic biomarkers of long-term lung function decline in textile workers: a 35-year longitudinal study

BACKGROUND

Occupational exposures contribute significantly to obstructive lung disease among textile workers. However, biomarkers associated with such declines are not available.

OBJECTIVES

We conducted a large-scale proteomic study to explore protein biomarkers potentially associated with long-term lung function decline.

METHODS

Shanghai Textile Workers Cohort was established in 1981 with 35 years of follow-up, assessing textile workers' lung functions every five years. Quantitative serum proteomics was performed on all 453 workers at 2016 survey. We employed four distinct models to examine the association between forced expiratory volume in one second (FEV1) and proteins, and consolidated the findings using an aggregated Cauchy association test. Furthermore, proteomic data of UK Biobank (UKB) was used to explore the associations of potential protein markers and decline of FEV1, and the interactions of these proteins were examined through STRING database. Associations were also externally validated using two-sample Mendelian randomizations (MR).

RESULTS

15 of 907 analyzed proteins displayed potential associations with long-term FEV1 decline, including two hemoglobin subunits: hemoglobin subunit beta (HBB, FDR-qACAT = 0.040), alpha globin chain (HBA2, FDR-qACAT = 0.045), and four immunoglobulin subunits: immunoglobulin kappa variable 3-7 (IGKV3-7, FDR-qACAT = 0.003), immunoglobulin heavy chain variable region (IgH, FDR-qACAT = 0.011). Five proteins were significantly associated with the rate of decline of FEV1 in UKB, in which RAB6A, LRRN1, and BSG were also found to be associated with proteins identified in Shanghai Textile Workers Cohort using STRING database. MR indicated bidirectional associations between HBB and FEV1 (P < 0.05), while different immunoglobulin subunits exhibited varying associations with FEV1.

IMPACT STATEMENT

We performed a large-scale proteomic study of the longest-follow-up pulmonary function cohort of textile workers to date. We discovered multiple novel proteins associated with long-term decline of FEV1 that have potential for identifying new biomarkers associated with long-term lung function decline among occupational populations, and may identify individuals at risk, as well as potential pharmaceutical targets for early intervention.

Effect of high-dose N-acetylcysteine on exacerbations and lung function in patients with mild-to-moderate COPD: a double-blind, parallel group, multicentre randomised clinical trial

Evidence for the treatment of patients with mild-to-moderate chronic obstructive pulmonary disease (COPD) is limited. The efficacy of N-acetylcysteine (an antioxidant and mucolytic agent) for patients with mild-to-moderate COPD is uncertain. In this multicentre, randomised, double-blind, placebo-controlled trial, we randomly assigned 968 patients with mild-to-moderate COPD to treatment with N-acetylcysteine (600 mg, twice daily) or matched placebo for two years. Eligible participants were 40-80 years of age and had mild-to-moderate COPD (forced expiratory volume in 1 second [FEV1] to forced vital capacity ratio <0.70 and an FEV1 ≥ 50% predicted value after bronchodilator use). The coprimary outcomes were the annual rate of total exacerbations and the between-group difference in the change from baseline to 24 months in FEV1 before bronchodilator use. COPD exacerbation was defined as the appearance or worsening of at least two major symptoms (cough, expectoration, purulent sputum, wheezing, or dyspnoea) persisting for at least 48 hours. Assessment of exacerbations was conducted every three months, and lung function was performed annually after enrolment. The difference between the N-acetylcysteine group and the placebo group in the annual rate of total exacerbation were not significant (0.65 vs. 0.72 per patient-year; relative risk [RR], 0.90; 95% confidence interval [CI], 0.80-1.02; P = 0.10). There was no significant difference in FEV1 before bronchodilator use at 24 months. Long-term treatment with high-dose N-acetylcysteine neither significantly reduced the annual rate of total exacerbations nor improved lung function in patients with mild-to-moderate COPD. Chinese Clinical Trial Registration: ChiCTR-IIR-17012604.

Design of the SPIROMICS Study of Early COPD Progression: SOURCE Study

Background

The biological mechanisms leading some tobacco-exposed individuals to develop early-stage chronic obstructive pulmonary disease (COPD) are poorly understood. This knowledge gap hampers development of disease-modifying agents for this prevalent condition.

Objectives

Accordingly, with National Heart, Lung and Blood Institute support, we initiated the SubPopulations and InteRmediate Outcome Measures In COPD Study (SPIROMICS) Study of Early COPD Progression (SOURCE), a multicenter observational cohort study of younger individuals with a history of cigarette smoking and thus at-risk for, or with, early-stage COPD. Our overall objectives are to identify those who will develop COPD earlier in life, characterize them thoroughly, and by contrasting them to those not developing COPD, define mechanisms of disease progression.

Methods/Discussion

SOURCE utilizes the established SPIROMICS clinical network. Its goal is to enroll n=649 participants, ages 30-55 years, all races/ethnicities, with ≥10 pack-years cigarette smoking, in either Global initiative for chronic Obstructive Lung Disease (GOLD) groups 0-2 or with preserved ratio-impaired spirometry; and an additional n=40 never-smoker controls. Participants undergo baseline and 3-year follow-up visits, each including high-resolution computed tomography, respiratory oscillometry and spirometry (pre- and postbronchodilator administration), exhaled breath condensate (baseline only), and extensive biospecimen collection, including sputum induction. Symptoms, interim health care utilization, and exacerbations are captured every 6 months via follow-up phone calls. An embedded bronchoscopy substudy involving n=100 participants (including all never-smokers) will allow collection of lower airway samples for genetic, epigenetic, genomic, immunological, microbiome, mucin analyses, and basal cell culture.

Conclusion

SOURCE should provide novel insights into the natural history of lung disease in younger individuals with a smoking history, and its biological basis.

It is high time to discard a cut-off of 0.70 in the diagnosis of COPD

INTRODUCTION

Chronic obstructive pulmonary disease (COPD) has traditionally been diagnosed based on the criterion of an FEV1/FVC <0.70. However, this definition has limitations as it may only detect patients with later-stage disease, when pathologic changes have become irreversible. Consequently, it potentially omits individuals with early-stage disease, in whom the pathologic changes could be delayed or reversed.

AREAS COVERED

This narrative review summarizes recent evidence regarding early-stage COPD, which may not fulfill the spirometric criteria but nonetheless exhibits features of COPD or is at risk of future COPD progression.

EXPERT OPINION

A comprehensive approach, including symptoms assessment, various physiologic tests, and radiologic features, is required to diagnose COPD. This approach is necessary to identify currently underdiagnosed patients and to halt disease progression in at- risk patients.

Susceptible Young Adults and Development of Chronic Obstructive Pulmonary Disease Later in Life

Rationale: Chronic obstructive pulmonary disease (COPD) has its origin in early life, and the Global Initiative for Chronic Obstructive Lung Disease (GOLD) proposes a predisease state termed "pre-COPD." Objectives: We tested the hypothesis that susceptible young adults identified with chronic bronchitis and subtle lung function impairment will develop COPD later in life. Methods: We followed random individuals without COPD ages 20-50 years from two population-based cohorts from different smoking eras-the Copenhagen General Population Study from 2003 (N = 5,497) and the Copenhagen City Heart Study from 1976-1978 (N = 2,609)-for 10 and 25 years, for the development of COPD (FEV1/FVC <0.70) and COPD GOLD Stages 2-4 (additionally, FEV1 <80% predicted). Measurements and Main Results: After 10 years, 28% developed COPD and 13% developed COPD GOLD Stages 2-4 in individuals susceptible to COPD, compared with 8% and 1% in those without any susceptibility to COPD. Correspondingly, after 25 years, 22% versus 13% developed COPD and 20% versus 8% developed COPD GOLD Stages 2-4. More than half of incident COPD cases developed from a susceptible state. Compared with those without susceptibility to COPD, multivariable-adjusted odds ratios in those susceptible to COPD were 3.42 (95% confidence interval: 2.78-4.21) for COPD and 10.1 (6.77-15.2) for COPD GOLD Stages 2-4 after 10 years and were 1.54 (1.23-1.93) and 2.12 (1.64-2.73) after 25 years. The ability of a COPD risk score-consisting of the state of susceptibility to COPD with smoking and asthma as risk factors-to predict COPD later in life was high. Conclusions: Our study suggests the existence of a predisease state of COPD, which can be used for early identification of susceptible individuals at risk for COPD later in life.

Comprehensive appraisal of lung function in young COPD patients: a single center observational study

PURPOSE

The present study aimed to investigate the clinical characteristics and lung function impairment in young people diagnosed with chronic obstructive pulmonary disease (COPD).

PATIENTS AND METHODS

We retrospectively enrolled patients with COPD who underwent symptom assessment and comprehensive pulmonary function tests at the First Affiliated Hospital of Guangzhou Medical University between August 2017 and March 2022. The patients were categorized into two groups based on age: a young COPD group (aged 20-50 years) and an old COPD group (aged > 50 years).

RESULTS

A total of 1282 patients with COPD were included in the study, with 76 young COPD patients and 1206 old COPD patients. Young COPD patients exhibited a higher likelihood of being asymptomatic, lower rates of smoking, and a lower smoking index compared to old COPD patients. Although young COPD patients had higher median post-bronchodilator forced expiratory volume in 1 s (post-BD FEV1) (1.4 vs.1.2 L, P = 0.019), diffusing capacity of the lung for carbon monoxide (DLCO) (7.2 vs. 4.6, P<0.001), and a lower median residual volume to total lung capacity ratio (RV/TLC) compared to their older counterparts, there were no differences observed in severity distribution by GOLD categories or the proportion of lung hyperinflation (RV/TLC%pred > 120%) between two groups. Surprisingly, the prevalence of reduced DLCO was found to be 71.1% in young COPD, although lower than in old COPD (85.2%).

CONCLUSION

Young COPD showed fewer respiratory symptoms, yet displayed a similar severity distribution by GOLD categories. Furthermore, a majority of them demonstrated lung hyperinflation and reduced DLCO. These results underscore the importance of a comprehensive assessment of lung function in young COPD patients.

Risk factors of acute exacerbation and disease progression in young patients with COPD

OBJECTIVE

We aimed to elucidate the clinical factors associated with acute exacerbation and disease progression in young patients with chronic obstructive pulmonary disease (COPD).

METHODS

This retrospective longitudinal observational study included patients with COPD aged between 20 and 50 years with post-bronchodilator forced expiratory volume in one second (FEV1)/forced vital capacity (FVC)<0.7. Eligible patients were followed up with ≥2 spirometry examinations at 1 year interval after COPD diagnosis. The primary outcome was moderate-to-severe acute exacerbation in young patients with COPD. Secondary outcomes were early initiation of regular inhalation therapy and accelerated annual post-bronchodilator FEV1 decline.

RESULTS

A total of 342 patients were followed up during a median of 64 months. In multivariable analyses, risk factors for moderate-to-severe exacerbation were history of asthma (adjusted HR (aHR)=2.999, 95% CI=[2.074-4.335]), emphysema (aHR=1.951, 95% CI=[1.331-2.960]), blood eosinophil count >300/µL (aHR=1.469, 95% CI=[1.038-2.081]) and low FEV1 (%) (aHR=0.979, 95% CI=[0.970-0.987]). A history of asthma, sputum, blood eosinophil count >300/µL, low FEV1 (%) and low diffusing capacity of the lung for carbon monoxide (DLCO) (%) were identified as clinical factors associated with the early initiation of regular inhalation therapy. The risk factors associated with worsened FEV1 decline were increasing age, female sex, history of pulmonary tuberculosis, sputum, low FEV1 (%) and low DLCO (%).

CONCLUSIONS

In young COPD patients, specific high-risk features of acute exacerbation and disease progression need to be identified, including a history of previous respiratory diseases, current respiratory symptoms, blood eosinophil counts, and structural or functional pulmonary impairment.

Treatable traits in pre-COPD: Time to extend the treatable traits paradigm beyond established disease

To date, the treatable traits (TTs) approach has been applied in the context of managing diagnosed diseases. TTs are clinical characteristics and risk factors that can be identified clinically and/or biologically, and that merit treatment if present. There has been an exponential increase in the uptake of this approach by both researchers and clinicians. Realizing the potential of the TTs approach to pre-clinical disease, this expert review proposes that it is timely to consider acting on TTs present before a clinical diagnosis is made, which might help to prevent development of the full disease. Such an approach is ideal for diseases where there is a long pre-clinical phase, such as in chronic obstructive pulmonary disease (COPD). The term 'pre-COPD' has been recently proposed to identify patients with respiratory symptoms and/or structural or functional abnormalities without airflow limitation. They may eventually develop airflow limitation with time but patients with pre-COPD are likely to have traits that are already treatable. This review first outlines the contribution of recently generated knowledge into lifetime lung function trajectories and the conceptual framework of 'GETomics' to the field of pre-COPD. GETomics is a dynamic and cumulative model of interactions between genes and the environment throughout the lifetime that integrates information from multi-omics to understand aetiology and mechanisms of diseases. This review then discusses the current evidence on potential TTs in pre-COPD patients and makes recommendations for practice and future research. At a broader level, this review proposes that introducing the TTs in pre-COPD may help reenergize the preventive approaches to health and diseases.

Can We Use Lung Function Thresholds and Respiratory Symptoms to Identify Pre-Chronic Obstructive Pulmonary Disease? A Prospective, Population-based Cohort Study

Rationale: The term "pre-chronic obstructive pulmonary disease" ("pre-COPD") refers to individuals at high risk of developing COPD who do not meet conventional spirometric criteria for airflow obstruction. New approaches to identifying these individuals are needed, particularly in younger populations. Objectives: To determine whether lung function thresholds and respiratory symptoms can be used to identify individuals at risk of developing COPD. Methods: The Tasmanian Longitudinal Health Study comprises a population-based cohort first studied in 1968 (at age 7 yr). Respiratory symptoms, pre- and post-bronchodilator (BD) spirometry, diffusing capacity, and static lung volumes were measured in a subgroup at age 45, and the incidence of COPD was assessed at age 53. For each lung function measure, z-scores were calculated using Global Lung Function Initiative references. The optimal threshold for best discrimination of COPD incidence was determined by the unweighted Youden index. Measurements and Main Results: Among 801 participants who did not have COPD at age 45, the optimal threshold for COPD incidence by age 53 was pre-BD FEV1/FVC z-score less than -1.264, corresponding to the lowest 10th percentile. Those below this threshold had a 36-fold increased risk of developing COPD over an 8-year follow-up period (risk ratio, 35.8; 95% confidence interval, 8.88 to 144), corresponding to a risk difference of 16.4% (95% confidence interval, 3.7 to 67.4). The sensitivity was 88%, and the specificity was 87%. Positive and negative likelihood ratios were 6.79 and 0.14, respectively. Respiratory symptoms, post-BD spirometry, diffusing capacity, and static lung volumes did not improve on the classification achieved by pre-BD FEV1/FVC alone. Conclusions: This is the first study, to our knowledge, to evaluate the discriminatory accuracy of spirometry, diffusing capacity, and static lung volume thresholds for COPD incidence in middle-aged adults. Our findings support the inclusion of pre-BD spirometry in the physiological definition of pre-COPD and indicate that pre-BD FEV1/FVC at the 10th percentile accurately identifies individuals at high risk of developing COPD in community-based settings.

Polygenic and transcriptional risk scores identify chronic obstructive pulmonary disease subtypes

Rationale

Genetic variants and gene expression predict risk of chronic obstructive pulmonary disease (COPD), but their effect on COPD heterogeneity is unclear.

Objectives

Define high-risk COPD subtypes using both genetics (polygenic risk score, PRS) and blood gene expression (transcriptional risk score, TRS) and assess differences in clinical and molecular characteristics.

Methods

We defined high-risk groups based on PRS and TRS quantiles by maximizing differences in protein biomarkers in a COPDGene training set and identified these groups in COPDGene and ECLIPSE test sets. We tested multivariable associations of subgroups with clinical outcomes and compared protein-protein interaction networks and drug repurposing analyses between high-risk groups.

Measurements and Main Results

We examined two high-risk omics-defined groups in non-overlapping test sets (n=1,133 NHW COPDGene, n=299 African American (AA) COPDGene, n=468 ECLIPSE). We defined "High activity" (low PRS/high TRS) and "severe risk" (high PRS/high TRS) subgroups. Participants in both subgroups had lower body-mass index (BMI), lower lung function, and alterations in metabolic, growth, and immune signaling processes compared to a low-risk (low PRS, low TRS) reference subgroup. "High activity" but not "severe risk" participants had greater prospective FEV 1 decline (COPDGene: -51 mL/year; ECLIPSE: - 40 mL/year) and their proteomic profiles were enriched in gene sets perturbed by treatment with 5-lipoxygenase inhibitors and angiotensin-converting enzyme (ACE) inhibitors.

Conclusions

Concomitant use of polygenic and transcriptional risk scores identified clinical and molecular heterogeneity amongst high-risk individuals. Proteomic and drug repurposing analysis identified subtype-specific enrichment for therapies and suggest prior drug repurposing failures may be explained by patient selection.

Structural Predictors of Lung Function Decline in Young Smokers with Normal Spirometry

Rationale: Chronic obstructive pulmonary disease (COPD) due to tobacco smoking commonly presents when extensive lung damage has occurred. Objectives: We hypothesized that structural change would be detected early in the natural history of COPD and would relate to loss of lung function with time. Methods: We recruited 431 current smokers (median age, 39 yr; 16 pack-years smoked) and recorded symptoms using the COPD Assessment Test (CAT), spirometry, and quantitative thoracic computed tomography (QCT) scans at study entry. These scan results were compared with those from 67 never-smoking control subjects. Three hundred sixty-eight participants were followed every six months with measurement of postbronchodilator spirometry for a median of 32 months. The rate of FEV1 decline, adjusted for current smoking status, age, and sex, was related to the initial QCT appearances and symptoms, measured using the CAT. Measurements and Main Results: There were no material differences in demography or subjective CT appearances between the young smokers and control subjects, but 55.7% of the former had CAT scores greater than 10, and 24.2% reported chronic bronchitis. QCT assessments of disease probability-defined functional small airway disease, ground-glass opacification, bronchovascular prominence, and ratio of small blood vessel volume to total pulmonary vessel volume were increased compared with control subjects and were all associated with a faster FEV1 decline, as was a higher CAT score. Conclusions: Radiological abnormalities on CT are already established in young smokers with normal lung function and are associated with FEV1 loss independently of the impact of symptoms. Structural abnormalities are present early in the natural history of COPD and are markers of disease progression. Clinical trial registered with www.clinicaltrials.gov (NCT03480347).

Heterogeneities and impact profiles of early chronic obstructive pulmonary disease status: findings from the China Pulmonary Health Study

Background

The prevalence, epidemiological and clinical heterogeneities, and impact profiles of individuals with preserved ratio impaired spirometry (PRISm), pre-COPD, young COPD, and mild COPD in general Chinese population were not known yet.

Methods

Data were obtained from the China Pulmonary Health study (2012-2015), a nationally representative cross-sectional survey that recruited 50,991 adults aged 20 years or older. Definitions of the four early disease status were consistent with the latest publications and the Global Initiative for Chronic Obstructive Lung Disease criteria.

Findings

The age-standardised prevalences of PRISm, pre-COPD, young COPD, and mild COPD were 5.5% (95% confidence interval, 4.3-6.9), 7.2% (5.9-8.8), 1.1% (0.7-1.8), and 3.1% (2.5-3.8), respectively. In summary, mild COPD was under more direct or established impact factor exposures, such as older age, male gender, lower education level, lower family income, biomass use, air pollution, and more accumulative cigarette exposures; young COPD and pre-COPD experienced more personal and parents' events in earlier lives, such as history of bronchitis or pneumonia in childhood, frequent chronic cough in childhood, parental history of respiratory diseases, passive smoke exposure in childhood, and mother exposed to passive smoke while pregnant; pre-COPD coexisted with heavier symptoms and comorbidities burdens; young COPD exhibited worse airway obstruction; and most of the four early disease status harbored small airway dysfunction. Overall, older age, male gender, lower education level, living in the urban area, occupational exposure, frequent chronic cough in childhood, more accumulated cigarette exposure, comorbid with cardiovascular disease and gastroesophageal reflux disease were all associated with increased presence of the four early COPD status; different impact profiles were additionally observed with distinct entities. Over the four categories, less than 10% had ever taken pulmonary function test; less than 1% reported a previously diagnosed COPD; and no more than 13% had received pharmaceutical treatment.

Interpretation

Significant heterogeneities in prevalence, epidemiological and clinical features, and impact profiles were noted under varied defining criteria of early COPD; a unified and validated definition for an early disease stage is warranted. Closer attention, better management, and further research need to be administrated to these population.

Funding

Chinese Academy of Medical Sciences Institute of Respiratory Medicine Grant for Young Scholars (No. 2023-ZF-9); China International Medical Foundation (No. Z-2017-24-2301); Chinese Academy of Medical Sciences Innovation Fund for Medical Sciences (No. 2021-I2M-1-049); National High Level Hospital Clinical Research Funding (No. 2022-NHLHCRF-LX-01); Major Program of National Natural Science Foundation of China (No. 82090011).

Small Airway Disease in Pre-Chronic Obstructive Pulmonary Disease with Emphysema: A Cross-Sectional Study

Rationale: Small airway disease is an important pathophysiological feature of chronic obstructive pulmonary disease (COPD). Recently, "pre-COPD" has been put forward as a potential precursor stage of COPD that is defined by abnormal spirometry findings or significant emphysema on computed tomography (CT) in the absence of airflow obstruction. Objective: To determine the degree and nature of (small) airway disease in pre-COPD using microCT in a cohort of explant lobes/lungs. Methods: We collected whole lungs/lung lobes from patients with emphysematous pre-COPD (n = 10); Global Initiative for Chronic Obstructive Lung Disease (GOLD) stage I (n = 6), II (n = 6), and III/IV (n = 7) COPD; and controls (n = 10), which were analyzed using CT and microCT. The degree of emphysema and the number and morphology of small airways were compared between groups, and further correlations were investigated with physiologic measures. Airway and parenchymal pathology was also validated with histopathology. Measurements and Main Results: The numbers of transitional bronchioles and terminal bronchioles per milliliter of lung were significantly lower in pre-COPD and GOLD stages I, II, and III/IV COPD compared with controls. In addition, the number of alveolar attachments of the transitional bronchioles and terminal bronchioles was also lower in pre-COPD and all COPD groups compared with controls. We did not find any differences between the pre-COPD and COPD groups in CT or microCT measures. The percentage of emphysema on CT showed the strongest correlation with the number of small airways in the COPD groups. Histopathology showed an increase in the mean chord length and a decrease in alveolar surface density in pre-COPD and all GOLD COPD stages compared with controls. Conclusions: Lungs of patients with emphysematous pre-COPD already show fewer small airways and airway remodeling even in the absence of physiologic airway obstruction.

Centrilobular emphysema and airway dysanapsis: factors associated with low respiratory function in younger smokers

Background

Low respiratory function in young adulthood is one of the important factors in the trajectory leading to the future development of COPD, but its morphological characteristics are not well characterised.

Methods

We retrospectively enrolled 172 subjects aged 40-49 years with ≥10 pack-years smoking history who underwent lung cancer screening by computed tomography (CT) and spirometry at two Japanese hospitals. Emphysema was visually assessed according to the Fleischner Society guidelines and classified into two types: centrilobular emphysema (CLE) and paraseptal emphysema (PSE). Airway dysanapsis was assessed with the airway/lung ratio (ALR), which was calculated by the geometric mean of the lumen diameters of the 14 branching segments divided by the cube root of total lung volume on a CT scan.

Results

Among the subjects, CLE and PSE were observed in 20.9% and 30.8%, respectively. The mean ALR was 0.04 and did not differ between those with and without each type of emphysema. Multivariable regression analysis models adjusted for age, sex, body mass index and smoking status indicated that CLE and a low ALR were independently associated with lower forced expiratory volume in 1 s (FEV1)/forced vital capacity (estimate -1.64 (95% CI -2.68- -0.60) and 6.73 (95% CI 4.24-9.24), respectively) and FEV1 % pred (estimate -2.81 (95% CI -5.10- -0.52) and 10.9 (95% CI 5.36-16.4), respectively).

Conclusions

CLE and airway dysanapsis on CT were independently associated with low respiratory function in younger smokers.

Plasmonic Alloys Enhanced Metabolic Fingerprints for the Diagnosis of COPD and Exacerbations

Accurate diagnosis of chronic obstructive pulmonary disease (COPD) and exacerbations by metabolic biomarkers enables individualized treatment. Advanced metabolic detection platforms rely on designed materials. Here, we design mesoporous PdPt alloys to characterize metabolic fingerprints for diagnosing COPD and exacerbations. As a result, the optimized PdPt alloys enable the acquisition of metabolic fingerprints within seconds, requiring only 0.5 μL of native plasma by laser desorption/ionization mass spectrometry owing to the enhanced electric field, photothermal conversion, and photocurrent response. Machine learning decodes metabolic profiles acquired from 431 individuals, achieving a precise diagnosis of COPD with an area under the curve (AUC) of 0.904 and an accurate distinction between stable COPD and acute exacerbations of COPD (AECOPD) with an AUC of 0.951. Notably, eight metabolic biomarkers identified accurately discriminate AECOPD from stable COPD while providing valuable information on disease progress. Our platform will offer an advanced nanoplatform for the management of COPD, complementing standard clinical techniques.

Association of non-obstructive dyspnoea with all-cause mortality and incident chronic obstructive pulmonary disease: a systematic literature review and meta-analysis

BACKGROUND

Controversy exists regarding the association between non-obstructive dyspnoea and the future development of chronic obstructive pulmonary disease (COPD) and mortality. Therefore, we aimed to evaluate the association of non-obstructive dyspnoea with mortality and incident COPD in adults.

METHODS

We searched PubMed, Embase, and Web of Science to identify studies published from inception to 13 May 2023. Eligibility screening, data extraction, and quality assessment of the retrieved articles were conducted independently by two reviewers. Studies were included if they were original articles comparing incident COPD and all-cause mortality between individuals with normal lung function with and without dyspnoea. The primary outcomes were incident COPD and all-cause mortality. The secondary outcome was respiratory disease-related mortality. We used the random-effects model to calculate pooled estimates and corresponding 95% confidence interval (CI). Heterogeneity was determined using the I² statistic.

RESULTS

Of 6486 studies, 8 studies involving 100 758 individuals fulfilled the inclusion and exclusion criteria and were included in the study. Compared with individuals without non-obstructive dyspnoea, individuals with non-obstructive dyspnoea had an increased risk of incident COPD (relative risk: 1.41, 95% CI: 1.08 to 1.83), and moderate heterogeneity was found (p=0.079, I2=52.2%). Individuals with non-obstructive dyspnoea had a higher risk of all-cause mortality (hazard ratio: 1.21, 95% CI: 1.14 to 1.28, I2=0.0%) and respiratory disease-related mortality (hazard ratio: 1.52, 95% CI: 1.14 to 2.02, I2=0.0%) than those without.

CONCLUSIONS

Individuals with non-obstructive dyspnoea are at a higher risk of incident COPD and all-cause mortality than individuals without dyspnoea. Further research should investigate whether these high-risk adults may benefit from risk management and early therapeutic intervention.

PROSPERO REGISTRATION NUMBER

CRD42023395192.

From treatable traits to GETomics in airway disease: moving towards clinical practice

The treatable traits approach represents a strategy for patient management. It is based on the identification of characteristics susceptible to treatments or predictive of treatment response in each individual patient. With the objective of accelerating progress in research and clinical practice relating to such a treatable traits approach, the Portraits event was convened in Barcelona, Spain, in November 2022. Here, while reporting the key concepts that emerged from the discussions during the meeting, we review the current state of the art related to treatable traits and chronic respiratory diseases management, and we describe the possible actions that clinicians can take in clinical practice to implement the treatable traits framework. Furthermore, we explore the new concept of GETomics and the new models of research in the field of COPD.

Global Initiative for Chronic Obstructive Lung Disease (GOLD) 2023 Guidelines Reviewed

The Global Initiative for Chronic Obstructive Lung Disease (GOLD) report is an essential resource for all clinicians who strive to provide optimal care to patients with chronic obstructive lung disease (COPD). The annual report of GOLD makes few revisions and updates besides including data from the preceding year. At an interval, GOLD comes up with a significant modification in its guidelines, which is generally a major overhaul of the pre-existing guidelines. According to the latest 2023 updates, published in November 2022, there have been significant advancements made in the field of COPD. These include the development of more precise definitions for COPD and its exacerbations, the introduction of a new set of parameters to measure exacerbation severity, and updating the COPD assessment tool. Additionally, revisions have been made to the initial and follow-up treatment guidelines. The report also simplifies the treatment algorithm and sheds light on new findings that suggest the use of pharmacological triple therapy can reduce mortality rates. Furthermore, the report includes discussions on inhaler device selection and adherence to COPD medications. These improvements demonstrate a continued effort to enhance COPD treatment and management. Although there are some areas that could benefit from more detailed guidance and explanation, such as the proper utilization of blood eosinophil counts for treatment decisions, and the establishment of treatment protocols post-hospitalization, the latest modifications to the GOLD recommendations will undoubtedly aid healthcare providers in addressing any gaps in patient care. We aim to highlight key changes in the GOLD 2023 report and present a viewpoint about their potential implications in a real-world clinical scenario.

The many faces of COPD in real life: a longitudinal analysis of the NOVELTY cohort

Background

The diagnosis of COPD requires the demonstration of non-fully reversible airflow limitation by spirometry in the appropriate clinical context. Yet, there are patients with symptoms and relevant exposures suggestive of COPD with either normal spirometry (pre-COPD) or preserved ratio but impaired spirometry (PRISm). Their prevalence, clinical characteristics and associated outcomes in a real-life setting are unclear.

Methods

To investigate them, we studied 3183 patients diagnosed with COPD by their attending physician included in the NOVELTY study (clinicaltrials.gov identifier NCT02760329), a global, 3-year, observational, real-life cohort that included patients recruited from both primary and specialist care clinics in 18 countries.

Results

We found that 1) approximately a quarter of patients diagnosed with (and treated for) COPD in real life did not fulfil the spirometric diagnostic criteria recommended by the Global Initiative for Chronic Obstructive Lung Disease (GOLD), and could be instead categorised as pre-COPD (13%) or PRISm (14%); 2) disease burden (symptoms and exacerbations) was highest in GOLD 3-4 patients (exacerbations per person-year (PPY) 0.82) and lower but similar in those in GOLD 1-2, pre-COPD and PRISm (exacerbations range 0.27-0.43 PPY); 3) lung function decline was highest in pre-COPD and GOLD 1-2, and much less pronounced in PRISm and GOLD 3-4; 4) PRISm and pre-COPD were not stable diagnostic categories and change substantially over time; and 5) all-cause mortality was highest in GOLD 3-4, lowest in pre-COPD, and intermediate and similar in GOLD 1-2 and PRISm.

Conclusions

Patients diagnosed COPD in a real-life clinical setting present great diversity in symptom burden, progression and survival, warranting medical attention.

Clinical relevance of lung function trajectory clusters in middle-aged and older adults

Background

The determinants and health outcomes of lung function trajectories in adults among the general population are poorly understood. We aimed to identify and characterise clusters of lung function trajectories in adults aged ≥45 years.

Methods

Gaussian finite-mixture modelling was applied to baseline and annualised change of forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC) and FEV1/FVC ratio z-scores in participants of the Rotterdam Study, a prospective population-based cohort study, with repeated spirometry (n=3884; mean±sd age 64.7±8.9 years). Longitudinal outcomes were all-cause mortality, respiratory outcomes (symptoms, COPD (FEV1/FVC <0.7 in absence of asthma), preserved ratio impaired spirometry (PRISm; FEV1/FVC ≥0.7 and FEV1 or FVC <80%)), smoking cessation and weight changes. Independent risk factors, including genetics, were identified by multiple logistic regression.

Results

We identified eight trajectory clusters, with the reference group having persistently normal spirometry (prevalence 42.8%). Three clusters showed higher mortality, adjusted for confounders: 1) the persistently low FEV1 cluster (prevalence 6.8%, hazard ratio (HR) 1.71, 95% CI 1.37-2.13); 2) rapid FEV1 decliners (prevalence 4.6%, HR 1.48, 95% CI 1.10-1.99); and 3) FVC decliners (prevalence 3.7%, HR 1.49, 95% CI 1.09-2.03). In contrast, FVC improvers (prevalence 6.7%, HR 0.61, 95% CI 0.41-0.90) and persistently high FEV1 (prevalence 29.2%, HR 0.82, 95% CI 0.69-0.98) were protective trajectory clusters. Clusters were characterised by differences in genetic predisposition (polygenic scores of FEV1 and FEV1/FVC), demographics, cigarette smoking, respiratory symptoms (chronic cough, wheezing and dyspnoea), cardiovascular factors (body mass index, hypertension and heart failure) and serum C-reactive protein levels. Frailty, weight changes and the development of respiratory symptoms, COPD and PRISm were significantly associated with trajectory clusters.

Conclusions

This study reveals clinically relevant lung function trajectory clusters in older adults of the general population.

Exploring perceptions and expectations of COPD patients: A grounded theory approach for personalized therapeutic interventions

Objectives: This study aimed to investigate the dynamic patterns of perception and expectations among COPD patients. Methods: Conducted at the Heart-Respiratory Rehabilitation Unit, IRCCS Fondazione Don Carlo Gnocchi, in Milan, Italy, the research involved 28 participants (16 males; mean age 72.8 ± 9.9) in face-to-face interviews. Utilizing a Grounded Theory approach, complemented by clinical data, recorded, and transcribed interviews underwent enhancement through the integration of two pictorial tools. Results: The central theme that emerged was a profound sense of responsibility toward their condition, perceived as a significant threat to life. Key symptoms, such as shortness of breath, coupled with negative expectations about their condition, contributed to depressive mood and avoidance behaviors. A notable proportion (N = 17; 60.71%) of participants struggled to envision a positive future, expressing a pervasive sense of hopelessness, which significantly influenced their health behaviors and adherence to medical recommendations. Conversely, individuals who felt supported and optimistic about treatment efficacy exhibited more positive expectations and adopted proactive coping strategies. Discussion: Recognizing the dynamic nature of patients' perceptions and negative illness expectations is essential to create personalized therapeutic interventions and meet the specific needs of COPD patients, ultimately improving the overall effectiveness of their care journey.

Breathlessness and "exacerbation" questions predictive for incident COPD (MARKO study): data after two years of follow-up

Aims

To determine the predictability of the MARKO questionnaire and/or its domains, individually or in combination with other markers and characteristics (age, gender, smoking history, lung function, 6-min walk test (6 MWT), exhaled breath temperature (EBT), and hsCRP for the incident chronic obstructive pulmonary disease (COPD) in subjects at risk over 2 years follow-up period).

Participants and Methods

Patients, smokers/ex-smokers with >20 pack-years, aged 40-65 years of both sexes were recruited and followed for 2 years. After recruitment and signing the informed consent at the GP, a detailed diagnostic workout was done by the pulmonologist; they completed three self-assessment questionnaires-MARKO, SGRQ and CAT, detailed history and physical, laboratory (CBC, hsCRP), lung function tests with bronchodilator and EBT. At the 2 year follow-up visit they performed: the same three self-assessment questionnaires, history and physical, lung function tests and EBT.

Results

A sample of 320 subjects (41.9% male), mean (SD) age 51.9 (7.4) years with 36.4 (17.4) pack-years of smoking was reassessed after 2.1 years. Exploratory factor analysis of MARKO questionnaire isolated three distinct domains (breathlessness and fatigue, "exacerbations", cough and expectorations). We have determined a rate for incident COPD that was 4.911/100 person-years (95% CI [3.436-6.816]). We found out that questions about breathlessness and "exacerbations", and male sex were predictive of incident COPD after two years follow-up (AUC 0.79, 95% CI [0.74-0.84], p < 0.001). When only active smokers were analyzed a change in EBT after a cigarette (ΔEBT) was added to a previous model (AUC 0.83, 95% CI [0.78-0.88], p < 0.001).

Conclusion

Our preliminary data shows that the MARKO questionnaire combined with EBT (change after a cigarette smoke) could potentially serve as early markers of future COPD in smokers.

Combined effect of ozone and household air pollution on COPD in people aged less than 50 years old

OBJECTIVES

Air pollution has been suggested as an important risk factor for chronic obstructive pulmonary disease (COPD); however, evidence of interactive effects on COPD between different factors was sparse, especially for young adults. We aimed to assess the combined effects of ambient ozone (O3) and household air pollution on COPD in young individuals.

METHODS

We conducted a population-based study of residents aged 15-50 years in the low-income and middle-income regions of western China. We used multivariable logistic regression models to examine the associations between long-term ozone exposure and COPD in young individuals.

RESULTS

A total of 6537 young cases were identified among the participants, with a COPD prevalence rate of 7.8 (95% CI 7.2% to 8.5%), and most young COPD individuals were asymptomatic. Exposure to household air pollution was associated with COPD in young patients after adjustment for other confounding factors (OR 1.82, 95% CI 1.41 to 2.37). We also found positive associations of COPD with O3 per IQR increase of 20 ppb (OR 1.92, 95% CI 1.59 to 2.32). The individual effects of household air pollution and O3 were 1.68 (95% CI 1.18 to 2.46) and 1.55 (95% CI 0.99 to 2.43), respectively, while their joint effect was 3.28 (95% CI 2.35 to 4.69) with the relative excess risk due to interaction of 1.05 (95% CI 0.33 to 1.78).

CONCLUSIONS

This study concludes that exposure to ambient O3 and household air pollution might be important risk factors for COPD among young adults, and simultaneous exposure to high levels of the two pollutants may intensify their individual effects.